GB2227740A - Lithium zirconate - Google Patents
Lithium zirconate Download PDFInfo
- Publication number
- GB2227740A GB2227740A GB9000908A GB9000908A GB2227740A GB 2227740 A GB2227740 A GB 2227740A GB 9000908 A GB9000908 A GB 9000908A GB 9000908 A GB9000908 A GB 9000908A GB 2227740 A GB2227740 A GB 2227740A
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- GB
- United Kingdom
- Prior art keywords
- lithium
- procedure according
- zirconium oxide
- powder
- zirconate
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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- C—CHEMISTRY; METALLURGY
- C01—INORGANIC CHEMISTRY
- C01G—COMPOUNDS CONTAINING METALS NOT COVERED BY SUBCLASSES C01D OR C01F
- C01G25/00—Compounds of zirconium
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- Chemical & Material Sciences (AREA)
- Organic Chemistry (AREA)
- Inorganic Chemistry (AREA)
- Inorganic Compounds Of Heavy Metals (AREA)
- Compositions Of Oxide Ceramics (AREA)
Description
1 - "Procedure to prepare lithium zirconate, thus prepared lithium
zirconate and intermediate product".
The invention relates to a procedure for preparing lithium zirconate, according to which zirconium oxide and a lithium compound are mixed and are thereafter allowed to react with each other through a thermal treatment, hereafter called calcination.
Lithium zirconates and more particularly the lithium metazirconate, are suitable to be applied as breeding material in the fusion reactors of the future.
obviously for such applications the quality of the zirconate will have to be very good and more particularly the micro homogeneity of the zirconium oxide lithium compound mixture will have to be excellent.
From the publication "Preparation, characterization and properties of Li2ZrO3 fabricated from Li2C03 and Zr02" of A.J. Flipot et al. published by the applicant in connection with the 15th "Symposium on Fusion Technology" Utrecht, September 1988, it is known to use lithium carbonate as lithium compound for the preparation of lithium metazirconate.
With that the lithium carbonate and the zirconium oxide are mixed dry after which they are ground wet. With the manufacture of over stoichiometrical (i.e. with an excess of lithium) lithium metazirconate, starting from lithium carbonate, after sintering, the presence of residues of a liquid phase on granular limits is determined. This liquid phase which is the result of the presence of low melting compounds, is very adverse for obtaining a fine grain and for the homogeneity of the microstructure.
Furthermore according to this known procedure it is not possible to form other lithium zirconates such as Li8ZrO6 and Li6Zr207.
J 11 This is possible if lithium peroxide is used as lithium compound. It was determined that in this case the formation of the above mentioned low melting compounds and thus the appearance of a liquid phase during the sintering of the lithium zirconate can be avoided.
In "The preparation,, characterisation and properties of lithium oxide and lithium metazirconate specimens irradiated in HFR Petten in second and third EXOTIC experiments" of P. Kennedy in "Proceedings of the 14th Symposium on Fusion Technology", eds. Pergamon Press (1986) (pages 10131018), the dry mixing of lithium peroxide and zirconium oxide is described. In order to prepare lithium zirconate starting from such a dry mixture, required.
high calcination. temperatures are however The powdery lithium zirconate obtained by P. Kennedy was hardly or not sinterable. This powder could only be transformed into components retaining their shape by means of heat pressing which from the industrial point of view is not interesting owing to the relatively low production capacity of such moulding technique.
The purpose of the invention is to remedy all these disadvantages and to provide a procedure for preparing lithium zirconate with which a lithium zirconate of good quality with a fine grain and a homogeneous microstructure can be obtained, with which if required other zirconates than lithium metazirconate can be prepared, and with which a powdery lithium zirconate is obtained which is particularly suitable for sintering.
For this purpose are prepared, on the one hand, a clear solution, free of dispersed solid particles, of a soluble lithium compound in water, and, on the other hand, a dispersion of zirconium oxide powder in water, this solution. and this dispersion are mixed, the mixture obtained is dried to a powdery product and this powdery product is subjected to calcination.
By preparing the zirconate in a wet manner, a micro homogeneous uncontaminated zirconate is obtained which can be moulded into the desired form via the usual techniques of pressing and sintering.
1 1 1 The procedure contains a limited number of steps and the composition of the powdery product before the calcination is easily reproducible and accurate.
This product has a high degree of purity because little contamination arises through contact with foreign materials such as the receptacles, mixing apparatus etc. and among others no grinding step is necessary.
