WO2008066119A1 - Céramique diélectrique et condensateur - Google Patents

Céramique diélectrique et condensateur Download PDF

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Publication number
WO2008066119A1
WO2008066119A1 PCT/JP2007/073060 JP2007073060W WO2008066119A1 WO 2008066119 A1 WO2008066119 A1 WO 2008066119A1 JP 2007073060 W JP2007073060 W JP 2007073060W WO 2008066119 A1 WO2008066119 A1 WO 2008066119A1
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Prior art keywords
parts
mass
terms
barium titanate
mol
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PCT/JP2007/073060
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English (en)
Japanese (ja)
Inventor
Katsuyoshi Yamaguchi
Ryota Kuki
Hiroaki Mino
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Kyocera Corporation
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Priority claimed from JP2007068614A external-priority patent/JP5137429B2/ja
Priority claimed from JP2007076138A external-priority patent/JP5137430B2/ja
Priority claimed from JP2007076140A external-priority patent/JP5137431B2/ja
Application filed by Kyocera Corporation filed Critical Kyocera Corporation
Priority to CN200780043818XA priority Critical patent/CN101541709B/zh
Publication of WO2008066119A1 publication Critical patent/WO2008066119A1/fr
Priority to US12/475,273 priority patent/US8107219B2/en

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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01G—CAPACITORS; CAPACITORS, RECTIFIERS, DETECTORS, SWITCHING DEVICES, LIGHT-SENSITIVE OR TEMPERATURE-SENSITIVE DEVICES OF THE ELECTROLYTIC TYPE
    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/002—Details
    • H01G4/018—Dielectrics
    • H01G4/06—Solid dielectrics
    • H01G4/08—Inorganic dielectrics
    • H01G4/12—Ceramic dielectrics
    • H01G4/1209—Ceramic dielectrics characterised by the ceramic dielectric material
    • H01G4/1218—Ceramic dielectrics characterised by the ceramic dielectric material based on titanium oxides or titanates
    • H01G4/1227—Ceramic dielectrics characterised by the ceramic dielectric material based on titanium oxides or titanates based on alkaline earth titanates
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B82—NANOTECHNOLOGY
    • B82Y—SPECIFIC USES OR APPLICATIONS OF NANOSTRUCTURES; MEASUREMENT OR ANALYSIS OF NANOSTRUCTURES; MANUFACTURE OR TREATMENT OF NANOSTRUCTURES
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    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/46—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates
    • C04B35/462—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates based on titanates
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    • C04B35/4682—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on titanium oxides or titanates based on titanates based on alkaline earth metal titanates based on barium titanates based on BaTiO3 perovskite phase
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    • H01B3/02—Insulators or insulating bodies characterised by the insulating materials; Selection of materials for their insulating or dielectric properties mainly consisting of inorganic substances
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    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3231—Refractory metal oxides, their mixed metal oxides, or oxide-forming salts thereof
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    • C04B2235/32—Metal oxides, mixed metal oxides, or oxide-forming salts thereof, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
    • C04B2235/3262—Manganese oxides, manganates, rhenium oxides or oxide-forming salts thereof, e.g. MnO
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    • C04B2235/34—Non-metal oxides, non-metal mixed oxides, or salts thereof that form the non-metal oxides upon heating, e.g. carbonates, nitrates, (oxy)hydroxides, chlorides
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    • H—ELECTRICITY
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    • H01G4/00—Fixed capacitors; Processes of their manufacture
    • H01G4/30—Stacked capacitors

Definitions

  • the present invention relates to a dielectric ceramic formed of crystal particles mainly composed of barium titanate and a capacitor using the dielectric ceramic for a dielectric layer.
  • Digital terrestrial broadcasting is about to be deployed in the near future when the spread of digital electronic devices such as mobile computers and mobile phones is remarkable.
  • Digital electronic devices that are receivers for terrestrial digital broadcasting include liquid crystal displays and plasma displays. Many digital LSIs are used in these digital electronic devices.
  • the capacitor used here is a multilayer ceramic capacitor having a high dielectric constant (for example, see Patent Document 1) when a high capacitance is required.
  • Patent Document 2 when importance is attached to temperature characteristics even at a low capacity, a temperature-compensated multilayer ceramic capacitor (see, for example, Patent Document 2) having a small capacitance change rate is employed.
  • the dielectric layer is composed of crystal grains of dielectric ceramics having ferroelectricity, so that the temperature change of the relative dielectric constant changes. There was a problem that the rate was large and the hysteresis in the electric field dielectric polarization characteristics was large.
  • Patent Document 1 JP 2001-89231 A
  • Patent Document 2 JP 2001-294481 A
  • the problem to be solved by the present invention is to provide a dielectric ceramic exhibiting a temperature characteristic of a high dielectric constant and a stable relative dielectric constant, and a capacitor using the dielectric ceramic.
  • the dielectric ceramic of the present invention is composed of crystal grains mainly composed of barium titanate and a grain boundary phase formed between the crystal grains, and the dielectric porcelain constituting the barium titanate.
  • 1 mol of magnesium 0.01 to 0.06 mol of magnesium in terms of MgO, 0007 to 0.03 monolayers in terms of YO, and 0.00002 to 0.03 monoles of manganese in terms of MnO
  • niobium is contained in an amount of 4.2-33.3 parts by Nb 2 O, and the average grain size of the crystal grains is 0.05-0.25 m is the special feature.
  • the magnesium is converted to MgO in an amount of 0.017 to 0.06 mol, and the yttrium is converted to an YO in the range of 0.005 to 0.00.
  • MgO in an amount of 0.017 to 0.06 mol
  • yttrium is converted to an YO in the range of 0.005 to 0.00.
  • the molar ratio of titanium to 1 mole of barium contained in 6 parts by mass and constituting the barium titanate is 0.97-0.98.
  • the dielectric ceramic according to the present invention with respect to 100 parts by mass of the barium titanate, 0.73-6.3 parts by mass of silicon in terms of SiO and 0.31-2. It is desirable to include part by mass.
