JPH0747487B2 - Method for producing powder for easily sinterable microwave dielectric - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a powder for microwave dielectric material, and more particularly to a powder having excellent dielectric properties synthesized by a hydrothermal synthesis method.

(Prior Art) A communication system using microwaves, that is, satellite communication and satellite broadcasting is rapidly developing with the increase of communication information amount, and a relative dielectric constant is large in a resonance element of a communication or broadcasting device, resulting in a dielectric loss. Is used (a large Q value). Generally, a microwave refers to an electromagnetic wave having a high frequency of about 500 MHz or higher. This dielectric material powder has a relative dielectric constant of 20.
Although a material having a large Q value has been used as described above, various Q values are used depending on the relative dielectric constant. The larger the relative permittivity, the smaller the size of the dielectric element. The larger the Q value, the smaller the energy loss. Therefore, the relative permittivity and the Q value are appropriately selected and used. When the ratio is the same, the larger the Q value is, the more preferable. The following materials are used as the materials actually used. That is, MgTiO ₃ , (CaLa) TiO ₃ -MgTiO ₃ , MgTi ₂ O ₅ -TiO ₂ , M
gO-Nd ₂ O ₃ , (La ₂ O ₃ ) -TiO ₂ , (CaSrBa) (ZrTi) O ₃ , Ba (Mg
_1/3 Ta _2/3 ) O ₃ , Ba (Zn _1/3 Nb _2/3 ) O ₃ -Ba (Zn _1/3 Ta _2/3 ) O ₃ , B
a (Zn _1/3 Nb _2/3 ) O _3- Sr (Zn _1/3 Nb _2/3 ) O ₃ , Ba (NiTa) O ₃ -Ba
(ZrZnTa) O ₃ , Ba (ZnTa) O ₃ -BaZrO ₃ , (SrCa) (LiNbTi) O ₃ ,
(ZrSn) TiO ₄ , BaTi ₄ O ₉ , Ba ₂ Ti ₉ O ₂₀ and BaO ・ 4TiO ₂・ O.1WO ₃
And so on.

Conventionally, microwave dielectric powders having the above-described compositions have been manufactured through processes such as weighing of raw materials, mixing, and firing, like ordinary ceramics. For example, Ba (Zn _1/3
Ta _2/3 ) O ₃ -Ba (Zn _1/3 Nb _2/3 ) O ₃ ceramics (abbreviation BSTN)
About ("Trends in Microwave Dielectric Ceramics (Overview)", Electronic Ceramics, March 1988 issue,
19). According to this, that is, first, the active ingredient in the obtained solid raw material is quantitatively analyzed, and weighed and collected so as to have a desired chemical composition ratio. Next, in order to carry out the solid-phase reaction uniformly, dry mixing is carried out by using a ladle machine or wet mixing is carried out by a ball mill. The raw materials that have been mixed are calcined at a temperature slightly lower than the firing temperature (about 1000 ° C) and then pulverized. The conditions of calcination are 900 ° C to 1100 ° C for 2 to 10 hours so that no gas is generated due to thermal decomposition of carbonate during sintering and the sinterability of the powder is not lost. The pulverization after calcination adjusts the particle size of the powder to an average particle size of 2 to 10 μm, and abnormal expansion and contraction in the subsequent steps are reduced to facilitate the production of dense ceramics. Binder, lubricant and water are added to the crushed powder to make granules. Polyvinyl alcohol and starch are used as the binder, and stearates, carbowaxes and the like are used as the lubricant. The granulated powder is put into a mold having a predetermined shape, and is pressed and compressed by a hydraulic press or a mechanical press to be molded. When molding a thick plate or a columnar or cylindrical sample, it is necessary to smooth the powder flow in the mold and make the stress distribution uniform. When the stress distribution is non-uniform, firing strain occurs and the density distribution of the sintered body becomes non-uniform. The molding pressure is about 1 to 3 t / cm ² . The molded body is put in a magnesia with a lid or an alumina sheath,
After the binder and the lubricant are burned out, they are fired in an oxidizing atmosphere at a predetermined temperature (1350 to 1550 ° C.) for a required time (2 to 120 hours). These sinters are finished by grinding or polishing to the required dimensions to make the final products.

