Soft-chemical routes to synthesis of solid oxide materials

Abstract

We describe three different families of metal oxides, viz., (i) protonated layered perovskites, (ii) framework phosphates of NASICON and KTiOPO4 (KTP) structures and (iii) layered and three-dimensional oxides in the H-V-W-O system, synthesized by 'soft-chemical' routes involving respectively ion-exchange, redox deintercalation and acid-leaching from appropriate parent oxides. Oxides of the first family, HyA2B3O10(A = La/Ca; B = Ti/Nb), exhibit variable Bronsted acidity and intercalation behaviour that depend on the interlayer structure. V2(PO4)3 prepared by oxidative deintercalation from Na3 V2(PO4)3 is a new host material exhibiting reductive insertion of lithium/hydrogen, while K0.5Nb0.5 M0.5OPO4 (M = Ti, V) are novel KTP-like materials exhibiting second harmonic generation of 1064nm radiation. HxVxW1-xO3 for x = 0-125 and 0.33 possessing α-MoO3 and hexagonal WO3 structures, prepared by acid-leaching of LiVWO6, represent functionalized oxide materials exhibiting redox and acid-base intercalation reactivity. © 1994 Indian Academy of Sciences.