METHOD OF MAKING HIGHLY SINTERABLE LANTHANUM CHROMITE POWDER

摘要

A highly sinterable powder consisting essential-ly of LaCrO3, containing from 5 weight % to 20 weight % ofa chromite of dopant Ca, Sr, Co, Ba, or Mg and a coatingof a chromate of dopant Ca, Sr, Co, Ba, or Mg; is made by(1) forming a solution of La, Cr, and dopant; (2) heatingthe solutions; (3) forming a combined solution having adesired ratio of La, Cr, and dopant and heating to reducesolvent; (4) forming a foamed mass under vacuum; (5) burn-ing off organic components and forming a charred material;(6) grinding the charred material; (7) heating the char atfrom 590°C to 950°C in inert gas containing up to 50,000ppm O2 to provide high specific surface area particles;(8) adding that material to a mixture of a nitrate of Crand dopant to form a slurry; (9) grinding the particlesin the slurry; (10) freeze or spray drying the slurry toprovide a coating of nitrates on the particles; and (11)heating the coated particles to convert the nitratecoating to a chromate coating and provide a highlysinterable material having a high specific surface area ofaver 7 m2/g.