(Problems to be Solved by the Invention) The quality factor Q of a microwave dielectric is given by the reciprocal of the dielectric loss, but in order to reduce the dielectric loss and increase Q, impurity lattice defects such as grain boundaries are required. Except for the above, it is necessary to make a dense ceramic that is homogeneous and has little warpage and bending. This is because the temperature stability of the relative permittivity and the dielectric loss of the microwave dielectric material directly determine the quality of the dielectric element or component, for example, the dielectric resonator.

Conventionally, as described above, solid powder raw materials were mixed and calcined to produce powders for microdielectrics, so various impurities are likely to be included during the mixing and calcination process, and the average grain size of the produced powders. Since the diameter was as large as 1 μm or more and the particle size distribution was wide, it was necessary to raise the firing temperature. For this reason, the composition is likely to change during high-temperature firing, impurities and lattice defects are likely to enter the sintered body, the grain size is not uniform, warpage and bending are likely to occur, it is difficult to be dense, and the Q value is It had the problem of becoming smaller.

In order to solve the above-mentioned problems of the conventional powder for microwave dielectrics, the present inventors have synthesized conventional barium ferrite, barium titanate (BaTiO ₃ ) and lead-containing oxide powder for piezoelectric ceramics and capacitors. The hydrothermal synthesis method, which was used only for the above, was improved so that it could be used for the production of powders for microwave dielectrics, and as a result of diligent efforts, the content of impurities was small, the average particle size was small, and the particle size distribution was small. Narrow, low firing temperature, less likely to cause compositional changes during firing, grain boundaries, impurities, lattice defects, etc. are less likely to enter when made into a sintered body, uniform, warpage, bending are less likely to occur, and it tends to be dense, The inventors have found a method for producing a powder having a large Q value, and have reached the present invention.

(Means for Solving the Problem) That is, the present invention is summarized as follows.

Easily sinterable microwave dielectric with a particle size of 0.1-0.5 μm characterized by charging an autoclave with the material from which the chlorine ions adhering to the metal hydroxide have been removed, and then hydrothermally synthesizing it. A method for producing body powder.

Hereinafter, the present invention will be described in more detail.

The microwave dielectric powder referred to in the present invention has a frequency of 500M.
It is a raw material powder of ceramics having a high relative dielectric constant of about 20 or more and a high Q value, which is used for a dielectric element or part for microwave circuits of about Hz or higher, such as a dielectric resonator.

If the application powder composition of the present invention is specifically shown below, for example, MgTiO ₃ , (CaLa) TiO ₃ -MgTiO ₃ , MgTi ₂ O ₅ -TiO ₂ , M
gO-Nd ₂ O ₃ , (La ₂ O ₃ ) -TiO ₂ , (CaSrBa) (ZrTi) O ₃ , Ba (Mg
_1/3 Ta _2/3 ) O ₃ , Ba (Zn _1/3 Nb _2/3 ) O ₃ -Ba (Zn _1/3 Ta _2/3 ) O ₃ , B
a (Zn _1/3 Nb _2/3 ) O _3- Sr (Zn _1/3 Nb _2/3 ) O ₃ , Ba (NiTa) O ₃ -Ba
(ZrZnTa) O ₃ , Ba (ZnTa) O ₃ -BaZrO ₃ , (SrCa) (LiNbTi) O ₃ ,
(ZrSn) such as _{TiO 4, BaTi 4 O 9,} Ba 2 Ti 9 O 20, BaO · 4TiO 2 · O.1WO 3 and the like. However, the present invention is not limited to the above composition.

The metal hydroxide referred to in the present invention means, for example, the metal hydroxide of the metal constituting the powder composition to which the present invention is applied.

A hydrothermal synthesis method is used for producing the powder for easily sinterable microwave dielectric material of the present invention. The hydrothermal synthesis method is well known as a single crystal synthesis method in which high-temperature and high-pressure water or an aqueous solution participates in the reaction, but it is a fine particle of microwave dielectric powder and has a uniform shape and particle size and a high purity. This method is also suitable for the synthesis of high-quality powder.

