Phase Transitions of Ba2NaNb5(1-x)Ta5xO15

Ceramic samples of the mixed system Ba2NaNb5(1-x)Ta5xO15 were investigated through dielectric and Raman scattering measurements. It was revealed that with the increase of x from 0 to 1, the ferroelectric Curie point decreases from 833 K to about 40 K, whereas the ferroelastic phase transition point decreases from 573 K to the 250 K range.