JPH01133974A - Composition based on doped barium titanate - Google Patents

Abstract

PURPOSE: To produce the subject composition narrow in particle size distribution, having a dispersion property and having a grain size of submicron order, by using a specified doped BaTiO₃ as a base.

CONSTITUTION: A slurry containing at least one kind doping agent selected from an oxide of lanthanoide series, Co, Mn, Mg, Y, Bi, Al, B, W, Nb, Cr, Ni, Mo, Fe, Sb, V, Ta, Cu, Ag, Zn, Cd and Si, at least one kind hydrated oxide selected among TiO₂, SnO₂, ZrO₂ and the (hydrated) oxide of Ca is subjected to a hydrothermal treatment at ≤200°C, and after cooling to 60-150°C Ba(OH)₂ is added, and the slurry is kept at 70-100°C for 1-12 min, then heated to 120-225°C, and the composition expressed by formula ((x) and (y) are 0.9-1.1; 0<z<0.1; y, y' and y" are 0-0.3; y+y'+y"<0.4; 0<x'<0.4; D is an doping agent oxide) and having 0.05-0.4 μ average size of the primary particle is obtained.

COPYRIGHT: (C)1989,JPO

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to compositions based on barium titanate, and more particularly to dispersive, submicron, doped titanate having a narrow particle size distribution. It concerns the barium coforme.

Compositions based on barium titanate are used in the electronics industry to produce capacitors, capacitors, and PTCRs.
Widely used in the manufacture of devices (with positive humidity coefficient of resistance). Barium titanate is particularly effective and versatile in electronics applications because its electrical properties can be substantially modified by the incorporation of additives and/or dopants. . A frequently used additive is a MAO3 compound, where M is a divalent cation and A is a tetravalent cation, having a BaTiO3 pelkovskite structure. Typical additives include titanates, zirconates, and stannates of calcium, strontium, barium, and lead. Since the one or more additives have the same crystal structure as BaTiO3, they easily go into solid solution during calcination or sintering.

, generally the additive is a preparation based on more than 3 mol % BaTiO3. Dopants include a wide range of metal oxides. Generally, these are preparations based on less than 5 mol % of total BaTiO3. The one or more dopants used may be completely miscible with the velorskite lattice, partially miscible, or immiscible with the velorskite lattice. Examples of six dopants used include La, lantafide, Y, Nb5T
aSCtJ, MOLW, Mn, Fe, Go, Ni, zn
1Aj! , 3i, 3b and Bi oxides.

When carried out industrially, the production of preparations based on barium titanate can be carried out either by admixing the necessary pure titanates, zirconates, stannate, and doping agents, or by mixing barium, calcium, etc. , oxides such as titane, or oxide precursors (e.g. carbonates, hydroxides,
or by direct production of the desired powder, by subjecting a well-mixed mixture of appropriate stoichiometry of nitric acid salts) to a high temperature pre-reaction.Pure titanates, zirconates, Stannates and the like are also typically produced by high-temperature solid phase reaction methods.

Although prior art methods of producing barium titanate and barium titanate-based compositions by solid state reactions are relatively simple, they still suffer from notable disadvantages. First, the grinding step acts as a source of contaminants, which can adversely affect electrical properties.

Second, compositional inhomogeneities caused by incomplete mixing at the microscale can lead to the formation of undesirable phases such as barium orthotitanate, Ba2TiO4, and barium orthotitanate is may cause sensitive properties. Third, during calcination, substantial grain growth and interparticle sintering occurs. As a result,
The milled product consists of irregularly shaped broken agglomerates resulting in a wide particle size distribution ranging from about 0.2 microns to about 10 microns. Moreover, in as-built bodies in which such agglomerates are formed from agglomerate powders with a wide particle size distribution, high sintering temperatures are required and sintering with a wide particle size distribution It has been proven that it produces objects.

A number of techniques have been developed to attempt to overcome the limitations of conventional methods of pre-reaction. Gala Oher teaches the precipitation of either doped barium titanyl oxalate or doped barium titanyl oxalate in which the barium is partially substituted with strontium or lead and the titanium with zirconium.
], [Manufacture of Semiconducting Titanates by Chemical Methods 1, Journal of American Chemical Society [J, Aa+cr, Chem, Soc,] Volume 46, Page 359 (1963), Schley [5chre
"Influence of Dll on the chemical production of barium-strontium titanate", Journal of the American Ceramic Society [J, Al11cr, Cc
r, Soc, Volume 48, Page 401 (1965), and Vincenzini's [
"Chemical Preparation of Doped BaTiO3", Proceedings of the 12th International Conference on Science of Ceramics [5c
ience of Ceraa+ics] Volume 12,
151 pages (1983). The oxalate decomposes at high temperatures to produce doped barium titanate-based compositions. U.S. Patent No. 3.637゜531
In the teachings of that patent, a simple solution of a dopant, a titanium compound, and an alkaline earth salt is heated to form a semisolid mass, which is calcined to form the desired titanate-based product. convert it into The disclosure of U.S. Pat.
Blending with an aqueous slurry of SCa or MO carbonate precipitation. The solid is calcined to the desired product. Kakegawa et al., “Synthesis of Nb-doped barium titanate semiconductors by wet-dry combination technique 1,” Journal Materials Science Letters [J, Hat, S.
ci, Letsl vol. 4, p. 1266 (1985) describes a similar synthetic method.

