JPS6153119A - Lead-containing oxide powder and its preparation - Google Patents

Abstract

PURPOSE:To prepare a lead-containing oxide powder which can be sintered easily to form a sintered material having high density, by using an oxide powder containing >=2 kinds of metals in addition to lead as the constituent components, and distributing the lead component in higher concentration at the outer layer that at the inner part. CONSTITUTION:An oxide containing at least two kinds of metals as the constituent components or its precursor powder is prepared beforehand. A lead compound is added to the above oxide powder. The amount of the lead compound is stoichiometric amount to the powdery composition, or excess to the stoichiometric amount by <=8mol%. The mixture is calcined to 400-1,200 deg.C to obtain a lead-containing oxide powder containing at least two kinds of metals in addition to lead, as the constituent components, and containing the lead component at higher concentration in the outer layer than in the inner part.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of use in buried ore materials) The present invention provides an easily sinterable lead-containing oxide powder and a method for producing the same;
More specifically, we will discuss easily sinterable lead-containing oxide powders in which the lead content near the surface of the object is larger than in the inside of the powder, and oxides containing various metals constituting the lead-containing oxide powders, or their precursors. (Prior art and problems) Concerning a method for producing easily sinterable lead-containing oxide powder, which is characterized by firing the powder and a lead-containing compound at high temperatures and causing a reaction between them. Many of them are useful as piezoelectric materials, pyroelectric materials, etc. Therefore, there is a need for an easily sinterable lead-containing oxide powder that can yield a high-density sintered body by low-temperature firing, and a method for producing the same.

Conventionally, it has been known that sintering is promoted by adding lead in an amount larger than the stoichiometric amount. (“
"Powder and Powder Metallurgy", Vol. M17, No. 3, p. 116, Osamu Yamaguchi "Study on sintering of PbO and PZT") This is zirconium titanate to which lead oxide is added in an amount of 10 to 60% in excess of the stoichiometric amount. Acid lead is related to the so-called liquid phase sintering mechanism in which excess lead oxide generates a liquid phase during g8 sintering and promotes sintering. However, according to this method, excessive lead oxide remained in the sintered body, causing problems in electrical properties and mechanical properties. In addition, liquid phase sintering generally causes rapid sintering shrinkage in the initial stage of sintering, which causes the pores in the sintered body to become trapped and become residual pores, which has the disadvantage that the final density of the sintered body cannot be increased. Ta. This is limited to the example of lead zirconate titanate containing lead [! This is a common problem when producing compound sintered bodies.

(Another Means to Solve the Problems) The present invention promotes sintering by a liquid phase sintering mechanism, and produces a lead-containing oxide sinter with a composition in which the lead content is close to stoichiometric and has a high final sintering density. The object of the present invention is to provide an easily sinterable lead-containing oxide powder and a method for producing the same.

The first aspect of the present invention is an easily sinterable lead-containing oxide powder having a lead oxide layer on the surface of the various metal oxide powders or a surface layer having a higher lead content than the inside of the various metal oxide powders. The second invention is a step of preparing powder of an oxide or its precursor containing various metals constituting the lead-containing oxide powder in producing the lead-containing oxide powder. bl A step of adding and mixing a lead compound powder that forms the desired phase to the powder obtained in step (a), (C
1. The powder mixture obtained in the above (bl step) is heated to a temperature of 400~
This is a method for producing lead-containing oxide powder by combining each step of firing at 1200°C.

The present invention will be explained in more detail below. First, the first invention will be explained in order.

In the present invention, easily sinterable lead-containing oxide powder refers to the lead content determined by analyzing the composition of the entire powder sample by means such as chemical analysis or fluorescent X-ray dispersion. This powder is characterized by having a lead oxide layer on the surface of the powder or a surface layer having a higher lead content than the inside of the powder. Powder surface spotting methods include X-ray photoelectron spectroscopy, electron probe microanalysis, Auger electron spectroscopy, scanning Auger electron microscopy, particle beam excited X-ray spectroscopy, ion scattering spectroscopy, angle-resolved X-ray photoelectron spectroscopy, and vortices. Ford backscattering spectroscopy, atomic Zorobe field ion microscopy, secondary ion scattering spectroscopy, ion microprobe i
Examples include spectroscopic methods such as i-analysis method. Although any of these measurement methods can be used, a method using an X-ray photoelectron spectrometer is particularly preferred.

