Fluoritmischphasen der Dioxide von Uran, Thorium, Cer und Zirkonium mit Wismutoxid

The preparations, colours, lattice constants, experimental and X‐ray densities of fluorite‐type mixed phases between bismuth(III) oxide and the dioxides of U, Th, Ce, and Zr are described. In the systems UO2BiO1.5, ThO2BiO1.5 and CeO2BiO1.5, fluorite phases occur from 0 to 100, 60 and 40 mole per cent BiO1.5, respectively, with all cation positions being occupied and anion vacancies increasing with higher BiO1.5 contents. In the system ZrO2BiO1.5, ThO2BiO1.5 and CeO2BiO1.5, fluorite phases occur from 0 to 100, 60 and 40 mole per cent BiO1.5, respectively, with all cation positions being occupied and anion vacancies increasing with higher BiO1.5 contents. In the system ZrO2BiO1.5 the two‐dimensionally ordered fluorite superstructure of β‐Bi2O3 occurs from 30 to 100 mole per cent BiO1.5. Whereas the pure β‐Bi2O3 has an ideally occupied cation lattice and vacancies in the anion lattice, at 40 mole per cent BiO1.5 there is an ideally filled anion lattice with interstitial cations.