  • the magnesium is converted to MgO in terms of 0.017 to 0.06 mol, and the yttrium is converted to YO.
  • the magnesium contains 0.01.01-.01 monole
  • the above manganese contains 0.01-0.0.03 monole in terms of MnO, and the niobium in terms of NbO in terms of 100 parts by mass of barium titanate.
  • the dielectric ceramic according to the present invention with respect to 100 parts by mass of the barium titanate, 0.73 to 6.3 parts by mass of silicon in terms of SiO and 0.31 to 2. It is desirable to contain 1 part by mass.
  • the magnesium is converted into MgO in terms of 0.017 to 0.06 mol, and the yttrium is converted to Y 2 O.
  • the capacitor of the present invention is composed of a laminate of a dielectric layer made of a dielectric ceramic and a conductor layer, and the dielectric ceramic has crystal grains mainly composed of barium titanate, and It consists of a grain boundary phase formed between crystal grains, and with respect to 1 mol of barium that constitutes the barium titanate, magnesium is 0.01 to 0.06 mol in terms of MgO and yttrium is 0.0 in terms of YO. 0007—0.03 Monole, Manganese containing 0.00002—0.03 Monole in terms of MnO
  • niobium is converted to NbO with respect to 100 parts by mass of the barium titanate.
  • the dielectric layer has a magnesium content of 0.017 to 0.06 mol in terms of MgO and the yttrium in terms of YO in terms of 1 mol of barium constituting the barium titanate.
  • ⁇ 0 ⁇ 01 monole manganese is converted to MnO 0 ⁇ 0 ⁇ 0 ⁇ 03
  • the niobium is contained in the amount of 6.3-15.6 parts by mass in terms of Nb 2 0, and the titanium is contained in 1 mol of barium constituting the barium titanate. It is desirable that the molar ratio is 0 ⁇ 97-0.98.
  • the dielectric porcelain may further include 0.73 to 6.3 parts by mass of silicon in terms of SiO and 0.3 to 0.3 in terms of boron with respect to 100 parts by mass of the barium titanate;! To 2.1. It is desirable to contain part by mass.
  • the dielectric layer has a magnesium content of 0.017 to 0.06 mol in terms of MgO and yttrium in terms of YO with respect to 1 mol of barium constituting the barium titanate.
  • ⁇ 0 ⁇ 01 monole containing manganese in 0 ⁇ 0 to 0 ⁇ 03 mol in terms of ⁇ , and niobium in terms of NbO with respect to 100 parts by mass of barium titanate 6.3-15.6 mass
  • 0.73 to 3.13 parts by weight of silicon in terms of SiO and 0.31 to 1.04 parts by weight of boron in terms of BO and It is desirable that the molar ratio of titanium to 1 mol of barium constituting barium titanate is 0.97-0.98.
  • the dielectric ceramic with respect to 100 parts by mass of the barium titanate, 0.73-6.3 parts by mass of silicon in terms of SiO and 0.31-2.1 parts by mass of lithium in terms of Li 2 O It is desirable to contain a part.
  • the dielectric layer has a magnesium content of 0.017 to 0.06 mol in terms of MgO and yttrium in terms of YO with respect to 1 mol of barium constituting the barium titanate.
  • ⁇ 0 ⁇ 01 monole containing manganese in 0 ⁇ 0 to 0 ⁇ 03 mol in terms of ⁇ , and niobium in terms of NbO with respect to 100 parts by mass of barium titanate 6.3-15.6 mass
  • To 1.04 parts by mass It is desirable that the molar ratio of titanium to 1 mol of barium constituting the barium titanate is 0 ⁇ 97 ⁇ 0.98.
  • the temperature change rate of the relative permittivity is smaller than that of a conventional dielectric ceramic having a ferroelectric property, and compared to a conventional dielectric ceramic having a paraelectric property.
  • High It is a dielectric constant, has a temperature characteristic of a stable relative dielectric constant, and can reduce spontaneous polarization.
  • liquid phase sintering can be performed, and firing at a low temperature (1100 to 1250 °) becomes possible.
  • liquid phase sintering can be performed, and firing at a low temperature (1100 to 1250 ° C.) becomes possible.
  • the dielectric layer is composed of a dielectric ceramic having a high dielectric constant and a stable relative dielectric constant and having a low spontaneous polarization.
  • a capacitor having a high capacity and stable capacitance-temperature characteristics can be formed.
  • FIG. 1 is a schematic cross-sectional view showing a capacitor according to first to third embodiments of the present invention.
  • FIG. 2 is a graph showing the X-ray diffraction results of Sample No. I-4 in Example I.
  • FIG. 3 is a drawing showing the rate of change in relative permittivity of Sample Nos. I-4, 33 and 34 in Example I.
  • FIG. 4 is a graph showing the dielectric polarization (V—Q) characteristics of Sample No. I-4 in Example I.
  • FIG. 5 is a graph showing the X-ray diffraction results of Sample No. II-4 in Example II.
  • FIG. 6 is a graph showing the X-ray diffraction results of Sample No. Ill-4 in Example III.
  • FIG. 1 is a schematic cross-sectional view showing the capacitor of this embodiment.
  • the dielectric ceramic of the present embodiment is mainly composed of barium titanate, and contains magnesium, yttrium, manganese and niobium.
  • the content of magnesium is MgO equivalent to 1 mol of barium. Containing 0.01 to 0.06 mole of yttrium in the range of 0007 to 0.03 monole in terms of YO and manganese in the range of 0.002 to 0.03 monole in terms of MnO and 100 parts by mass of the barium titanate.
  • Niobium converted to Nb O In 4.2 to 33.3 parts by mass.
  • the dielectric ceramic according to the present embodiment includes crystal grains mainly composed of barium titanate and a grain boundary phase formed between the crystal grains.
  • the grain boundary phase is an amorphous or other crystalline phase caused by the subcomponents such as magnesium, yttrium, manganese and niobium, and is formed by liquid phase sintering of barium titanate and these subcomponents. Is.