When the surface layer is a crystalline phase, analysis by powder X-Fuchi diffraction is particularly preferred. The diffraction peak intensity of the crystalline phase in the surface layer, such as lead oxide, or the crystalline phase with a higher lead content than in the interior of the powder, as measured by powder X-ray diffraction of the present invention, indicates the desired lead-containing oxide powder composition. 0.01 to 30%, more preferably 0.01 to 30% of the diffraction peak intensity of the lead oxide or lead-rich phase measured when the lead content is lead oxide or a lead-rich phase. 1-10
% lead-containing oxide powder. In addition, the required thickness of the surface layer of the powder, which has a higher lead content than the inside of the powder, varies depending on the sintering conditions. Although it varies depending on the time and other factors, the surface layer generally becomes a liquid phase under sintering conditions, and after sintering, the surface layer diffuses into the powder to form a uniform lead-containing oxide sintered phase, which is the desired phase. The thickness of the surface layer that becomes the aggregate is preferably 1 to 80% of the powder diameter.

However, it also depends on what kind of microstructure the lead-containing sintered body is intended for. For example, if a lead oxide layer or a phase with a high lead content is required at grain boundaries, the thickness of the surface layer is increased and the firing time is shortened as the firing conditions. On the other hand, if it is desired to eliminate a lead oxide layer or a phase with a high lead content at the grain boundaries, methods include reducing the thickness of the surface layer and increasing the firing time.

Next, the second invention will be explained. The second invention consists of three steps. Each step will be explained below in order.

The oxide powder containing various metals constituting the lead-containing oxide powder used in the present invention is a mixture of oxides of various metals or a solid solution or compound of various metals, in which various metals are uniformly distributed. is preferable, and those with small particle size and narrow particle size distribution are preferable.

Precursor powders are those that become oxides when reacting with lead-containing compounds, such as hydroxides, carbonates, oxalates, formates, etc., and mixtures thereof. It is preferable to form particles in which various metals are uniformly distributed as described above when the particle size is 1.
Preferably, the particle size distribution is narrow. The method for producing the powder of oxides containing various metals or their precursors constituting the lead-containing oxide powder is not particularly limited, and the Kokyu method is used, but it is possible to uniformly distribute the various metals. Preferred is a method in which a particle with a narrow particle size distribution is obtained by forming a particle with a small particle size distribution. These manufacturing methods are broadly classified into gas phase methods, liquid phase methods, and solid phase methods.

Starting with the gas phase method, there are the evaporation-condensation method and the gas phase chemical reaction method. The former is a method in which the raw material is heated to a high temperature using an arc or plasma jet to vaporize it, and then rapidly cooled by the large temperature gradient of the arc or plasma flame to coagulate it into particles. The latter gas phase chemical reaction method is based on a chemical reaction of volatile metal compound vapor, and includes thermal decomposition of a single chemical species and reaction between two or more chemical species.

Further, as liquid phase methods, there are, for example, a method of manufacturing by melting, such as a molten metal IIJl' method or a plasma jet method, and a method of manufacturing from a bath i'D' by precipitation formation or solvent removal.

To explain further, methods that involve precipitation □ formation include the coprecipitation method, homo-precipitation method, alkoxide method, and electrolyte method, while methods that involve solvent removal include spray drying, freeze-drying, and hot kerosene method. , liquid drying method, emulsion method, etc.
There is a so-called sol-gel method, which is an intermediate method between precipitation generation and solvent removal methods.

Examples of these solutions include aqueous solutions containing various amounts constituting the lead-containing oxide powder, such as acid solutions (nitric acid solution, hydrochloric acid solution), alkoxy 1 bath solution, etc. Examples of precipitants include alkaline solutions, water, alcohol bath solutions, various salts and their solutions, such as carbonates, and ShuI! ! Examples include di-salts and formates.