What removed the chloride ion adhering to the metal hydroxide is a metal hydroxide prepared in advance, or a hydroxide produced by neutralizing a metal compound such as metal chloride with an acidic solution. Is made into a slurry with water or a solvent, and chlorine ions liberated in the liquid of the slurry are removed. Whether or not chlorine ions have been removed refers to a state in which even if silver nitrate is dropped into the cleaning solution for the metal hydroxide, it does not become cloudy, that is, a state where chlorine ions are 10 ppm or less.

Here, the case of synthesizing BaTi ₄ O ₉ will be described. As a raw material for hydrothermal synthesis, hydroxides of Ba and Ti are preferable, and commercially available hydroxide crystals may be used, or a hydroxide precipitate may be synthesized by neutralizing an acidic solution or the like. When the acidic solution is neutralized, it is preferable to filter the precipitate once and sufficiently wash it so that impurity ions such as chlorine ions are 10 ppm or less. When such ions remain, impurities are easily mixed into the crystal grain boundaries and crystals of the microwave dielectric powder synthesized by hydrothermal synthesis, and crystal defects are easily generated. This is because it may impair the dielectric properties. During cleaning, basic element hydroxides such as Ba dissolve in water, so hydroxides of elemental elements that are easily soluble in water do not get a precipitate by neutralization, but have high purity. It is preferable to use hydroxide crystals. This is because it is easy to match the stoichiometry of the manufactured powders.

Next, the hydroxide crystal or hydroxide precipitate is dispersed in pure water. Since basic elements such as Ba have high solubility in water, it is necessary to appropriately select the ratio of the amount of hydroxide to the amount of water. This is because if the amount of water is too large, the basic element such as Ba will be dissolved in the aqueous medium even after the hydrothermal reaction, and the powder having the intended composition cannot be synthesized. In the case of _{BaTi 4 O 9 (Ba (OH} ) 2 · 8
The reaction may be performed at a mass ratio of H ₂ O crystal / H ₂ O) of about 1/20 or more.

Water in which hydroxides of Ba and Ti are dispersed is charged into an autoclave to allow the hydrothermal reaction to proceed. The reaction temperature and reaction pressure conditions not only control the reaction rate and powder particle size, but also change the crystal system of the powder to be synthesized, so the temperature and pressure conditions suitable for the crystal system to be synthesized must be selected. I have to. BaTi ₄ O
In the case of _9, 150 ℃ ~300 ℃, is reacted with ^{10kg / cm 2 ~100kg / cm 2} , it can be synthesized powder of about grain size 0.3 [mu] m. Since the filling rate of water with respect to the volume of the autoclave determines the pressure of the system at the reaction temperature, the filling rate of water should be selected appropriately according to the temperature and pressure to be reacted. When BaTi ₄ O ₉ is reacted at 200 ° C. and about 30 kg / cm ² , the filling rate can be selected to be about 50%.

In the case of the easily sinterable microwave dielectric powder of the present invention, the reaction is carried out at a high temperature of 100 ° C. or higher. This is because at 100 ° C or lower, the reaction rate is too small to be suitable for practical use. When the temperature is increased, the reaction rate increases and the particle size of the produced powder increases. Above 374 ° C, which is the critical point of water, the reaction rate and the particle size of the powder become particularly large. In order to impart low-temperature sinterability to the powder, it is necessary to make the powder have a particle size of 0.1 to 0.5 μm and an average particle size of about 0.3 μm, so it is necessary to keep the reaction temperature below the critical point. The synthesized powder is taken out by filtration or centrifugation and dried. You may granulate by a spray dry method as needed.

The autoclave may be a batch type or a continuous type. Generally, a batch type is suitable for producing small quantities of multi-quality products, and a continuous type is suitable for producing a large number of small kinds of products.