  • the average particle size of the crystal particles is 0.05 to 0.25 m.
  • the relative dielectric constant at room temperature (25 ° C) described later is 250 or more
  • the relative dielectric constant at 125 ° C is 230 or more
  • 25 ° C The temperature coefficient of relative dielectric constant between ⁇ 125 ° C (( ⁇ - ⁇ ) / ⁇ (125 ⁇ 25)) in absolute value 100
  • 0 can be a chi 10- 6 / ° c or less, an electric field - to be able to form small dielectric ceramic hysteresis in the dielectric polarization characteristics / it is advantageous cormorants.
  • the dielectric ceramic according to the present embodiment is obtained by dissolving magnesium, yttrium, manganese, and niobium in barium titanate.
  • magnesium, yttrium, manganese, and niobium are solid-dissolved in barium titanate, which has a tetragonal crystal structure and strong conductivity, and crystal grains mainly composed of barium titanate in which these components are dissolved.
  • the average particle size of the particles in the range of 0.05 to 0. 25 m, the crystal structure of the crystal particles can be mainly composed of a cubic system.
  • the ferroelectricity due to the tetragonal crystal structure is reduced, the paraelectricity can be increased, and the spontaneous polarization can be reduced by increasing the paraelectricity.
  • niobium has a function of suppressing the coarsening of crystal grains mainly composed of barium titanate, and niobium is converted into Nb 2 O in terms of Nb 2 O with respect to 100 parts by mass of barium titanate. . Contains 3 parts by mass.
  • the dielectric constant of the dielectric ceramic is high, but the temperature coefficient of the relative dielectric constant is large. It will be a thing.
  • the niobium content relative to 100 parts by weight of barium titanate is more than 33.3 parts by weight in terms of NbO, the relative dielectric constant at 25 ° C will be lower than 250.
  • the relative dielectric constant at 125 ° C. is less than 230.
  • magnesium, yttrium, and manganese are as follows. Magnesium is converted to Mg ⁇ O ⁇ 01—0.06 mol, and yttrium is converted to Y 2 O in terms of 1 ⁇ mol.
  • the dielectric constant of the dielectric ceramic is high, but the temperature coefficient of the relative permittivity becomes large.
  • the temperature coefficient of the dielectric constant of the dielectric ceramic is large.
  • the dielectric ceramic according to the present embodiment has an average particle size force of crystal particles mainly composed of barium titanate.
  • the crystal particles mainly composed of barium titanate have a cubic system. It has a crystalline structure as the main component, and has a small hysteresis in the electric field dielectric polarization characteristics and can exhibit characteristics close to paraelectricity.
  • the average particle size of the crystal particles mainly composed of barium titanate is smaller than 0.05 in, the contribution of orientation polarization is lost, so that the dielectric The relative dielectric constant of the ceramic body is reduced.
  • the crystal structure mainly composed of cubic system means that the intensity of diffraction peak of (110) plane which is the strongest peak of cubic system barium titanate is larger than the intensity of diffraction peak of different phase. State.
  • the average charge of crystal grains is more preferably 0.14-0.18 111 in that the polarization charge at 0V can be 20 nC / cm 2 or less. I want it.
  • niobium, magnesium, yttrium and manganese contents are as follows. Magnesium in terms of MgO is 0 ⁇ 17-17.06 monole, and yttrium is in the YO equivalent of 0.005–0.01. Mono and Manganese in MnO conversion 0 ⁇ 01 ⁇ 0.03 Mono
  • the molar ratio of titanium to 1 mol of barium is 0 ⁇ 97-0.98.
  • Dielectric porcelain in this range has a relative permittivity at 25 ° C of 400 or more, a relative permittivity at 125 ° C of 380 or more, and a relative permittivity temperature coefficient of 400 X 10-6 / ° C or less in absolute value. It becomes possible to do.
  • the average particle diameter of the crystal particles mainly composed of barium titanate is determined by polishing a fracture surface of a sample having a dielectric ceramic force after firing, as described later, and then using a scanning electron microscope. This is a value obtained by taking a picture of the internal structure using the image, processing the contours of the crystal grains shown in the picture, treating each particle as a circle, determining its diameter, and averaging. More specifically, the magnification of the photograph is approximately 30000 times, the number of observation points is 3 for each sample, and the average value is obtained.
  • the relative dielectric constant at 25 ° C. and 125 ° C. is determined by using a dielectric ceramic force sample formed into a predetermined pellet shape and having a conductor film formed on the surface, as described later.
  • a meter 4284A manufactured by HP
  • Temperature coefficient of relative permittivity between 25 ° C and 125 ° C The numbers are calculated by applying the relative permittivity at 25 ° C and 125 ° C to the following formula (1).
  • BaCO powder, TiO powder, MgO powder, Y 2 O powder, and manganese carbonate (MnCO 3) powder each having a purity of 99% or more are used as the raw material powder.
  • These raw material powders are based on 1 mole of barium constituting barium titanate, MgO is 0.001-0.06 mono, Y0 is 0.007-0.03 monole, and MnCO is 0.00. 0002—0.03 Harm of monole 'J combination.
  • the mixture of the raw material powders described above is wet-mixed and dried, and then calcined at a temperature of 900 to 11100 ° C to prepare a calcined powder, and the calcined powder is pulverized.
  • the dielectric structure with a high dielectric constant that maintains the temperature characteristics of the relative dielectric constant close to normal dielectricity is obtained by growing the grains so that the crystal structure of the calcined powder is mainly cubic. It becomes possible to obtain porcelain.
  • the average particle size of the calcined powder is preferably 0.04-0 .; 1 m. Thereby, the expression of ferroelectricity can be suppressed in the calcined powder.
  • the average particle diameter of the calcined powder is determined by dispersing the calcined powder on a sample stage for an electron microscope, taking a picture with a scanning electron microscope, and The contour is image-processed, each powder is regarded as a circle, its diameter is obtained, and averaged.
