Low-frequency acoustic study of ferroelastic phase transitions in Ba₂NaNb₅O₁₅

Abstract

The peculiarities of low-frequency internal friction near the first order low-temperature (110 K) and second order high-temperature (573 K) phase transitions in improper Ba₂NaNb₅O₁₅ ferroelastic were studied. A large and wide internal friction peak and diffused step-like change in the temperature dependence of shear modulus were also observed within an incommensurate phase between these two phase transitions.

Key Words:

• improper ferroelastic
• phase transition
• internal friction