WO2003080516A1

WO2003080516A1 - Tungstate compound and method for production thereof

Info

Publication number: WO2003080516A1
Application number: PCT/JP2003/003424
Authority: WO
Inventors: Kiyotaka Dohke; Tamayoshi Yoshioka
Original assignee: Asahi Kasei Kabushiki Kaisha
Priority date: 2002-03-22
Filing date: 2003-03-20
Publication date: 2003-10-02
Also published as: AU2003221446A1; JPWO2003080516A1

Abstract

A method for producing a oxide (A 1-Z DZ)(W1-XRX)2O8 wherein A is Zr or Hf or a mixture thereof, D is an element capable of forming a solid solution with a zirconium oxide or a hafnium oxide, Z is a number of 0 to 0.2, R is an element capable of forming a solid solution with a tungsten oxide, and X is a number of 0 to 0.25, which comprises mixing a composition comprising a zirconium compound or hafnium compound or a mixture thereof and a tungsten compound, firing the resultant mixture, followed by quenching, and then treating the resultant product with an alkaline solution. The method can be used for producing a powder of zirconium tungstate or the like which has enhanced purity, in particular, is suppressed in the content of simple tungsten oxide.

Description

Acid compound and method for producing the same

The present invention relates to a method for producing a powder having a negative coefficient of thermal expansion and having various uses for controlling thermal expansion of a substance, and more particularly to a powder having higher purity by removing impurities from the powder. The present invention relates to a method for producing a powder which can easily obtain a powder. The invention, more particularly, formula _{_{(A - Z D Z) (}} W 1 _ X R X) 2 0 8 (A is Z r or H f or a mixture thereof, D is a solid zirconium oxide or acid Ihihafuniumu Soluble elements, Z is less than the maximum solid solution atomic ratio limited by the type of each element, R is solid solution in tungsten oxide

The element to be obtained, X is a value less than the maximum solid solution atom ratio limited by the type of each element. This method is hereinafter referred to as zirconium tungstate).

Background art

Zirconium tungstate or the like is a heat-shrinkable oxide, and by utilizing its negative thermal expansion characteristics, as described in JP-A-10-96827, as a member for suppressing other thermal expansion in contact with it. Applied to electronic parts materials, optical parts materials, precision machine parts materials.

As a method for producing zirconium tungstate or the like, JP-A-2002-104877, JP-A-2002-265274, or Solid

As described in State Communications (2000, Vol. 114, pp. 453-455), zirconium oxide or oxidized hafnium or a mixture thereof (hereinafter referred to as acid) Dry zirconium) and tantalum oxide are mixed, squeezed, and calcined, and then quenched. In the dry method, raw material powders are mixed at a stoichiometric ratio and synthesized. Since it is volatilized at a temperature of C or higher, the stoichiometric ratio is easily lost, and zirconium oxide and the like are likely to remain as impurities. Zirconium tandastate has a purity of more than 90% for use in the above applications as having a negative thermal expansion property. Therefore, the presence of such impurities should be eliminated as much as possible. Therefore, in the above-mentioned Japanese Patent Application Laid-Open No. 10-96887, the volatilization of the tundasten oxide is prevented by wrapping or shaking it with platinum foil so that the tungsten oxide does not sublime. Further, in Japanese Patent Application Laid-Open No. 2002-2657024, the particle size of the raw material powder is defined, and the size and the molding pressure of the molded body are defined within a certain range during molding. It is trying to prevent volatilization of tungsten oxide and control the generation of impurities other than zirconium tungstate in the product. As described in US Pat. No. 5,514,360, a solution of zirconium oxide or zirconyl nitrate or the like and tandastanoic acid is used to form a salt. A wet method has been proposed, in which syrups are dried, synthesized by firing, and quenched.

Both methods are metastable by rapidly cooling a compound such as zirconium tungstate that is stably present at a temperature of 1,105 to 1,257 ° C to synthesize zirconium tungstate. It includes the step of recovering as a substance. In other words, a quenching step is essential for recovering zirconium tungstate at room temperature.

