Preparation of lanthanum chromate and lanthanum chromite powders

Details Preparation of lanthanum chromate and lanthanum chromite powders Preparation of lanthanum chromate and lanthanum chromite powders

1987-10-23

1989-05-16

Stoll, Robert L.

Compositions

Electrically conductive or emissive compositions

Metal compound containing

252518, 501152, 423263, 423265, H01B 102

Patent

active

048307807

ABSTRACT:
This invention relates to a process for the preparation of a crystalline compound having an empirical formula LaCr.sub.x A.sub.1-x O.sub.4 yH.sub.2 O where A is a metal selected from the group consisting of Mg, Sr, Ca and Ba, x ranges from 0.99 to about 0.7 and y ranges from 0 to 0.15. The process comprises adding a solution of the appropriate metal salts to a solution of ammonium hydroxide thereby precipitating a hydroxide gel intermediate, which is dried and calcined in air to yield the resultant crystalline compound which has a huttonite structure. Additionally, this invention relates to a process for the preparation of a ceramic powder having the empirical formula LaCr.sub.x A.sub.1-x O.sub.3, where A is a metal selected from the group consisting of Mg, Sr, Ca and Ba, and x ranges from 0.99 to about 0.7. Finally, a ceramic composition having the empirical formula LaCr.sub.x A.sub.1-x O.sub.4 yH.sub.2 O having a huttonite structure is also disclosed.

REFERENCES:
patent: 3330697 (1967-07-01), Pechini
patent: 3630968 (1971-12-01), Hamano et al.
patent: 3893821 (1975-07-01), Davies et al.
patent: 3922236 (1975-11-01), Douglas et al.
patent: 3974108 (1976-08-01), Staut et al.
Leslie Groupp and Harlan U. Anderson, J. Amer. Ceram. Soc., vol. 59, No. 9-10, 449-50 (1976).
C. N. R. Rao et al., "Synthesis of Complex Metal Oxides Using Hydroxide, Cyanide and Nitrate Solid Solution Precursors", Journal of Solid State Chemistry, vol. 58, 29-37 (1985).
P. Hutton, "Huttonites, A New Monoclinic Thorium Silicate", American Mineralogy, vol. 36, 60-65 (1951).
H. Schwarz, "Rare Earth Chromates. 1 Lanthanum Chromate (V) LaCrO.sub.4 ". Z. Anorg. Allgem. Chem., Band 322, 1-14 (1963).
M. D. Vasileha et al., Dapov. Akad. Nauk Ukr. RSR, Ser. B: Geol., Khim. Biol. Nauki 1977 (5), 410-13, (with abstract).

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