WO2015115421A1 - Manufacturing method for semiconductor ceramic composition, semiconductor ceramic composition, ptc element, and heating element module - Google Patents

Manufacturing method for semiconductor ceramic composition, semiconductor ceramic composition, ptc element, and heating element module Download PDF

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WO2015115421A1
WO2015115421A1 PCT/JP2015/052182 JP2015052182W WO2015115421A1 WO 2015115421 A1 WO2015115421 A1 WO 2015115421A1 JP 2015052182 W JP2015052182 W JP 2015052182W WO 2015115421 A1 WO2015115421 A1 WO 2015115421A1
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calcined powder
tio
bia
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bar
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雄太郎 寺門
武司 島田
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日立金属株式会社
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Definitions

  • the present invention relates to a method for manufacturing a semiconductor ceramic composition, a semiconductor ceramic composition, a PTC element, and a heating element module used for heating element modules such as a PTC heater, a PTC thermistor, a PTC switch, and a temperature detector.
  • BaTiO 3 -based semiconductor ceramic compositions have a Curie temperature of around 120 ° C. These semiconductor porcelain compositions need to shift the Curie temperature depending on the application. For example, it has been proposed to shift the Curie temperature by adding SrTiO 3 oxide to BaTiO 3 oxide, but in this case, the Curie temperature is shifted only in the negative direction and in the positive direction. Do not shift.
  • PbTiO 3 is a material that is currently in practical use and is known as an additive that shifts the Curie temperature in the positive direction.
  • lead is an element that causes environmental pollution, a lead-free semiconductor ceramic composition containing no lead is desired.
  • Patent Document 1 discloses a semiconductor ceramic composition in which a part of Ba in BaTiO 3 is replaced with Bi-Na as a lead-free semiconductor ceramic composition.
  • step of preparing (BiNa) TiO 3 calcined powder step of mixing (BaQ) TiO 3 calcined powder and (BiNa) TiO 3 calcined powder, mixing
  • a method for producing a semiconductor porcelain composition including a step of forming and sintering a calcined powder.
  • the (BaQ) TiO 3 composition (Q is a semiconducting element) and the (BiNa) TiO 3 composition are prepared separately, the (BaQ) TiO 3 composition is at a relatively high temperature, and (BiNa) TiO 3 is prepared.
  • the composition is relatively calcined and calcined at the optimum temperature according to each. Thereby, the volatilization of Bi in the (BiNa) TiO 3 composition is suppressed, the composition shift of Bi—Na is prevented, and the generation of heterogeneous phases is suppressed. And, it is described that by mixing, calcining and sintering these calcined powders, a semiconductor ceramic composition having a low room temperature resistivity and a suppressed Curie temperature variation can be obtained (paragraph ( 0013)).
  • the semiconductor ceramic composition having PTC characteristics is desired to have a low resistivity at room temperature (hereinafter referred to as room temperature resistivity ⁇ ) so that power loss is small when used as a PTC element.
  • room temperature resistivity ⁇ room temperature
  • Tc Curie temperature
  • an object of the present invention is to provide a novel manufacturing method capable of adjusting the Curie temperature Tc of the semiconductor ceramic composition to be large and the room temperature resistivity ⁇ to be small. Moreover, it aims at providing the semiconductor ceramic composition, PTC element, and heat generating module which are obtained by the manufacturing method.
  • the present invention provides (BiA) TiO 3 (A is at least one of Na, Li, K) calcined powder and (BaR) [TiM] O 3 (R is at least one of rare earth elements including Y) as raw materials. , M is at least one of Nb, Ta, and Sb, and either R or M is indispensable) is prepared, and (BiA) TiO 3 calcined powder and (BaR) [TiM] A method of manufacturing a semiconductor porcelain composition in which O 3 calcined powder is mixed and then molded and sintered, and the (BiA) TiO 3 calcined powder and (BaR) [TiM] O 3 calcined powder are mixed Before, the BET value of the (BiA) TiO 3 calcined powder is a, the BET value of the (BaR) [TiM] O 3 calcined powder is b, a / b ⁇ 2.0 .
  • the (BiA) TiO 3 calcined powder is subjected to a treatment for increasing the BET value a, and / or Alternatively, the (BaR) [TiM] O 3 calcined powder may be subjected to a treatment for reducing the BET value b.
  • the (BiA) TiO 3 calcined powder is subjected to a treatment for increasing the BET value a, and / or The (BaR) [TiM] O 3 calcined powder may be subjected to a treatment for decreasing the BET value b.
  • (BaR) [TiM] O 3 wherein the calcining temperature of the calcined powder (BIA) TiO 3 calcined powder was higher than the calcination temperature, the (BaR) [TiM] O 3 Average grain calcined powder The diameter may be larger than the average particle diameter of the (BiA) TiO 3 calcined powder, and the BET value may be a / b ⁇ 2.0.
  • the (BiA) TiO 3 calcined powder is pulverized to give the (BiA) TiO 3 calcined powder.
  • the BET value a of the powder may be increased.
  • the BET value a is preferably 1.0 m 2 / g or more and 30 m 2 / g or less.
  • the BET value b is preferably 0.1 m 2 / g or more and 15 m 2 / g or less.
  • the semiconductor ceramic composition has a composition formula [(BiA) x (Ba 1-y R y ) 1-x ] [Ti 1-z M z ] O 3 (A is at least one of Na, Li, and K).
  • R is represented by at least one of rare earth elements including Y
  • M is represented by at least one of Nb, Ta, and Sb
  • x, y, and z are 0 ⁇ x ⁇ 0.2, 0 ⁇ y ⁇ 0.05, It is preferable that 0 ⁇ z ⁇ 0.01 (where y + z> 0) is satisfied.
  • the sintering is preferably performed at 1300 ° C. or higher and 1450 ° C. or lower.
  • a semiconductor ceramic composition can be obtained by the above production method.
  • an electrode can be formed on this semiconductor ceramic composition to obtain a PTC element.
  • it can be set as a heat generating body module using this PTC element.
  • the present invention it is possible to provide a novel manufacturing method capable of adjusting the Curie temperature Tc of the semiconductor porcelain composition to be large and the room temperature specific resistance ⁇ to be small.
  • the method for producing a semiconductor ceramic composition of the present invention is such that the average particle diameter of the (BiA) TiO 3 calcined powder is smaller than the average particle diameter of the (BaR) [TiM] O 3 calcined powder by a predetermined value or more. Specifically by the so the difference more than twice the ratio of the BET value, after mixing when sintering (1300 ° C. or higher 1450 ° C. or less) (BaR) [TiM] O 3 in calcined powder ( BiA) TiO 3 calcined powder is easily dissolved, and (BiA) TiO 3 calcined powder suppresses the volatilization of Bi. As a result, the Curie temperature Tc of the semiconductor ceramic composition is increased, and the room temperature resistivity ⁇ Can be adjusted small.
  • the value of a / b is preferably 5 or more, and more preferably 10 or more.
  • the upper limit of a / b is not particularly limited, but a / b ⁇ 50 is preferable.
  • a / b exceeds 50, that is, when the BET value a of (BiA) TiO 3 calcined powder increases or the BET value b of (BaR) [TiM] O 3 calcined powder decreases.
  • the BET value a of the (BiA) TiO 3 calcined powder is too large, the pulverization time of the (BiA) TiO 3 calcined powder becomes longer, or the (BiA) TiO 3 calcined powder aggregates and the reactivity deteriorates.
  • Curie temperature Tc tends to be small because it is difficult to dissolve in (BaR) [TiM] O 3 calcined powder. If the BET value b of the (BaR) [TiM] O 3 calcined powder is too small, the particle size of the (BaR) [TiM] O 3 calcined powder is large, so that (BiA) TiO 3 calcined during sintering It becomes difficult to form a solid solution with the powder, and the room temperature resistivity ⁇ tends to increase.
  • the BET value is obtained by adsorbing molecules (usually N 2 gas) whose surface area is known on the surface of the powder particles, and obtaining the specific surface area of the powder particles from the amount of the molecules.
  • the specific surface area is obtained by measuring the unimolecular adsorption amount vm by the BET equation (Brunauer, Emmet and Teller's equation) from the relationship of the amount v.
  • a specific surface area measuring device Macsorb, manufactured by Mountec Co., Ltd.
  • the means for adjusting the BET values of the (BiA) TiO 3 calcined powder and the (BaR) [TiM] O 3 calcined powder is not particularly limited, but the following method can be applied.
  • the obtained (BiA) TiO 3 calcined powder is pulverized by a known means such as a ball mill, and the average particle size is reduced (BET value a is increased) relative to (BaR) [TiM] O 3 calcined powder. ) Method can be adopted.
  • (BiA) TiO 3 calcined powder is subjected to a treatment for increasing the BET value a, and / or The (BaR) [TiM] O 3 calcined powder may be subjected to a treatment for reducing the BET value b.
  • (BaR) [TiM] O 3 calcining temperature of calcined powder (BIA) TiO 3 calcined powder was higher than the calcination temperature, (BaR) [TiM]
  • the average particle size of O 3 calcined powder Can be made larger than the average particle diameter of the (BiA) TiO 3 calcined powder, and the BET value can be a / b ⁇ 2.0.
  • the time of calcining of (BaR) [TiM] O 3 calcined powder is lengthened and the average particle diameter of (BaR) [TiM] O 3 calcined powder is changed to the average particle diameter of (BiA) TiO 3 calcined powder. Can be larger.
  • (BiA) TiO 3 calcined powder is subjected to a treatment to increase the BET value a, and / or , (BaR) [TiM] O 3 calcined powder may be subjected to a treatment for decreasing the BET value b.
  • the BET value a of the baked powder can be increased.
  • the (BaR) [TiM] O 3 calcined powder can be heat treated again to reduce the BET value b of the (BaR) [TiM] O 3 calcined powder.
  • the BET value a of the (BiA) TiO 3 calcined powder is preferably 1.0 m 2 / g or more and 30 m 2 / g or less.
  • the BET value a is less than 1.0 m 2 / g, the average particle size of the (BiA) TiO 3 calcined powder is large, so that (BaR) [TiM] O 3 calcined powder (BiA)
  • the TiO 3 calcined powder is not easily dissolved, and the Curie temperature Tc tends to decrease.
  • the BET value a exceeds 30 m 2 / g, problems such as longer grinding time appear.
  • (BiA) TiO 3 calcined powder is agglomerated and the reactivity deteriorates, and (BiA) TiO 3 calcined powder is difficult to dissolve in (BaR) [TiM] O 3 calcined powder.
  • Curie temperature Tc tends to decrease.
  • a more preferable range of the BET value a is 1.5 m 2 / g or more and 25 m 2 / g or less.
  • the BET value b of the (BaR) [TiM] O 3 calcined powder is preferably 0.1 m 2 / g or more and 15 m 2 / g or less.
  • the BET value b is less than 0.1 m 2 / g, the particle size of the (BaR) [TiM] O 3 calcined powder is large, so that during sintering, the (BaR) [TiM] O 3 calcined powder is It becomes difficult to form a solid solution with the (BiA) TiO 3 calcined powder, and the room temperature resistivity ⁇ tends to increase.
  • the BET value b exceeds 15 m 2 / g, the crystal grain size of the sintered body becomes small due to the small particle size of the (BaR) [TiM] O 3 calcined powder, and the room temperature specific resistance ⁇ is also large. Prone.
  • a more preferable range of the BET value b is 0.2 m 2 / g or more and 2 m 2 / g or less.
  • step 1 of FIG. 1 before mixing (BiA) TiO 3 calcined powder and (BaR) [TiM] O 3 calcined powder, the BET value of (BiA) TiO 3 calcined powder is set to a, BaR) [TiM] O 3
  • the BET value of the calcined powder is b, and a / b ⁇ 2.0.