Regarding the quenching step, Japanese Patent Application Laid-Open No. 2002-265652 describes a method in which a press-formed body heated to a high temperature by sintering is rapidly taken out into an atmosphere outside a furnace near room temperature and naturally cooled. A method of forcibly cooling by spraying a non-reactive gas, a method of directly or separately adding a fired body into a large amount of a non-reactive liquid, a non-reactive cooling gas such as spraying from a cylinder such as nitrogen, etc. A method for forcibly cooling a fired body with a non-reactive liquefied gas is disclosed.

However, when zirconium tungstate or the like is industrially produced, even in these quenching steps, the entire fired body is not completely quenched during the quenching, and some of the zirconium tungstate is decomposed to obtain powder. There was a problem that impurities were mixed in the body. These impurities are the decomposition products, i.e., zirconium acid and tungsten oxide.Since these impurities and zirconium tungstate have similar scientific structures, it is not easy to separate and purify them. It was inevitable to use those containing impurities in a certain proportion or more. Tungsten oxide is known to dissolve in high-temperature alkaline aqueous solutions. As disclosed in Journalof Crystal Growth (2000), No. 212, pp. 167-172. In addition, it is known that the dissolution rate of zirconium tungstate or the like is higher in a 5% aqueous sodium hydroxide solution, and separation is difficult.

In particular, tungsten oxide dissolves in a trace amount of water, and its diffusion occurs over time, causing problems such as coloring. At the same time, there has been a concern that tungsten oxide has both electrical conductivity and ion conductivity, and also has a problem of absorbing electrons, which may adversely affect electronic parts and materials. Tungsten oxide is yellow-green, and if it is contained even in trace amounts, zirconium tungstate and the like tend to be colored, so zirconium tungstate is used to control the temperature sensitivity of Bragg gratings There was also a concern that the diffusion of tungsten oxide would adversely affect light transmission.

Thus, in the prior art, an industrial method for obtaining high-purity (particularly, close to 100% high-purity) zirconium tungstate or the like from zirconium tungstate containing impurities after the firing and quenching steps has been established. Did not. Accordingly, an object of the present invention is to provide a method for easily producing high-purity zirconium tungstate or the like, and in particular, to provide a method for producing zirconium tungstate or the like having a low content of a simple tungsten oxide. That is.

Disclosure of the invention

According to the present invention, the above object is achieved by treating zirconium tungstate or the like containing an unreacted substance or a decomposed substance with an alkali solution, and the content of high purity, particularly the tungsten oxide of the problem, is low. A method for producing zirconium acid or the like is provided. That is, aspects of the present invention are as follows.

(1) Sani匕物_{_{(- Z D Z) (Wi-}} X R X) 2 0 8 (A is Z r or H f or et mixtures, D is capable of solid solution in the zirconium oxide or hafnium oxide element , Z is a value of 0 or more and 0.2 or less, R is an element that can be dissolved in tungsten oxide, and X is a value of 0 or more and 0.25 or less).

(i) a zirconium compound or a hafnium compound or a mixture thereof, and tan Mixing a composition comprising a dasten compound,

(ii) firing the mixed composition, followed by quenching;

(iii) The above-mentioned production method, comprising a step of treating the quenched composition with an alkaline solution.

(2) In the step (i), the molar ratio of zirconium and / or Z or hafnium in the zirconium compound, hafnium compound or a mixture thereof to tungsten in the tandastene compound is 0.25 or more and less than 0.5. The production method according to the above (1).

(3) The production method according to the above (1) or (2), wherein Z = 0 and X-0.

(4) The production method according to the above (1) or (2), wherein the step (ii) includes performing an alkali solution treatment using an ammonia solution.

(5) The production method according to the above (1) or (2), wherein Z = 0 and X = 0, and the step (iii) includes treating with an alkaline solution using an ammonium solution. .

