Structure Parameter Changes in MnO2 at the Onset of Antiferromagnetism

摘要

A low temperature X-ray camera was built (rate of evaporation of 1 liter per hour for liquid hydrogen or 3 liters per hour for liquid helium) and was used to study the lattice distortions occurring in antiferromagnetic MnO2 at its Curie temperature (85°K). It was found that the tetragonal c axis expands as the temperature is lowered and that the a axes contract. The data suggest a change in the slope of the volume vs. temperature curve but are not conclusive in this respect.