  • This step may include a step of preparing (BiA) TiO 3 calcined powder and a step of preparing (BaR) [TiM] O 3 calcined powder.
  • a manufacturing process including a step of providing a step, and (BaR) [TiM] O 3 calcined powder to prepare (BIA) TiO 3 calcined powder.
  • (BiA) TiO 3 (A is at least one of Na, Li, and K) calcined powder and (BaR) [TiM] O 3 (R is at least one of rare earth elements including Y, M is Nb, Prepare at least one of Ta and Sb, and either R or M is essential).
  • (BiA) TiO 3 calcined powder As raw materials for (BiA) TiO 3 calcined powder, A 2 CO 3 (Na 2 CO 3 , Li 2 CO 3 , K 2 CO 3 ), Bi 2 O 3 , TiO 2 and the like are used. Another A compound, Bi compound, or Ti compound may be used.
  • R element oxides such as BaCO 3 , TiO 2 , and La 2 O 3
  • M element oxides such as Nb 2 O 5 , and the like are used as raw materials for the (BaR) [TiM] O 3 calcined powder.
  • R and M are used as semiconducting elements.
  • the semiconductor ceramic composition finally obtained when the composition does not contain both R and M increases the room temperature resistivity ⁇ , so at least one of R and M is essential.
  • Another Ba compound or Ti compound may be used. These raw materials may be pulverized according to the particle size of the raw material powder.
  • the raw material powder may be mixed by either wet mixing using pure water or ethanol or dry mixing. However, when dry mixing is performed, compositional deviation is more easily prevented.
  • the raw material for the (BiA) TiO 3 calcined powder is preferably calcined at 700 ° C. or higher and 950 ° C. or lower.
  • the calcining temperature is less than 700 ° C, unreacted A 2 CO 3 , Bi, Ti and unreacted A 2 O react with the moisture in the furnace atmosphere or in the case of wet mixing, and generate heat and composition. Deviates from the desired value and the PTC characteristics tend to become unstable.
  • the calcination temperature exceeds 950 ° C.
  • the volatilization of Bi proceeds, causing a composition shift, and the generation of a heterogeneous phase is easily promoted.
  • the calcination time is preferably 0.5 hours or more and 10 hours or less.
  • the calcining time is less than 0.5 hours, the obtained PTC characteristics tend to be unstable for the same reason as when the calcining temperature is less than 700 ° C.
  • the calcination time exceeds 10 hours, the generation of a heterogeneous phase is likely to be promoted for the same reason as when the calcination temperature exceeds 950 ° C.
  • This calcination is preferably performed in the air.
  • the raw material for the (BaR) [TiM] O 3 calcined powder is preferably calcined at 900 ° C. or higher and 1300 ° C. or lower.
  • (BaR) [TiM] O 3 is not completely formed. For this reason, a part of BaO decomposed from BaCO 3 reacts with water, or a part of the remaining BaCO 3 dissolves in water, which may cause a composition shift and vary in characteristics.
  • the raw material of the (BaR) [TiM] O 3 calcined powder is preferably calcined at a higher temperature than the raw material of the (BiA) TiO 3 calcined powder.
  • the calcining time is preferably 0.5 hours or more. If the calcining time is less than 0.5 hours, it tends to cause a composition shift.
  • the calcination of the raw material of the (BaR) [TiM] O 3 calcined powder is preferably performed in the air.
  • the calcining temperature of the raw material of the (BaR) [TiM] O 3 calcined powder is 1100 ° C. or higher and 1300 ° C. or lower.
  • Step 1 the volatilization of Bi is suppressed, and the composition shift of Bi-A can be prevented to suppress the generation of a heterogeneous phase containing the A element. For this reason, while reducing the room temperature specific resistance (rho) of the obtained semiconductor ceramic composition, the variation in Curie temperature Tc can be suppressed.
  • Step 2 After mixing each calcined powder in a predetermined amount, they are mixed.
  • the mixed raw material may be referred to as a third raw material.
  • Mixing may be either wet mixing using pure water or ethanol, or dry mixing. However, it is preferable to perform dry mixing because the compositional deviation can be further prevented.
  • the third raw material is formed into a desired shape. You may granulate a pulverized powder with a granulator as needed before shaping
  • the compact density after molding is preferably 2.5 to 3.5 g / cm 3 .
  • Sintering is preferably performed at a sintering temperature of 1300 ° C. or higher and 1450 ° C. or lower. If the sintering temperature is less than 1300 ° C, the sintering will be insufficient. If the sintering temperature exceeds 1450 ° C., the temperature coefficient of resistance ⁇ decreases or the heat resistance decreases.
  • the sintering temperature is more preferably 1420 ° C. or lower.
  • the sintering atmosphere is preferably performed in the air, a reducing atmosphere, or an inert gas atmosphere having a low oxygen concentration.
  • a semiconductor ceramic composition having a large resistance temperature coefficient ⁇ can be obtained while keeping the room temperature specific resistance ⁇ at 200 ⁇ cm or less.
  • the sintering time is preferably 1 hour or more and 10 hours or less. If the sintering time is less than 1 hour, sintering is insufficient. When the sintering time exceeds 10 hours, there is a possibility that the Bi concentration in the crystal grains becomes uniform and the resistance temperature coefficient ⁇ becomes small. A more preferable sintering time is 2 hours or more and 6 hours or less.
  • This semiconductor ceramic composition has a composition formula of [(BiA) x (Ba 1-y R y ) 1-x ] [Ti 1-z M z ] O 3 (A is at least one of Na, Li, and K, R is represented by at least one of rare earth elements including Y, M is represented by at least one of Nb, Ta, and Sb), and x, y, and z are 0 ⁇ x ⁇ 0.2, 0 ⁇ y ⁇ 0.05, 0 ⁇ Those satisfying z ⁇ 0.01 (where y + z> 0) are preferred.
  • ⁇ Curie temperature Tc can be set to 130 ° C to 200 ° C by setting the range of x to more than 0 and 0.2 or less. If x exceeds 0.2, it is not preferable because a different phase is easily formed.
  • the room temperature specific resistance ⁇ exceeds 200 ⁇ cm, so y + z> 0.
  • both R and M are not necessarily required, and at least one of them may be used.
  • y indicating the R amount is preferably in the range of 0 ⁇ y ⁇ 0.05. If y is 0, the composition does not become a semiconductor, and if it exceeds 0.05, the room temperature resistivity ⁇ increases, which is not preferable.
  • the valence can be controlled by changing the value of y. However, when the valence control of the composition is performed in a system in which a part of Ba in the BaTiO 3 oxide is substituted with Bi and A, the addition of a trivalent cation as a semiconducting element results in a monovalent effect. There is a problem that the room temperature resistivity ⁇ increases due to the presence of A ions. Therefore, a more preferable range is 0.002 ⁇ y ⁇ 0.03.
  • R is at least one element selected from rare earths (Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Tb, Tm, Yb, Lu), particularly La and Y are preferable because excellent PTC characteristics can be obtained.
  • rare earths Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Tb, Tm, Yb, Lu
  • z indicating the amount of M is preferably in the range of 0 ⁇ z ⁇ 0.01. If z is 0, the valence cannot be controlled and the composition does not become a semiconductor, and if z exceeds 0.01, the room temperature resistivity ⁇ increases or the Curie temperature Tc decreases, which is not preferable. A more preferable range is 0.001 ⁇ z ⁇ 0.005. As M, Nb is particularly preferable because an excellent PTC characteristic can be obtained.
  • (BiA) in the composition formula refers to (Bi 0.5 A 0.5 ).
  • Si raw materials and Ca raw materials can be used as sintering aids.
  • Si and Ca may be included in the composition formula of the semiconductor ceramic composition.
  • the temperature coefficient of resistance ⁇ was calculated by measuring the resistance-temperature characteristics of the semiconductor ceramic composition while raising the temperature from room temperature 25 ° C. to 270 ° C. in a thermostatic bath.
  • the Curie temperature T C is resistivity and a temperature of which becomes 2 times the room temperature resistivity [rho.
  • the room temperature specific resistance ⁇ ( ⁇ cm) of the semiconductor ceramic composition was measured at 25 ° C. by a four-terminal method.
  • Example 1 The following procedure was performed as (Step 1). First, as a raw material, a raw material of (BiA) TiO 3 calcined powder and a raw material of (BaR) [TiM] O 3 calcined powder were prepared. In this example, raw material powder of Na 2 CO 3 , Bi 2 O 3 and TiO 2 was prepared as a raw material for (BiA) TiO 3 calcined powder, and the Bi / Na molar ratio Bi / Na was 1.0 (Bi 0.5 Na 0.5 ) TiO 3 was blended and dry mixed.
  • raw material powders of BaCO 3 , TiO 2 , and La 2 O 3 were prepared as raw materials for (BaR) [TiM] O 3 calcined powder, blended to become (Ba 0.994 La 0.006 ) TiO 3, and pure water And dried.
  • the raw material of (BiA) TiO 3 calcined powder and the raw material of (BaR) [TiM] O 3 calcined powder were calcined at different temperatures.
  • the raw material of (BiNa) TiO 3 calcined powder was calcined in air at 800 ° C. for 2 hours, and the raw material of (BaLa) TiO 3 calcined powder was calcined in air at 1200 ° C.
  • the BET value of the (BiA) TiO 3 calcined powder was a and the BET value of the (BaR) [TiM] O 3 calcined powder was b
  • the BET value was adjusted so that a / b ⁇ 2.0.
  • the (BiNa) TiO 3 calcined powder was pulverized by using a ball having a media diameter of 5 mm, using pure water as a medium and changing the pulverization time by a pot mill, and then dried.
  • the (BaLa) TiO 3 calcined powder was used without being pulverized.
  • the BET value a (BiNa) TiO 3 calcined powder also described in Table 1 the ratio a / b of the BET value divided by the BET value b of (BaLa) TiO 3 calcined powder.
  • (BiA) TiO 3 calcined powder and (BaR) [TiM] O 3 calcined powder were mixed (Step 2).
  • (BiNa) TiO 3 calcined powder and (BaLa) TiO 3 calcined powder were mixed so as to be [(Bi 0.5 Na 0.5 ) 0.085 (Ba 0.994 La 0.006 ) 0.915 ] TiO 3 .
  • This material was mixed and pulverized with a pot mill using pure water as a medium, and then dried to obtain a third raw material.
  • the third raw material was heat-treated in air at 1150 ° C. for 4 hours (not shown). . Thereafter, 1.5 mol% of Y 2 O 3 , 0.74 mol% of Ba 6 Ti 17 O 40 and 2 mol% of CaCO 3 were added as the Y raw material to the third raw material. Thereafter, the mixture was mixed and pulverized with a pot mill using pure water as a medium, and then dried (not shown).
  • Step 3 10% by mass of PVA was added to the third raw material, mixed, and then granulated with a granulator.
  • the obtained granulated powder was molded with a uniaxial press machine, and then debindered at 700 ° C.
  • Step 4 sintering was performed at 1400 ° C. for 4 hours under nitrogen at an oxygen concentration of 0.01 vol% (100 ppm) to obtain a sintered body.
  • the obtained sintered body is processed into a plate of 10 mm x 10 mm x 1 mm to prepare a test piece, an ohmic electrode is applied, a cover electrode is further applied, dried at 180 ° C and then held at 600 ° C for 10 minutes. An electrode was formed by baking.
  • Table 1 shows the measured room temperature specific resistance ⁇ , Curie temperature Tc, and resistance temperature coefficient ⁇ .
