Structural phase transitions and processes of “order-disorder” in the ferroelectric Li0.12Na0.88TayNb1−yO3 solid solution

The system of the Li
x
Na
1−x
Ta
y
Nb
1−y
O
3
solid solutions based on sodium niobate with oxygen-octahedral type of structure is of great interest because the changes of the components concentration and the temperature are accompanied by a variety of structural phase transitions. Particularly, the Li
0.12
Na
0.88
Ta
y
Nb
1−y
O
3
solid solution is promising as a material with high superionic conductivity. When x = 0.12 the structure orders in such a way as to make the phase transition to the superionic state possible. Besides, at temperatures 315–350 °C in the Li
0.12
Na
0.88
Ta
y
Nb
1−y
O
3
solid solution the phase transition from ferroelectric to antiferroelectric phase taking place before the superionic one can be observed. They were found at ∼ 400÷460 °C.