v Luther [Hulderl's r B a T i O
3 and other ceramic powders by co-precipitation of citrate in alcohol", Ceramic Bretin [Ce
ramic Bulletin] Volume 49, pages 990-993 (1970), doped 5
Bioacids based on arto and sa■'to3 are produced by spraying an aqueous solution of the component citrate or formic salt into alcohol to cause dehydration and coprecipitation. Co-precipitated citrate or formate powder,
The calcined product consists primarily of closely packed spherules with particle sizes ranging from 3 to 10 microns. U.S. Pat. No. 4,061,583 discloses a doped BaTiO3 based solution prepared by adding a solution of either the nitrate or chloride of the required components to an alkaline aqueous solution containing hydrogen peroxide. A composition is described.

The peroxide-containing precipitate decomposes at about 100°C to form B
An amorphous composition based on a T i O3 is produced. If the amorphous product is calcined at about 600°C,
A crystalline powder is obtained. Unfortunately, the particle size characteristics of the primary particles of the product are not known. In a replication of some of the examples listed in the patent specification, the amorphous powder has shown a primary particle size of substantially less than 0.05 microns. A transmission electron micrograph of the product shows that at 600°C,
The primary particles of the calcined product showed agglomeration.

In the exemplary prior art process examples described above, calcination is used to complete the synthesis of particles of the composition in situ. For the reasons already pointed out, this high temperature operation is harmful. This is because this produces an agglomerate product which, after grinding, produces smaller agglomerate fragments with a wider particle size distribution.

U.S. Pat. No. 4,233,282, No. 4.29
No. 3,534 and No. 4,487.755 describe the synthesis of BaTiO3 and compositions based on BaTiO3,
Part of a is replaced with M by Sr, and part of Ti is replaced by Zr, resulting in a molten salt reaction. The product is characterized by being chemically homogeneous and consisting of relatively monodisperse submicron crystallites. Doped B a T
No iO3-based products were synthesized. Yoon, outside [semiconductor B a T i O
3], Materials Research Bulletin [Hat, Ras, Bul, ] Vol. 21, p. 1429 (1986), using the molten salt method, the composition is Ba(0,900-x) SrO, 100
teaches the synthesis of the product Sbx-”03,
In the formula, the values of X are 0.001.0.002.0.003 and 0.004. Objects produced by the molten salt method have a greater effect on the resistivity-temperature characteristic PTCR than comparable samples made from powders produced by calcination of mixtures of oxides and oxide precursors. , the specific resistance at room temperature was large, and the current fluctuation value of the current-time characteristic was large. The reason for the difference was the use of KCl in the molten salt synthesis method and the smaller size and size distribution of the particles in the derived samples. Although doped submicron products with narrow particle size distributions can be obtained using molten salt-based synthesis methods, contamination of the powder with alkali sites is inevitable. This is because the molten salt consists of an alkali metal salt. Needless to say, in most electronic applications, alkali metals are harmful contaminants.

Some water-based methods include B a T i O3
8a as well as the preparation of compositions based on TiO3, in which Ba is partially replaced by Sr and TiO3 is used.
is partially replaced by 3n and in some cases by lr. In the method taught in U.S. Pat. No. 3,577,487, doped multicomponent alkaline earth and/or Pb
The titanate, stannate, zirconate, and/or hafnium Wa salt of (II) are manufactured. In these cases, the co-precipitated hydrogel may be treated with an alkaline earth hydroxide and subjected to treatment steps similar to those used for the production of saT+o3, or the gel and alkaline earth hydroxide required may be The materials are added to the pre-made B a T + 03 slurry, which is then jet milled and calcined.

Unfortunately, the properties of the product prior to jet milling were not clear. However, in experience.

The doped multicomponent product may exhibit a specific surface area of more than 20 TrL2/g before milling, which means that the particle size of the primary particles of the powder is approximately 0.05μ.
It shows that it is smaller than .