  • the BET value a (BiNa) TiO 3 calcined powder 1.28, the BET value b of (BaLa) TiO 3 calcined powder is 0.81 (Sample No. 1-1).
  • the calcined powder of this comparative example has a BET value ratio a / b of 1.6, and the semiconductor ceramic composition obtained using this calcined powder has a room temperature resistivity ⁇ of 46.2 ⁇ ⁇ cm.
  • the BET value ratio a / b is 2.0 times or more.
  • sample number 1-9 of this embodiment has a slightly higher room temperature resistivity ⁇ and a lower Curie temperature Tc than sample number 1-8, but a lower room temperature than sample number 1-1 of the comparative example. It is a semiconductor ceramic composition having a specific resistance ⁇ and a high Curie temperature Tc.
  • Example 2 Experiments were performed by changing the BET value b of the (BaLa) TiO 3 calcined powder.
  • (BaLa) TiO 3 Example except that the calcining temperature of the raw material of calcined powder was 1150 ° C (sample number 2-1), 1175 ° C (sample number 2-2), 1300 ° C (sample number 2-3) The calcined powder was prepared in the same manner as in Sample No. 1-5.
  • (BiNa) a BET value b of TiO 3 and BET value a calcined powder (BaLa) TiO 3 calcined powder are shown in Table 2.
  • the BET value ratio a / b is also shown in Table 2.
  • Table 2 shows the measured room temperature specific resistance ⁇ , Curie temperature Tc, and resistance temperature coefficient ⁇ .
  • a novel method for producing a semiconductor ceramic composition capable of adjusting the Curie temperature Tc and increasing the room temperature specific resistance ⁇ .

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Abstract

Provided is a novel manufacturing method which can perform adjustment so that the Curie temperature of a semiconductor ceramic composition becomes higher, and the room temperature resistivity ρ becomes lower. The method is a manufacturing method for a semiconductor ceramic composition in which a (BiA)TiO3 (A is at least one from among Na, Li, and K) calcined powder and a (BaR)[TiM]O3 (R is at least one from among the rare-earth elements including Y, M is at least one from among Nb, Ta, and Sb, and either R or M is required) calcined powder are prepared, the (BiA)TiO3 calcined powder and the (BaR)[TiM]O3 calcined powder are mixed, and subsequently, molding and sintering are performed, said manufacturing method for a semiconductor ceramic composition characterized in that prior to the mixing of the (BiA)TiO3 calcined powder and the (BaR)[TiM]O3 calcined powder, a/b ≥ 2.0 is satisfied, where a is the BET value of the (BiA)TiO3 calcined powder and b is the BET value of the (BaR)[TiM]O3 calcined powder.

Description

半導体磁器組成物の製造方法、半導体磁器組成物、ＰＴＣ素子、及び発熱体モジュールSemiconductor porcelain composition manufacturing method, semiconductor porcelain composition, PTC element, and heating element module
　この発明は、PTCヒータ、PTCサーミスタ、PTCスイッチ、温度検知器などの発熱体モジュールに用いられる、半導体磁器組成物の製造方法、半導体磁器組成物、ＰＴＣ素子、及び発熱体モジュールに関する。 The present invention relates to a method for manufacturing a semiconductor ceramic composition, a semiconductor ceramic composition, a PTC element, and a heating element module used for heating element modules such as a PTC heater, a PTC thermistor, a PTC switch, and a temperature detector.
　従来より、PTC（Positive Temperature Coefficient of resistivity）特性を示す材料として、BaTiO3系酸化物に様々な半導体化元素を加えたり酸素欠陥を形成させて半導体化させた半導体磁器組成物が提案されている。この半導体磁器組成物に電極を設けたものは、PTC素子として使用することができ、このＰＴＣ素子は発熱体モジュールに使用できる。 Conventionally, as a material exhibiting PTC (Positive Temperature Coefficient of Reactive) characteristics, semiconductor porcelain compositions in which various semiconducting elements are added to BaTiO 3 oxides or oxygen defects are formed into semiconductors have been proposed. . This semiconductor ceramic composition provided with electrodes can be used as a PTC element, and this PTC element can be used in a heating element module.
　BaTiO3系酸化物の半導体磁器組成物は、そのキュリー温度が120℃前後であるものが殆どである。これらの半導体磁器組成物は、用途に応じてキュリー温度をシフトさせることが必要になる。例えば、BaTiO3系酸化物にSrTiO3系酸化物を添加することによってキュリー温度をシフトさせることが提案されているが、この場合、キュリー温度は負の方向にのみシフトし、正の方向にはシフトしない。現在実用化されている材料で、キュリー温度を正の方向にシフトさせる添加物として知られているのはPbTiO3である。しかし、鉛は環境汚染を引き起こす元素であるため、鉛を含まない非鉛の半導体磁器組成物が要望されている。 Most BaTiO 3 -based semiconductor ceramic compositions have a Curie temperature of around 120 ° C. These semiconductor porcelain compositions need to shift the Curie temperature depending on the application. For example, it has been proposed to shift the Curie temperature by adding SrTiO 3 oxide to BaTiO 3 oxide, but in this case, the Curie temperature is shifted only in the negative direction and in the positive direction. Do not shift. PbTiO 3 is a material that is currently in practical use and is known as an additive that shifts the Curie temperature in the positive direction. However, since lead is an element that causes environmental pollution, a lead-free semiconductor ceramic composition containing no lead is desired.
　特許文献1は、非鉛の半導体磁器組成物として、BaTiO3のBaの一部をBi-Naで置換した半導体磁器組成物が開示され、その具体的な製造方法として、(BaQ)TiO3仮焼粉（Qは半導体化元素）を用意する工程、(BiNa)TiO3仮焼粉を用意する工程、(BaQ)TiO3仮焼粉と(BiNa)TiO3仮焼粉を混合する工程、混合仮焼粉を、成形、焼結する工程とを含む半導体磁器組成物の製造方法が提案されている。 Patent Document 1 discloses a semiconductor ceramic composition in which a part of Ba in BaTiO 3 is replaced with Bi-Na as a lead-free semiconductor ceramic composition. As a specific manufacturing method thereof, (BaQ) TiO 3 temporary Step of preparing calcined powder (Q is semiconducting element), step of preparing (BiNa) TiO 3 calcined powder, step of mixing (BaQ) TiO 3 calcined powder and (BiNa) TiO 3 calcined powder, mixing There has been proposed a method for producing a semiconductor porcelain composition including a step of forming and sintering a calcined powder.
　特許文献１では、(BaQ)TiO3組成物（Qは半導体化元素）と(BiNa)TiO3組成物は別々に用意され、(BaQ)TiO3組成物は比較的高温で、(BiNa)TiO3組成物は比較的低温で、それぞれに応じた最適温度で仮焼される。これにより、(BiNa)TiO3組成物のBiの揮散が抑制され、Bi-Naの組成ずれが防止されて異相の生成が抑制される。そして、これらの仮焼粉を混合して、成形、焼結することにより、室温比抵抗が低く、キュリー温度のバラツキが抑制された半導体磁器組成物が得られることが記載されている（段落(0013)参照）。 In Patent Document 1, the (BaQ) TiO 3 composition (Q is a semiconducting element) and the (BiNa) TiO 3 composition are prepared separately, the (BaQ) TiO 3 composition is at a relatively high temperature, and (BiNa) TiO 3 is prepared. 3 The composition is relatively calcined and calcined at the optimum temperature according to each. Thereby, the volatilization of Bi in the (BiNa) TiO 3 composition is suppressed, the composition shift of Bi—Na is prevented, and the generation of heterogeneous phases is suppressed. And, it is described that by mixing, calcining and sintering these calcined powders, a semiconductor ceramic composition having a low room temperature resistivity and a suppressed Curie temperature variation can be obtained (paragraph ( 0013)).
国際公開第２００６／１１８２７４号公報International Publication No. 2006/118274
　PTC特性をもつ半導体磁器組成物は、PTC素子として用いた際に電力ロスが小さくなるように、室温における抵抗率（以後、室温比抵抗ρという）が小さいものが望まれる。一方、キュリー温度（Ｔｃ）は大きなものが望まれる。特許文献１では、これらの特性向上を効果としているものの、顧客からさらに高い特性を要求される場合、もう一段特性を向上させ、かつ、特許文献１の製造方法と併用可能な手段を検討する必要がある。
　そこで本発明では、半導体磁器組成物のキュリー温度Tcを大きく、かつ、室温比抵抗ρを小さく調整することが可能である新規な製造方法を提供することを目的とする。
　また、その製造方法により得られる、半導体磁器組成物、ＰＴＣ素子、及び発熱体モジュールを提供することを目的とする。 The semiconductor ceramic composition having PTC characteristics is desired to have a low resistivity at room temperature (hereinafter referred to as room temperature resistivity ρ) so that power loss is small when used as a PTC element. On the other hand, a large Curie temperature (Tc) is desired. In Patent Document 1, although the improvement of these characteristics is effective, when a higher characteristic is required from the customer, it is necessary to improve the characteristics one more time and to examine means that can be used in combination with the manufacturing method of Patent Document 1. There is.
Accordingly, an object of the present invention is to provide a novel manufacturing method capable of adjusting the Curie temperature Tc of the semiconductor ceramic composition to be large and the room temperature resistivity ρ to be small.
Moreover, it aims at providing the semiconductor ceramic composition, PTC element, and heat generating module which are obtained by the manufacturing method.
　本発明は、原料として、(BiA)TiO3（AはNa,Li,Kのうち少なくとも一種）仮焼粉と、(BaR)[TiM]O3（RはYを含む希土類元素のうち少なくとも一種、MはNb、Ta、Sbのうち少なくとも一種であり、R,Mはどちらか一方が必須である）仮焼粉を用意し、前記(BiA)TiO3仮焼粉と(BaR)[TiM]O3仮焼粉を混合し、その後、成形、焼結する半導体磁器組成物の製造方法であって、前記(BiA)TiO3仮焼粉と(BaR)[TiM]O3仮焼粉を混合する前に、前記(BiA)TiO3仮焼粉のBET値をa、前記(BaR)[TiM]O3仮焼粉のBET値をbとして、a/b≧2.0にすることを特徴とする。 The present invention provides (BiA) TiO 3 (A is at least one of Na, Li, K) calcined powder and (BaR) [TiM] O 3 (R is at least one of rare earth elements including Y) as raw materials. , M is at least one of Nb, Ta, and Sb, and either R or M is indispensable) is prepared, and (BiA) TiO 3 calcined powder and (BaR) [TiM] A method of manufacturing a semiconductor porcelain composition in which O 3 calcined powder is mixed and then molded and sintered, and the (BiA) TiO 3 calcined powder and (BaR) [TiM] O 3 calcined powder are mixed Before, the BET value of the (BiA) TiO 3 calcined powder is a, the BET value of the (BaR) [TiM] O 3 calcined powder is b, a / b ≧ 2.0 .
　前記(BiA)TiO3仮焼粉と前記(BaR)[TiM]O3仮焼粉を用意する工程で、前記(BiA)TiO3仮焼粉にBET値ａを大きくする処理を施し、および／または、前記(BaR)[TiM]O3仮焼粉にBET値ｂを小さくする処理を施してもよい。 In the step of preparing the (BiA) TiO 3 calcined powder and the (BaR) [TiM] O 3 calcined powder, the (BiA) TiO 3 calcined powder is subjected to a treatment for increasing the BET value a, and / or Alternatively, the (BaR) [TiM] O 3 calcined powder may be subjected to a treatment for reducing the BET value b.