The mixture before the calcination has a very great micro homogeneity. The lithium compound in solution is divided in an homogeneous manner between the dispersed solid zirconium oxide. With the drying the lithium compound crystallises in an homogeneous manner between, on and around the zirconium oxide powder particles. Without a grinding step being necessary, an homogeneous mixture is obtained which then gives an uncontaminated micro homogeneous zirconate through the calcination.
In order to obtain a clear solution from the lithium compound, the lithium compound may not exceed a solubility limit. Exceeding this limit would give a solution with remaining solid particles of the lithium compound through which therefore no micro homogeneous mixture would be obtained after drying.
A suitable lithium compound for the clear solution is lithium peroxide (hydrate and/or perhydrate).
With such a lithium compound the concentration of lithium in the clear solution is maintained below 30 g lithium per litre of solution.
Lithium carbonate is conversely not suitable since lithium carbonate is not easily soluble in water.
The clear solution of lithium peroxide (hydrate and/or perhydrate) is efficiently manufactured in situ by allowing lithium hydroxide or lithium hydroxide monohydrate to react with an over-measure of hydrogen peroxide for forming a viscous watery dispersion after which a sufficient amount of water is added in order to bring the concentration of lithium below the solubility limit and thus to obtain a clear solution.
In a preferably applied embodiment of the invention the mixture obtained is dried by spray drying.
Before the calcination the powder can possibly be subjected to a granulation treatment in order so to obtain a product with suitable powder rheological properties (with this the liquidity of the product is intended necessary for a good filling of a matrix in case the product is subjected to a cold pressure treatment for the manufacture of components retaining their shape).
The lithium zirconate powder or granulate can thereafter be subjected to a sinter treatment under oxidising or neutral atmosphere whereby it is sintered at a temperature above 900'C. A sintered powder or a sintered granulate, with a density up to 95% theoretical density, can be obtained in this manner.
The invention also relates to the lithium zirconate prepared according to the procedure according to one of the aforementioned embodiments.
The invention also relates to the intermediate product namely the mixture of zirconium oxide and a lithium compound obtained according to the procedure according to one of the aforementioned embodiments applied up to and including the drying of the mixture.
Other details and advantages of the invention will appear from the following description of a procedure to prepare lithium zirconate and of a thus prepared lithium zirconate and intermediate product according to the invention; this description is only given as an example.
To prepare lithium metazirconate, on the one hand, a clear solution of lithium peroxide (hydrate and/or perhydrate), and, on the other hand, a dispersion of zirconium oxide in water, are prepared, after which this clear solution and this dispersion are mixed, the mixture obtained is dried to a powdery product and this powdery product is subjected to calcination in order to make the lithium peroxide and the zirconium oxide react with each other.
In order to prepare the clear solution of lithium peroxide (hydrate and/or perhydrate), lithium hydroxide or lithium hydroxide monohydrate in solid form is allowed to react with an over-measure of hydrogen peroxide in order 1 1 le so to obtain a viscous watery dispersion of Li202-M202)x. (H20)y.
To this dispersion a sufficient amount of water is then added in order to bring the concentration of Li202. (H202)x#.(H20)y' (x' and y' depend on the concentration) below the solubility limit whereby a completely homogeneous and clear solution is thus obtained in complete absence of remaining amounts of. dispersed solid material. For that purpose it is ensured that the concentration of lithium is situated below 30 g of lithium per litre of solution.
In order to prepare the zirconium oxide dispersion in water, the desired amount of zirconium oxide is moistened with water after which the required amount of water is added as dispersing liquid until the desired concentration of zirconium oxide particles in the water is attained. In order to avoid sedimentation of the zirconium oxide particles, the dispersion is stirred lightly.
The above mentioned clear solution of a lithium compound and the homogeneous dispersion of zirconium oxide are subsequently mixed with each other so that the lithium peroxide (hydrate and/or perhydrate) is completely homogeneously spread in dissolved state between the zirconium oxide particles in dispersion. In order to avoid sedimentation of the zirconium oxide particles, the dispersion is stirred continuously.
Subsequently the mixture obtained of the zirconium oxide and the lithium compound is dried by means of spray drying until a powdery product is obtained consisting of the original zirconium oxide particles and around. on and between these particles on micro scale extremely homogeneously spread and crystallised lithium peroxide (hydrate andlor perhydrate).
During the drying itself, as long as there is still a solution. the lithium compound must be stabilised in the solution by means of extra addition of hydrogen peroxide, since Zr02 has a catalytic effect on the dissolution of H202.