Even after jet milling at exit temperatures higher than 800°, the multicomponent products mentioned in the examples had specific surface areas greater than 18 m2/'7. On calcination, the surface area could be further reduced. This will lead to the formation of agglomerated products for the reasons already discussed.

Our pending patent application, U.S. Patent Application No. 859.57
In specification No. 7, the general formula is Ba(1-x-x, -x, , MxM'X"X"T'
(1-y-V'-V"IAV△V'△" V,,o3
In the formula, M is Pb (It), M' is Ca (I[), and M LJ is 3r.
(II), Δ is 5n(rV), and Δ′ is Zr
(Iv) and Kaa” t, tHf’ (■) T
- Yes, 8, X J , #, and y, y' and y
'' are the atomic fractions of divalent cations and tetravalent cations, respectively, and each is the sum, (x+x'+x'') or (y+y'
+y″) are independent values ranging from O to 0.3, unless either exceeds 0.4. Each cothome has the characteristics of being chemothermetic, dispersive, submicron, and having a narrow particle size distribution.

Doping of barium titanate cottome was not studied in pending US Pat. No. 859.577. Therefore, in the prior art, particles containing calcium and/or lead or divalent and tetravalent multication components, which are dispersible, spherical, and submicron, with a narrow particle size distribution, The doped barium titanate cotome is completely lacking.

Therefore, the particle size distribution is narrow, dispersible, and submicron.
It is an object of the present invention to provide a doped barium titanate cotome.

- a wide variety of doped BaTiQ, with the particle size ranging between 0.05μ and 0.4μ;
It is another object of the present invention to provide a dark blue acid product of BaTiO3 based on.

It is another object of the present invention to provide a composition based on doped barium titanate with equiaxed sub-particles.

It is another object of the present invention to provide a composition based on doped barium titanate that is substantially free of grinding media.

It is another object of the present invention to provide a composition based on doped barium titanate in which all components are intimately mixed on a particle size scale.

SUMMARY OF THE INVENTION The present invention encompasses a diverse, broadly dispersible, doped barium titanate cotome that is substantially spherical, well mixed on the particle size scale, and has a particle size distribution. It has a narrow submicron width. In one important embodiment of the invention, the doped barium titanate cotsium has the general formula % where X, Y and Z are coefficients and the values of x and y are 0. 9 and 1.1, and Z is a value greater than O and less than 0.1, and y, y' and yn are independent values ranging from O to 0.3. , the sum (y+y′+y″) is less than 0.4, and X
' is greater than O and less than 0.4 J, and D is one or more dopant oxides.

In another important embodiment of the invention, the doped barium titanate ]nono- is generally represented by the formula, where X, Y and 7 are coefficients, and the values of X and Y are 0. ．．
9 and 1.1, and the value of Z is greater than 0 and 0
．． is less than 1, y1y' and y'' are independent values ranging from O to 0.3, the sum (V + y'10'')/'') is less than 0.4, and X is greater than O is less than 0.4, and D is one or more dopant oxides.

In yet another baking soda embodiment of the invention, the barium titanate coform is represented by the general formula, where X, Y, and Z are coefficients, and X and Y are 0.9 and 1.1. and Z is a value greater than O but less than 0.1, and XSX',
X″, y, y′ and y″ are each independent and have values greater than 0 but less than 0.3, and the sum (X+X”
+X” ”) is smaller than 0.4, and the sum (y+y′+y
'') is less than 0.4, and D is one or more dopant oxides.

Each of the doped barium titanate-based cots of the present invention has the same unique physical properties. The average particle size of the primary particles of doped barium titanate-based cotsomes ranges from 0.05μ to 0.4μ.

Moreover, the average particle size determined by image analysis is
On), the average particle size is comparable to the average particle size measured in 1999, indicating that the cotsome is dispersive. The particle size distribution curve of the doped cot ohm particles has a four-orientation ratio less than or equal to 2.0, which indicates that the doped barium titanate based cot ohm has a fairly narrow particle size distribution. I am confirming that I am doing so. Additionally, it is important to note that the dispersive, submicron, doped barium titanate dielectric compositions of the present invention can be produced in a single step using conventional hydrothermal methods.

These and other details and advantages of the invention will be explained in conjunction with the drawings, in which FIG.

().

Φ C IO D LO Φ 6 a: 1 ~ to 0 O; ° 6 of the submicron multi+p dopant complex coform in the molecule 1ifl according to the invention, with a magnification of 50,000
Figure 2 is a transmission electron micrograph at a magnification of 50.000 times of the A-dopant complex barium titanate coforme whose general formula is Ω 0 to o O . 2 is a photograph showing a crystal structure of the cot ohm that is substantially similar to that of the complex-doped cot ohm of FIG. 1. FIG.

DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention is a doped cotzome of - Φ of H Σ - × of Φ, where ×, Y and Z are divalent, tetravalent. and the coefficient for the dopant cation, where x and Y are in the range 0.9 to 1.1, and more preferably in the range 0.95 to 1.05, and Z is a value up to 0.1 larger than O, and preferably up to 0.05 larger than O, ×,
X′, x IT indicates the atomic fraction of divalent cations and is greater than O up to 0.3, more preferably 0 to 6
independent values ranging up to 0.2, and the sum (x+X'1X") being values ranging up to 0.4, more preferably 0 or 60.3, and y , y′ and y″ are the atomic fractions of tetravalent cations and are independent values ranging from up to 0.3 greater than O, more preferably up to 0.25 greater than O, and The sum (V+1'+V'') is up to 0.4 greater than O, more preferably 0.3 greater than O.
The value ranges from . D is barium titanate
Dopant oxides with different cotsomes.

The fine, dispersible, submicron powders of the present invention are made from doped barium titanate cots containing between greater than 0 and up to 30 E-le% of both tetravalent and divalent metal ion substituents. It is preferable that The divalent barium ions can be partially replaced with either lead, calcium, strontium or mixtures thereof. Additionally, the tetravalent titanium ions can be partially replaced with tin, zirconium, hafnium, or mixtures thereof.

Compositions based on barium titanate include raantadide, cobalt, manganese, magnesium, scandium, yttrium, antimony, bismuth, zinc, cadmium, aluminum, boron, tungsten,
Doped with a small amount of one or more various dopants including oxides of chromium, nickel, molybdenum, iron, niobium, vanadium, tantalum, copper, silicon, and mixtures thereof. The amount of one or more dopant oxides contained in the cotsium ranges from greater than 0 to 10 mol%, preferably greater than 0 and up to 5 mol%. Regardless of which dopant or blend of dopants is used in the barium titanate cotome, compositions based on barium titanate are uniquely identified by the crystallographic characteristics described above. Therefore, both the single and multiple dopant complex coformes of barium titanate consist of substantially spherical fraction FIIt'4 particles, with the particle size of the -order particles being .
It has a narrow particle size distribution within the range of 0.05μ and 0.4μ.

A preferred approach for preparing doped barium titanate-based cots is to thoroughly mix - or more dopants with one or more tetravalent hydrated oxides. Sufficient and good mixing can be achieved in one of a variety of ways. The dopant may be precipitated with a tetravalent hydrated oxide. Alternatively, the dopant can be precipitated as a high surface area hydrated oxide, washed, and then
Can be combined with tetravalent hydrated oxides. lastly,
Since the dopants can be precipitated in alkaline media containing Ba(II), their solutions are preferably prepared as acetic, formic or nitric acid salts, or as ammonium salts, in the form of tetravalent can be added to the hydrated oxides of The slurry of hydrated oxide and dopant is hydrothermally treated with the oxide or hydrated oxide of lead and/or calcium at temperatures up to 200°C. The slurry is then cooled to a temperature between 60°C and 150°C. Barium hydroxide, or a solution of barium hydroxide partially replaced with strontium hydroxide, has been heated to a temperature between 70°C and 100°C and Add to the slurry of insoluble divalent cation, tetravalent hydrated oxide, and dopant at a constant rate over time. slurry from 10 minutes to 3
Hold at higher temperature for 0 min, then increase from 120°C to 2
Heating to a temperature of up to 25° C. ensures that the reaction between the hydrated oxide and the soluble divalent cation hydroxide occurs to the extent necessary.

The particle size and particle size distribution of the primary particles of cotsome produced in a hydrothermal process are the same whether the doped barium titanate conform contains just one type of dopant or several types of dopants.

This is true for the multiple dopant complex coform in Figure 1, ←
O a to 9 ヱO LO Φ・a:ll,,I to O O; - It can be clearly beaten immediately from the transmission electron micrograph of The particle size of the primary particles is 0.20μ, and the quadrant ratio is 1.29, indicating the narrow size distribution of the primary particles of the product. The multi-component doped complex Pari-cum-titanate-based cotzome in FIG. 1 and the formula Ω 0 C'31. in FIG. Comparison with a transmission electron microscopy perspective view of a single dopant barium titanate cot ome, J, shows that the crystal structures of each barium titanate-based composition are very similar. This is further substantiated by the results of image analysis, which show that the product in Figure 2 has a primary particle size of 0.18μ and a quarter image ratio of 1.26. ing.