　前記(BiA)TiO3仮焼粉と前記(BaR)[TiM]O3仮焼粉を用意した後に、前記(BiA)TiO3仮焼粉にBET値ａを大きくする処理を施し、および／または、前記(BaR)[TiM]O3仮焼粉にBET値ｂを小さくする処理を施してもよい。 After preparing the (BiA) TiO 3 calcined powder and the (BaR) [TiM] O 3 calcined powder, the (BiA) TiO 3 calcined powder is subjected to a treatment for increasing the BET value a, and / or The (BaR) [TiM] O 3 calcined powder may be subjected to a treatment for decreasing the BET value b.
　前記(BaR)[TiM]O3仮焼粉の仮焼き温度を前記(BiA)TiO3仮焼粉を仮焼温度より高くして、前記(BaR)[TiM]O3仮焼粉の平均粒径を前記(BiA)TiO3仮焼粉の平均粒径より大きくし、前記BET値をa/b≧2.0にしてもよい。 Wherein (BaR) [TiM] O 3 wherein the calcining temperature of the calcined powder (BIA) TiO 3 calcined powder was higher than the calcination temperature, the (BaR) [TiM] O 3 Average grain calcined powder The diameter may be larger than the average particle diameter of the (BiA) TiO 3 calcined powder, and the BET value may be a / b ≧ 2.0.
　前記(BiA)TiO3仮焼粉と前記(BaR)[TiM]O3仮焼粉を用意した後に、前記(BiA)TiO3仮焼粉に粉砕処理を施して前記(BiA)TiO3仮焼粉のBET値ａを大きくしてもよい。 After preparing the (BiA) TiO 3 calcined powder and the (BaR) [TiM] O 3 calcined powder, the (BiA) TiO 3 calcined powder is pulverized to give the (BiA) TiO 3 calcined powder. The BET value a of the powder may be increased.
　前記BET値aは、1.0m2/g以上30m2/g以下であることが好ましい。
　前記BET値bは、0.1m2/g以上15m2/g以下であることが好ましい。
　また、前記半導体磁器組成物は、組成式が[(BiA)x(Ba1-yRy)1-x][Ti1-zMz]O3（AはNa,Li,Kのうち少なくとも一種、RはYを含む希土類元素のうち少なくとも一種、MはNb、Ta、Sbのうち少なくとも一種）で表わされ、x、y、ｚが、0＜x≦0.2、0≦y≦0.05、0≦z≦0.01（但し、ｙ＋ｚ＞0）を満足することが好ましい。
　また、前記焼結は1300℃以上1450℃以下で行うことが好ましい。
　上記の製造方法で半導体磁器組成物を得ることができる。
　さらに、この半導体磁器組成物に電極を形成してＰＴＣ素子とすることができる。
　さらに、このＰＴＣ素子を用いて発熱体モジュールとすることができる。 The BET value a is preferably 1.0 m 2 / g or more and 30 m 2 / g or less.
The BET value b is preferably 0.1 m 2 / g or more and 15 m 2 / g or less.
The semiconductor ceramic composition has a composition formula [(BiA) x (Ba 1-y R y ) 1-x ] [Ti 1-z M z ] O 3 (A is at least one of Na, Li, and K). One, R is represented by at least one of rare earth elements including Y, M is represented by at least one of Nb, Ta, and Sb), and x, y, and z are 0 <x ≦ 0.2, 0 ≦ y ≦ 0.05, It is preferable that 0 ≦ z ≦ 0.01 (where y + z> 0) is satisfied.
The sintering is preferably performed at 1300 ° C. or higher and 1450 ° C. or lower.
A semiconductor ceramic composition can be obtained by the above production method.
Furthermore, an electrode can be formed on this semiconductor ceramic composition to obtain a PTC element.
Furthermore, it can be set as a heat generating body module using this PTC element.
　本発明によれば、半導体磁器組成物のキュリー温度Tcを大きく、かつ、室温比抵抗ρを小さく調整することが可能な新規な製造方法を提供できる。 According to the present invention, it is possible to provide a novel manufacturing method capable of adjusting the Curie temperature Tc of the semiconductor porcelain composition to be large and the room temperature specific resistance ρ to be small.
本発明の半導体磁器組成物の製造方法を示す図である。It is a figure which shows the manufacturing method of the semiconductor ceramic composition of this invention.
　本発明の半導体磁器組成物の製造方法は、(BiA)TiO3仮焼粉の平均粒径を(BaR)[TiM]O3仮焼粉の平均粒径よりも所定値以上に小さくなるよう、具体的にはBET値の比で2倍以上の差になるようにすることで、混合後に焼結（1300℃以上1450℃以下）する際に(BaR)[TiM]O3仮焼粉に(BiA)TiO3仮焼粉が固溶されやすくなって(BiA)TiO3仮焼粉に含まれるBiの揮発を抑え、その結果、半導体磁器組成物のキュリー温度Tcを大きくし、室温比抵抗ρを小さく調整することができる。a/bの値は5以上とすることが好ましく、10以上とすることがより好ましい。 The method for producing a semiconductor ceramic composition of the present invention is such that the average particle diameter of the (BiA) TiO 3 calcined powder is smaller than the average particle diameter of the (BaR) [TiM] O 3 calcined powder by a predetermined value or more. Specifically by the so the difference more than twice the ratio of the BET value, after mixing when sintering (1300 ° C. or higher 1450 ° C. or less) (BaR) [TiM] O 3 in calcined powder ( BiA) TiO 3 calcined powder is easily dissolved, and (BiA) TiO 3 calcined powder suppresses the volatilization of Bi. As a result, the Curie temperature Tc of the semiconductor ceramic composition is increased, and the room temperature resistivity ρ Can be adjusted small. The value of a / b is preferably 5 or more, and more preferably 10 or more.
　a/bの上限は特に限定されないが、a/b≦50とすることが好ましい。a/bが50を超える場合は、つまり(BiA)TiO3仮焼粉のBET値aが大きくなるか、または(BaR)[TiM]O3仮焼粉のBET値bが小さくなる場合であるが、(BiA)TiO3仮焼粉のBET値aが大きすぎると(BiA)TiO3仮焼粉の粉砕時間が長くなったり、(BiA)TiO3仮焼粉が凝集して反応性が悪化し(BaR)[TiM]O3仮焼粉に対して固溶しづらくなるためキュリー温度Tcが小さくなりやすい。(BaR)[TiM]O3仮焼粉のBET値bが小さすぎると、(BaR)[TiM]O3仮焼粉の粒径が大きいために焼結の際に(BiA)TiO3仮焼粉と固溶しづらくなり、室温比抵抗ρが大きくなりやすい。 The upper limit of a / b is not particularly limited, but a / b ≦ 50 is preferable. When a / b exceeds 50, that is, when the BET value a of (BiA) TiO 3 calcined powder increases or the BET value b of (BaR) [TiM] O 3 calcined powder decreases. However, if the BET value a of the (BiA) TiO 3 calcined powder is too large, the pulverization time of the (BiA) TiO 3 calcined powder becomes longer, or the (BiA) TiO 3 calcined powder aggregates and the reactivity deteriorates. Curie temperature Tc tends to be small because it is difficult to dissolve in (BaR) [TiM] O 3 calcined powder. If the BET value b of the (BaR) [TiM] O 3 calcined powder is too small, the particle size of the (BaR) [TiM] O 3 calcined powder is large, so that (BiA) TiO 3 calcined during sintering It becomes difficult to form a solid solution with the powder, and the room temperature resistivity ρ tends to increase.
　なお、BET値とは、粉体粒子の表面に占有面積の分かった分子（通常，N2ガス）を吸着させ、その量から粉体粒子の比表面積を求めたものであり、圧力pと吸着量vの関係からBET式（Brunauer,Emmet and Teller's equation）によって、単分子吸着量vmを測定し比表面積を求めるものである。本発明においては、仮焼粉0.5ｇを常温で十分に真空脱気した後、比表面積測定装置（株式会社マウンテック製、Macsorb）を用いて、窒素吸着によるBET式から得られた値を用いた。 The BET value is obtained by adsorbing molecules (usually N 2 gas) whose surface area is known on the surface of the powder particles, and obtaining the specific surface area of the powder particles from the amount of the molecules. The specific surface area is obtained by measuring the unimolecular adsorption amount vm by the BET equation (Brunauer, Emmet and Teller's equation) from the relationship of the amount v. In the present invention, 0.5 g of the calcined powder was sufficiently vacuum degassed at room temperature, and then a value obtained from the BET equation by nitrogen adsorption was used using a specific surface area measuring device (Macsorb, manufactured by Mountec Co., Ltd.). .
　(BiA)TiO3仮焼粉と(BaR)[TiM]O3仮焼粉のBET値の調整手段は特に限定されないが、以下の方法を適用できる。例えば、得られた(BiA)TiO3仮焼粉を、ボールミル等の既知の手段で粉砕し、(BaR)[TiM]O3仮焼粉に対して平均粒径を小さく(BET値aを大きく)する方法が採用できる。また、(BaR)[TiM]O3仮焼粉の仮焼温度を高くしたり、粒径が大きいTiO2原料を使用して平均粒径を大きく(BET値bを小さく)する方法なども採用できる。あるいは、上記のBET値aを大きくする手法とBET値bを小さくする手法の両方を採用してもよい。つまり、
・(BiA)TiO3仮焼粉と(BaR)[TiM]O3仮焼粉を用意する工程で、(BiA)TiO3仮焼粉にBET値ａを大きくする処理を施し、および／または、(BaR)[TiM]O3仮焼粉にBET値ｂを小さくする処理を施してもよい。例えば、(BaR)[TiM]O3仮焼粉の仮焼き温度を(BiA)TiO3仮焼粉を仮焼温度より高くして、(BaR)[TiM]O3仮焼粉の平均粒径を(BiA)TiO3仮焼粉の平均粒径より大きくし、BET値をa/b≧2.0にすることができる。あるいは、(BaR)[TiM]O3仮焼粉の仮焼きの時間を長くして(BaR)[TiM]O3仮焼粉の平均粒径を(BiA)TiO3仮焼粉の平均粒径より大きくすることができる。
・あるいは、(BiA)TiO3仮焼粉と(BaR)[TiM]O3仮焼粉を用意した後に、(BiA)TiO3仮焼粉にBET値ａを大きくする処理を施し、および／または、(BaR)[TiM]O3仮焼粉にBET値ｂを小さくする処理を施してもよい。例えば、(BiA)TiO3仮焼粉と(BaR)[TiM]O3仮焼粉を用意した後に、ボールミルなどで(BiA)TiO3仮焼粉に粉砕処理を施して(BiA)TiO3仮焼粉のBET値ａを大きくすることができる。また、(BaR)[TiM]O3仮焼粉を再度熱処理して(BaR)[TiM]O3仮焼粉のBET値bを小さくすることができる。 The means for adjusting the BET values of the (BiA) TiO 3 calcined powder and the (BaR) [TiM] O 3 calcined powder is not particularly limited, but the following method can be applied. For example, the obtained (BiA) TiO 3 calcined powder is pulverized by a known means such as a ball mill, and the average particle size is reduced (BET value a is increased) relative to (BaR) [TiM] O 3 calcined powder. ) Method can be adopted. In addition, methods such as increasing the calcining temperature of (BaR) [TiM] O 3 calcined powder or increasing the average particle size (decreasing BET value b) using TiO 2 raw material with large particle size are also adopted. it can. Alternatively, both the method for increasing the BET value a and the method for decreasing the BET value b may be employed. That means
In the step of preparing (BiA) TiO 3 calcined powder and (BaR) [TiM] O 3 calcined powder, (BiA) TiO 3 calcined powder is subjected to a treatment for increasing the BET value a, and / or The (BaR) [TiM] O 3 calcined powder may be subjected to a treatment for reducing the BET value b. For example, (BaR) [TiM] O 3 calcining temperature of calcined powder (BIA) TiO 3 calcined powder was higher than the calcination temperature, (BaR) [TiM] The average particle size of O 3 calcined powder Can be made larger than the average particle diameter of the (BiA) TiO 3 calcined powder, and the BET value can be a / b ≧ 2.0. Alternatively, the time of calcining of (BaR) [TiM] O 3 calcined powder is lengthened and the average particle diameter of (BaR) [TiM] O 3 calcined powder is changed to the average particle diameter of (BiA) TiO 3 calcined powder. Can be larger.
