Effect of point defects on Curie temperature of lithium niobate.

The effect of point defects on the Curie temperature ( Tc) of LiNbO3 ( LN) was investigated by combining Tc measurements with an analysis of the defect structures of LN doped with impurities having various valences. The data show that Tc of congruent LN increases with the impurity concentration up to around 3 and 2 mol% for divalent and trivalent impurities, respectively, whereas it decreases continuously with increased concentrations of tetravalent impurities. These Tc variations were examined with respect to the defect structures of impurity-doped LN, which are expressed in the form chemical formulae using Kröger-Vink notation. The defect structures of divalent and trivalent impurity-doped LN are [ABSTRACT FROM AUTHOR]