(Function) In the present invention, a material obtained by removing chloride ions adhering to metal hydroxide of a metal constituting a powder for microwave dielectrics is charged as a raw material into an autoclave, hydrothermally synthesized, and then dried. The average grain size is as small as 1 μm or less, the grain size distribution is narrow at 0.1-0.5 μm, the low-temperature sinterability is excellent, and the inclusion of impurities in crystal grain boundaries and crystals is small.
It is a high-purity powder in which crystal defects are less likely to occur, the firing temperature can be selected to be low, and a powder for microwave dielectric having a high Q value when made into a sintered body can be obtained.

(Examples) Hereinafter, examples will be described in detail.

[Example 1] A 16% titanium chloride aqueous solution was added dropwise to 250 g of a 2N NaOH aqueous solution with stirring until pH = 10 to obtain a titanium hydroxide precipitate slurry. This slurry was put into a centrifuge and the supernatant was removed to obtain a precipitate. Next, ion-exchanged water was added to this precipitate and dispersed with stirring in an ultrasonic cleaner.
It was made into a slurry again. In this way, the steps of centrifugation and redispersion of the precipitate were repeated three times to wash chloride ions attached to the precipitate. When the supernatant was collected after the fourth centrifugation and silver nitrate was added dropwise, a white precipitate did not occur, so it was found that chlorine ions adhering to the precipitate were almost removed.

Further, this titanium hydroxide precipitate slurry was added with Ba (O
H) ₂ · 8H ₂ O was 67.876g mixture, was 1500ml added to bring the total amount of ion-exchanged water to the precipitation mixture. 10 ml of the supernatant
When it was separated and silver nitrate was added dropwise, a white precipitate was not formed. The rest was stirred and dispersed in an ultrasonic cleaner, and the resulting slurry was placed in a Hasteloh C 4l autograve and heated to 240 ° C in 120 minutes while stirring at 100 to 150 rpm, and hydrothermally treated for 0.5 hours. did.

After the reaction was completed, the slurry was filtered and washed with water. After drying in a vacuum drier, the X-ray diffraction pattern was measured with the RAD-IIB type diffractometer manufactured by Rigaku Denki, and the chemical composition was analyzed by fluorescent X-ray measurement.
It was revealed that crystals were obtained that _maintained the composition of Ba _1.0 Ti _4.0 O _9.0 . The particle size distribution of the powder measured by the centrifugal sedimentation method particle size distribution analyzer was distributed between 0.1 μm and 0.5 μm, and the histogram had a single peak. The average particle size was 0.3 μm as shown in Table 1. The results of measuring the content of impurities by the optical emission spectrometry are shown in Table 2. All elements were 10 ppm or less, and the purity was high.

A 5 wt% PVA aqueous solution was added to this powder in an amount of 5 wt% based on the mass of the powder.
In addition, it granulated. The granulated powder was put into a cylindrical mold having a diameter of 8 mm, and was compressed by a hydraulic press at 1 t / cm ² to be molded.
The molded body was put into a pod of a magnesia with a lid and fired at 1200 ° C. for 5 hours in an oxidizing atmosphere. As a result, as shown in Table 1, the density of the sintered body was 99% of the theoretical density.
Further, when the ε and Q values were measured, ε at room temperature was 40 and Q was 12300. A YHP network analyzer was used for the measurement, and a Murata jig was used as the sample holder. The measurement frequency was 1 GHz.

Comparative Example 1 BsCO ₃ and TiO ₂ raw materials were weighed so that the ratio of Ba: Ti was 1: 4. Next, in order to carry out the solid-phase reaction uniformly, wet mixing was performed with a ball mill or the like. 1000 mixed raw materials
After calcination at 10 ° C. for 10 hours, it was wet pulverized using a ball mill.

When the X-ray diffraction pattern was measured, a BaTi ₄ O ₉ diffraction pattern was obtained. When the chemical composition of this powder was analyzed by X-ray fluorescence analysis, the expected Ba
It was revealed that it possesses the composition of _1.0 Ti _4.0 O _9.0 .
In addition, when the particle size distribution of the powder was measured with a centrifugal sedimentation method particle size distribution analyzer, it was found to be distributed between 0.5 μm and 7.5 μm.
The histogram had multiple peaks. The average particle size was 2.3 μm as shown in Table 1. However, the amount of impurities measured by optical emission analysis is as shown in Table 2, and the contents of Na, Ca, Al, Fe, and Mn were larger than those in Example 1.