(6) The production method according to the above (1) or (2), wherein the step (iii) comprises treating with an alkaline solution having a pH of 11.0 to 13.5.

(7) above (1) to (6) any one oxides prepared by the method described in Section section (Ai- _{_Z} D _Z) (Wi one _{_X} R _X) ₂ 0 _8o

(8) at L * a * b * color system display, a guard 1 or 0 or less, and there is b is 0 or 2.5 or less, transparent or oxides exhibiting white (A - _Z D _Z )

_{_{(W ^ xRx) 2 0 8}} ( wherein, A is Z r or H f or a mixture thereof, D is capable of solid solution in the acid zirconium or acid Ihihafuniumu element, Z is 0 or 0.2 following values, R is an element capable of forming a solid solution in tungsten oxide, and X is a value of 0 to 0.25).

BEST MODE FOR CARRYING OUT THE INVENTION

Hereinafter, the present invention will be described in detail.

The zirconium tungstate or the like in the present invention, the composition formula _{_{(Ai- Z D Z) (!}} _XR x) 2 ° 8 (A is Z r or H f or a mixture thereof, D is Sani匕zirconate Elements that can form a solid solution in dium or hafnium oxide; Z is a value less than the maximum solid solution atomic ratio defined by the type of each element; R is an element that can form a solid solution in tungsten oxide; is limited by the type of each element Value less than or equal to the maximum solid solution atomic ratio. ).

The A-containing compound (zirconium compound or hafnium compound or a mixture thereof) and the tungsten compound used in the production method of the present invention are typically zirconium oxide, hafnium oxide or a mixture thereof, and tungsten oxide. Or a salt of zirconium oxide or the like or zirconium nitrate or the like with tungstic acid. In the following description of the present specification, zirconium oxide, hafnium oxide or a mixture thereof, and tungsten oxide used in the dry method will be described. First a mixture of raw material powder, the composition when calcined formula (Ai- _{_Z} D _Z)

(W ^ XRX) so as to satisfy the 20 _8, were added alone or compound powder of D and Z or R to A-containing compound powder and tungsten of compound powder to prepare a mixed powder by dry or wet mixing. Here, A is Zr or Hf or! :as well as! ^ The compounds of D and R include oxides, hydroxides, chlorides, nitrides, carbides, and oxyacid salts such as nitrates and carbonates.

D is an element capable of forming a solid solution with zirconium oxide or ichhafnium oxide, and examples thereof include an alkaline earth metal such as Ca and a rare earth metal such as Y. Z is specifically 0.2 or less, and is typically from 0 to 0.1.

R is an element capable of forming a solid solution in tungsten oxide, and examples thereof include elements of Group I1 or Group I or Group IA. X is specifically 0.25 or less, typically 0-0.2.

When z = o and x = o, it is preferable to produce a powder having remarkable negative thermal expansion characteristics.

Zirconium tungstate (Z rW ₂ 〇 ₈₎ and hafnium tungstate (Hf W ₂ O _s) are both acid I arsenide having a negative thermal expansion coefficient, in the manufacture how the present invention, can be applied to both of It is.

Generally, the raw material powders zirconium oxide and hafnium oxide are

(Zircon-ZrSi0 _4), usually called baddeleyite (Baddeleyite'Zr0 _2):! Zirconium ore containing ~ 2% hafnium (zirconium oxide and hafnium oxide Ore mixture). When zirconium oxide is used for nuclear applications, and except that it is refined as metal zirconium or metal hafnium, it is generally used as a raw material named “zirconium oxide” without being separated from zirconia and hafnium oxide. Sold as' used. The mixture obtained as a raw material in the production method of the present invention without separation is used, or zirconium oxide and hafnium oxide are added in desired amounts according to the purpose (or with only one of them). ) Can be used.

