JPS59207839A - Microspherical rare earth metal oxide and its production - Google Patents

Abstract

PURPOSE:To produce a rare earth metal oxide composed of small spherical particles having low primary agglomeration force, by reacting an aqueous solution of a water-soluble salt of a rare earth element with an alkaline aqueous solution, and calcining the resultant amorphous gel of the rare earth metal hydroxide. CONSTITUTION:An aqueous solution of a water-soluble salt of a rare earth element (e.g. YCl2) is added rapidly with more than equivalent (>=3 equivalent) of an alkaline aqueous solution (e.g. NaOH solution), and made to react with each other keeping the pH at >=9. The reaction product is separated e.g. by a centrifugal separator using a G-3 level glass filter or a filter cloth corresponding to 800 mesh, and washed with water. The obtained amorphous gel of the rare earth metal hydroxide is calcined in a furnace maintained at several hundred deg.C. An easily pulverizable microspherical rare earth metal oxide containing small bubbles in the particle and useful as a ceramic material can be obtained by this process.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention has a fine particle size necessary for a ceramic material and
The present invention relates to a rare earth oxide whose particle shape is nearly spherical, and a method for producing the same.

Conventionally, the common method for producing rare earth element oxides is to roast rare earth element oxalates or carbonates.
When using this as a stabilizer for ceramic materials, such as a stabilizer for zirconia sintered bodies or a sintering aid for silicon nitride sintered bodies, fine particles are required, so a pulverizer such as a ball mill or jet mill is used. It was used to atomize the particles. The rare earth oxide powder obtained in this way has a polygonal shape similar to sand obtained by crushing rocks, and
- Due to the large cohesive force of secondary particles, when mixing with powders of ceramic base materials such as zirconia and silicon nitride and press-forming, we cannot expect much movement or deformation at grain boundaries. In order to increase the density of the molded product and fully demonstrate its properties, high-pressure molding was required. Therefore,
The equipment required to manufacture these molded bodies is complex, and
Productivity was low.

Among the properties expected of ceramic material powder are that the shape is close to a sphere, that the secondary particles are small, and that the cohesive force between the secondary particles is small.

The present inventors have conducted research on the generation of hydroxides using alkalis from water-soluble salts of rare earth elements, and have found that rare earth hydroxides obtained under certain conditions have a spherical shape and an extremely small particle size. The present invention was completed based on the discovery that by roasting this rare earth hydroxide, a rare earth element oxide that retains its shape and has a small primary cohesive force can be obtained.

That is, the present invention provides a fine spherical rare earth oxide obtained by roasting a gel-like amorphous rare earth oxide obtained by reacting an aqueous solution of a water-soluble salt of a rare earth element with an aqueous alkali solution, and a method for producing the same. be.

The present invention will be explained in detail below.

The water-soluble bases of rare earth elements used in the present invention include praseodymium, neodymium, samarium, 2-robium, gadolinium, terbium, yttrium, cisglosium,
Holmium, erbium.

Hydrochloride, nitrate or organic acid salt (eg acetate, formate) selected from thulium, ytterbium and lutetium. Although not particularly limited, among these, hydrochloride and nitrate are preferred. Further, in the present invention, these may be used alone or in combination of two or more thereof.

The aqueous alkali solution used in the present invention is specifically an aqueous solution of ammonia, aqueous soda, aqueous potassium, various organic amines, and the like. Among these, ammonia water is preferred.

The amount used must be 3 equivalents or more based on 1 part of the rare earth element, so that the water-soluble salt of the rare earth element reacts with the alkali according to the reaction formula below.

(Reaction formula: LnXs+ROH-+Ln(OH)s+3RX3(Ln
; Rare earth element, X; NO8, C#CH3COO.

Indicates acid residues such as HCOO, and alkali species such as R; NH, Na, and the like. ) The gel-like amorphous rare earth hydroxide in the present invention can be obtained by reacting an aqueous solution of a water-soluble rare earth salt with an aqueous alkali solution. At this time, P in the reaction system must be reacted at a pH higher than that indicated by the rare earth hydroxide aqueous solution or slurry.The pH varies depending on the type of rare earth element used, but in practical terms If the pH of the system is maintained at 9 or higher, a gel-like amorphous hydroxide can be obtained.