As a surface phase method, there is a method in which a solid phase reaction is repeatedly carried out by mixing and pulverizing various salts such as metal oxides and carbonates constituting the lead-containing oxide and calcining them.

Furthermore, even products produced from oxides containing various metals or precursors thereof that form the lead-containing oxide powder by the various methods described above or a combination thereof may be used as the raw material of the present invention. .

Examples of the lead-containing compound used in the present invention include glutin, lead, lead carbonate, cyclic lead carbonate, lead hydroxide, lead oxalate, lead formate, lead chloride, and the like.

In the present invention, the method of reacting the lead-containing oxide powder with a lead-containing compound and the powder of an oxide or its precursor containing various metals that release Tf# includes various metals constituting the lead-containing oxide powder. It is possible to mix a powder of a butyride containing lead or its precursor and a lead-containing compound using a conventional mixing method such as a mortar or ball mill, and then perform a high temperature treatment. It is preferable that the mixing be as thorough as possible to make it as uniform as possible, but since there is the problem of impurities being introduced during mixing, in the case of a ball mill, about 0.5 to 12 hours is appropriate.

Specifically, the method of high-temperature treatment includes calcination in a normal electric furnace or the like. At this time, in order to prevent evaporation of lead, as is generally done when calcining a lead-containing oxide, it is preferable to carry out the calcining in a sealed state or in a lead atmosphere. The calcination conditions are determined by analyzing the powder surface layer after calcination as described above or by evaluating it by powder X-source diffraction. Generally, the calcination temperature is 400-1
200°C, preferably 600 to 1000°C. The reason for this limitation is that if the temperature is less than 400°C, the solid phase reaction of the mixed powder will be insufficient, and if it exceeds 1200°C, the powder will become coarse.

In addition, as a method of reacting a powder of an oxide containing various metals constituting the lead-containing oxide powder or a powder of its precursor with a lead-containing compound, an ashigan compound containing various metals constituting the lead-containing oxide powder is used. Or, after mixing the powder of its precursor and a solution containing lead, such as an acidic aqueous solution containing lead ions or a lead alkoxide solution, the mixture is reacted with a precipitant, such as aqueous ammonia, ammonium carbonate, ammonium oxalate, an aqueous alcohol solution, or water. . By obtaining a mixture precipitate of a powder of an oxide or its precursor containing various metals constituting the lead-containing oxide powder and a lead-containing compound, the precipitate is washed, filtered, etc., and then dried. Another example is a method of high-temperature treatment.

The high temperature treatment method and conditions are the same as above. (Example) The present invention will be further described in detail below with reference to Examples.

Example 1 Zirconium oxide and titanium oxide were mixed so that the atomic ratio of zirconium to titanium was Ll, 52:0.48, and wet pulverization with a ball mill and calcination at a temperature of 900"C were repeated to form zirconium and titanium. An oxide powder containing the following was obtained.When measured by powder Xa diffraction, it was found to be a +TiO4 phase. After adding monoacid and mixing, the temperature is 800℃.
It was calcined for 1 hour. When this powder was examined by powder xMA diffraction, it was found that P b (Zy t T i )03
In addition to the phase, a peak of the lead oxide phase was observed, and the peak intensity was the same as the peak of the lead oxide phase measured by adding monoacid and mixing to obtain the Pb(ZY0-52 Tio, 4E1)03 composition. This corresponded to about 5% of the strength. In addition, when this powder was analyzed for composition, it was found that Pb1-ool (Zyo-51
9Tie-481) 03, and the lead content was approximately the same as chemical children's theoretical amount.
The heat shrinkage curve was measured for a sample molded at a pressure of .

As a result, as shown in FIG. 1, shrinkage started around 700°C. In addition, this powder was molded into a disc shape of 20mmφ at a molding pressure of 1DOO[1/-, and the temperature was 950'Q.
ro, pb(zr,'ri,)o3 was a single phase with a peak of the lead oxide phase (no cracks were observed, and it was a uniform sintered body.
When we measured the lead content in the depth direction of the powder using X-A lightning spectroscopy, we found that the lead content was very high near the surface and decreased in the depth direction. .