-Alternatively, after preparing (BiA) TiO 3 calcined powder and (BaR) [TiM] O 3 calcined powder, (BiA) TiO 3 calcined powder is subjected to a treatment to increase the BET value a, and / or , (BaR) [TiM] O 3 calcined powder may be subjected to a treatment for decreasing the BET value b. For example, (BIA) TiO 3 calcined powder and (BaR) [TiM] O 3 after preparing the calcined powder, a ball mill or the like (BIA) is subjected to grinding treatment to TiO 3 calcined powder (BIA) TiO 3 Provisional The BET value a of the baked powder can be increased. Further, the (BaR) [TiM] O 3 calcined powder can be heat treated again to reduce the BET value b of the (BaR) [TiM] O 3 calcined powder.
　(BiA)TiO3仮焼粉のBET値aは、1.0m2/g以上30m2/g以下であることが好ましい。BET値aが1.0m2/g未満であると、(BiA)TiO3仮焼粉の平均粒径が大きいために焼結の際に(BaR)[TiM]O3仮焼粉に(BiA)TiO3仮焼粉が固溶されづらくなり、キュリー温度Tcが小さくなりやすい。一方、BET値aが30m2/gを超えると粉砕時間が長くなるなどの問題が出る。さらに、(BiA)TiO3仮焼粉が凝集して反応性が悪化し、(BiA)TiO3仮焼粉が(BaR)[TiM]O3仮焼粉に対して固溶しづらくなるため、キュリー温度Tcが小さくなりやすい。さらに好ましいBET値aの範囲は、1.5m2/g以上25m2/g以下である The BET value a of the (BiA) TiO 3 calcined powder is preferably 1.0 m 2 / g or more and 30 m 2 / g or less. When the BET value a is less than 1.0 m 2 / g, the average particle size of the (BiA) TiO 3 calcined powder is large, so that (BaR) [TiM] O 3 calcined powder (BiA) The TiO 3 calcined powder is not easily dissolved, and the Curie temperature Tc tends to decrease. On the other hand, when the BET value a exceeds 30 m 2 / g, problems such as longer grinding time appear. Furthermore, (BiA) TiO 3 calcined powder is agglomerated and the reactivity deteriorates, and (BiA) TiO 3 calcined powder is difficult to dissolve in (BaR) [TiM] O 3 calcined powder. Curie temperature Tc tends to decrease. A more preferable range of the BET value a is 1.5 m 2 / g or more and 25 m 2 / g or less.
　(BaR)[TiM]O3仮焼粉のBET値bは、0.1m2/g以上15m2/g以下であることが好ましい。BET値bが0.1m2/g未満であると、(BaR)[TiM]O3仮焼粉の粒径が大きいために焼結の際に、(BaR)[TiM]O3仮焼粉が(BiA)TiO3仮焼粉と固溶しづらくなり、室温比抵抗ρが大きくなりやすい。一方、BET値bが15m2/gを超えると、(BaR)[TiM]O3仮焼粉の粒径が小さいために焼結体の結晶粒径も小さくなり、やはり室温比抵抗ρが大きくなりやすい。さらに好ましいBET値bの範囲は、0.2 m2/g以上2m2/g以下である。 The BET value b of the (BaR) [TiM] O 3 calcined powder is preferably 0.1 m 2 / g or more and 15 m 2 / g or less. When the BET value b is less than 0.1 m 2 / g, the particle size of the (BaR) [TiM] O 3 calcined powder is large, so that during sintering, the (BaR) [TiM] O 3 calcined powder is It becomes difficult to form a solid solution with the (BiA) TiO 3 calcined powder, and the room temperature resistivity ρ tends to increase. On the other hand, when the BET value b exceeds 15 m 2 / g, the crystal grain size of the sintered body becomes small due to the small particle size of the (BaR) [TiM] O 3 calcined powder, and the room temperature specific resistance ρ is also large. Prone. A more preferable range of the BET value b is 0.2 m 2 / g or more and 2 m 2 / g or less.
　本発明の製造方法について、図1を用いて詳細に説明する。
　図１のStep1の工程は、(BiA)TiO3仮焼粉と(BaR)[TiM]O3仮焼粉を混合する前に、(BiA)TiO3仮焼粉のBET値をa、前記(BaR)[TiM]O3仮焼粉のBET値をbとして、a/b≧2.0にするものである。
　この工程は、(BiA)TiO3仮焼粉を用意する工程、及び(BaR)[TiM]O3仮焼粉を用意する工程を含んでもよい。
　以下に、(BiA)TiO3仮焼粉を用意する工程、及び(BaR)[TiM]O3仮焼粉を用意する工程を含む製造工程を説明する。 The production method of the present invention will be described in detail with reference to FIG.
In step 1 of FIG. 1, before mixing (BiA) TiO 3 calcined powder and (BaR) [TiM] O 3 calcined powder, the BET value of (BiA) TiO 3 calcined powder is set to a, BaR) [TiM] O 3 The BET value of the calcined powder is b, and a / b ≧ 2.0.
This step may include a step of preparing (BiA) TiO 3 calcined powder and a step of preparing (BaR) [TiM] O 3 calcined powder.
Hereinafter, a manufacturing process including a step of providing a step, and (BaR) [TiM] O 3 calcined powder to prepare (BIA) TiO 3 calcined powder.
　先ず、(BiA)TiO3（AはNa,Li,Kのうち少なくとも一種）仮焼粉と、(BaR)[TiM]O3（RはYを含む希土類元素のうち少なくとも一種、MはNb、Ta、Sbのうち少なくとも一種であり、R,Mはどちらか一方が必須である）仮焼粉を用意する。 First, (BiA) TiO 3 (A is at least one of Na, Li, and K) calcined powder and (BaR) [TiM] O 3 (R is at least one of rare earth elements including Y, M is Nb, Prepare at least one of Ta and Sb, and either R or M is essential).
　(BiA)TiO3仮焼粉の原料としてA2CO3(Na2CO3、Li2CO3、K 2CO3)、Bi2O3、TiO2等が用いられる。別のA化合物、Bi化合物、Ti化合物を用いてもよい。
　また、(BaR)[TiM]O3仮焼粉の原料としてBaCO3、TiO2、La2O3等のR元素酸化物、Nb2O5等のM元素酸化物等が用いられる。R，Mは半導体化元素として用いるものである。R、Mが共に添加されない組成であると最終的に得られる半導体磁器組成物は室温比抵抗ρが大きくなるため、少なくともR,Mのどちらかは必須とする。別のBa化合物、Ti化合物を用いてもよい。
　これらの原料は、原料粉末の粒度に応じて粉砕を施してもよい。また、原料粉末の混合は純水やエタノールを用いた湿式混合または乾式混合のいずれでもよいが、乾式混合を行うと、組成ずれをより防止しやすい。 As raw materials for (BiA) TiO 3 calcined powder, A 2 CO 3 (Na 2 CO 3 , Li 2 CO 3 , K 2 CO 3 ), Bi 2 O 3 , TiO 2 and the like are used. Another A compound, Bi compound, or Ti compound may be used.
In addition, R element oxides such as BaCO 3 , TiO 2 , and La 2 O 3 , M element oxides such as Nb 2 O 5 , and the like are used as raw materials for the (BaR) [TiM] O 3 calcined powder. R and M are used as semiconducting elements. The semiconductor ceramic composition finally obtained when the composition does not contain both R and M increases the room temperature resistivity ρ, so at least one of R and M is essential. Another Ba compound or Ti compound may be used.
These raw materials may be pulverized according to the particle size of the raw material powder. The raw material powder may be mixed by either wet mixing using pure water or ethanol or dry mixing. However, when dry mixing is performed, compositional deviation is more easily prevented.
　次に、(BiA)TiO3仮焼粉を製造する際の仮焼条件について詳述する。
　(BiA)TiO3仮焼粉の原料は、700℃以上950℃以下で仮焼することが好ましい。仮焼温度が700℃未満では、未反応のA2CO3やBi、Tiと未反応のA2Oが、炉内雰囲気の水分あるいは湿式混合の場合はその溶媒と反応して発熱し、組成が所望の値からずれてPTC特性が不安定になりやすい。一方、仮焼温度が950℃を超えると、Biの揮散が進み、組成ずれを起こし、異相の生成が促進されやすい。
　仮焼時間は0.5時間以上10時間以下が好ましい。仮焼時間が0.5時間未満では仮焼温度が700℃未満のときと同様の理由で、得られるPTC特性が不安定になりやすい。仮焼時間が10時間を超えると、仮焼温度が950℃を超えるときと同様の理由で、異相の生成が促進されやすい。
　この仮焼は大気中で行うことが好ましい。 Next, the calcining conditions for producing the (BiA) TiO 3 calcined powder will be described in detail.
The raw material for the (BiA) TiO 3 calcined powder is preferably calcined at 700 ° C. or higher and 950 ° C. or lower. When the calcining temperature is less than 700 ° C, unreacted A 2 CO 3 , Bi, Ti and unreacted A 2 O react with the moisture in the furnace atmosphere or in the case of wet mixing, and generate heat and composition. Deviates from the desired value and the PTC characteristics tend to become unstable. On the other hand, when the calcination temperature exceeds 950 ° C., the volatilization of Bi proceeds, causing a composition shift, and the generation of a heterogeneous phase is easily promoted.
The calcination time is preferably 0.5 hours or more and 10 hours or less. When the calcining time is less than 0.5 hours, the obtained PTC characteristics tend to be unstable for the same reason as when the calcining temperature is less than 700 ° C. When the calcination time exceeds 10 hours, the generation of a heterogeneous phase is likely to be promoted for the same reason as when the calcination temperature exceeds 950 ° C.
This calcination is preferably performed in the air.
　次に、 (BaR)[TiM]O3仮焼粉を製造する際の仮焼条件について詳述する。
　(BaR)[TiM]O3仮焼粉の原料は900℃以上1300℃以下で仮焼することが好ましい。仮焼温度が900℃未満であると(BaR)[TiM]O3が完全に形成されない。このため、BaCO3から分解した一部のBaOが水と反応したり、残存したBaCO3の一部が水に溶解するため、組成ずれの原因となって特性がばらつく可能性がある。一方、仮焼温度が1300℃を超えると、仮焼粉の一部が互いに焼結し、後に混合する(BiA)TiO3仮焼粉との固溶の妨げになることがある。
　(BaR)[TiM]O3仮焼粉の原料は(BiA)TiO3仮焼粉の原料よりも高い温度で仮焼することが好ましい。
　仮焼時間は0.5時間以上が好ましい。仮焼時間が0.5時間未満では組成ずれの原因となりやすい。
　(BaR)[TiM]O3仮焼粉の原料の仮焼は大気中で行うことが好ましい。 Next, the calcining conditions for producing the (BaR) [TiM] O 3 calcined powder will be described in detail.