When the reaction is carried out while maintaining the pH at 9 or less, the resulting product has a structure incorporating acid residues present in the reaction system. For example, when aqueous ammonia is slowly added to an aqueous solution of yttrium chloride and the reaction is carried out while maintaining the pH at 9 or less, the resulting product is not the gel-like amorphous yttrium hydroxide of the present invention, The composition formula is Y
Crystalline basic yttrium chloride such as 2(OH)5Cl・nH2O is generated, and when a gadolinium nitrate aqueous solution and a sodium hydroxide aqueous solution are reacted while maintaining the pH below 9, Gd2(OH)5NO3・nH2O Basic gadolinium nitrate is produced. Therefore, when a water bathing liquid of a rare earth element is added to an aqueous alkaline solution having an amount equal to or more than the reaction equivalent, pH adjustment is easy and a gel-like amorphous rare earth hydroxide is easy to produce. Furthermore, since the gel-like amorphous rare earth hydroxide gradually changes into crystalline rare earth hydroxide when heated in water, reaction at high temperatures is not preferred. However, since the gel-like amorphous rare earth hydroxide is initially produced during the reaction at high temperatures, this method can be implemented if a means is provided to take it out of the reaction system.

Therefore, conditions are selected depending on the mode of implementation. Furthermore, depending on the sTh of the alkali used, ammonium salts, sodium salts, etc. generated from the alkali and rare earth salts may be dissolved in the gelled amorphous rare earth hydroxide solution, which is the reaction product. It may remain in the rare earth oxide product after firing. In such cases, measures such as washing and dilution may be required. At this time, the gel-like amorphous rare earth hydroxide undergoes no deterioration.

The produced Kel-shaped amorphous rare earth hydroxide is a translucent amorphous substance, whereas ordinary rare earth hydroxide is white crystalline. That is, the shape of the gel-like amorphous rare earth hydroxide is an aggregate of minute spheres, as can be seen from the SEM photographs shown in Figures 1 and 7.
As can be seen from the X-ray diffraction chart shown in Figure 0, the crystal lattice has not grown sufficiently (and as seen from the infrared absorption spectra shown in Figures 3 and 11, it has clear hydroxyl groups). It is expected that the gel-like amorphous hydroxide is obtained by dehydration condensation polymerization of several molecules of rare earth hydroxide.In addition, the gel-like amorphous hydroxide is a glass filter with a mesh size of G-3 level, Considering that the gel can be easily separated using a centrifuge using a 800-mesh f cloth and the color of the gel is translucent, it is possible that a large amount of water is present in the rare earth hydroxide in the polymerized state. The structure is thought to be hydrated.Therefore, it exhibits behavior in water intermediate between that of a normal slurry of powder and water and an aqueous solution of soluble salts, and during the process of heating and dehydrating it, the movement and arrangement of hydroxides occur. It is thought that it occurs freely and becomes spherical due to the effects of surface tension, cohesive force, etc.

Although the method of roasting the gelled amorphous rare earth hydroxide in the present invention is not particularly limited, the rare earth oxide obtained by heating the rare earth hydroxide in a water-containing state is usually
Since it tends to form solid lumps with strong agglomeration, there is a method in which a slurry of gel-like amorphous rare earth hydroxide is roasted as fine suspended particles by spraying, or a slurry of gel-like amorphous rare earth hydroxide that adheres to or A method is useful in which the contained water is rapidly vaporized to widen the particle spacing and prevent the movement of fine primary particles necessary for aggregation. Specifically, there is a method in which the above gel is introduced little by little into a furnace maintained at a temperature of several hundred degrees, or a method in which the above gel is directly introduced all at once into a furnace maintained at several hundred degrees. Moreover, the temperature is 1- the temperature at which the gel-like amorphous rare earth hydroxide is converted into the corresponding rare earth oxide.