It can be seen that there is a layer with high lead content near the surface of the powder.

Ratio example 1 Fused zirconium, titanium oxide, and lead oxide were mixed with Pb (Zro
, sz Tio, 4s)031m, wet milling in a ball mill and calcination at 900°C were repeated to obtain Pb(Z'?0.52 Tio, 48)03 powder.

When examined by xH diffraction at the end of this powdered tree, Pb(ZY
, Ti)03 single phase, and no Pbo phase peak was observed. Did you analyze the composition of this powder bed? bx-oo1c
Zro, 519Tie, 481) 03, and the lead content was approximately stoichiometric C. In addition, dll+ was determined in the same manner as in Example 1. The heat shrinkage curve starts shrinking near 900'C4·y, as shown by the peak. This temperature was 200°C higher than in Example 1. In addition, when five pieces of the same material as in Example 1 were sintered at 950°C for 1 hour, the sintered density was 5.0.
It was 197'a''.

When the sintered body was crushed and powder XSJ diffraction was performed, Pb
(Zr, Ti)03 was a single phase, and when the lead content in the depth direction of the powder was measured using X-ray photoelectron spectroscopy, there was no significant difference in the lead content near the surface and inside. It was found that there was no layer with many buttock pieces.

Example 2 The same z, 'r:to, powder as used in Example 1 was added to a lead nitrate aqueous solution (gold arm degree 1.22 mo17)).
) and 0.52TiO-4803 and mixed with stirring. The resulting suspension was adjusted to pH with ammonium carbonate.
The mixture was dropped into a tank maintained at a temperature of 8 to obtain a slurry-like material. This was washed and dried in a filter pot, and then calcined once at 800°C for 1 hour. The heat shrinkage curve of the obtained powder was similar to that of Example 1, and the shrinkage started around 700'C. When sintered at a temperature of 950°C for 1 hour, the sintered density was 7.78. Example 3 Magnesium oxide, niobium oxide, titanium oxide, zirconium oxide, and manganese dioxide were mixed at a composition ratio (Mg''/3Nb
”/sun0・4375 Ti0・4375 zyo-
After mixing so that it becomes 125"0-035, the temperature is 9
After calcination at 00°C for 3 hours, wet grinding in a ball mill and further calcination at 900°C for 3 hours, lead oxide was reduced to a composition ratio of P.
b1. oo (Mgyo/SNb''/3) 0.4375
Tio・4375 Zro・125 was mixed and calcined for 1 hour at a temperature of 850°C. The resulting powder was examined by powder X-ray diffraction, and it was found that a perovskite phase and a very small amount of 3Pb O-2Nb2O5 phase peak were observed. I was seen. , as a result of composition transmission °, Pb(
Mgl/3N+)”/3) o-4375Tie, 43
75 Zro9.2s 03+0.035Mn02 composition.

! 611] was determined by photoelectron spectroscopy, and it was found that there was a large amount of lead near the surface of the powder bed. The lead was replaced with Pb (containing (gl/s IJb"/3) having the same composition as in Example 3. -4375T
i. -4375Zr-o-us 03 +0.035
MnO2 Tonaruyo 5 After FCinn, calcining at 900°C for 3 hours, wet grinding in a ball mill, and further heating at 900°C.
When the powder obtained by sintering for 06 hours was examined by powder x-ray diffraction, it was found to be almost the same as in Example 3, with the peaks of the perovskite phase and a very small amount of 3 pb O, 2 mb205 phase being observed. As a result of compositional analysis, Pb(M
gl/3Nb″/3)., 43f5Ti0.4375
zr 04125 o3+Q, 035 Mn○2 composition with ivy. Also, in the subtext of X-take photoelectron spectroscopy,
It was not observed that there were many lead-containing particles near the powder surface.

The heat shrinkage curve was similar to that of Comparative Example 1, and it was found that the shrinkage start temperature was 200° C. higher than that of Example 6.

! After sintering at 950°C for 3 hours, the sintered density was 5.
41 P/cjn," which was considerably lower than that of Example B, and almost no sintering occurred.