EXPERIMENTAL METHODS Various tests were carried out in the laboratory to determine the physical and chemical properties of the doped barium titanate-based cots for the present invention. Reagent grade chemicals or fm a1't chemicals were used throughout. The Ba (OH) 8H20 product used has an Sr of approximately 1.0
mol, or 0.3 mol%, which tended to agglomerate in the product.

A solution of Ba(OH)2 has a temperature of 71/' (from 770°C to 9
Maintained at 0°C and filtered before use to remove all carbonates present/;:, CaCO3 at 80
Calcined to CaO at 0°C. The latter compound produces Ca(OH)2 when contacted with water. Tungsten was introduced as an ammonium tungstate solution. This is done by heating tungstic acid, WO31-120, and dissolving it in a 2M ammonia solution while stirring! ! The resulting solution was metastable and was used immediately after production.

Hydrated oxides of TiO, 5n02 and ZrO2 were prepared by neutralizing their respective chloride aqueous solutions with aqueous ammonia at ambient temperature. The product was filtered off and washed until a filtration free of chloride was obtained, as determined with AqNO3. Hydrated Nb(V)M compound was prepared in the same manner by neutralizing a solution of Nb(V) fluoride. TiO and SnO2,
and mixed hydrated oxides of TiO and 5b203 similarly neutralize solutions containing chlorides of Ti(IV) and Sn(rV), and Ti(IV) and 3b(I[[), respectively. Manufactured. Hydrated T i O2 and Bi
The coprecipitate of 2O3 is Ti(IV) chloride and Bi(I
f) Produced by neutralizing an aqueous solution containing nitrate. The percentage of solids present in the washed wet cake is 9
Measurements were taken after calcination for 1 hour at 00°C. Different wet cakes of each product were used during the course of the operation.

All synthesis experiments are 2j! It was done in an autoclave.

To prevent contamination, all wetted parts of the autoclave should be made of titanium metal or Teflon®.
lonR) coating.

All synthesis experiments were conducted with CO2 excluded. The filtered Ba(OH>2 solution is maintained at a temperature of approximately 80°C and the Ba(01-1>2 solution is added by high pressure pump or in a heated bomb for rapid addition. was introduced into the autoclave either by expelling it into the autoclave within 10 seconds with high pressure N2.The contents of the autoclave were operated at 1000 to 1500 revolutions per minute during the synthesis process. After synthesis, the resulting slurry was mixed without exposure to the atmosphere (to prevent the formation of insoluble BaCO3).
The mixture was transferred to a pressure filter, filtered, and dried under vacuum at 100°C.

Image analysis was used to determine the particle size and particle size distribution of the product, secondary particles. These were measured by sizing from 500 particles to 1000 particles in multiple TEM fields to obtain equivalent sphere diameters of primary particles. Two or more particles in contact were visually observed for aggregation, h+IL,+, and the individual particle sizes of the primary particles were measured. Using equivalent sphere diameters, the cumulative distribution percentage of nodules was estimated as a function of primary particle size. The median particle size was considered to be the particle size of the primary particles of the sample based on the heavy ff1W standard. The quadrant ratio, QR, was defined as the upper quadrant diameter divided by the lower quadrant diameter (on a weight basis) and was taken as a standard measurement of the width of the distribution.

The QR value of the monodisperse product was 1.0. QR value is 1.
Products with QR values ranging from 0 to 1.5 are classified as having narrow particle size distributions, and those with QR values ranging from 1.5 to about 2.0 are classified as having moderately narrow particle size distributions. and those with QR values greater than about 2.0 were classified as having a broad particle size distribution.

Experiments have shown that doped cotsomes can be classified as narrow, moderately narrow, and broad size distributions by visual inspection in the TEM field. Based on this experiment, visual inspection was used to classify the particle size distribution of the products of this study. The large number of doped cotsomes produced in this study had a narrow particle size distribution, so −
The average particle size of the secondary particles was determined reliably by sizing 20 to 30 particles under a microscope. Both quantitative and semi-quantitative methods of particle size determination show that doped barium titanate based cotsomes have a particle size of 0.
．． It was shown to be in the range between 0.05μ and 0.4μ.

Particle size was also calculated from surface area measured by nitrogen adsorption. In these calculations, the density of the product was calculated from the composition of the powder and the density of the pure ingredients according to the Bethel Busyte literature. Since the concentration of the dopant in the sample is small, and the density of the dopant is not significantly different from the density of the target velorskite, the effect of the dopant on the density of the product is deliberately ignored. did. This approximation method introduces only a small amount of error.