Alternatively, it is also possible to form a hydroxide powder without agglomeration at a temperature that can remove adhering or adsorbed moisture of the gel-like amorphous rare earth hydroxide, and then raise the temperature to a temperature necessary to form an oxide. Furthermore, if agglomeration is observed in the product after removing the adhering or adsorbed water of the gel-like amorphous rare earth hydroxide, it may be removed by a deagglomeration operation at this stage, that is, by a ball mill, a jet mill, or the like. This operation is easier than when the gel-like deficient rare earth hydroxide is roasted to form an oxide and then loosened. It will not re-agglomerate if it becomes a substance.

Example-1 Aqueous solution of yttrium chloride at o, iM/A concentration 1. , e
110 ml of ammonia water with a concentration of 3 M/l was added at once to the mixture, and the mixture was stirred for 30 minutes. (The pH of the solution was 9.8) The resulting slurry was filtered through a G-3 glass filter to obtain gel-like amorphous yttrium hydroxide. A portion of the yttrium hydroxide is taken out, washed with water, and then dissolved in nitric acid to form a solution with a concentration of 01 PA/e. Although it was analyzed using a chromatograph, neither ion was detected.

In addition, when a part of the obtained gel-like amorphous yttrium hydroxide was analyzed by X-ray diffraction, the pattern was
As shown in the figure, the characteristics of amorphous objects were well expressed.

In addition, a portion of the obtained gel-like amorphous yttrium hydroxide was taken out, washed with water, and vacuum-dried without heating. Infrared spectroscopic analysis was performed, as shown in Fig. 3 (bud 3). It did not show a clear absorption peak for hydroxyl groups, and it was found that the molecular structure was in a gel state in which hydroxyl groups were bonded to water molecules.

In addition, 1 of the obtained gel-like amorphous hydroxide (IJ)
When the particle size distribution was measured using a light transmission centrifugal sedimentation method, it was found that the grain size was sharp as shown in Fig. 4, and the average grain size was small.

Then, the obtained gel-like amorphous yttrium hydroxide was added to 1
Roasting was performed at 100°C for 2 hours. The X-ray diffraction pattern of the obtained powder was found to be the same as that of IJium oxide (as described in ASTM), as shown in Figure 5.

When the shape of the obtained yttrium oxide powder was observed by SEM, it was found that fine spherical primary particles aggregated to form cloud-like secondary particles as shown in Figure 1.

In addition, the yttrium oxide obtained by roasting was slightly lumpy, so it was loosened using a vibrating ball mill.
The particle size distribution was measured by a light transmission centrifugal sedimentation method, and as shown in Figure 7, it was found to be an extremely fine powder with an average particle size of 0.32 μm.

Example 2 A gel-like amorphous yttrium hydroxide was prepared in the same manner as in Example 1, and was lightly calcined at 30°C and 700C for 30 minutes. The obtained white lump was loosened using a ball mill in the same manner as in Example-1. Each of the obtained powders was roasted at a temperature of 1100 U for 1 hour, and the X-ray diffraction pattern of each was measured.
Agreed.

In addition, when the particle size distribution of each of the obtained oxides was measured by the light transmission centrifugal sedimentation method in the same manner as in Example 1, the results were as shown in Figure 8, and the average particle size of each was measured at 300°C. @
The baked product (A in the same figure) is 0.3 μm.

The product lightly fired at 700°C (B in the figure) had a diameter of 0.32 μm.

Examples 3 to 9 Yttrium nitrate (Example 3), Yttrium formate (Example 4), Yttrium acetate (Example 5), Gadolinium chloride (Example 6), Erbium chloride (Example 7), Holmium chloride (Example 8), lutetium chloride (Example 9)
) with a concentration of 0.1 M/Jl, Example-
Gel-like amorphous hydroxides of each of the above rare earth elements were prepared in the same manner as in Example 1. The X-ray diffraction pattern of each of the obtained paste-like hydroxides showed almost the same pattern as the X-ray diffraction pattern (half figure) of the gel-like amorphous yttrium hydroxide prepared in Example-1, and the amorphous It was shown that it was a gel-like substance.

Each gel-like amorphous hydroxide obtained above was lightly baked in a heating furnace at 300°C for 30 minutes, then loosened in a ball mill in the same manner as in Example-2, and then roasted at a temperature of 1100°C for 1 hour. did. The xlv diffraction pattern of the obtained powders matched well with the values written on the AsTM card of the corresponding rare earth element oxides, indicating that the corresponding rare earth element oxides were obtained.

