High Temperature Ceramic Superconductors.

Mazdiyasni, K. S.; Chen, K. C.; DeHope, W.J.; Duggan, D.M.; Glatter, E.; Lin‐Liu, Y. R.; McQuillan, B.W.; Montgomery, Fred C.; Pak, S.S.; Stephens, R. B.

doi:10.21236/ada239813

Cited by 1 publication

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“…Chemically synthesized ceramic powders have numerous potential benefits over solid-state derived powders including increased phase purity, reduced particle size, reduced milling demand, and improved sintering properties. There are numerous processes reported for the production of alkali-earth zirconates and titanates, including hydrothermal, sol-gel, sol precipitation, hydroxide, peroxide, oxalate, citrate and freeze-drying processes [2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18] . Sol-gel and sol-precipitation methods in particular, have high equipment costs due to the sensitivity of reagents to moisture, and very high costs for reagents.…”

Section: Introductionmentioning

confidence: 99%

Oxalate-precursor processing for high quality BaZrO3

et al. 2005

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BaZrO3 is by far the most inert crucible material that has been used for melt processing of high quality single crystal YBCO superconductors. To overcome the processing difficulties of existing solid-state methods, solution processing methods are increasingly important in powder synthesis. This study investigates several methods of producing oxalate precursors for subsequent thermal decomposition to BaZrO3 with a view to producing high quality BaZrO3 ceramics. The most favourable system used barium acetate, ammonium oxalate and zirconium oxychloride, which unlike other previously reported oxalate processes allowed near stoichiometric precipitation without requiring a large excess of Ba reagents, elevated precipitation temperatures or slow addition of reagents. Precise control over precipitate stoichiometry was achieved by variation of the solution Ba:[Zr+Hf] mole ratio without requiring accurate control over oxalate addition. XRF, XRD, N2 BET adsorption, DTA/TGA and TEM analysis showed this process to be capable of producing BaZrO3 powders suitable for ceramics applications. The phase purity, particle size and surface areas of BaZrO3 powders produced by calcination of these precursors can be adjusted by variation of stoichiometry and calcination temperature. Crucibles formed from oxalate precursors have been able to contain Y2O3-BaCuO2-CuO melts for up to seven days.Comment: 28 pages, 7 figures, PDF forma

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