Example 4 Mg:Nb:Ti powders of magnesium oxide, niobium oxide, titanium oxide, zirconium oxide, and manganese oxide
:ZH:Mn molar ratio is 0.15:0.30:0
．． 40:015:0.035, wet milling with a ball mill and calcining at a temperature of 900°C were repeated. P'b (M
gl/3 Nb'/s) o, 4s Tie, 40 Zr
Pb(Mg1/3N1:1'
, /3) o-+s Tio・+o Zro-xs Os
In addition to the solid solution phase peak, lead oxide and lead niobate phases (
A peak of 3PbO, 2Nb2o5) was observed. The peak intensity of the lead oxide phase corresponded to about 3% of the peak intensity measured during sieving when mixing lead oxide. Further, compositional analysis of this powder revealed that the lead oxide content was approximately stoichiometric. When the heat shrinkage curve was measured, it was found that the shrinkage started at around 700°C.Also, when measured by X-ray photoelectron spectroscopy, it was found that the closer to the surface of the powder, the higher the lead content.

After sintering at 1050°C for 2 hours, the sintered density was 7.
A sintered body of 72 mm/m3 was obtained.

The heat shrinkage curve showed the same curve as Example 1, and the temperature was 700°C.
Contraction had begun nearby. When sintering was performed at a temperature of 950°C for 3 hours using the same method as in Example 1, the sintered density was 7.
．． Example 5 Lead oxide, zirconium oxide, and titanium were mixed in the composition ratio Pb:
z, : Ti-0,98: 0.52: 0.
48, wet pulverization using a ball mill and calcination at a temperature of 900° C. were repeated. The obtained powder was examined by powder xi diffraction and was found to have a single perovskite phase. Further lead oxide was added to this powder as pb:Zy-:Ti
-1,00: 0.52: 0.48 composition, and the properties of the powder bed obtained by calcining at 800°C for 1 hour after mixing were the same as in Example 1 (the composition of the present invention). Effects] The effects of the present invention are listed as follows.

1) With the product of the present invention, a high-density sintered body can be obtained at low firing rates.

2) According to the method of the present invention, the shrinkage start temperature is lowered.

[Brief explanation of the drawing]