Furthermore, as a result of particle shape observation by SEH of each powder, each oxide showed that, similar to the yttrium oxide obtained in Example-1, fine spherical primary particles aggregated to form cloud-like secondary particles. I realized what I was doing.

In addition, the average particle size of each powder obtained was determined as in Example-1.
When measured by a light transmission centrifugal sedimentation method, the diameter of the one made from yttrium nitrate was 0.29 μm.

The one made from yttrium formate is 0.28 μm, the one made from yttrium acetate is 0.35 μm, the one made from gadolinium chloride is 0.20 μm, the one made from erbium chloride is 0.41 μm, the one made from holmium chloride is 0, The diameter was 38 μm, and the one made from lutetium chloride was 0.33 μm.

In addition, the SEM photograph, X-string diffraction chart, and external absorption spectrum of dihydroxide in Example 6 are 9 to 1.
1, and the Xi diffraction pattern and SEM photographs of the oxide of Example 6 are shown in FIGS. 12 and 13.

Example 10 A 3M/4a degree strength soda aqueous solution zxom was added at once to an aqueous solution of yttrium chloride with a concentration of
Separation yielded gel-like amorphous yttrium hydroxide.

Example 1 The obtained gel-like amorphous hydroxide (IJ)
The X-ray diffraction pattern and infrared absorption spectrum were measured in the same manner as above. The results were very good (in agreement) with those of the gel-like amorphous yttrium hydroxide prepared in Example-1.

The obtained gel-like deficient yttrium hydroxide was used in Example 2.
As described in , the material was lightly baked at 30°C, loosened with a ball mill, and then roasted at 100°C for 1 hour.

The X-ray diffraction pattern of the obtained white powder was the same as that of the yttrium oxide obtained in Example=1.

Further, when the particle shape of the obtained yttrium oxide was observed by SEM, it was similar to the yttrium oxide of Example-1 shown in Fig. 6.

In addition, the obtained IJ oxide powder was used in Example-1
When measured using the light transmission centrifugal sedimentation method in the same manner as above, the average particle diameter was 0.31 μm.

Example-11 o, lh(
Yttrium chloride at a concentration of /-g was added dropwise with stirring. The time required for dropping was 2 hours.

The obtained slurry was separated into a gel-like substance. After washing the gel with water, the X-ray diffraction pattern and infrared absorption spectrum were examined in the same manner as in Example-1, and the results showed good agreement with those of the gel-like deficient yttrium hydroxide of Example-j.

The resulting gel was lightly calcined at 300°C, milled in a ball mill, and then roasted at 1100°C.

The obtained white powder was found to be yttrium oxide from the X-ray diffraction pattern.

Furthermore, when the particle shape of the obtained powder was observed using a SEM, it was found that it was an aggregate of fine spheroidal bodies as in Example-1.

Furthermore, the particle size distribution of the obtained powder was measured in the same manner as in Example-1, and as a result, it was found that the average particle size was 0.32 μm.

Comparative Examples 1 and 2 1.05 liters of caustic soda aqueous solution with a concentration of 0.3 M/l was added to 1 liter of each 0.1 M/l aqueous solution of yttrium chloride (Comparative Example 1) and gadolinium chloride (Comparative Example 2). The mixture was then heated to 95° C. and stirring was continued for 3 hours.

When the obtained slurry was separated into P and X-ray diffraction patterns were examined, it had a Schabner diffraction peak as shown in Figure 15 (Comparative Example 1) and Figure 20 (Comparative Example 2), and it was Yttrium hydroxide,
It matched well with the diffraction peak of gadolinium hydroxide.

In addition, as shown in Figure 14 (Comparative Example 1) and Figure 19 (Comparative Example 2), each of the obtained hydroxides has columnar crystals, and the size of 7 is also large. I understand that.

In addition, the infrared absorption spectra of each of the obtained hydroxides are shown in Figure 18 (comparison multiplex) and Figure 21 (comparative example 2).There is a sharp absorption peak unique to hydroxyl groups around <3600 crrL. .

