Abstract

The incommensurate phase of ThBr₄ [1] and ThCl₄ have been found recently. The complete study of the crystal structure by neutron diffraction leads to the following results : - ThBr₄ shows a phase transition at 95 K and, down to 4 K, the observed phase is incommensurate all over this temperature range (without any lock-in). A similar behaviour is exhibited by ThCl₄ with a temperature transition at 70 K.

© 1984 Optical Society of America