NEW TRANSITION-METAL PHOSPHATES RELATED TO KTIOPO4 - SYNTHESIS OF K0.5M0.5M'0.5OPO4 (M=NB, TA M'=TI, V) AND K1-XTI1-XVXOPO4 EXHIBITING NONLINEAR-OPTICAL BEHAVIOR

Several transition metal phosphates of the general formula KM0.5M0.5'OPO4, where M = Nb(V) or Ta(V) and M' = Ti(III), V(III) Cr(III), Fe(III), possessing the KTiOPO4 (KTP) structure have been synthesized. Unlike KTP, none of these phosphates exhibit second harmonic generation (SHG) of the 1064-nm radiation. Soft-chemical oxidation of the Ti(III) and V(III) phosphates using chlorine in CHCl3, however, restores the SHG property to the oxidized mate-rials, K0.5M0.5M0.5'OPO4 (M = Nb(V), Ta(V); M' = Ti(IV), V(IV)). K1-x Ti1-xVxOPO4 (x less-than-or-equal-to 0.25) prepared similarly from KTi1-xVxOPO4 also exhibit SHG. The results reveal that exclusive presence of d0 cations at the Ti(IV) site preserves the SHG response of KTP derivatives. (C) 1994 Academic Press, Inc.