Then, each of the obtained hydroxides was lightly calcined at 300°C,
Grind with a ball mill in the same manner as Example-1, then 110
When the particle shape of the obtained valley oxide was observed by SEM after roasting at a temperature of 0°C for 1 hour, the shape of each hydroxide (
(columnar) remained intact.

In addition, when the particle size distribution of the obtained yttrium hydroxide was measured, it showed a distribution as shown in Figure Kaya 16, with an average particle size of 1.
．． It was 55 μm. Furthermore, the particle size distribution of the obtained yttrium oxide was wide (and the average particle size was as large as 21 nn), as shown in FIG.

Comparative Example-3 Aqueous solution I of yttrium chloride at o, xM/43114 degrees
1.01 of an aqueous solution of oxalic acid at a concentration of 0.15 M/4 was added to J3 to prepare oxalate of oxalic acid. The oxalate is 1
Yttrium oxide was produced by roasting at a temperature of 100°C for 2 hours. When the shape of the powder obtained by pulverizing the yttrium oxide with a jet mill was observed using SEIVI, it was found that
As shown in Figure 2, it was found to be a polyhedral crushed stone.

Moreover, the average particle size of the obtained powder was 1.0 μm.

The rare earth oxide powder obtained by the method of the present invention is different from the rare earth oxide powder obtained by a conventional method, and has characteristics such as a small average particle size and a nearly spherical particle shape. In addition, the rare earth oxide produced by the method of charging rare earth hydroxide in a gel-like unshaped form in a furnace maintained at several hundred degrees has fine air bubbles inside the powder particles, making it easy to This type of imitation powder can be said to be ideal as a ceramic material, and the present invention contributes to the development of ceramics.
It can be said that this technology contributes to

[Brief explanation of drawings]