The drawing is a diagram showing the relationship between temperature and shrinkage of molded bodies obtained by molding the powders of Example 1 of the present invention and Comparative Example 1. Patent Applicant: Denki Kagaku Kogyo Co., Ltd. Procedural Amendment September 13, 1980 Patent Application No. 172425 of 1980 2, Name of Invention Lead-containing oxide powder and its manufacturing method 6, Person making the amendment Related Patent Applicant Address 1-4-1 Yurakucho, Chiyoda-ku, Tokyo Name (3
29) Detailed explanation of the invention column 5 of Denki Kagaku Kogyo Co., Ltd. specification, content of amendment 5-1) The following sentence is added between lines 9 and 10 on page 15 of the specification. "The heat shrinkage curve shows a curve similar to Example 1, and
When sintering was performed at a temperature of 950°C for 3 hours using the same method as above, the sintered density was 7.6s g/cIr? A sintered body was obtained. 5-2) Delete "Heat shrinkage curve...obtained" from page 17, line 14 to 18 of the specification 0 Procedural amendment October 26, 1980 Director General of the Patent Office Manabu Shiga Tono Showa 1959 Patent Application No. 172425 2, Name of the invention Lead-containing oxide powder and its manufacturing method 3, Relationship with the amended person's case Patent applicant address 1-4-1 Yurakucho, Chiyoda-ku, Tokyo Name (6)
29) Add the following sentence between lines 8 and 9 of page 18 of the detailed description of the invention in the specification of Denki Kagaku Kogyo Co., Ltd., column 5 of the detailed description of the invention. Example 6 Composition ratio of magnesium oxide, niobium oxide, titanium oxide, zolconium oxide, and manganese dioxide (Mg 'A
Nb%) o-+37s 0-4375
After mixing to give 0.125" and 0.035, the temperature is 95
Powder 9 obtained by calcining for 0'05 hours, crushing in a ball mill for 10 hours, and repeating the above calcining and crushing twice.
．． 8056& was mixed with 25.52449 lead oxide and calcined at 780°C for 1 hour. When the obtained powder was examined by powder X-ray diffraction, peaks of the perovskite phase and the lead oxide phase were observed, and the peak intensity was 0.1 of the peak intensity of the lead oxide phase measured at the time when lead oxide was added and mixed.
It was equivalent to 1. Also, use this powder as IDDOICg/i
Molded into a 20Uφ disc shape at a pressure of 9.
After sintering at 50° for 1 hour, the sintered density was 7.78.
．． It was M3. Further, compositional analysis of this powder revealed that the lead oxide content was approximately stoichiometric. When the heat shrinkage curve was measured, it was found that the shrinkage started at around 700°C as in Example 1. Furthermore, measurements using X-ray photoelectron spectroscopy revealed that the closer the powder was to the surface, the higher the lead content. Example 7 Magnesium oxide, niobium oxide, and titanium oxide were mixed in the composition ratio (
Mg% co〃). After mixing so that , asTio, z,
After calcining at a temperature of 950° for 5 hours, it was crushed in a ball mill for 10 hours, and then the calcining and crushing were repeated 72 times (the powder obtained by repeating the calcining and crushing: *9.4284, lead oxide in F was 22.5432
I was added and mixed and calcined at a temperature of 780°C for 1 hour. When the obtained powder was examined by powder X-ray diffraction, peaks of perovskite phase and lead oxide phase were observed.
The strength was equivalent to 0.1% of the peak strength of the lead oxide phase measured at the time when lead oxide was added and mixed. When this powder was molded into a disk shape of 20 mm diameter under a pressure of 1000 kg/art2 and sintered for 7 times for 950001 hours, the sintered density was 7.701/c-. Further, compositional analysis of this powder revealed that the lead oxide content was approximately stoichiometric. When the heat shrinkage curve was measured, it was 70 as in Example 1.
Shrinkage started around 0°C. Furthermore, measurements using X-ray photoelectron spectroscopy revealed that the closer the powder was to the surface, the higher the lead content. Procedural amendment January 18, 1985 Manabu Shiga, Director General of the Patent Office1, Indication of the case Patent Application No. 172425 of 19822, Name of the invention Lead-containing oxide powder and its manufacturing method6, Amendments made Relationship with the case Patent applicant address 1-4-1 Yurakucho, Chiyoda-ku, Tokyo Name (3
29) Denki Kagaku Kogyo Co., Ltd. specification column 5, detailed explanation of the invention, contents of amendment 5-1) Between the first and second lines of page 7 of the specification, “various metal oxide powders” Specific examples of the constituent metals include Zr,
Ti, Mg, Nb, Mn, Sn, Z
n. 8″・A1 小°・0°・0°・ゞ”で１】、・0”・S
r, Ba, Ca, Cd, In, L
a, Se, Cu, Y. Examples include Yb, Te, and Re. ” to join. 5-2) On page 9 of the specification, line 8 “Lead-containing compound” is corrected to “Lead-containing compound powder,” and lines 11 and 12 are corrected to read “The particle size of lead compound powder is Although it varies depending on the particle size of the oxide containing various metals constituting the oxide powder or the powder of its precursor, fine particles are preferable, specifically 15 μm or less, more preferably 5 μm or less. is 1 μm or less.” is added. Procedure Neichi-Ten1ding (Voluntary) November 79, 1985

Claims (1)

[Scope of Claims] 1) Easily sinterable lead-containing oxide powder having a lead oxide layer on the surface of various metal oxide powders or a surface layer having a higher lead content than the inside of the various metal oxide powders. . 2) In producing the lead-containing oxide powder, (a) the step of preparing powder of an oxide or its precursor containing various metals constituting the lead-containing oxide powder, (b) the step of (a) ) adding and mixing an amount of lead compound powder to form the desired phase to the powder obtained in step (c) heating the powder mixture obtained in step (b) above at a temperature of 40°C.
A method for producing lead-containing oxide powder, which combines the steps of firing at 0 to 1200°C.