  • Nb 2 O powder is mixed at a ratio of 4.0 to 32 parts by mass with respect to 100 parts by mass of the calcined powder. Thereafter, the mixed powder is formed into a pellet and fired in the air at a temperature range of 1150 ° C. to 1250 ° C., whereby the dielectric ceramic according to the present embodiment can be obtained.
  • the firing temperature is lower than 1150 ° C., the growth of the crystal grains and densification are suppressed, so that the density of the dielectric ceramic becomes low.
  • the firing temperature is higher than 1250 ° C In such a case, the crystal grains of the dielectric ceramic may grow too much.
  • the following capacitors can be formed.
  • the capacitor of this embodiment is one in which external electrodes 12 are provided at both ends of a capacitor body 10 as shown in FIG.
  • the capacitor body 10 is composed of a multilayer body 1 in which a plurality of dielectric layers 13 and a plurality of conductor layers 14 that are internal electrode layers are alternately laminated.
  • the dielectric layer 13 is formed by the dielectric ceramic of the present embodiment described above. That is, the dielectric layer 13 exhibits a temperature characteristic of a high dielectric constant and a stable relative dielectric constant, and by applying the dielectric ceramic having a small spontaneous polarization, the capacitance is higher than that of a conventional capacitor and the capacitance temperature characteristic is more stable. It becomes a simple capacitor. For this reason, when this capacitor is used in a power supply circuit, it is possible to suppress the generation of noise noise caused by electrically induced distortion.
  • the thickness of the dielectric layer 13 is preferably 1 to 30 m. In particular, if the thickness of the dielectric layer 13 is not more than m, there is an advantage that the capacitance of the capacitor can be increased by making the dielectric layer 13 thinner.
  • Base layer 14 such as Ni or Cu is desirable because conductor layer 14 can suppress manufacturing costs even when the number of layers is increased, and Ni is more advantageous in terms of simultaneous firing with dielectric layer 13. desirable.
  • the conductor layer 14 preferably has an average thickness of 1 m or less.
  • the above-mentioned mixed powder is formed into a green sheet.
  • a conductor paste to be the conductor layer 14 is prepared, printed on the surface of the green sheet, laminated and fired to form the laminate 1.
  • a conductor paste is further printed on both end faces of the laminate 1 and fired to form the external electrode 12, whereby the capacitor of this embodiment can be obtained.
  • the dielectric ceramic according to the present embodiment is mainly composed of barium titanate and contains magnesium, yttrium, manganese, niobium, silicon, and boron. Nesym is converted to MgO as 0 ⁇ 01—0.06 mol, Yttrium is converted to YO as 0 ⁇ 0007—0. 03 mol and manganese in an amount of 0 ⁇ 0002–0.03 mol in terms of MnO, and 4.2 to 33.3 parts by mass of niobium in terms of Nb 2 O with respect to 100 parts by mass of the barium titanate.
  • the dielectric ceramic according to the present embodiment includes crystal particles mainly composed of barium titanate and a grain boundary phase formed between the crystal particles, and the average particle size of the crystal particles is 0. 05 to 0.25 ⁇ m.
  • the relative dielectric constant at 25 ° C is 250 or more
  • the relative dielectric constant at 125 ° C is 230 or more
  • the temperature coefficient of relative permittivity between 125 ° C (( ⁇ - ⁇ ) / ⁇ (125 ⁇ 25))
  • Absolute value can below 1000 X 10- 6 / ° c, the field - dielectric polarization characteristics in the hysteresis small les, if capable of forming a dielectric ceramic Les is advantageous cormorants.
  • Such a dielectric ceramic according to the present embodiment includes magnesium, yttrium, manganese and niobium in solid solution in barium titanate, and silicon and boron are contained in the grain boundary phase.
  • magnesium, yttrium, manganese, and niobium are solid-dissolved in barium titanate having a tetragonal crystal structure and ferroelectricity, and the average particle size of crystal grains mainly composed of barium titanate is determined.
  • the crystal structure of the crystal grains can be mainly composed of cubic system.
  • the ferroelectricity due to the tetragonal crystal structure is lowered, the paraelectricity can be increased, and the spontaneous polarization can be reduced by increasing the paraelectricity.
  • the rate of change of the relative dielectric constant is the same as in the first embodiment.
  • the curve showing the curve becomes flat in the temperature range of -55 ° C to 125 ° C, and the hysteresis in the electric field-dielectric polarization characteristics is reduced. Therefore, it is possible to obtain a dielectric ceramic having a low relative dielectric constant temperature coefficient even though the relative dielectric constant is 250 or more.
  • the temperature coefficient of relative permittivity is The dielectric ceramic has a positive dielectric characteristic.
  • the temperature of the relative dielectric constant is increased. The coefficient can be reduced and the temperature characteristics can be flattened. In this case, the curve indicating the rate of change of the relative dielectric constant has two peaks centered at 25 ° C in the temperature range of -55 ° C to 125 ° C.
  • liquid phase sintering can be performed, and baking at a low temperature (1100 to 1250 ° C) becomes possible.
  • each of the oxides of niobium, silicon, and boron has a function of suppressing the coarsening of the crystal grains mainly composed of barium titanate, and two nibbs with respect to 100 parts by mass of barium titanate.
  • silicon is 0.73-6.3 parts by mass in terms of SiO
  • boron is 0.3 in terms of BO;! -2.1 parts by mass.
  • the dielectric constant of the dielectric ceramic is high, but the temperature coefficient of the relative permittivity is large. It will be a thing.
  • the niobium content relative to 100 parts by weight of barium titanate is more than 33.3 parts by weight in terms of NbO, the relative dielectric constant at 25 ° C will be lower than 250.
  • the relative dielectric constant at 125 ° C. is less than 230.
  • the silicon content relative to 100 parts by mass of barium titanate is less than 0.73 parts by mass in terms of SiO, or the boron content is less than 0.31 parts by mass in terms of B 2 O.