The raw material for the (BaR) [TiM] O 3 calcined powder is preferably calcined at 900 ° C. or higher and 1300 ° C. or lower. When the calcining temperature is less than 900 ° C., (BaR) [TiM] O 3 is not completely formed. For this reason, a part of BaO decomposed from BaCO 3 reacts with water, or a part of the remaining BaCO 3 dissolves in water, which may cause a composition shift and vary in characteristics. On the other hand, when the calcining temperature exceeds 1300 ° C., some of the calcined powders may sinter to each other and hinder solid solution with the (BiA) TiO 3 calcined powder mixed later.
The raw material of the (BaR) [TiM] O 3 calcined powder is preferably calcined at a higher temperature than the raw material of the (BiA) TiO 3 calcined powder.
The calcining time is preferably 0.5 hours or more. If the calcining time is less than 0.5 hours, it tends to cause a composition shift.
The calcination of the raw material of the (BaR) [TiM] O 3 calcined powder is preferably performed in the air.
　(BaR)[TiM]O3仮焼粉の原料の仮焼温度を1100℃以上1300℃以下とすることがより好ましい。これにより、仮焼後の原料にBa濃度、Ti濃度が高い部分が残ることを抑制でき、Bi濃度が局所的に高くなる半導体磁器組成物を得やすくなる。 More preferably, the calcining temperature of the raw material of the (BaR) [TiM] O 3 calcined powder is 1100 ° C. or higher and 1300 ° C. or lower. Thereby, it can suppress that the part with high Ba density | concentration and Ti density | concentration remains in the raw material after calcination, and it becomes easy to obtain the semiconductor ceramic composition in which Bi density | concentration becomes high locally.
　(Step1)の工程により、Biの揮散が抑制されるとともに、Bi-Aの組成ずれを防止してA元素を含有する異相の生成を抑制できる。このため、得られる半導体磁器組成物の室温比抵抗ρを低下させるとともに、キュリー温度Ｔｃのバラツキを抑制することができる。 By the step (Step 1), the volatilization of Bi is suppressed, and the composition shift of Bi-A can be prevented to suppress the generation of a heterogeneous phase containing the A element. For this reason, while reducing the room temperature specific resistance (rho) of the obtained semiconductor ceramic composition, the variation in Curie temperature Tc can be suppressed.
　a/b≧2.0となるようにBET値を調整する方法は既に説明済みであるため、ここでの説明は省略する。 Since the method for adjusting the BET value so that a / b ≧ 2.0 has already been explained, the explanation here is omitted.
　次に、(BiA)TiO3仮焼粉と(BaR)[TiM]O3仮焼粉を混合する工程について説明する。この工程は図１の（Step2）に該当する。
　（Step2）で、各仮焼粉を所定量で配合した後、混合する。以後、この混合した原料を第3の原料と呼ぶことがある。
　混合は、純水やエタノールを用いた湿式混合または乾式混合のいずれでもよいが、乾式混合を行うと、組成ずれをより防止することができ好ましい。 Next, the process of mixing the (BiA) TiO 3 calcined powder and the (BaR) [TiM] O 3 calcined powder will be described. This step corresponds to (Step 2) in FIG.
In (Step 2), after mixing each calcined powder in a predetermined amount, they are mixed. Hereinafter, the mixed raw material may be referred to as a third raw material.
Mixing may be either wet mixing using pure water or ethanol, or dry mixing. However, it is preferable to perform dry mixing because the compositional deviation can be further prevented.
　次に、成形の工程について説明する。この工程は図１の（Step3）に該当する。
　第3の原料を所望の形状に成形する。成形前に必要に応じて粉砕粉を造粒装置によって造粒してもよい。成形後の成形体密度は2.5～3.5g／cm3が好ましい。 Next, the molding process will be described. This step corresponds to (Step 3) in FIG.
The third raw material is formed into a desired shape. You may granulate a pulverized powder with a granulator as needed before shaping | molding. The compact density after molding is preferably 2.5 to 3.5 g / cm 3 .
　次に、焼結の工程について説明する。この工程は図１の（Step4）に該当する。
　焼結は、焼結温度1300℃以上1450℃以下で行うことが好ましい。焼結温度が1300℃未満では焼結が不十分となる。焼結温度が1450℃を超えると抵抗温度係数αが小さくなったり耐熱性が低下してしまう。焼結温度は1420℃以下とすることがより好ましい。
　焼結雰囲気は大気中または還元雰囲気中、あるいは低酸素濃度の不活性ガス雰囲気で行うことが好ましい。例えば、酸素濃度200ppm以下の雰囲気中で焼結することにより、室温比抵抗ρを200Ωｃｍ以下に保ったまま、抵抗温度係数αが大きな半導体磁器組成物を得ることができる。
　焼結時間は１時間以上10時間以下とすることが好ましい。焼結時間が１時間未満では焼結が不十分となる。焼結時間が10時間を超えると、結晶粒内のBi濃度が均一化され抵抗温度係数αが小さくなってしまう可能性がある。さらに好ましい焼結時間は2時間以上6時間以下である。 Next, the sintering process will be described. This step corresponds to (Step 4) in FIG.
Sintering is preferably performed at a sintering temperature of 1300 ° C. or higher and 1450 ° C. or lower. If the sintering temperature is less than 1300 ° C, the sintering will be insufficient. If the sintering temperature exceeds 1450 ° C., the temperature coefficient of resistance α decreases or the heat resistance decreases. The sintering temperature is more preferably 1420 ° C. or lower.
The sintering atmosphere is preferably performed in the air, a reducing atmosphere, or an inert gas atmosphere having a low oxygen concentration. For example, by sintering in an atmosphere having an oxygen concentration of 200 ppm or less, a semiconductor ceramic composition having a large resistance temperature coefficient α can be obtained while keeping the room temperature specific resistance ρ at 200 Ωcm or less.
The sintering time is preferably 1 hour or more and 10 hours or less. If the sintering time is less than 1 hour, sintering is insufficient. When the sintering time exceeds 10 hours, there is a possibility that the Bi concentration in the crystal grains becomes uniform and the resistance temperature coefficient α becomes small. A more preferable sintering time is 2 hours or more and 6 hours or less.
　次に、上記の製造方法で得られる半導体磁器組成物について説明する。この半導体磁器組成物は、組成式が[(BiA)x(Ba1-yRy)1-x][Ti1-zMz]O3（AはNa,Li,Kのうち少なくとも一種、RはYを含む希土類元素のうち少なくとも一種、MはNb、Ta、Sbのうち少なくとも一種）で表わされ、x、y、ｚが、0＜x≦0.2、0≦y≦0.05、0≦z≦0.01（但し、ｙ＋ｚ＞0）を満足するものが好ましい。 Next, the semiconductor ceramic composition obtained by the above production method will be described. This semiconductor ceramic composition has a composition formula of [(BiA) x (Ba 1-y R y ) 1-x ] [Ti 1-z M z ] O 3 (A is at least one of Na, Li, and K, R is represented by at least one of rare earth elements including Y, M is represented by at least one of Nb, Ta, and Sb), and x, y, and z are 0 <x ≦ 0.2, 0 ≦ y ≦ 0.05, 0 ≦ Those satisfying z ≦ 0.01 (where y + z> 0) are preferred.
　ｘの範囲を0を超え0.2以下とすることでキュリー温度Ｔｃを130℃～200℃にすることができる。ｘが0.2を超えてしまうと異相ができ易くなるため好ましくない。 ∙ Curie temperature Tc can be set to 130 ° C to 200 ° C by setting the range of x to more than 0 and 0.2 or less. If x exceeds 0.2, it is not preferable because a different phase is easily formed.
　R、Mが共に添加されない組成（ｙ＝ｚ＝0）であると、室温比抵抗ρが200Ωｃｍを超えてしまうため、ｙ＋ｚ＞0とする。ただし、RとMの両方を必須とする必要はなく、少なくともどちらか一方を用いれば良い。 If the composition is such that neither R nor M is added (y = z = 0), the room temperature specific resistance ρ exceeds 200 Ωcm, so y + z> 0. However, both R and M are not necessarily required, and at least one of them may be used.
　ｚ＝0の時、R量を示すｙは、0＜y≦0.05が好ましい範囲である。yが0では組成物が半導体化せず、0.05を超えると室温比抵抗ρが大きくなるため好ましくない。yの値を変化させることで原子価制御ができる。但し、BaTiO3系酸化物におけるBaの一部をBiおよびAで置換した系において組成物の原子価制御を行う場合、3価の陽イオンを半導体化元素として添加すると半導体化の効果が1価のAイオンの存在のために低下し、室温比抵抗ρが高くなるという問題がある。そのため、より好ましい範囲は0.002≦y≦0.03である。Rは希土類（Sc,Y,La,Ce,Pr,Nd,Pm,Sm,Eu,Gd,Tb,Dy,Ho,Tb,Tm,Yb,Lu）から選ばれる少なくとも一種以上の元素であり、特にLa,Yが優れたPTC特性を得られるため好ましい。 When z = 0, y indicating the R amount is preferably in the range of 0 <y ≦ 0.05. If y is 0, the composition does not become a semiconductor, and if it exceeds 0.05, the room temperature resistivity ρ increases, which is not preferable. The valence can be controlled by changing the value of y. However, when the valence control of the composition is performed in a system in which a part of Ba in the BaTiO 3 oxide is substituted with Bi and A, the addition of a trivalent cation as a semiconducting element results in a monovalent effect. There is a problem that the room temperature resistivity ρ increases due to the presence of A ions. Therefore, a more preferable range is 0.002 ≦ y ≦ 0.03. R is at least one element selected from rare earths (Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Tb, Tm, Yb, Lu), particularly La and Y are preferable because excellent PTC characteristics can be obtained.
　ｙ＝0の時、M量を示すzは、0＜z≦0.01が好ましい範囲である。zが0では原子価制御ができずに組成物が半導体化せず、zが0.01を超えると室温比抵抗ρが高くなったりキュリー温度Ｔｃが低下するため好ましくない。より好ましい範囲は0.001≦ｚ≦0.005である。Mとして、特にNbが優れたPTC特性を得られるため好ましい。 When y = 0, z indicating the amount of M is preferably in the range of 0 <z ≦ 0.01. If z is 0, the valence cannot be controlled and the composition does not become a semiconductor, and if z exceeds 0.01, the room temperature resistivity ρ increases or the Curie temperature Tc decreases, which is not preferable. A more preferable range is 0.001 ≦ z ≦ 0.005. As M, Nb is particularly preferable because an excellent PTC characteristic can be obtained.
　組成式における(BiA)とは(Bi0.5A0.5）を指す。0.5は有効数字の範囲を含み、つまりは、BiとAの比は、Bi：A＝0.45：0.54～0.54：0.45の範囲である。この範囲内であれば異相の増大を抑制できるので、室温比抵抗ρの増大や経時変化を抑制できる。 (BiA) in the composition formula refers to (Bi 0.5 A 0.5 ). 0.5 includes a range of significant figures, that is, the ratio of Bi to A is in the range of Bi: A = 0.45: 0.54 to 0.54: 0.45. If it is within this range, the increase in the heterogeneous phase can be suppressed, so that the increase in room temperature resistivity ρ and the change with time can be suppressed.
　なお、上記原料の他にも焼結助剤としてSi原料、Ca原料を用いることができ、この場合は上記半導体磁器組成物の組成式にSi,Caが含まれることもある。 In addition to the above raw materials, Si raw materials and Ca raw materials can be used as sintering aids. In this case, Si and Ca may be included in the composition formula of the semiconductor ceramic composition.