Finally the powder obtained after drying is subjected to a calcination at a temperature situated between 500 and 900C under an oxidising or neutral atmosphere. The zirconium oxide reacts with the lithium peroxide to form lithium metazirconate according to the following reaction:
Zr02 + Li202------)U2Zr03 + 1/2 02 Before the calcination the powder obtained can possibly be subjected to a granulation treatment in order to obtain a product with suitable powder rheological properties and more particularly the desired liquidity in order to obtain a good filling of the matrix in case the product is subj ected to a cold pressure treatment for the manufacture of components retaining their shape.
Because the preparation is effected in a wet manner and the procedure includes a limited number of steps, it is industrially very interesting.
The composition of the dried mixture that is subjected to calcination, is very precisely and easily reproducible. This mixture has a high degree of purity and is micro homogeneous. With the drying the lithium peroxide, that is spread in a homogeneous manner between the dispersed solid zirconium oxide in the solution, will crystallise in a homogeneous manner between, on and around the zirconium oxide powder particles. An extra grinding step is not necessary in order to obtain a homogeneous mixture.
The lithium zirconate powder or granulate obtained after calcination can be subjected to a sinter treatment under oxidising or neutral atmosphere at a temperature above 9000C. In the case of a sintered granulate the individual granulate particles can even reach a density up to 95% of the theoretical density.
Before the sintering the powder or the granulate can still be subjected to a compacting treatment such as cold pressing by means of a mechanical, hydraulic or cold isostatic press. The components thus obtained are then subjected to the above mentioned sintering in order to obtain objects retaining their shape of the desired form 1 1 with densities greater than 70% and up to 95% of the theoretical density.
From the point of view of production speed cold pressing and sintering is to be chosen rather than hot pressing.
The sintered pieces obtained have a granular size less than 2 pn and preferably less than 1 pm and a completely open porosity whereby the pore diameter is less than 0.6 gm.
The invention will be further illustrated hereafter with the help of the following examples:
Example 1
73.12 g of lithium hydroxide monohydrate from the company Baker is added to an over-measure of 150 ml of hydrogen peroxide (30% H202 in H20). The viscous dispersion is stirred for 60 minutes. After the transformation of the lithium hydroxide monohydrate into lithium peroxide (hydrate andlor perhydrate) the viscous dispersion is diluted with water until a clear solution with 15 g of lithium per litre of water is obtained.
105.00 g zirconium oxide powder, with a specific surface area of 25 m2/g and an apparent density of 0.2 g/cm3 from the company Criceram in Prance, is also dispersed in water until a concentration of 125 g per litre zirconium oxide powder particles is attained.
The first mentioned solution is added to the zirconium oxide dispersion and the mixture is homogenised by stirring. The mixture is dried by spray drying. During the drying the mixture is stirred in order to avoid sedimentation of the zirconium oxide particles in the dispersion. At regular intervals extra hydrogen peroxide is added in order to compensate the hydrogen peroxide catalytically dissolved by the zirconium oxide.
After the spray drying a white powder consisting of an intimate mixture of lithium peroxide (hydrate and/or perhydrate) and zirconium oxide is obtained.
After a precompacting at a pressure of 20 MPa the compacted powder is granulated to particles less than 1 mm.
This granulate is calcined at 65CC for 20 hours under a dry nitrogen atmosphere.
Finally the calcined granulate is mixed with a suitable lubricant and with the assistance of a hydraulic press this granulate is compacted in a tungsten carbide matrix at a pressure of 100 MPa to pastilles with a diameter of 18 mm. The green pastilles obtained with this show a density of 44.5% of the theoretical density.
The green pastilles are finally sintered at a temperature of 101CC for 15 hours under an atmosphere of dry air.
The pastilles ultimately obtained have 80% of the theoretical density.
According to a roentgen diffraction a density of analysis the structure appears to consist of pure lithium metazirconate. The fluorine content of the sintered pastilles is less than 5 ppm and the chlorine content less than 10 ppm.
The contamination by metallic impurities is not higher than in the original products. By means of S.E.M. a granular size of 1.1 pm is measured. The pores are completely open.
Example 2
A mixture of lithium peroxide and zirconium oxide is manufactured in the same manner as under example 1 but the powder obtained after spray drying is now directly calcined, without granulation, for 1 hour at 7500C.
The calcined powder is compressed into cylinders by means- of cold isostatic pressing at a pressure of 300 MPa. The green cylinders show a density of 54% of the theoretical density.
The cylinders are sintered under an atmosphere of dry air at a temperature of 950'C for 15 hours.
The density after the sintering amounts to 73% of the theoretical density.
Example 3
73.12 g of lithium hydroxide monohydrate from the company Baker is added to an over-measure of 150 ml of hydrogen peroxide (30% H202 in H20).