  • magnesium, yttrium, and manganese are as follows. Magnesium is converted to Mg ⁇ O ⁇ 01—0.06 mol in terms of MgO, and yttrium is converted to Y ⁇ O in terms of O ⁇ 0007—0.
  • the dielectric constant of the dielectric ceramic is high, but the temperature coefficient of the relative permittivity becomes large.
  • the temperature coefficient of the dielectric constant of the dielectric ceramic is large.
  • the dielectric ceramic of the present embodiment has an average particle size force of .05-0.25 ⁇ m of crystal particles mainly composed of barium titanate.
  • the barium titanate is the main component as in the first embodiment.
  • the crystal grains to be made have a crystal structure mainly composed of a cubic system, and have a small hysteresis force in the electric field dielectric polarization characteristics and exhibit characteristics close to paraelectricity.
  • the average particle size of the crystal grains containing barium titanate as the main component is smaller than 0.05 in, the contribution of orientational polarization is lost and the dielectric constant of the dielectric ceramic decreases.
  • the average particle diameter of the crystal grains is more preferably 0.15-0.2 111 in that the polarization charge at 0V can be 20 nC / cm 2 or less in the electric field dielectric polarization characteristics.
  • magnesium with respect to 1 mol of barium is in the form of Mg ⁇ O ⁇ 17 ⁇ -0.06 monole and yttrium force in terms of ⁇ .
  • Mg ⁇ O ⁇ 17 ⁇ -0.06 monole and yttrium force in terms of ⁇ .
  • 0015 ⁇ 0.01 Monore Manganese power 0.0 ⁇ 01 in terms of ⁇ ⁇
  • the dielectric ceramic of this range the definitive relative dielectric constant 25 ° C 400 or more, 380 or more relative dielectric constant at 125 ° C, the temperature coefficient of the dielectric constant in absolute value 400 X 10- 6 / ° C or less It becomes possible to. Next, a method for manufacturing the dielectric ceramic according to the present embodiment will be described.
  • BaCO powder with a purity of 99% or more TiO powder
  • MgO is 0.01 to 0.06 monole
  • YO is 0.00007 to 0.03 monole
  • MnCO is 0.00002 to 0 per mol of barium constituting barium titanate. .03
  • crystal particles mainly composed of barium titanate can be liquid phase sintered, and firing at a low temperature becomes possible.
  • ceramic particles have a force S, which is considered to facilitate grain growth, and the above composition can suppress grain growth during liquid phase sintering.
  • the mixed powder is formed into a pellet and fired in the air at a temperature range of 1100 ° C to 1250 ° C to obtain the dielectric ceramic according to the present embodiment.
  • the firing temperature varies with the amount of SiO and B 2 O added, but when the firing temperature is lower than 1100 ° C, it cannot be sufficiently densified and the density of the dielectric ceramic becomes low. On the other hand, if the firing temperature is higher than 1250 ° C, the crystal grains may grow too much.
  • the capacitor of this embodiment will be described.
  • the dielectric layer 13 shown in FIG. 1 exhibits temperature characteristics of a high dielectric constant and a stable relative dielectric constant, has a small spontaneous polarization, and is formed by the dielectric ceramic of this embodiment described above. /! Therefore, the capacitor of the present embodiment is a capacitor having a higher capacity and a more stable capacitance-temperature characteristic than the conventional capacitor, like the capacitor described in the first embodiment. For this reason, when this capacitor is used in a power supply circuit, it is possible to suppress the generation of noise noise due to the electrically induced distortion.
  • the dielectric ceramic according to the present embodiment is mainly composed of barium titanate and contains magnesium, yttrium, manganese, niobium, silicon and lithium. The content thereof is magnesium with respect to 1 mol of barium. Is converted to MgO as 0 ⁇ 01—0.06 mol, and yttrium is converted to YO as 0 ⁇ 0007—0
  • the dielectric ceramic according to the present embodiment includes crystal grains mainly composed of barium titanate and a grain boundary phase formed between the crystal grains, and the average grain size of the crystal grains is 0. 05 to 0.25 ⁇ m.
  • the relative dielectric constant at 25 ° C is 250 or more and the relative dielectric constant at 125 ° C, as in the first and second embodiments. Over 230 and 25 ° C ⁇ ; temperature coefficient of relative permittivity between 125 ° C (( ⁇ - ⁇ ) / ⁇ (125 ⁇ 25))
  • the absolute value can below 1000 X 10- 6 / ° c, the field - dielectric polarization hysteresis in the characteristic small les, if capable of forming a dielectric ceramic Les is advantageous cormorants.
  • magnesium, yttrium, manganese, and niobium are dissolved in barium titanate, and silicon and lithium are included in the grain boundary phase.
  • magnesium, yttrium, manganese, and niobium are dissolved in barium titanate having a tetragonal crystal structure and ferroelectricity, and the average particle size of crystal grains mainly composed of barium titanate is determined.
  • the crystal structure of the crystal grains can be mainly composed of cubic system.
  • the ferroelectricity due to the tetragonal crystal structure is lowered, the paraelectricity can be increased, and the spontaneous polarization can be reduced by increasing the paraelectricity.
  • the relative dielectric constant is obtained. Rate of change The curve showing is flat in the temperature range of ⁇ 55 ° C. to 125 ° C. In both cases, the hysteresis in the electric field-induced polarization characteristics is reduced. Therefore, it is possible to obtain a dielectric ceramic having a low relative dielectric constant temperature coefficient despite having a relative dielectric constant of 250 or more.
  • liquid phase sintering can be performed by containing silicon and lithium in a specific ratio, and firing at a low temperature (1100 to 1250 ° C) becomes possible.
  • each of the oxides of niobium, silicon, and lithium has a function of suppressing the coarsening of crystal grains mainly composed of barium titanate, and niobium is added to 100 parts by mass of barium titanate.
  • niobium is added to 100 parts by mass of barium titanate.
  • the dielectric constant of the dielectric ceramic is high, but the temperature coefficient of the relative dielectric constant is large. It will be a thing.
