EPR spectroscopy and optical microscopy study of ferroic states in pyrochlore

Abstract

The EPR spectroscopy (using as the EPR probe) and optical microscopy studies of pyrochlore were carried out in the temperature range of 80 K-300 K which included phase transitions at and . The evidence for coexistence of a proper ferroelectric-ferroelastic state and an improper ferroelectric-ferroelastic state in the ferroelectric phase of is presented. While the former appears below , the latter comes from the improper ferroelastic state of the precedent phase . The unusual behaviour of the ferroic states on a temperature scale is discussed from the viewpoint of a two-weakly-bonded-network description of the pyrochlore structure.