A 5 wt% PVA aqueous solution was added to this powder in an amount of 5 wt% based on the mass of the powder.
In addition, it granulated. The granulated powder was put into a cylindrical mold and pressed by a hydraulic press at 1 t / cm ² to be molded. Put the molded body in the pod of a magnesia with a lid, in an oxidizing atmosphere,
Even after firing at 1200 ° C. for 5 hours, a sufficient sintered body density could not be obtained. As a result of increasing the firing temperature and confirming the sinterability,
As shown in Table 1, when sintered at 1380 ° C. for 5 hours, the density of the sintered body was 99% of the theoretical density, and the same density as in Example 1 was obtained. However, the relative dielectric constant at room temperature was 38, and the Q value was 8800, which was particularly inferior to that of Example 1.

Example 2 To 250 g of a 25 wt% tantalum chloride aqueous solution, a 2N NaOH aqueous solution was added dropwise with stirring until pH = 10 to obtain a slurry of tantalum hydroxide precipitation. The slurry was put into a centrifuge and the supernatant was removed to obtain a precipitate. Ion-exchanged water was added to the precipitate and dispersed with stirring in an ultrasonic cleaner to form a slurry again. For this purpose, the steps of centrifuging and redispersing the precipitate were repeated three times to wash chloride ions attached to the precipitate. When the supernatant was collected after the fourth centrifugation and silver nitrate was added dropwise, a white precipitate did not occur, so it was found that the chlorine ions adhering to the precipitate were almost removed.

Furthermore, this tantalum hydroxide precipitate has a purity of 99.8% and a particle size of about 0.
3.5 g of 3 μm MgO powder and 315.3 g of Ba (OH) ₂ · 8H ₂ O were mixed, and ion-exchanged water was added to this precipitation mixture to bring the total amount to 1500.
ml. When 10 ml of the supernatant was taken and silver nitrate was added dropwise, white precipitate was not formed. The slurry obtained by stirring and dispersing the rest in an ultrasonic cleaner is Hastelloy C.
It was charged in a 4 liter autoclave manufactured by Kuraray Co., Ltd., heated to 240 ° C. in 120 minutes with stirring at 100 to 150 rpm, and hydrothermally treated for 0.5 hour.

After the reaction was completed, the slurry was filtered and washed with water. The X-ray diffraction pattern was measured after drying in a vacuum drier, and no peaks appeared other than the diffraction pattern of Ba (Mg _1/3 Ta _2/3 ) O ₃ , indicating a single phase. Do you get it. Analysis of the chemical composition of this powder by fluorescent X-ray measurement revealed that it possessed the composition of Ba: Mg: Ta = 3.0: 1.0: 2.0 as expected. The particle size distribution of the powder measured by the centrifugal sedimentation method particle size distribution measuring device is 0.1 μm to 0.5 μm.
And the histogram had a single peak. The average particle size is 0.3 μm as shown in Table 1.
Met. The contained impurity elements found by optical emission analysis are shown in Table 2, and the content of each element was 10 ppm or less.

A 5 wt% PVA aqueous solution was added to this powder in an amount of 5 wt% based on the mass of the powder.
In addition, it granulated. The granulated powder was put into a cylindrical mold and compressed by a hydraulic press at 1 t / cm ² to be molded. Put the molded body in a pod of magnesia with a lid, in an oxidizing atmosphere,
It was baked at 1200 ° C. for 5 hours. The results are shown in Table 1, and the density of the sintered body was 99% of the theoretical density. Also, the relative permittivity and Q
When the values were measured, the relative dielectric constant at room temperature was 20, and the Q value was 19,200.