  • the niobium content relative to 100 parts by weight of barium titanate is more than 33.3 parts by weight in terms of NbO, the relative dielectric constant at 25 ° C will be lower than 250.
  • the relative dielectric constant at 125 ° C. is less than 230.
  • the silicon content relative to 100 parts by mass of barium titanate is less than 0.73 parts by mass in terms of SiO, or the lithium content is less than 0.31 parts by mass in terms of Li 2 O.
  • V in the case of firing at a low temperature (1100-; 1250 ° C), the dielectric porcelain cannot be densified and the relative dielectric constant may be lowered.
  • magnesium, yttrium, and manganese are 0 ⁇ 01—0.06 mol in terms of MgO and 0 ⁇ 0007—0 in terms of Y 2 O with respect to 1 mol of normium.
  • the temperature coefficient of the dielectric constant of the dielectric ceramic increases.
  • the yttrium content per mole of norium is 0.000 in terms of Y 2 O.
  • the dielectric constant of the dielectric ceramic is high, but the temperature coefficient of the relative permittivity becomes large.
  • the temperature coefficient of the dielectric constant of the dielectric ceramic is large.
  • the dielectric ceramic according to the present embodiment has an average particle size force of crystal particles mainly composed of barium titanate.
  • the crystal grains mainly composed of cubic have a crystal structure mainly composed of a cubic system, and the hysteresis in the electric field dielectric polarization characteristics is small and the characteristics close to paraelectricity can be obtained.
  • the average particle size of the crystal grains mainly composed of barium titanate is smaller than 0.05 m, the contribution of the orientation polarization is lost and the relative permittivity of the dielectric ceramic is lowered.
  • the average particle size of the crystal particles is larger than 0.25 m, a tetragonal crystal phase is observed in the measurement by X-ray diffraction, and the temperature coefficient of the dielectric constant of the dielectric ceramic becomes large.
  • the average grain size of the crystal grains is that the polarization charge at 0 V can be reduced to 20 nC / cm 2 or less.
  • the diameter is more preferably 0.15-0.2 111.
  • magnesium per mol of barium is 0.017—0.06 monole in terms of MgO and 0.05 in terms of yttrium force. ⁇ 0.01 Monore, Manganese power 0.0 in terms of ⁇
  • niobium is less than 100 parts by weight of barium titanate. 6. 0 5 conversion 3-15. 6 parts by weight, silicon 0.1 in Si_ ⁇ 2 terms 73-3. 13 parts by mass of Lithium is 0. In Li O terms 31-1. In the range of 04 parts by weight In addition, the molar ratio of titanium to 1 mole of barium is 0.997-0.98.
  • BaCO powder with a purity of 99% or more TiO powder
  • MgO is 0.01 to 0.06 monole
  • YO is 0.00007 to 0.03 monole
  • MnCO is 0.00002 to 0 per mol of barium constituting barium titanate. Mix in the proportion of 03 moles.
  • the dielectric ceramic of this embodiment can be obtained by forming the mixed powder into a pellet and firing it in the air at a temperature range of 1100 ° C to 1250 ° C.
  • the firing temperature changes with the amount of SiO or Li 2 O added.
  • the firing temperature is lower than 1100 ° C, it cannot be sufficiently densified and the density of the dielectric ceramic becomes low.
  • the firing temperature is higher than 1250 ° C, crystal grains may grow too much.
  • the capacitor of this embodiment will be described.
  • the dielectric layer 13 shown in FIG. 1 exhibits temperature characteristics of a high dielectric constant and a stable relative dielectric constant, has a small spontaneous polarization, and is formed by the dielectric ceramic of this embodiment described above. /! Gatsutsu
  • the capacitor according to the present embodiment is a capacitor having a higher capacity and a more stable capacitance-temperature characteristic than the conventional capacitor. For this reason, when this capacitor is used in a power supply circuit, it is possible to suppress the generation of noise caused by electrical induced distortion.
  • the evaluation sample was produced as follows. First of all, BaC with 99.9% purity
  • TiO powder, MgO powder, Y 2 O powder, and MnCO powder were prepared and mixed at the ratio shown in Table 1 to prepare a mixed powder.
  • the amounts of magnesium (Mg), yttrium (Y) and manganese (Mn) shown in Table 1 are the amounts corresponding to MgO, Y 2 O and MnO, respectively.
  • Titanium (Ti) is a molar ratio with respect to 1 mole of barium (Ba).
  • the mixed powder prepared above was calcined at a temperature of 1000 ° C. to prepare a calcined powder, and then the calcined powder obtained was pulverized to have the average particle size shown in Table 1.
  • a calcined powder was obtained.
  • the average particle size of the calcined powder is determined by dispersing the obtained calcined powder on a sample stage for an electron microscope, observing it with a scanning electron microscope, taking a picture, and taking the photograph of the calcined powder reflected in the photograph.
  • the contour was image-processed, each powder was regarded as a circle, its diameter was determined and averaged.
  • the magnification of the photo was 30000 times, the number of observation points was 3 for each sample, and the average value was obtained.
  • Nb 2 O powder having a purity of 99.9% was mixed at a ratio shown in Table 1 with respect to 100 parts by mass of the calcined powder.
  • This mixed powder was granulated and formed into pellets having a diameter of 16.5 mm and a thickness of 1 mm.
  • the average particle size of crystal particles mainly composed of barium titanate was determined as follows. First, the fracture surface of the fired sample is roughly polished with # 1200 abrasive paper, then polished with a 3 m diameter diamond paste applied on a hard buff, and then soft buffed. Alumina abrasive grains having a particle size of 0.3 m were applied on the surface, and finish polishing was performed. Next, after etching with an acidic aqueous solution (hydrochloric acid hydrogen fluoride), a photograph of the internal tissue was taken using a scanning electron microscope.
  • an acidic aqueous solution hydroochloric acid hydrogen fluoride
  • the magnitude of the electrically induced strain was obtained by measuring dielectric polarization (polarization charge).
  • the evaluation was made based on the amount of charge (residual polarization) at 0 V when the voltage was changed in the range of ⁇ 1250 V.