Figure A-1 is an SEM photograph of gel-like amorphous yttrium hydroxide produced in Example 1 of the present invention, and Figure A-2 is a photograph of gel-like amorphous yttrium hydroxide produced in Example 1 of the present invention.
Figure 3 is an infrared absorption spectrum of the gelled amorphous yttrium hydroxide produced in Example 1 of the present invention, and Figure 724 is the infrared absorption spectrum of the gelled amorphous yttrium hydroxide produced in Example 1 of the present invention. Figure 15 is an X-ray diffraction chart of microspherical yttrium oxide prepared in Example 1 of the present invention, Figure 16 is an example of the present invention. Figure 7 shows the particle size distribution pattern of the microspherical yttrium oxide produced in Example 1 of the present invention by a light transmission centrifugal sedimentation method. This is the particle size distribution pattern of the microspherical yttrium oxide produced in Example-2, where A is the one that was lightly fired at 300°C and then roasted at 0°C, and B is the one that was lightly fired at 700°C and then roasted at 1100°C. Fig. 9 is an SEM photograph of the gel-like amorphous gadolinium hydroxide produced in Example 6 of the present invention, and Fig. 10 is a photograph of the gel-like amorphous gadolinium hydroxide produced in Example 6 of the present invention. X-ray diffraction chart of gadolinium oxide, 1
Figure 713 shows an infrared absorption spectrum of the gelled amorphous gadolinium hydroxide produced in Example 6 of the present invention, Figure 12 is an X-ray diffraction chart of microspherical gadolinium oxide produced in Example 6 of the present invention. Figure 714 is an SEI photograph of microspherical gadolinium oxide produced in Example 6 of the present invention, Figure 714 is an SEM photograph of hydroxide (gadolinium) produced in Comparative Example 1 of the present invention, and Figure 15 is an SEM photograph of gadolinium oxide produced in Comparative Example 1 of the present invention. Yttrium hydroxide made by X
Line diffraction chart, ? Figure 16 shows the particle size pattern of yttrium hydroxide produced in Comparative Example 1 of the present invention by the light transmission centrifugal sedimentation method, and Figure 117 shows the light transmission of yttrium oxide produced in Comparative Example 1 of the present invention. Particle size by centrifugal sedimentation method 1j butter/
, Figure 718 is an infrared absorption spectrum of yttrium hydroxide produced in Comparative Example 1 of the present invention, Figure 19 is an SEM photograph of gadolinium hydroxide produced in Comparative Example 2 of the present invention, Figure 120 is a comparative example. Gadolinium hydroxide made in step 2
Linear diffraction Naya-1., Figure 7-21 shows the external absorption spectrum of gadolinium hydroxide produced in Comparative Example 2 of the present invention, and Figure 422 shows the fine particle yttrium oxide produced by jet mill pulverization in Comparative Example 3 of the present invention. This is an SEM photo of. 0, Figure 8 Grain B: (pm) Figure 9 O,! 5P, first place! l Figure 18 te skin cover (xl○2cm-') Figure 22 package, OP procedure amendment (method) % formula % (1) (2) 1, Indication of matter A11 1': Mn584 block I9 side λ7
No. 9420 (3). 2. Name of the invention Fine spherical rare earth oxide and its manufacturing method d. 3.7 Relationship with the city arrest case Patent applicant Daiichikun 1-2-6 Dojihama, Kita-ku, Osaka (003) Asahi Kasei Kogyo Teru Miyazaki, President and Representative Director of Co., Ltd. 4, F Yoi of Amendment Order” April 4, 1980 (Shipping port 59./12□1) 5, Subject of amendment 1 [Brief explanation of 1 drawing of Book 11] Column 6, Contents of Sleeve ■' As shown in the attached sheet, rsEMJ on page 19, line 11 of the amended statement of contents is corrected to "particle-structured electron beam." rsEMJ on page 20, lines 2.11 and 19 is corrected to ``one-particle electron beam''. rSIEM-1 on page 21, lines 1.13 and 19,
It has been corrected to "an electron beam with a one-particle structure." Written amendment to the above procedure (spontaneous May 8, 1980, Mr. Kazuo Wakasugi, Commissioner of the Japan Patent Office, 1981) Patent Application No. 79420, 1982, 2, Title of Invention: Fine spherical rare earth oxide and process for producing the same. 3. Person making the amendment Relationship with the case 2. Patent applicant 1-2-6-5 Dojimahama, Kita-ku, Osaka-shi, Osaka Prefecture Contents of the amendment Contents of the amendment (1) as shown in the attached sheet, page 7, line 15 of the specification Correct rSEMJ to "electron beam, j." (2) Correct rsEMj on page 11, line 12 to "electron beam." (3), rSEMJ on page 13, line 16 is corrected to "electron beam". (4), rsEMj on page 14, lines 10 and 13,
Corrected to "electron beam." (5), rsEMJ on page 15, line 14 is corrected to "electron beam". (6), rsEMj on page 16, line 12 is corrected to "electron beam". (7) 6. rsEMJ on page 17, lines 9 and 20 of
Corrected to "electron beam." (8), rSEMJ on page 18, line 15 is corrected to "electron beam". that's all

Claims (1)

[Scope of Claims] (2) Fine spherical rare earth oxide 28 earth obtained by roasting a gel-like amorphous rare earth hydroxide obtained by reacting an aqueous solution of a water-soluble salt of a rare earth element with an aqueous alkali solution. Claim 1, characterized in that a gel-like amorphous rare earth hydroxide is used, which can be obtained by rapidly adding an aqueous solution of alkali equal to or more than the reaction equivalent to an aqueous solution of a water-soluble salt of an element. A patent characterized in that it uses a gel-like amorphous rare earth hydroxide obtained by adding a microscopic spherical rare earth oxide 3, an aqueous solution of a water-soluble salt of a rare earth element to an aqueous solution of an alkali in the reaction equivalent plate 2. The fine spherical rare earth oxide 4 described in claim 1 is characterized in that the water-soluble salt of the rare earth element is selected from the hydrochloride and nitrate of yttrium or gado IJnium. The fine spherical rare earth oxide 5 according to claim 1, the fine spherical rare earth oxide 6 according to claim 1, characterized in that the aqueous alkali solution is aqueous ammonia, and the gel-like amorphous rare earth hydroxide are roasted. Fine spherical rare earth oxide 7 according to claim 1, wherein the baking method is to directly introduce the gelled amorphous rare earth hydroxide into a roaster in a high temperature atmosphere, a water-soluble salt of a rare earth element. an aqueous solution of
A method for producing a fine spherical rare earth oxide, which comprises roasting a gel-like amorphous rare earth hydroxide obtained by reacting it with an aqueous alkali solution.