It should be mentioned that an exact agreement between the microscopically determined particle size and the surface area determined particle size can only be expected for monodisperse spherical powders. As the width of the distribution increases, the degree of sphericity decreases and the roughness of the particle surface increases, increasing the difference between the particle sizes measured by the two-pronged method. In other words, in a real system, the particle size measured with a microscope is
Typically, the particle size is larger than the particle size calculated from the surface area.

In this study, the agreement of both coefficients between the two particle size measurements was taken as evidence of less suspension of fine-grained precipitates accompanying the particles.

The dispersibility of the product was evaluated by comparing the particle size of the primary particles determined by image analysis and particle size analysis with comparable values determined by the sedimentation method. Stokes (5joker) of particles by sedimentation method
) diameter, which roughly corresponds to the diameter of an equivalent sphere measured by image analysis. In this study, we used Micromeritics Sedigraph [(Hicroieritics 5
edi*raph ) ] (Jossia, USA,
Norcross [NorcrossSGeorgia]
) to measure the cumulative distribution percentage of nodules by Stokes diameter and from this the median Stokes diameter and Q
The R value was calculated.

Before settling, the powder was treated with Enphos [E
iphos ] ・PS-21△ (520 Madison Avenue, New York, USA [520 Madison 8vC
1. To N lol Yorkl's Liteco Organics Divis [formerly tco 0roanics Divis
ion] ) in isobuO panol containing 0.12% by weight by ultrasonication for 15 to 30 minutes.

Particle size measurement is based on different principles depending on whether it is determined by sedimentation or by image analysis. For this reason, exact agreement in particle size by these two methods cannot always be obtained. Moreover, as already pointed out, in image analysis, particles in contact may be somewhat bonded to each other;
Visually break down the agglomeration. In sedimentation, both the contacting and bound particles act as a single entity. These entities exist because there are bonds (e.g., entanglements) between some of the primary particles, forming bonded aggregates that cannot be easily broken during sonication; Both occur because the dispersion stability is lower than optimal, resulting in some agglomeration. In this study, if the median weight particle size measurement of the particles agrees within a factor of 2 between the image analysis value and the sedimentation value, this is considered an indication that the product is dispersible. . It is also expected (and observed) that the QR values measured by sedimentation are larger than those found by image analysis.

It is reasonable to assume that under optimal conditions of dispersion, the QR value lies between the values determined by image analysis and those determined by sedimentation. In this study, an additional criterion used to measure dispersibility was that the QR value obtained for settling of the powder was less than 2.0.

Qualitative methods were also used to assess dispersibility. Experience in this study has shown that a product can be classified as dispersive if the majority of the primary particles are present as single particles in the TEM field. This qualitative evaluation of dispersibility satisfies the quantitative standards previously described for expressing the characteristics of dispersion.

Measurement of sample uniformity was by transmission electron microscopy scanning with energy dispersive X-ray analysis capacity. The composition of the primary particles of the seed rod was measured. A product was considered homogeneous if at least 80% of the particles contained all of the powder components on the particle size scale. In practice, this criterion was always met when performing STEM analysis. Moreover, the loadings of the various components, although not weighed, appeared to be reasonably comparable on a particle-to-particle basis from maximum strength.

The composition of the product was determined by elemental analysis using inductively coupled plasma spectroscopy, IPC after dissolving the sample. The accuracy of the analysis regarding the main components was approximately ±2%. The precision of the results for Shaofeng elements was lower than this number. Ba(II)/T(I
V) Atomic ratios were also determined by X-ray fluorescence. These ratios are somewhat more accurate than those determined by solution analysis;
Used where applicable.

Doped barium titanate coforms according to the present invention include forms in which a portion of the divalent barium is replaced with divalent lead or calcium. Doped cotshomes also include those in which a portion of the divalent barium is replaced with a mixture of lead and calcium, or a mixture of lead, calcium, and strontium. Partial replacement of tetravalent titanium cations with tin, zirconium and hafnium is also within the scope of this invention.

As shown in pending US patent application Ser. No. 859,577, regardless of the specific cation substitution, divalent or tetravalent, the properties of the crystal structure of barium titanate cotsium are the same. Therefore, in the following non-limiting examples, merely further? ! The same applies to the properties of the crystal structure of barium lead titanate, barium calcium titanate, and doped cotshomes of which some of these tetravalent cations have been changed, although this includes crude barium titanate cotshomes. This is an attempt to provide representative teachings.