  • the composition analysis of the sample was performed by ICP (Inductively Coupled Plasma) analysis or atomic absorption analysis.
  • ICP Inductively Coupled Plasma
  • the obtained sample was mixed with boric acid and sodium carbonate, and the molten material was dissolved in hydrochloric acid.
  • qualitative analysis of the elements contained in the sample was performed by atomic absorption spectrometry, and then identified.
  • the diluted standard solution for each element was used as a standard sample and quantified by ICP emission spectroscopic analysis.
  • the amount of oxygen was determined using the valence of each element as the valence shown in the periodic table.
  • Table 1 shows the prepared composition, the average particle size of the calcined powder, and the firing temperature
  • Tables 2 and 3 show the average particle size and characteristics of the fired crystal particles (relative permittivity and temperature coefficient of relative permittivity). Absolute values, specific dielectric constant temperature change curves, and polarization charges) are shown.
  • the amount of Nb 2 O added in Table 1 is a ratio with respect to 100 parts by mass of the calcined powder.
  • the NbO content in Tables 2 and 3 is the titanium content in the dielectric ceramic (sample). It is a ratio with respect to 100 parts by mass of barium acid.
  • the amounts of Mg, Y and Mn shown in Tables 2 and 3 are oxide equivalents.
  • “average particle size of crystal particles” means the average particle size of crystal particles mainly composed of barium titanate.
  • “Absolute value of temperature coefficient of relative permittivity” in Tables 2 and 3 means the absolute value of the average value of the temperature coefficient of relative permittivity obtained above. In Tables 2 and 3, those with no circles in the curve of the relative dielectric constant temperature change are those for which the two peaks centered at 25 ° C were not observed. If the column is marked with a circle, it indicates that the polarization charge is less than 20nC / cm 2 ! /, And the sample.
  • the main component of barium titanate is 100 parts by mass of Nb 2 O.
  • the content of NbO is 6.3-15. 6 parts by mass, and titanium per mol of norm Sample Nos. I—3 to 5, 11, 12, 17 to; 19, 24, 25, 27
  • Fig. 2 shows the X-ray diffraction pattern of the dielectric ceramic of sample No. I-4 arbitrarily selected from these samples
  • Fig. 3 shows the graph showing the change in relative permittivity of the sample.
  • Figure 4 shows the electric field dielectric polarization characteristics.
  • Sample Nos. 1 33 and 34 which are samples outside the scope of the present invention, are shown for comparison.
  • the dielectric ceramic of Sample No. I-4 has a crystal structure mainly composed of a cubic system, and the temperature characteristics of relative permittivity is 25. It had two peaks centered around ° C, the rate of change of relative permittivity was small, and the hysteresis of electric field dielectric polarization characteristics was small. In addition, the other samples had a crystal structure mainly composed of a cubic system, and the rate of change in relative permittivity was small.
  • the evaluation sample was produced as follows. First, prepare BaCO powder, TiO powder, MgO powder, YO powder, and MnCO powder with a purity of 99.9%, and the proportions shown in Table 4 And mixed powder was prepared.
  • Example Nos. II— in Tables 5 and 6;! -45 The average particle size of the crystal particles mainly composed of barium titanate was determined in the same manner as in Example I.
  • Example I For these samples, which were dielectric ceramics, the dielectric constant, the temperature coefficient of the dielectric constant, and the polarization charge were determined in the same manner as in Example I. Further, the composition analysis of the sample was performed in the same manner as in Example I. Further, the oxygen amount was determined in the same manner as in Example I.
  • Table 4 shows the preparation composition, the average particle size and calcining temperature of the calcined powder, and Table 5 and Table 6 show the results of the average particle size and characteristics of the crystal particles after firing, respectively.
  • average particle size of crystal particles in Tables 5 and 6 means the average particle size of crystal particles mainly composed of barium titanate.
  • “Absolute value of temperature coefficient of relative permittivity” in Tables 5 and 6 means the absolute value of the average value of the temperature coefficient of relative permittivity. In Tables 5 and 6, those with no circles in the curve of the relative permittivity temperature change curve are those for which the two peaks centered at 25 ° C were not observed. The ones not marked with ⁇ in the column indicate that the polarization charge is not less than 20 nC / cm 2 ! /, Respectively.
  • Figure 5 shows the X-ray diffraction pattern of the dielectric ceramic of Sample No. II-4 arbitrarily selected from these samples. As shown in Fig. 5, the dielectric ceramic of Sample No. II-4 was mainly composed of cubic crystal.
  • samples outside the scope of the present invention (Sample Nos. 11-1, 1, 2, 9, 10, 16, 17, 23, 30, 33, 34, 40, 42 to 45) twenty five.
  • the force , or less than ⁇ conductivity force 250 at C of hysteresis to dielectric polarization, the temperature coefficient of the relative dielectric constant was in absolute value 1009 X 10- 6 / ° C or more.
  • Sample No. II-34 has not been evaluated due to insufficient sintering.
  • the evaluation sample was produced as follows. First, BaC O powder, TiO powder, MgO powder, YO powder, and MnCO powder each having a purity of 99.9% were prepared and mixed at the ratios shown in Table 7 to prepare a mixed powder. [0123] Next, after the mixed powder prepared above was calcined at a temperature of 1000 ° C to prepare a calcined powder, the obtained calcined powder was pulverized to have an average particle size shown in Table 7 A calcined powder was obtained. The average particle size of the calcined powder was determined in the same manner as in Example I.
  • Nb 2 O powder, SiO powder and Li 2 O powder with a purity of 99.9% were mixed in a proportion shown in Table 7 with respect to 100 parts by mass of the calcined powder.
  • This mixed powder was granulated and formed into a pellet shape having a diameter of 16.5 mm and a thickness of 1 mm.
  • Example Nos. Ill— 10 pellets of each composition were fired at a temperature shown in Table 7 in the air.