The viscous dispersion is stirred for 60 minutes.
i i After the transformation of the lithium hydroxide monohydrate into lithium peroxide, the viscous dispersion is diluted with water to a clear solution with 20 g of lithium per litre.
103.02 g zirconium oxide powder, with a specific surface area of 16 m2/g and an apparent density of 0.32 g/cm3 from the company Criceram in Francei is dispersed in water to a concentration of 125 g zirconium oxide per litre.
The first mentioned solution is added to the zirconium oxide dispersion and the mixture obtained is homogenised by stirring.
Thereafter the solution is dried by means of spray drying whereby during the drying the mixture is stirred in order to avoid sedimentation of the zirconium oxide particles.
At regular intervals extra hydrogen peroxide is added in order to compensate the hydrogen peroxide catalytically dissolved by the zirconium oxide.
A white powder consisting of an intimate mixture of lithium peroxide (hydrate andlor perhydrate) and zirconium oxide is obtained.
This powder is compacted at a pressure of 100 MPa, the compacted powder is broken and it is granulated.
The granulate is subsequently fractionated by means of sieves until a fraction with particle sizes situated between 355 pn and 1000 pm is obtained.
This fraction is calcined under a dry nitrogen atmosphere at a temperature of 675C for 20 hours.
The calcined granulate is subsequently sintered under an atmosphere of dry air at a temperature of 1000C for 20 hours.
Roentgen diffraction analysis shows that the sintered granulate consists of pure lithium metazirconate.
After the sintering the original granulate form appeared to be preserved so that the sintered lithium metazirconate in particle form is suitable to be used in a liquefied layer or for applications with gas liquefied particle transport.
- 10 The invention is in no way restricted to the embodiments described above and within the scope of the patent application many changes can be applied to the described embodiments, among others regarding the form, the composition and the number of components which are used with the implementation of the invention.
In particular the procedure is not necessarily limited to the manufacture of metazirconate. Other zirconates can be manufactured in an analogue manner.
Furthermore it is not necessary to start from lithium peroxide. Other lithium compounds can be used which are more easily soluble in water, thus among others with exclusion of the difficultly soluble lithium, carbonate.
i i 1 1
Claims (18)
1. Procedure for preparing lithium according to which zirconium oxide and a lithium compound are mixed and are thereafter allowed to react with each other through a thermal treatment. hereafter called calcinationp characterised in that on the one hand, a clear solution. free of dispersed solid particles, of a soluble lithium compound in water, and. on the other hand. a dispersion of zirconium oxide powder in water are prepared, this solution and this dispersion are mixed, the mixture obtained is dried to a powdery product and this powdery product is subjected to calcination.
2. Procedure according to claim 1, characterised in that lithium peroxide (hydrate and/or perhydrate) is used as lithium compound.
3. Procedure according to claim 2. characterised in that the clear solution of lithium peroxide is prepared in situ by allowing lithium hydroxide or lithium hydroxide monohydrate to react with an over-measure of hydrogen peroxide after which a sufficient amount of water is added in order to bring the concentration of lithium within the solubility limit in order to obtain a clear solution.
4. Procedure according to claims 2 and 3, characterised in that the concentration of lithium in the clear solution is maintained below 30 g lithium per litre of solution.
5. Procedure according to one of the claims 1 through 4, characterised in that the zirconium oxide dispersion is prepared by first moistening zirconium oxide in powder form and subsequently adding the desired amount of water to it.
6. Procedure according to one of the claims 1 through 5. characterised in that the mixture obtained is dried by spray drying.
7. Procedure according to claim 6, characterised in that the mixture of the clear solution and of the dispersion of zirconium oxide in water is stabilised during the spray drying by the addition of hydrogen zirconate A peroxide.
8. Procedure according to one of the claims 1 through 7, characterised in that the dry mixture obtained is calcined at a temperature between 500 and 900C in oxidising or neutral atmosphere.
9. Procedure according to one of the claims 1 through 8, characterised in that the calcined powder is further sintered.
10. Procedure according to claim 9, 'characterised in that the calcined powder is granulated before the sintering.
11. Procedure according to one of the claims 1 through 8, characterised in that the mixture obtained is granulated before the calcination.
12. Procedure according to one of the claims 9 through 11, characterised in that the calcined powder or granulate is sintered at a temperature above 9000C.
13. Procedure according to claims 9 through 11, characterised in that the calcined and dried powder or granulate is shaped through cold pressing and thereafter sintered at a temperature above 900"C.
14. Lithium zirconate prepared according to the procedure according to one of the preceding claims.
15. Lithium zirconate prepared according to the procedure according to one of' the claims 9 through 13, characterised in that the sintered product obtained has a granular size which is less than 2 pm.
