Ceramic Properties of Europium Oxide

Abstract

Europium oxide of 99.7% purity was compacted into small bars and pellets which were fired at temperatures from 1050° to 1700°C. for 2 to 120 hours in atmospheres that were oxidizing, mildly reducing (open furnace), or strongly reducing. It was found that (1) europium oxide compacts fired in oxygen for 2 hours at 1500°C. bad attained a density of 90% of theoretical and were stable in boiling water, (2) compacts fired under mildly reducing conditions at 1500°C. for 2 hours had attained a density of 84% of theoretical and disintegrated in boiling water, and (3) those fired similarly in a hydrogen atmosphere began to fuse at 1500°C. The linear thermal expansion of the compacts fired at 1500°C. in the open furnace was 10.5 x 10 ‐6 in. perin. per°C. between 0° and 1000 °C. and their molar specific heat between 0° and 800°C. was 33.3 cal. Careful investigation of the structural changes occurring in europium oxide with rising temperature revealed that (1) the low‐temperature (body‐centered cubic) form inverts slowly to the high‐temperature form at approximately 1050°C., (2) the high‐temperature form has monoclinic symmetry, and (3) it does not revert readily to the cubic form; its theoretical density was calculated to be 8.18 gm. per cm. 3 .