The method for producing zirconium tandastate or the like of the present invention includes the steps of mixing oxidized zirconium and the like with tungsten oxide, pressing (if necessary), calcining, and quenching. The tungsten oxide, which is an unreacted substance or a decomposition product, is dissolved and removed by subjecting the sintered body of the present invention to a solution treatment. It can also be applied to the removal of unreacted or acid tungsten contained as a decomposition product in zirconium tandastate manufactured through any known mixing method such as a dry method and a wet method described in It is a thing. The molar ratio of zirconium oxide to tungsten oxide in the mixing step is preferably from 0.25 to 0.5. In addition, any of the well-known methods can also be used for each of the above-described pressing, firing, and quenching steps.

When making a solid solution with other elements such as zirconium tungstate, mix the element to be dissolved (D and / or R above) with zirconium tungstate, etc. It can be obtained by raising the temperature to 00 ° C and then quenching.

Tungsten oxide contained in zirconium tungstate or the like can be selectively separated alone by dissolving it in an alkaline solution without affecting other components, for example, without simultaneously dissolving zirconium tungstate. Therefore, in order not to leave zirconium oxide etc. alone as much as possible, the molar ratio of zirconium oxide etc. to tungsten oxide is made lower than 0.5, and the residual tungsten oxide is treated with aluminum. High purity of zirconium tungstate can be achieved. The molar ratio of zirconium oxide to tungsten oxide is more preferably 0.25 to 0.499, more preferably 0.35 to 0.495, and-. Or 0.45 to 0.492.

By this method, impurities such as tungsten oxide and zirconium oxide can be reduced as much as possible, and high-purity zirconium tungstate can be obtained. If the zirconium tungstate or the like contains no zirconium oxide and does not cause any problem, the ratio can be reversed.However, even in this case, the tungsten oxide is included as an impurity due to decomposition such as rapid cooling. Therefore, solution processing is required. In the present invention, the "solution treatment" refers to immersing zirconium tungstate or the like (whether manufactured by a dry method or a method manufactured by a wet method) in the solution. Refers to

The hydrogen ion concentration (pH) of the alkaline solution for the alkaline solution treatment is preferably in the range of 11.0 to 13.5. If the pH is less than 11.0, it takes time to dissolve the tungsten oxide, and if the pH exceeds 13.5, zirconia tungstate also dissolves, and the yield may decrease. is there. As a guideline of pH, in the case of sodium hydroxide, which is a typical alcohol solution, the pH is about 14.0 at 5 wt%, the pH is about 13.9 at 2.5 wt%, 0 In the case of 16 wt%, the pH is about 12.7, in the case of aqueous ammonia, the pH is about 14.5 in the case of 25 wt%, in the case of 1 wt% the pH is about 13.0, in the case of 5 ^ 7% H is about 12.5.

As the alkaline solution for the alkaline solution treatment, an alkaline aqueous solution such as an alkaline metal hydroxide or an alkaline earth metal, or an ammonia solution such as an ammonium hydroxide is used. Is possible. Among them, an aqueous ammonia solution that does not leave ions such as alkali metals after washing and is easy to remove is preferable. Also, from the viewpoint of safety, a relatively weak basic aqueous ammonia solution is preferable. It is possible to obtain zirconium tungstate or the like having a purity of nearly 100% by the treatment with the aqueous ammonium solution.

In the present invention, the allowable content of oxidized tungsten contained as an impurity in an oxide such as zirconium tungstate varies depending on the application to be applied, but is determined by converting the amount of tungsten eluted into the aluminum oxide. It is preferable that the content of tungsten oxide as the calculated value is not more than 10% by weight of the whole. This amount is 5% by weight or less is more preferable. It is more preferably at most 1% by weight, more preferably at most 0.5% by weight.