　本発明を評価するにあたり、抵抗温度係数α、室温比抵抗ρの評価方法は以下のように行った。
（抵抗温度係数α）
　抵抗温度係数αは、半導体磁器組成物を恒温槽で室温25℃から270℃まで昇温しながら抵抗－温度特性を測定して算出した。
尚、抵抗温度係数αは次式で定義される。
　α＝(lnRL-lnRC)×100/(TL-TC)
　TLは270℃、RLはTL(270℃)における抵抗率、TCはキュリー温度、RCはTCにおける抵抗率である。ここでキュリー温度TCは抵抗率が室温比抵抗ρの2倍となる温度とした。 In evaluating the present invention, the evaluation methods of the resistance temperature coefficient α and the room temperature specific resistance ρ were performed as follows.
(Resistance temperature coefficient α)
The temperature coefficient of resistance α was calculated by measuring the resistance-temperature characteristics of the semiconductor ceramic composition while raising the temperature from room temperature 25 ° C. to 270 ° C. in a thermostatic bath.
The resistance temperature coefficient α is defined by the following equation.
α = (lnR L -lnR C ) × 100 / (T L -T C )
T L is 270 ° C., R L is the resistivity at T L (270 ° C.), T C is the Curie temperature, and R C is the resistivity at T C. Here the Curie temperature T C is resistivity and a temperature of which becomes 2 times the room temperature resistivity [rho.
（室温比抵抗ρ）
　半導体磁器組成物の室温比抵抗ρ（Ωcm）は、25℃、4端子法で測定した。 (Room temperature resistivity ρ)
The room temperature specific resistance ρ (Ωcm) of the semiconductor ceramic composition was measured at 25 ° C. by a four-terminal method.
（実施例1）
　(Step1)として以下の手順で作業を行った。
　先ず、原料として、(BiA)TiO3仮焼粉の原料と(BaR)[TiM]O3仮焼粉の原料をそれぞれ用意した。
　本実施例では、(BiA)TiO3仮焼粉の原料として、Na2CO3、Bi2O3、TiO2の原料粉末を準備し、BiとNaのモル比率Bi/Naが1.0の(Bi0.5Na0.5)TiO3となるように配合し、乾式混合した。また、(BaR)[TiM]O3仮焼粉の原料としてBaCO3、TiO2、La2O3の原料粉末を準備し、(Ba0.994La0.006)TiO3となるように配合し、純水で混合し、乾燥した。
　次に、(BiA)TiO3仮焼粉の原料と(BaR)[TiM]O3仮焼粉の原料をそれぞれ異なる温度で仮焼した。
　本実施例では、(BiNa)TiO3仮焼粉の原料は800℃で2時間大気中で仮焼し、(BaLa)TiO3仮焼粉の原料は1200℃で4時間大気中で仮焼した。
　次に(BiA)TiO3仮焼粉のBET値をa、(BaR)[TiM]O3仮焼粉のBET値をbとして、a/b≧2.0となるようにBET値を調整した。
　本実施例では、(BiNa)TiO3仮焼粉を、メディア径が５ｍｍのボールを用い、純水を媒体としてポットミルにより粉砕時間を変えて粉砕し、その後、乾燥した。また、(BaLa)TiO3仮焼粉は粉砕せずに使用した。なお試料番号1-9のみ、(BiNa)TiO3仮焼粉を、メディア径が０．１ｍｍのボールを用い、純粋を媒体としてビーズミルにより粉砕し、その後、乾燥した(Step1)。
　また、試料番号1-1には、(BiNa)TiO3仮焼粉の粉砕を行っていない。
　(BiNa)TiO3仮焼粉のBET値aと(BaLa)TiO3仮焼粉のBET値bを表１に示す。また、(BiNa)TiO3仮焼粉のBET値aを、(BaLa)TiO3仮焼粉のBET値bで割ったBET値の比a/bも表１に記載する。 (Example 1)
The following procedure was performed as (Step 1).
First, as a raw material, a raw material of (BiA) TiO 3 calcined powder and a raw material of (BaR) [TiM] O 3 calcined powder were prepared.
In this example, raw material powder of Na 2 CO 3 , Bi 2 O 3 and TiO 2 was prepared as a raw material for (BiA) TiO 3 calcined powder, and the Bi / Na molar ratio Bi / Na was 1.0 (Bi 0.5 Na 0.5 ) TiO 3 was blended and dry mixed. In addition, raw material powders of BaCO 3 , TiO 2 , and La 2 O 3 were prepared as raw materials for (BaR) [TiM] O 3 calcined powder, blended to become (Ba 0.994 La 0.006 ) TiO 3, and pure water And dried.
Next, the raw material of (BiA) TiO 3 calcined powder and the raw material of (BaR) [TiM] O 3 calcined powder were calcined at different temperatures.
In this example, the raw material of (BiNa) TiO 3 calcined powder was calcined in air at 800 ° C. for 2 hours, and the raw material of (BaLa) TiO 3 calcined powder was calcined in air at 1200 ° C. for 4 hours. .
Next, assuming that the BET value of the (BiA) TiO 3 calcined powder was a and the BET value of the (BaR) [TiM] O 3 calcined powder was b, the BET value was adjusted so that a / b ≧ 2.0.
In this example, the (BiNa) TiO 3 calcined powder was pulverized by using a ball having a media diameter of 5 mm, using pure water as a medium and changing the pulverization time by a pot mill, and then dried. The (BaLa) TiO 3 calcined powder was used without being pulverized. For sample number 1-9 only, (BiNa) TiO 3 calcined powder was pulverized by a bead mill using a ball having a media diameter of 0.1 mm and pure as a medium, and then dried (Step 1).
Sample No. 1-1 was not pulverized from (BiNa) TiO 3 calcined powder.
(BiNa) a BET value b of TiO 3 and BET value a calcined powder (BaLa) TiO 3 calcined powder shown in Table 1. Moreover, the BET value a (BiNa) TiO 3 calcined powder, also described in Table 1 the ratio a / b of the BET value divided by the BET value b of (BaLa) TiO 3 calcined powder.
　その後、(BiA)TiO3仮焼粉と(BaR)[TiM]O3仮焼粉を混合した(Step2)。
　本実施例では、(BiNa)TiO3仮焼粉と(BaLa)TiO3仮焼粉を、[(Bi0.5Na0.5)0.085(Ba0.994La0.006)0.915]TiO3となるように混合した。この材料を純水を媒体としてポットミルにより混合、粉砕し、その後、乾燥させて第3の原料とした。 Thereafter, (BiA) TiO 3 calcined powder and (BaR) [TiM] O 3 calcined powder were mixed (Step 2).
In this example, (BiNa) TiO 3 calcined powder and (BaLa) TiO 3 calcined powder were mixed so as to be [(Bi 0.5 Na 0.5 ) 0.085 (Ba 0.994 La 0.006 ) 0.915 ] TiO 3 . This material was mixed and pulverized with a pot mill using pure water as a medium, and then dried to obtain a third raw material.
　また本実施例では、(BiNa)TiO3仮焼粉と(BaLa)TiO3仮焼粉を反応させるため、第3の原料を1150℃で４時間大気中で熱処理を行った(図示せず)。
　その後、第3の原料に対して、Y原料としてY2O3を1.5mol%、Ba6Ti17O40を0.74mol%、CaCO3を2mol%加えた。その後、純水を媒体としてポットミルにより混合、粉砕した後、乾燥させた(図示せず)。 In this example, in order to react (BiNa) TiO 3 calcined powder and (BaLa) TiO 3 calcined powder, the third raw material was heat-treated in air at 1150 ° C. for 4 hours (not shown). .
Thereafter, 1.5 mol% of Y 2 O 3 , 0.74 mol% of Ba 6 Ti 17 O 40 and 2 mol% of CaCO 3 were added as the Y raw material to the third raw material. Thereafter, the mixture was mixed and pulverized with a pot mill using pure water as a medium, and then dried (not shown).
　その後、成形した(Step3)。本実施例では、第3の原料に対してPVAを10質量％添加し、混合した後、造粒装置にて造粒した。得られた造粒粉を一軸プレス装置で成形し、その後、700℃で脱バインダーした。 After that, it was molded (Step 3). In this example, 10% by mass of PVA was added to the third raw material, mixed, and then granulated with a granulator. The obtained granulated powder was molded with a uniaxial press machine, and then debindered at 700 ° C.
　その後、焼結した(Step4)。本実施例では、1400℃、4時間保持で窒素中、酸素濃度0.01vol％（100ｐｐｍ）の条件にて焼結し、焼結体を得た。 After that, it was sintered (Step 4). In this example, sintering was performed at 1400 ° C. for 4 hours under nitrogen at an oxygen concentration of 0.01 vol% (100 ppm) to obtain a sintered body.
　得られた焼結体を10mm×10mm×1mmの板状に加工して試験片を作製し、オーミック電極を塗布し、さらにカバー電極を塗布して180℃で乾燥後600℃、10分保持で焼き付けて電極を形成した。
　測定した室温比抵抗ρ、キュリー温度Tc、抵抗温度係数αを表1に示す。 The obtained sintered body is processed into a plate of 10 mm x 10 mm x 1 mm to prepare a test piece, an ohmic electrode is applied, a cover electrode is further applied, dried at 180 ° C and then held at 600 ° C for 10 minutes. An electrode was formed by baking.
Table 1 shows the measured room temperature specific resistance ρ, Curie temperature Tc, and resistance temperature coefficient α.
Figure JPOXMLDOC01-appb-T000001
   　 
(試料番号に*が付くものは比較例の結果を示す)
Figure JPOXMLDOC01-appb-T000001
(Sample numbers marked with * indicate the results of comparative examples)
　粉砕を行わない状態では、(BiNa)TiO3仮焼粉のBET値aは1.28、(BaLa)TiO3仮焼粉のBET値bは0.81である(試料番号1-1)。この比較例の仮焼粉はそのBET値の比a/bが1.6であり、この仮焼粉を用いて得られた半導体磁器組成物は室温比抵抗ρが46.2Ω・cmである。
　対して、BET値の比a/bが2.0倍以上となる(BiNa)TiO3仮焼粉と(BaLa)TiO3仮焼粉を用いた本実施形態試料番号1-2～1-8では、室温比抵抗ρは45.0Ω・cm以下であり、かつ、BET値の比が大きくなるほど室温比抵抗ρが小さくなる傾向があることがわかる。
　また、本実施形態試料番号1-9は、試料番号1-8に比べて若干室温比抵抗ρが大きくキュリー温度Ｔｃも小さくなっているが、比較例の試料番号1-1に比べて小さい室温比抵抗ρと高いキュリー温度Ｔｃを持つ半導体磁器組成物である。
  In a state that does not perform grinding, the BET value a (BiNa) TiO 3 calcined powder 1.28, the BET value b of (BaLa) TiO 3 calcined powder is 0.81 (Sample No. 1-1). The calcined powder of this comparative example has a BET value ratio a / b of 1.6, and the semiconductor ceramic composition obtained using this calcined powder has a room temperature resistivity ρ of 46.2 Ω · cm.
On the other hand, in the present embodiment sample numbers 1-2 to 1-8 using the (BiNa) TiO 3 calcined powder and the (BaLa) TiO 3 calcined powder, the BET value ratio a / b is 2.0 times or more. It can be seen that the room temperature resistivity ρ is 45.0 Ω · cm or less, and the room temperature resistivity ρ tends to decrease as the BET value ratio increases.
In addition, sample number 1-9 of this embodiment has a slightly higher room temperature resistivity ρ and a lower Curie temperature Tc than sample number 1-8, but a lower room temperature than sample number 1-1 of the comparative example. It is a semiconductor ceramic composition having a specific resistance ρ and a high Curie temperature Tc.