Example 1 A series of cotomes containing a single dopant was prepared as -E/
Ti020゜167.3nO,066,Z in L/unit
rO,02, Pb00.022, CaOO,022
, and dopant salt added as liI'I salt 0
．． The slurry 0.641 containing 006 was heated from room temperature to 200° C. for about 7 minutes while stirring vigorously. The slurry was cooled to 120°C, then 70°C and 9°C.
When heated between 0°C and B a (OH) 2 about 0
．． Ba(01-1)2 solution containing 21 mol 0.46
1 was added to the slurry in (3,0+0.2> minutes).

The temperature of the resulting slurry was maintained at 120°C for about 30 minutes and then heated to 200°C for about 30 minutes. Samples of the slurry were filtered and dried before surface area, chemical and crystallographic properties were determined.

Nn(If) 0.819 0.10? 0.10
5 0. OOG O,8280,0720,1000
,030La(I[l) 0.802 0.100
0.08F+-0,00130,8410,0800,
0B7 0.027Cr(III) 0.792 0
．． 102 0.09B 0.006 0.830 0
．． 072 0.09B 0.032Go (H)
0.998 10.8 0.09
0.1B Narrow Mn(If) 1.
o37 12.4 0.0B 0
．． 15 y, La (II[) 0.
993 10.9 0.09 0.
19 Narrow Cr (I[I) 0.99
B 10.9 o, o (3o, +9
The concentrations of dopant and tetravalent hydrated oxide in the narrow filtrate were all lower than the detection concentration of the instrument (less than 1xlO'mol/1). Therefore, these metals
It can be assumed that most of the molecules are quantitatively bound in the solid phase. TEMS showed the product particles to be substantially spherical and submicron. The particle size measured by surface area agreed with the particle size measured using a microscope within a factor of 2, indicating that small substances with fine particle sizes were bonded to the particles. All doped cotsomes are classified as being dispersive. TEMS visual inspection of the cobalt-doped product showed an interquartile ratio of 1.26. Visual evaluation of the TEMS of other products revealed similar particle size distributions. A quantitative evaluation of dispersibility was obtained for the manganese-doped product using a sedimentation method. In this method, the product has a particle size of 0.21
The value of μ is in good agreement with the particle size obtained by TEMS, and the interquartile ratio is 1.69.

These annual data confirm that the product is dispersive.

Example 2 A complex cotome containing three dopants was prepared by a hydrothermal treatment method, but the equivalent of the tetravalent hydrated oxide and alkaline earth cation and Pb (II) cation used in Example 1 A suitable hanging and supply source was used. 0.002 mole of each dopant, either as nitrate or as a wet cake of Nt)(OH), in the case of niobium, to the slurry of the tetravalent hydrated oxide before adding the barium hydroxide. ,
Added.

After the hydrothermal treatment operation, the tetravalent and divalent atomic ratio of the solid phase was found to be similar to that of Example 1, but is not described herein.

Dopant oxide vs. Go(II) Nb(V) 0.031 1.0
35 10.0 0.10 0.20M
n(H) Cr (I[[) Go(IT) 0.024 1.0
34 12.6 0. oa O, 15
AI(I[I) Approximately 50% to 60% AI(I[I) has been reported for the filtrate, and therefore the molar ratio of these dopant oxides to perovskites, i.e., doped with chromeco/\luthoaluminum, is The coefficient laZ for the cobalt-niobium-manganese doped cocottome was smaller than the value for the cobalt-niobium-manganese doped cocottome. The products were all essentially spherical, appeared to be dispersed, and had a narrow particle size distribution.

Image analysis shows that the cobalt-niobium-manganese doped cotsome has an initial particle size of 0.20 μ;
And the interquartile ratio was 1.29. Sedimentation studies showed the product to have a particle size of 0.26μ and an interquartile ratio of 1.67. Both quantitative measurements confirmed the qualitative assessment that the product was dispersive and had a narrow particle size distribution. A further indication of dispersibility is that the particle size measured under a microscope and the particle size determined by surface area calculation agree within a coefficient of 2.

A complex barium titanate cotzome doped with cobalt-niobium-manganese was subjected to STEM analysis. The particles were all found to contain approximately equal proportions of Baum, Calcium, Strontium, Titanium, Zirconium, Tin, Manganese, Cobalt, and Niobium.

STFM results demonstrate that the complex cotome of multiply doped barium titanate is homogeneous at the grain scale.

[Brief explanation of the drawing]

Figure 1 shows that the general formula is HiO L・ Oo It is a child microscopic photograph, Figure 2 shows that the general formula is , Ω 0 0.