As a result of expanding the X-ray diffraction pattern and confirming the content of zirconium oxide and the like before and after the treatment with the alkaline solution, the peak ratio on the chart to zirconium tungstate such as zirconium oxide before treatment was 1%. It was 0.4 after the treatment, and it was found that zirconium oxide and the like were removed as secondary (with removal of tungsten oxide). This is very convenient for removing impurities by decomposition during quenching.

The mechanism of the secondary removal of zirconium oxide and the like is as follows. When tungsten oxide is eluted from the solid matter of the decomposed zirconium oxide and the like and the titanium oxide, on the other hand, fine powder zirconium oxide and the like are generated. It was presumed that it would be easily removed by filtration or the like.

Alrikuri solution processing is better in the form of powder in terms of efficiency! / ,. The grinding after the quenching step can be sufficiently performed by reducing the average particle size to 1 mm or less. More preferably, the average particle size is 100 microns or less. More preferably, the average particle size is 50 microns or less. More preferably, it is 10 microns or less. It is preferable to reduce the particle size in order to shorten the dissolution time of tungsten oxide from the powder.

In the alkali treatment, it is preferable to heat and stir to promote the separation of tungsten oxide by alkali. The heating temperature is preferably higher, but is preferably in the range from 70 ° C to the boiling temperature of the alkali solution. More preferably, the temperature is preferably from 80 to: L 00 ° C in order to shorten the processing time.

However, if boiled, the powder will easily boil in the lower part of the high density alkaline solution where the powder has settled, so it is better not to boil. Tungsten oxide can be treated in an alkaline solution at a concentration of about 1% by weight. Although the amount of the alkaline solution depends on the concentration, it is preferably larger than the degree of completely immersing the powder, and the mass ratio of the alkaline solution to the powder is preferably 2 to 20 and more preferably 5 to 1 It is 0. The remaining alkaline solution can be reused.

A general method for synthesizing zirconium tungstate or the like is as follows: 1, 105-1, In this method, calcined compounds that are stably present at a temperature of 257 ° C are dropped in water or quenched by liquid nitrogen or the like, and are recovered as metastable substances. Therefore, when a compact is used, it is important from the viewpoint of removing impurities that the metastable substance, such as zirconium tungstate, is not decomposed. It is preferred to reduce the dimensions to 10 mm or less, more preferably 5 mm or less, more preferably 2 mm or less.

When zirconium tungstate or the like is an electronic component material, the amount of tungsten oxide is ideally completely zero, but is preferably 1% by weight or less. It is more preferably at most 0.5% by weight, more preferably at most 0.2% by weight.

The content of tungsten oxide such as zirconium tungstate is calculated from the tungsten extracted by alkali from the comminuted compound. An example of the analysis is described below step by step.

(1) Weigh 0.1 g of the finely ground sample in a beaker to 0.01 mg and collect.

(2) Pour dilute aqueous ammonia (about 2%) and heat to 150 ° C!] To dissolve the remaining tungsten oxide.

(3) Filter with 5C filter paper, wash several times with warm dilute ammonia water, and then wash with distilled water. Discard the filtrate.

(3) Transfer the filter paper into a crucible, dry it and heat it slightly with a burner to carbonize the filter paper.

(4) After carbonization until the generation of gas disappears, transfer to an electric Matsufuru furnace at 550 ° C for complete incineration.

(5) Add 1 g of sodium carbonate as an alkali flux to the incinerated sample and melt it with a wrench.

(6) Allow the sufficiently melted sample to cool, add distilled water, and heat and dissolve.

(7) Filter off the insoluble matter using 5 C filter paper and wash several times with warm water. Transfer the washing solution together with the filtrate to a volumetric flask, and make up to constant volume with distilled water. (Solution A)

(8) Transfer the filter paper to a crucible, dry it and heat it slightly with a wrench to carbonize the filter paper. (9) After carbonization until the generation of gas disappears, transfer to an electric Matsufuru furnace at 550 ° C to completely incinerate.

(10) Apply 1 g of potassium hydrogen sulphate as an acid flux to the incinerated sample and melt it with a burner.

