23Na second-order quadrupolar shifts and heat capacity anomalies in Na β-alumina

Abstract

In the temperature region 100–140 K the second‐order quadrupolar shifts of ²³Na in β‐alumina undergo a gradual but unusual change. In the same temperature range, contributions to the heat capacity of atoms in the conducting plane exhibit a maximum. These facts are considered as evidence for a 2D ’’melting transition’’ in the conducting plane of β‐alumina. The nature of the phenomena responsible for these anomalies is discussed.