Preparation and properties of LiTaO3-based solid solutions with cation vacancies

It has been found that nonstoichiometric solid solutions $\text{(}\text{Li}{}_{\mathrm{<mtext>1?</mtext><mtext>x</mtext>}}\text{M}{}^{\mathrm{2+}}{}_{\mathrm{<mtext>x</mtext><mtext>2</mtext>}}\text{□}{}_{\mathrm{<mtext>x</mtext><mtext>2</mtext>}}\text{)}\text{TaO}\text{3}$ with M=Zn, Ni, Mg and Ca exist over wide ranges. In the case of the Zn-system, especially, a LiTaO₃ structure was still stable even at x=0.5, where 25% of the Li sites are vacant. A new series of solid solutions shows ferroelectric properties. The Curie temperature is closely related with the axial ratio c/a of the hexagonal cell.