(1 1) Allow the fully melted sample to cool, add diluted nitric acid, and heat and dissolve.

(12) Transfer the solution to a volumetric flask, and make up to constant volume with distilled water. (Solution B)

(13) Dilute solutions A and B, and determine the tungsten concentration in the solution using an inductively coupled plasma emission spectrometer (ICP-AES).

Using this analytical method, 99.9 wt% of tungsten oxide or 99.9 wt% of zirconium oxide was added as an impurity to a 99.1% pure zirconium tungstate sample. The linear regression of the purity of zirconium tungstate was determined and found to be 99.96% reliable.

Tungsten oxide, which is an impurity, has a yellow-green color, and the other components, zirconium tungstate and zirconium oxide, are white. For this reason, the amount of tungsten oxide can be evaluated by measuring the color of the product. Known methods can be used for color measurement, such as XYZ color system display, L * a * b * color system display, L * C * h color system display, The color measurement can be performed using the uncertainty color system display and the L * u * V * display. (For example, coloring materials, Vol. 69, No. 8, pp. 539-550, or

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The chromaticity of the oxide powder of the present invention, in the L * a * b * color system display, preferably a is 1.1 or more, 0 or less, and b is 0 or more, 2.5 or less, more preferably Is that a is -0.75 or more, 0 or less and b is 0 or more, 2.00 or less, and more preferably a mosquito, -0.5 or more, 0 or less and b is 0 or more, 1.5 or less, Most preferably, a can be represented by -0.3 or more and 0 or less, and b is 0 or more and 0.75 or less. L * a * b * as the absolute value of the color system displays a small Sani匕物AW ₂ 〇 ₈ exhibits more transparent or white.

Oxide _{_{(Ai- Z D Z) (W}} ! _ X R X) 2 〇 ₈ more transparent or to white to This is preferable because it is easy to find that the content of tundastene oxide as an impurity is small. In addition, tungsten oxide is manufactured by Wako Pure Chemical Co., Ltd.

According to MSDS No. 20-0346, harmful substances whose names, etc. to be notified under Article 57-2 of the Occupational Safety and Health Act (Ordinance Article 18-2) Preferably, it can be removed.

In addition, when coloring the oxide of the present invention with a color such as light pink or blue, it is necessary that the oxide be white or transparent because the color of the tungsten oxide affects the oxide. In addition, when used for applications that transmit or reflect light, it is desirable that the material be whiter or more transparent.

Example

Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.

Example 1

The molar ratio of tungsten oxide zirconium oxide to 0.49, and mixed for 2 hours at baud mill, and compression molded at 200 k GZC _m, quenched by calcined at 1, 200 ° C, dropping the fired body in water And then recovered. The fired body was colored yellow-green. The fired body is pulverized with a ball mill to obtain an average particle size of 3 μm, 10 g is weighed, immersed in 50 g of a 10% aqueous ammonia solution, heated to 80 ° C, immersed for 2 hours, and then buried in a Buchnarort. A 5 C filter paper was placed in the filter, filtered, washed 8 times using distilled water, and dried in the air at 99 ° C. to obtain a final powder. The powder after washing and drying was white. To measure the color difference before and after the treatment, the chromaticity was measured using a color difference meter CR-300 manufactured by Minolta Camera Co., Ltd. The powder before treatment is GY 95.45 (C = 6.38; h = 19.10) in the L * C * h color specification, and a = in the L * a * b * color specification. — 3.09, b = 5.58, the powder after processing is L * C * h color system GY 97.82 (C = 1.55; h = 10.99.4), L * In the a * b * color system display, a = —0.26 and b = 1.46 were shown. As a result of analysis by X-ray diffraction, no impurity could be confirmed as a peak. As a result of analysis using the above-mentioned analysis method, it was confirmed that the purity was 99.8%. When alkali treatment was not performed with the aqueous ammonia solution, it was 98.0%. Example 2

10 weight of tungsten oxide as impurity. The zirconium tungstate containing / o and zirconium tungstate powder having a purity of 99.8% obtained by the same method as in Example 1 were mixed so as to have an average particle diameter l O jum. Pulverize with a ball mill, immerse 50 g as a sample in 100 g of water each, and perform 50 temperature cycles of holding for 1 hour at each temperature of 20 ° C and 50 ° C as a temperature load added.