（実施例２）
　(BaLa)TiO3仮焼粉のBET値bを変えて実験を行った。
　(BaLa)TiO3仮焼粉の原料の仮焼温度を1150℃(試料番号2-1)、1175℃(試料番号2-2)、1300℃(試料番号2-3)とした以外は実施例１の試料番号1-5と同様にして仮焼粉の作製を行った。
　(BiNa)TiO3仮焼粉のBET値aと(BaLa)TiO3仮焼粉のBET値bを表2に示す。また、BET値の比a/bも表2に記載する。
　その後、試料番号1-5と同様にして、焼結体の製造と加工、及び電極の焼き付けを行った。測定した室温比抵抗ρ、キュリー温度Tc、抵抗温度係数αを表2に示す。 (Example 2)
Experiments were performed by changing the BET value b of the (BaLa) TiO 3 calcined powder.
(BaLa) TiO 3 Example except that the calcining temperature of the raw material of calcined powder was 1150 ° C (sample number 2-1), 1175 ° C (sample number 2-2), 1300 ° C (sample number 2-3) The calcined powder was prepared in the same manner as in Sample No. 1-5.
(BiNa) a BET value b of TiO 3 and BET value a calcined powder (BaLa) TiO 3 calcined powder are shown in Table 2. The BET value ratio a / b is also shown in Table 2.
Thereafter, in the same manner as in Sample No. 1-5, the sintered body was manufactured and processed, and the electrode was baked. Table 2 shows the measured room temperature specific resistance ρ, Curie temperature Tc, and resistance temperature coefficient α.
Figure JPOXMLDOC01-appb-T000002
  
Figure JPOXMLDOC01-appb-T000002
  
　(BaLa)TiO3仮焼粉のBET値bを1.67～0.20m2/gの範囲で変えても、BET値の比a/bが2.0倍以上となる(BiNa)TiO3仮焼粉と(BaLa)TiO3仮焼粉を用いた本実施形態の試料番号2-1～2-3は、室温比抵抗ρは45.0Ω・cm以下であり、比較例であるBET値の比a/bが1.6の試料番号1-1の室温比抵抗(46.2Ω・cm)と比較して小さい値を持つPTC素子が得られた。 Even if the BET value b of the (BaLa) TiO 3 calcined powder is changed in the range of 1.67 to 0.20 m 2 / g, the BET value ratio a / b becomes 2.0 times or more. (BiNa) TiO 3 calcined powder and ( Sample numbers 2-1 to 2-3 of this embodiment using BaLa) TiO 3 calcined powder have a room temperature resistivity ρ of 45.0 Ω · cm or less, and a BET ratio a / b as a comparative example is A PTC element having a smaller value than the room temperature specific resistance (46.2 Ω · cm) of sample number 1-1 of 1.6 was obtained.
　本発明を詳細にまた特定の実施態様を参照して説明したが、本発明の精神と範囲を逸脱することなく様々な変更や修正を加えることができることは当業者にとって明らかである。
　本出願は、2014年1月31日出願の日本特許出願（特願2014-016617）に基づくものであり、その内容はここに参照として取り込まれる。 Although the present invention has been described in detail and with reference to specific embodiments, it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the spirit and scope of the invention.
This application is based on a Japanese patent application filed on January 31, 2014 (Japanese Patent Application No. 2014-016617), the contents of which are incorporated herein by reference.
　本発明によれば、キュリー温度Tcを大きく、かつ、室温比抵抗ρを小さく調整することが可能である新規な半導体磁器組成物の製造方法が提供される。 According to the present invention, there is provided a novel method for producing a semiconductor ceramic composition capable of adjusting the Curie temperature Tc and increasing the room temperature specific resistance ρ.

Claims (12)

  1. 　(BiA)TiO3（AはNa,Li,Kのうち少なくとも一種）仮焼粉と、(BaR)[TiM]O3（RはYを含む希土類元素のうち少なくとも一種、MはNb、Ta、Sbのうち少なくとも一種であり、R,Mはどちらか一方が必須である）仮焼粉を用意し、前記(BiA)TiO3仮焼粉と前記(BaR)[TiM]O3仮焼粉を混合し、その後、成形、焼結する半導体磁器組成物の製造方法であって、
    　前記(BiA)TiO3仮焼粉と前記(BaR)[TiM]O3仮焼粉を混合する前に、前記(BiA)TiO3仮焼粉のBET値をa、前記(BaR)[TiM]O3仮焼粉のBET値をbとして、a/b≧2.0にすることを特徴とする半導体磁器組成物の製造方法。     (BiA) TiO 3 (A is at least one of Na, Li, K) calcined powder and (BaR) [TiM] O 3 (R is at least one of rare earth elements including Y, M is Nb, Ta, Prepare a calcined powder (at least one of Sb, one of R and M is essential), and prepare the (BiA) TiO 3 calcined powder and the (BaR) [TiM] O 3 calcined powder. A method for producing a semiconductor porcelain composition that is mixed and then molded and sintered,
    Before mixing the (BiA) TiO 3 calcined powder and the (BaR) [TiM] O 3 calcined powder, the BET value of the (BiA) TiO 3 calcined powder is set to a, the (BaR) [TiM] A method for producing a semiconductor porcelain composition, wherein the BET value of the O 3 calcined powder is b and a / b ≧ 2.0.
  2. 　前記(BiA)TiO3仮焼粉と前記(BaR)[TiM]O3仮焼粉を用意する工程で、前記(BiA)TiO3仮焼粉にBET値ａを大きくする処理を施し、および／または、前記(BaR)[TiM]O3仮焼粉にBET値ｂを小さくする処理を施すことを特徴とする請求項１に記載の半導体磁器組成物の製造方法。 In the step of preparing the (BiA) TiO 3 calcined powder and the (BaR) [TiM] O 3 calcined powder, the (BiA) TiO 3 calcined powder is subjected to a treatment for increasing the BET value a, and / or Alternatively, the method for producing a semiconductor ceramic composition according to claim 1, wherein the (BaR) [TiM] O 3 calcined powder is subjected to a treatment for reducing a BET value b.
  3. 　前記(BiA)TiO3仮焼粉と前記(BaR)[TiM]O3仮焼粉を用意した後に、前記(BiA)TiO3仮焼粉にBET値ａを大きくする処理を施し、および／または、前記(BaR)[TiM]O3仮焼粉にBET値ｂを小さくする処理を施すことを特徴とする請求項１または２に記載の半導体磁器組成物の製造方法。 After preparing the (BiA) TiO 3 calcined powder and the (BaR) [TiM] O 3 calcined powder, the (BiA) TiO 3 calcined powder is subjected to a treatment for increasing the BET value a, and / or 3. The method for producing a semiconductor ceramic composition according to claim 1, wherein the (BaR) [TiM] O 3 calcined powder is subjected to a treatment for reducing a BET value b.
  4. 　前記(BaR)[TiM]O3仮焼粉の仮焼き温度を前記(BiA)TiO3仮焼粉を仮焼温度より高くして、前記(BaR)[TiM]O3仮焼粉の平均粒径を前記(BiA)TiO3仮焼粉の平均粒径より大きくし、前記BET値をa/b≧2.0にすることを特徴とする請求項２に記載の半導体磁器組成物の製造方法。 Wherein (BaR) [TiM] O 3 wherein the calcining temperature of the calcined powder (BIA) TiO 3 calcined powder was higher than the calcination temperature, the (BaR) [TiM] O 3 Average grain calcined powder 3. The method for producing a semiconductor ceramic composition according to claim 2, wherein a diameter is larger than an average particle diameter of the (BiA) TiO 3 calcined powder, and the BET value is a / b ≧ 2.0.
  5. 　前記(BiA)TiO3仮焼粉と前記(BaR)[TiM]O3仮焼粉を用意した後に、前記(BiA)TiO3仮焼粉に粉砕処理を施して前記(BiA)TiO3仮焼粉のBET値ａを大きくする、請求項３に記載の半導体磁器組成物の製造方法。 After preparing the (BiA) TiO 3 calcined powder and the (BaR) [TiM] O 3 calcined powder, the (BiA) TiO 3 calcined powder is pulverized to give the (BiA) TiO 3 calcined powder. The method for producing a semiconductor ceramic composition according to claim 3, wherein the BET value a of the powder is increased.
  6. 　前記BET値aは、1.0m2/g以上30m2/g以下であることを特徴とする請求項１から５のいずれか一項に記載の半導体磁器組成物の製造方法。 The method for producing a semiconductor ceramic composition according to claim 1, wherein the BET value a is 1.0 m 2 / g or more and 30 m 2 / g or less.
  7. 　前記BET値bは、0.1m2/g以上15m2/g以下であることを特徴とする請求項１から５のいずれか一項に記載の半導体磁器組成物の製造方法。 The method for producing a semiconductor ceramic composition according to claim 1, wherein the BET value b is 0.1 m 2 / g or more and 15 m 2 / g or less.
  8. 　前記半導体磁器組成物は、組成式が[(BiA)x(Ba1-yRy)1-x][Ti1-zMz]O3（AはNa,Li,Kのうち少なくとも一種、RはYを含む希土類元素のうち少なくとも一種、MはNb、Ta、Sbのうち少なくとも一種）で表わされ、x、y、ｚが、0＜x≦0.2、0≦y≦0.05、0≦z≦0.01（但し、ｙ＋ｚ＞0）を満足することを特徴とする請求項１から７のいずれか一項に記載の半導体磁器組成物の製造方法。 The semiconductor ceramic composition has a composition formula of [(BiA) x (Ba 1-y R y ) 1-x ] [Ti 1-z M z ] O 3 (A is at least one of Na, Li, and K, R is represented by at least one of rare earth elements including Y, M is represented by at least one of Nb, Ta, and Sb), and x, y, and z are 0 <x ≦ 0.2, 0 ≦ y ≦ 0.05, 0 ≦ The method for producing a semiconductor ceramic composition according to claim 1, wherein z ≦ 0.01 (y + z> 0) is satisfied.
  9. 　前記焼結は1300℃以上1450℃以下で行うことを特徴とする請求項１から８のいずれか一項に記載の半導体磁器組成物の製造方法。 The method for producing a semiconductor ceramic composition according to any one of claims 1 to 8, wherein the sintering is performed at 1300 ° C or higher and 1450 ° C or lower.
  10. 　請求項１から９のいずれかの製造方法で得られた半導体磁器組成物。 A semiconductor ceramic composition obtained by the production method according to claim 1.
  11. 　請求項１０に記載の半導体磁器組成物に電極を形成したことを特徴とするＰＴＣ素子。 A PTC element comprising an electrode formed on the semiconductor ceramic composition according to claim 10.
  12. 　請求項１１のＰＴＣ素子を用いた発熱体モジュール。
          A heating element module using the PTC element according to claim 11.
PCT/JP2015/052182 2014-01-31 2015-01-27 Manufacturing method for semiconductor ceramic composition, semiconductor ceramic composition, ptc element, and heating element module WO2015115421A1 (en)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02106903A (en) * 1988-10-17 1990-04-19 Nippon Tungsten Co Ltd High-temperature ptc thermistor and manufacture thereof
JPH10218660A (en) * 1997-01-31 1998-08-18 Matsushita Electric Ind Co Ltd Barium titanate/based semiconductor porcelain material and production of semiconductor porcelain by using the same
WO2013157649A1 (en) * 2012-04-20 2013-10-24 日立金属株式会社 Semiconductor ceramic composition, method for producing same, and ptc element

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPH02106903A (en) * 1988-10-17 1990-04-19 Nippon Tungsten Co Ltd High-temperature ptc thermistor and manufacture thereof
JPH10218660A (en) * 1997-01-31 1998-08-18 Matsushita Electric Ind Co Ltd Barium titanate/based semiconductor porcelain material and production of semiconductor porcelain by using the same
WO2013157649A1 (en) * 2012-04-20 2013-10-24 日立金属株式会社 Semiconductor ceramic composition, method for producing same, and ptc element

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