Comparative Example 2 BaCO ₃ , MgO and Ta ₂ O ₅ raw materials were weighed and sampled so that the ratio of Ba: Mg: Ta was 3: 1: 2. Next, in order to carry out the solid-phase reaction uniformly, wet mixing using a ball mill or the like was performed. The mixed raw material was calcined at 1000 ° C. for 10 hours and then wet-milled using a ball mill.

When the X-ray diffraction pattern was measured, Ba (Mg _1/3 Ta
A diffraction pattern of _2/3 ) O ₃ was obtained. Analysis of the chemical composition of this powder by fluorescent X-ray measurement revealed that it possessed the composition of Ba: Mg: Ta = 3.0: 1.0: 2.0 as expected. However, the amount of impurities measured by optical emission analysis is the second
As shown in the table, the contents of Na, Ca, Al, Fe, Mn and Nb were higher than those in Example 2. Furthermore, when the particle size distribution of the powder was measured by a centrifugal sedimentation method particle size distribution analyzer, it was found to be distributed between 0.5 μm and 7.5 μm, and its histogram had a plurality of peaks. The average particle size is 2.
It was 3 μm.

A 5 wt% PVA aqueous solution was added to this powder in an amount of 5 wt% based on the mass of the powder.
In addition, it granulated. The granulated powder was put into a cylindrical mold and pressed by a hydraulic press at 1 t / cm ² to be molded. As shown in Table 1, even if the formed body was placed in a sheath of a magnesia with a lid and fired at 1200 ° C. for 5 hours in an oxidizing atmosphere, a sufficient sintered body density could not be obtained. When the sinterability was confirmed by further raising the firing temperature in sequence, the density of the sintered body was 99% of the theoretical density when fired at 1500 ° C. for 5 hours.
The same density was obtained. However, the relative dielectric constant at room temperature was 20 and the Q value was 14900, which was particularly inferior to that of Example 2.

[Example 3] Ammonia basic tantalum hydroxide slurry (Mitsui Mining & Smelting, Ta ₂ O ₅ 99.5%, Nb ₂ O ₅ 0.05%, Fe ₂ O ₃ <0.0005%, SiO 2
₂ 0.0020%, burning loss 71.4%) with ion-exchanged water
A 24.4 wt% slurry in terms of a ₂ O ₅ was prepared. Also, ammonia basic niobium hydroxide slurry (Mitsui Mining & Smelting, Ta
₂ O ₅ <0.02%, Fe ₂ O ₃ <0.0005%, SiO ₂ 0.0020%, and burning loss 67%), and similarly, a slurry of 24.2 wt% in terms of Nb ₂ O ₅ was prepared. After collecting 113.652 g of the prepared tantalum slurry in a beaker and mixing 7.658 g of the prepared niobium slurry, 5.7382 g of fine powder of ZnO (Shodo Kagaku, 99.82%) and Ba (OH) ₂
・ 76.677 g of 8H ₂ O (Wako Pure Chemical Industries, 98%) was added, and ion-exchanged water was added to bring the total amount to 500 ml. When 10 ml of the supernatant was collected and silver nitrate was added dropwise, white precipitate was not formed. The rest was uniformly dispersed using a stirring homogenizer. The mixture was placed in an alumina beaker placed in the same autoclave as in Example 1, heated to 290 ° C. in 120 minutes while stirring at 150 rpm with a stirrer, held for 30 minutes to react, and then cooled to room temperature, The reaction product was collected in a centrifuge tube. The powder separated at the bottom of the centrifuge tube by centrifugal separation,
It was washed in the same manner as in Example 1 to remove chlorine ions. When the powder was analyzed by the same method as in Example 1, it was found that Ba
(Zn _1/3 Ta _2/3 ) O ₃ single phase, as expected Ba: Zn: Ta: N
b = 3.07: 1.00: 1.90: 0.10, the content of impurities is 10ppm or less, and the average particle size is 0.3.
was μm.

This powder was molded in the same manner as in Example 1
After time firing, the density of the sintered body reached 7.63 g / cm ³ .
Further, when the dielectric properties were measured by the same method as in Example 1, the room temperature relative permittivity at the resonance frequency of 10.0 GHz was 30.5, and the Q value was 10,500.

