Pyrochlore-type compounds containing double oxides of trivalent and tetravalent ions

Abstract

A study has been mad e by X-ray diffract ion analyses of t he A20 3 :2B02-type double oxides. It was found that many of t hese mixed oxides, after appropriate heat treatment, formed compounds of the formula type A2B20 7 • Most of these compounds crystallized in the cubic system with a face-centered cell similar to that found for the mineral pyrochlore, although some were distorted from the ideal cubic struct ure. Ind exed X-ray diffraction powder patterns are given for t he cubic compounds 811l203· 2Ti02, Gd 20 3·2 t i02, Dy20 3·2TiOz, Y20 3·2Ti02, Ybz0 3·2TiOz, La20 3·28n02, Nd20 3· 28n02, La20 3·2Zr02, Nd20 3·2Zr02, and for the possible compounds Y20 3·2Zr02 and Nd20 3· 2UOz. Unindexed patterns are given for La20 3· 2Ti02, Nd20 3· 2Ti02 and Biz0 3·2Sn02. On the basis of the existence of the two compounds La20 3· 2Zr02 and Nd20 3·2Zr02, the phase diagrams for the systems La20 a-Zr02 and Nd20 3-Zr02 have been revised .