  • An indium gallium conductor layer was printed on the surface of the sample after firing to obtain a sample for evaluation of dielectric properties (Sample Nos. Ill— ;! to 45 in Table 8 and Table 9).
  • the average particle size of the crystal particles mainly composed of barium titanate was determined in the same manner as in Example I.
  • Example I For these samples, which were dielectric ceramics, the dielectric constant, the temperature coefficient of the dielectric constant, and the polarization charge were determined in the same manner as in Example I. Further, the composition analysis of the sample was performed in the same manner as in Example I. Further, the oxygen amount was determined in the same manner as in Example I.
  • Table 7 shows the preparation composition, the average particle size of the calcined powder, and the firing temperature, and Tables 8 and 9 show the results of the average particle size and characteristics of the crystal particles after firing.
  • the "average particle diameter of crystal grains” in Tables 8 and 9 means the average particle diameter of crystal grains mainly composed of barium titanate.
  • “Absolute value of temperature coefficient of relative permittivity” in Tables 8 and 9 means the absolute value of the average value of the temperature coefficient of relative permittivity.
  • those with no circle in the curve of the relative permittivity temperature change curve are those for which the two peaks centered at 25 ° C were not observed.
  • the ones not marked with ⁇ in the column indicate that the polarization charge is not less than 20 nC / cm 2 ! /, Respectively.
  • III-1 1 0.020 0.0007 0.010 0.980 8.5 1.5 0.5 0.1 1200
  • III-29 0.020 0.010 0.030 0.980 8.5 1.5 0.5 0.1 1200
  • III-36 0.020 0.010 0.010 0.980 8.5 2.5 0.5 0.1 1 170
  • sample No. Ill which is the dielectric ceramic of the present invention. -25 for 3-8, 11-15, 18- 22, 24-29, 31, 32, 35-39 and 41.
  • Contact Keru dielectric constant of 250 or more and C, and a dielectric constant of 230 or more at 125 ° C, 25 temperature coefficient of the dielectric constant at ⁇ 125 ° C is 1000 X 10- 6 / ° C or less in absolute value there were.
  • the relative permittivity at 25 ° C is 400 or more
  • the relative permittivity at 125 ° C is 380 or more
  • the relative permittivity temperature coefficient is absolute in no more than 400 X 10- 6 / ° C
  • relative dielectric constant change rate indicates to curve - has two peaks in a temperature range of 55 ° C ⁇ 125 ° C, and contact to the measurement of dielectric polarization ! / No big hysteresis was seen. No hysteresis was observed! /, And the sample had a polarization charge at 0 V! /, Which was less than 20 nC / cm 2 .
  • the dielectric porcelain of Sample No. Ill-4 has a crystal structure mainly composed of a cubic system.
  • A is the force ,, or ⁇ conductivity force less than 200 in the C of hysteresis to dielectric polarization, the temperature coefficient of the relative dielectric constant was in absolute value 1043 X 10- 6 / ° C or more. Sample No. Ill-34 has not been evaluated due to insufficient sintering.

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Abstract

La présente invention concerne une céramique diélectrique comprenant des grains cristallins essentiellement constitués de titanate de baryum. Cette céramique diélectrique contient de 0,01 à 0,06 mole de magnésium sous la forme de Mgo, de 0,0007 à 0,03 mole d'yttrium sous la forme de Y2O3 et de 0,0002 à 0,03 mole de manganèse sous la forme de MnO par mole du baryum constitutif du titanate de baryum ; elle contient également 4,2 à 33,3 parties en poids de niobium sous la forme de Nb2O5 pour 100 parties en poids du titanate de baryum. Les grains cristallins présentent une taille moyenne des particules de 0,05 à 0,25 µm. Est également décrit un condensateur composé d'un stratifié comportant une couche conductrice et une couche diélectrique constituée de ladite céramique diélectrique.
PCT/JP2007/073060 2006-11-29 2007-11-29 Céramique diélectrique et condensateur WO2008066119A1 (fr)

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CN200780043818XA CN101541709B (zh) 2006-11-29 2007-11-29 电介体瓷器及电容器
US12/475,273 US8107219B2 (en) 2006-11-29 2009-05-29 Dielectric ceramic and capacitor

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JP2006-321797 2006-11-29
JP2006321797 2006-11-29
JP2007-068614 2007-03-16
JP2007068614A JP5137429B2 (ja) 2006-11-29 2007-03-16 誘電体磁器およびコンデンサ
JP2007-076140 2007-03-23
JP2007-076138 2007-03-23
JP2007076138A JP5137430B2 (ja) 2007-03-23 2007-03-23 誘電体磁器およびコンデンサ
JP2007076140A JP5137431B2 (ja) 2007-03-23 2007-03-23 誘電体磁器およびコンデンサ

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JP2010052964A (ja) * 2008-08-27 2010-03-11 Murata Mfg Co Ltd 誘電体セラミックおよびその製造方法ならびに積層セラミックコンデンサ
US8383536B2 (en) * 2009-07-22 2013-02-26 Murata Manufacturing Co., Ltd. Dielectric ceramic and laminated ceramic capacitor

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JPH04349168A (ja) * 1991-05-27 1992-12-03 Tdk Corp セラミック誘電体材料、積層セラミックコンデンサおよび積層セラミックコンデンサの経時劣化防止方法
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JPH06251986A (ja) * 1993-02-25 1994-09-09 Taiyo Yuden Co Ltd 磁器コンデンサ及びその製造方法
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JP2001114559A (ja) * 1999-10-20 2001-04-24 Rohm Co Ltd 誘電体組成物
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JP2005145791A (ja) * 2003-11-19 2005-06-09 Tdk Corp 電子部品、誘電体磁器組成物およびその製造方法

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2010052964A (ja) * 2008-08-27 2010-03-11 Murata Mfg Co Ltd 誘電体セラミックおよびその製造方法ならびに積層セラミックコンデンサ
US8383536B2 (en) * 2009-07-22 2013-02-26 Murata Manufacturing Co., Ltd. Dielectric ceramic and laminated ceramic capacitor

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