[Comparative Example 3] BaCO ₃ (99.98%, Ishihara Sangyo) 18.4696 g, ZnO (99.82%,
Shodo Kagaku) 2.5179g, Ta ₂ O ₅ (99.8%, Mitsui Mining & Smelting) 1
2.3095g and Nb ₂ O ₅ (99.8%, Mitsui Mining & Smelting) 0.8218g 2
Weighed into a 50 ml pot and ball mill mixed with chlorothene as the medium. The mixed powder was dried, shaped into a disc at a pressure of 700 kg / cm ² , and then calcined at 1050 ° C for 8 hours, and this was crushed into fine particles by ball milling with water as a medium. became μm. After adding the binder, 1
Disc-shaped at a pressure of t / cm ² , 1350 ℃ to 1575 ℃
However, a dense sintered body could not be obtained.

[Example 4] 16% titanium chloride aqueous solution (Osaka Titanium) 100.00 g and 16
% Zirconium oxychloride aqueous solution (first rare element chemistry) 7
Mix 5.20g, tin chloride (97wt%, Wako Pure Chemical Industries) 4.5
29 g was added and dissolved, and 2N NaOH aqueous solution was added dropwise with stirring until pH = 10 to obtain a coprecipitate. This slurry was put into a centrifuge, and the supernatant was removed to separate the precipitate. Further, it was washed in the same manner as in Example 1 to remove chlorine ions. Ion-exchanged water was added to this mixture to make the total amount.
It was set to 500 ml. When 10 ml of the supernatant was collected and silver nitrate was added dropwise, white precipitate was not formed. The slurry obtained by stirring and dispersing the rest with an ultrasonic cleaner was charged into an autoclave in the same manner as in Example 3, heated to 240 ° C. in 120 minutes while stirring at 100 to 150 rpm, and hydrothermally treated for 0.5 hour. did.

After the reaction was completed, the slurry was filtered, washed with water, and dried in a vacuum dryer. When analyzed by the same method as in Example 1, the same crystal phase as ZrTiO ₄ was confirmed, and as expected, Zr: S
The composition had a composition of n: Ti = 0.80: 0.20: 1.00, the content of impurities in each element was 10 ppm or less, and the average particle size was 0.2 μm.

This powder was molded in the same manner as in Example 1, and was molded at 1250 ° C for 5
After time firing, the density of the sintered body reached 5.17 g / cm ³ .
When the dielectric characteristics were measured by the same method as in Example 1, the room temperature relative permittivity at a resonance frequency of 10 GHz was 37, and the Q value was 7,3.
It was 00.

[Comparative Example 4] Using ZrO ₂ , TiO ₂ and SnO ₂ as raw materials, mixing was performed for 20 hours using chlorothene in a 250 ml ball mill, and after drying, 950 ° C.
It was calcined for 2 hours. When this was hydrolyzed with a ball mill for 2 hours, the average particle size was 1.5 μm. Granulate using 5% PVA solution, shape into a disk at 1t / cm ² , and 1400 ℃
When baked for 5 hours, the density became 5.16 g / cm ³ . When the dielectric characteristics were measured by the same method as in Example 1, the room temperature relative dielectric constant at a resonance frequency of 10 GHz was 36, and the Q value was 6,680.

[Advantages of the Invention] The easily sinterable microwave dielectric powder of the present invention has a small average particle size of 1 μm or less, a narrow particle size distribution, excellent low-temperature sinterability, and a high-purity powder containing no impurities. Therefore, when it is made into a sintered body, grain boundaries, impurities, lattice defects, etc. are hard to be introduced, and it is possible to obtain a powder for microwave dielectric material that is homogeneous, has little warpage and bending, is dense, and has a high Q value. , Its industrial significance is extremely large.

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Claims (1)

[Claims] 1. A material obtained by removing chloride ions attached to a metal hydroxide is charged into an autoclave,
Particle size 0.1 ~ characterized by drying after hydrothermal synthesis
A method for producing a powder for a 0.5 μm easily sinterable microwave dielectric.