Peculiarities of low-frequency internal friction near the ferroelastic phase transition in Ba2NaNb5O15

The internal friction and shear elastic constant features in the vicinity of ferroelastic phase transition point at a frequency of ∼ 20Hz in the Ba2NaNb5O15 crystal were investigated. The behaviour of complex elasticity near the upper ferroelastic Curie point under the different external forces are discussed in terms of lattice defect dynamics.