16. Lithium zirconate according to claim 15, characterised in that the sintered product has a granular size which is less than 1 pm.
17. Lithium zirconate prepared according to the procedure according to claim 13, characterised in that the sintered product obtained has a density which is greater than 70% of the theoretical density and a completely open porosity whereby the pore diameter is less than 0.6 pm.
18. Powdery mixture of zirconium oxide and a lithium compound obtained according to the steps of the procedure according to one of the aforementioned claims up to and including the drying.
Pued at The Patent Officc.51AtA HOLLS61 High Holbcj,n. London WC1R4TPPurther copies may be obed trom The P&t4ntoMet. Sales Branch. St 1Lary Cray. Orpuigwn. Kent BM 3RD Printed by Muluplex tach=quez M. St Ilwy Cray, Kent. Con 1147 1 i
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| BE8900040A BE1002757A3 (en) | 1989-01-16 | 1989-01-16 | A process for preparing LITHIUMZIRKONAAT, thus prepared LITHIUMZIRKONAAT and Intermediate. |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB9000908D0 GB9000908D0 (en) | 1990-03-14 |
| GB2227740A true GB2227740A (en) | 1990-08-08 |
Family
ID=3883958
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB9000908A Withdrawn GB2227740A (en) | 1989-01-16 | 1990-01-16 | Lithium zirconate |
Country Status (5)
| Country | Link |
|---|---|
| BE (1) | BE1002757A3 (en) |
| CA (1) | CA2007763A1 (en) |
| DE (1) | DE4000608A1 (en) |
| FR (1) | FR2641774B3 (en) |
| GB (1) | GB2227740A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5834390A (en) * | 1992-05-11 | 1998-11-10 | Commissariat A L'energie Atomique | Copper-substituted, lithium zirconate-based ceramic usable as a tritium producing material |
| JP2006507205A (en) * | 2002-11-26 | 2006-03-02 | デグサ アクチエンゲゼルシャフト | Pyrolytic oxide powder, its manufacture and its use in separators for electrochemical cells |
| CN104556222A (en) * | 2014-12-23 | 2015-04-29 | 浙江大学 | Preparation method of lithium zirconate porous microsphere |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FR2715651B1 (en) * | 1994-01-28 | 1996-03-01 | Commissariat Energie Atomique | Tritogenic ceramic material containing lithium and its preparation process. |
| CN112736364B (en) * | 2020-12-28 | 2022-08-12 | 惠州亿纬创能电池有限公司 | Composite diaphragm and preparation method and application thereof |
Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0333041A1 (en) * | 1988-03-11 | 1989-09-20 | Tosoh Corporation | Method of producing a lithium zirconate powder |
Family Cites Families (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JPS6172626A (en) * | 1984-09-14 | 1986-04-14 | Toyo Soda Mfg Co Ltd | Production of zirconia fine powder |
-
1989
- 1989-01-16 BE BE8900040A patent/BE1002757A3/en active
-
1990
- 1990-01-11 DE DE19904000608 patent/DE4000608A1/en not_active Withdrawn
- 1990-01-15 CA CA 2007763 patent/CA2007763A1/en not_active Abandoned
- 1990-01-16 GB GB9000908A patent/GB2227740A/en not_active Withdrawn
- 1990-01-16 FR FR9000445A patent/FR2641774B3/en not_active Expired - Fee Related
Patent Citations (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0333041A1 (en) * | 1988-03-11 | 1989-09-20 | Tosoh Corporation | Method of producing a lithium zirconate powder |
Cited By (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5834390A (en) * | 1992-05-11 | 1998-11-10 | Commissariat A L'energie Atomique | Copper-substituted, lithium zirconate-based ceramic usable as a tritium producing material |
| JP2006507205A (en) * | 2002-11-26 | 2006-03-02 | デグサ アクチエンゲゼルシャフト | Pyrolytic oxide powder, its manufacture and its use in separators for electrochemical cells |
| CN104556222A (en) * | 2014-12-23 | 2015-04-29 | 浙江大学 | Preparation method of lithium zirconate porous microsphere |
| CN104556222B (en) * | 2014-12-23 | 2016-01-20 | 浙江大学 | The preparation method of lithium zirconate porous microsphere |
Also Published As
| Publication number | Publication date |
|---|---|
| FR2641774B3 (en) | 1991-04-26 |
| FR2641774A1 (en) | 1990-07-20 |
| DE4000608A1 (en) | 1990-07-19 |
| GB9000908D0 (en) | 1990-03-14 |
| CA2007763A1 (en) | 1990-07-16 |
| BE1002757A3 (en) | 1991-05-28 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |