Low Temperature Symmetry of Pyrochlore Oxide Cd2Re2O7

TL;DR

This study investigates the low-temperature structural phase transitions of the pyrochlore oxide Cd2Re2O7, revealing two symmetry-lowering transitions at 200K and 120K through X-ray analysis, indicating complex lattice deformations.

Contribution

The paper provides detailed X-ray evidence of two distinct symmetry-lowering structural transitions in Cd2Re2O7 at low temperatures, expanding understanding of its lattice behavior.

Findings

Second order transition at 200K from cubic to tetragonal structure

First order transition at 120K likely to a different tetragonal space group

Identification of specific space groups involved in the transitions

Abstract

We report the X-ray study for the pyrochlore oxide Cd2Re2O7. Two symmetry-lowering structural transitions were observed at Ts1=200K and Ts2=120K. The former is of the second order from the ideal cubic pyrochlore structure with space group Fd-3m to a tetragonally distorted structure with I-4m2, while the latter is of the first order likely to another tetragonal space group I4122. We discuss the feature of the lattice deformation.