Quantitative analysis of this water with an inductively coupled plasma emission spectrometer (ICP-AES) showed that from zirconium tungstate containing 10% by weight of tungsten oxide as an impurity, 0.055 g / water in terms of tungsten oxide was obtained. 100 g was detected. From the zirconium tungstate sample with a power purity of 99.8%, it was not detected below the detection limit.

Example 3

The same two types of powder having an average particle diameter of 10 // m as those prepared in Example 2 were adhered to a molded plate of epoxy resin, heated at 50 ° C for 60 days, and then the powder was removed. The surface analysis of the epoxy resin was performed using an X-ray microanalyzer (EPMA-C1 manufactured by Shimadzu Corporation). As a result, a peak of tungsten was detected from zirconium tungstate containing 10% by weight of tungsten oxide as an impurity, but the purity was 99.8. /. In the case of the sample of zirconium-tungstate, it is below the detection limit.

Industrial applicability

According to the present invention, a method for easily and industrially producing high-purity, particularly low content of a single element of tungsten oxide, such as zirconium tandate, is provided, so that problems such as coloring can be avoided, and It is applied to electronic component materials, optical component materials, and precision mechanical component materials by utilizing its negative thermal expansion characteristics without adversely affecting other electronic components. In addition, by avoiding the problem of coloring, even when used for controlling the temperature sensitivity of a black grating, it can be used without adversely affecting light transmission. In addition, when a weakly basic solution is used as the alkali solution in the alkali solution treatment of the present method, the safety when the present method is used industrially is enhanced.

Claims

The scope of the claims

1. oxide - a _{_{(A Z D Z) (W}} ^ xRx) process for producing ₂ 08, where, A is Z r or H f or a mixture thereof, D is Sani匕zirconium or hafnium oxide Z is a value from 0 to 0.2, R is an element that can form a solid solution in tungsten oxide, X is a value from 0 to 0.25,

(i) a step of mixing a composition comprising a zirconium compound or a hafnium compound or a mixture thereof, and a tandustene compound;

(i1) firing the mixed composition, followed by quenching;

(1ii) a step of treating the quenched composition with an alkaline solution

The manufacturing method described above.

2. In the above step (i), the molar ratio of zirconium and / or hafnium in the zirconium compound, hafnium compound or a mixture thereof to tungsten in the tandastene compound is 0.25 or more and less than 0.5. Item 1. The manufacturing method according to Item 1.

3. The production method according to claim 1, wherein Z = 0 and X = 0.

4. The production method according to claim 1, wherein in the step (ii), an alkali solution treatment is performed using an ammonium solution.

5. The production method according to claim 1, wherein Z = 0 and X = 0, and wherein the (ill) step includes performing an alkali solution treatment using an ammonium solution.

6. The production method according to claim 1 or 2, wherein the step (iii) includes treating with an alkaline solution having a pH of 11.0 to 13.5.

7. produced by a method according to any one of claims 1-6 wherein the Sani匕物(Ai one _{_{_{Z D Z) (W 1 _}}} X R X) 2 0 8.

8. In the L * a * b * color system display, a is -1 to 0 and b is 0 to 2.5 and the oxide is transparent or white.

(AT _ _Z D _Z ) (WI-R _X ) 2 ° 8 (where A is Zr or Hf or their Mixture, D is an element that can be dissolved in zirconium oxide or hafnium oxide, Z is a value between 0 and 0.2, R is an element that can be dissolved in tungsten oxide, X is a value between 0 and 0.25 Is).