Claims (18)

[Claims] (1) Consisting of substantially spherical particles, the formula is
Ti_(_1_−_y_−_y_′_−_y_″_)S
n_yZr_y′Hf_y_″O_2·ZD, where X and Y are values between 0.9 and 1.1, the value of Z is greater than 0 and less than 0.1, and y, the values of y' and y'' are independent and range from 0 to 0.3, and the sum (y+y'+y'') is less than 0.4;
x' is greater than 0 and less than 0.4, and D
is at least one dopant oxide, and the average particle size of the primary particles of the doped cohome ranges from 0.05μ to 0.4μ. (2) At least one dopant oxide D is selected from lanthanide, cobalt, manganese, magnesium, yttrium, bismuth, aluminum, boron, tungsten, niobium, chromium, nickel, molybdenum, iron, antimony, vanadium, tantalum, copper, The doped barium titanate cohome of claim 1 selected from the group consisting of oxides of silver, zinc, cadmium, silicon, and mixtures thereof. (3) Particle size measurements of primary particles are based on image analysis;
2. A cohome of doped barium titanate according to claim 1, which agrees within a factor of 2 with that due to precipitation. (4) The doped cohome was measured by image analysis and
Doped barium titanate cohomes according to claim 1, wherein the particle size distribution is narrow and the particle size distribution curve of the primary particles of the doped cohomes has a quartile ratio equal to or less than 2.0. . (5) The doped barium titanate coform of claim 1, wherein the ratio X/Y is 1.000±0.015. (6) the ratio X/Y is within the range of 0.95 and 1.1;
A doped barium titanate coform according to claim 1. (7) It consists of substantially granular particles, and the formula is XBa_(_1_-_x_)Pb_xO・YTi_(_
1_−_y_−_y_′_−_y_″_)Sn_yZr
_y_′Hf_y_″O_2・ZD, where X and Y are values between 0.9 and 1.1, the value of Z is greater than 0 and less than 0.1, and y, The values of y′ and y″ are independent and range from 0 to 0.3;
the sum (y+y'+y'') is less than 0.4, x is greater than 0 but less than 0.4, and D is at least one dopant oxide and the doped coform A coform based on doped barium titanate, in which the average particle size of the primary particles is in the range of 0.05μ and 0.4μ. (8) At least one dopant oxide D is selected from lanthanide, cobalt, manganese, magnesium, yttrium, bismuth, aluminum, boron, tungsten, niobium, chromium, nickel, molybdenum, iron, antimony, vanadium, tantalum, copper, 8. The doped barium titanate coform of claim 7 selected from the group consisting of oxides of silver, zinc, cadmium, silicon, and mixtures thereof. (9) The doped barium titanate coform of claim 7, wherein the particle size measurements of the primary particles by image analysis and by sedimentation agree within a factor of 2. (10) The doped coform has a narrow particle size distribution, as determined by image analysis, and the particle size distribution of the primary particles of the doped coform has an interquartile ratio of less than 2.0. , or equal to 2.0. (11) The doped barium titanate coform of claim 7, wherein the ratio X/Y is 1.000±0.015. (12) The doped barium titanate coform of claim 7, wherein the ratio X/Y is in the range of 0.95 and 1.1. (13) Consisting of substantially spherical particles, the formula is ▲There are mathematical formulas, chemical formulas, tables, etc.▼, in which the values of X and Y are between 0.9 and 1.1, and Z The value of is greater than 0 but less than 0.1, and x, x', x'', y, y' and y'' are each independent values greater than 0 but less than 0.3. , the sum (x+x′+x″) is less than 0.4, the sum (y+y′+y″) is less than 0.4, and D is at least one dopant oxide, and D is the doped cohome. The average particle size of the primary particles is 0
．． Cohomes based on doped barium titanate ranging from 0.05μ to 0.4μ. (14) At least one dopant oxide D is lanthanide, cobalt, manganese, magnesium, yttrium, bismuth, aluminum, boron, tungsten, niobium, chromium, nickel, molybdenum, iron, antimony, vanadium, tantalum, copper, 14. The doped barium titanate cohome of claim 13 selected from the group consisting of oxides of silver, zinc, cadmium, silicon, and mixtures thereof. (15) The doped barium titanate cohome according to claim 13, wherein the particle size of the primary particles is such that a value measured by image analysis and a value measured by sedimentation agree within a factor of 2. (16) The doped cohome has a narrow particle size distribution, as determined by image analysis, and the particle size distribution of the primary particles for the doped cohome has a quartile ratio smaller than 1.5, or 14. The doped barium titanate cohome of claim 13 equal to 1.5. (17) The doped barium titanate cohome according to claim 13, wherein the ratio X/Y is 1.000±0.015. (18) A doped barium titanate cohome according to claim 13, wherein the ratio X/Y is in the range between 0.95 and 1.1.