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, H_yA₂B₃O₁₀(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 K_0.5Nb_0.5 M_0.5OPO₄ (M = Ti, V) are novel KTP-like materials exhibiting second harmonic generation of 1064nm radiation. H_xV_xW_1-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.

A new series of layered oxides, Li₃(Li_1.5xFe_3−(x+1.5x)Te_x)O₆, (0.1 ≤ 𝑥 ≤ 1.0) possessing rock-salt superstructures crystallizing in monoclinic (S.G. C2/m) symmetry is reported here. Investigations based on single crystal and powder X-ray diffraction studies for the 𝑥 = 1 member, Li₃(Li_1.5Fe_0.5Te)O₆, (a=5.1834(1); b=8.8858(2); c=5.16840(8) Å; 𝛽=110.660(1)°) confirmed the stabilization of (Li_1.5Fe_0.5Te_1.0O₆)³⁻ honeycomb arrays with a very high amount of lithium ions. The structure for the x = 0.5 member (Li_3.75Fe_1.75Te_0.5O₆) has also been confirmed by the powder X-ray diffraction Rietveld refinements. Li₃(Li_1.5Fe_0.5Te)O₆ and Li₃(Li_0.75Fe_1.75Te_0.5)O₆ oxides exhibited Curie–Weiss behaviour in the temperature range of 50–300 K with negative 𝜃 values. Their respective ionic conductivities were found to be 6.76 × 10⁻⁵ S cm⁻¹ and 2.21 × 10⁻⁶ S cm⁻¹ at 573 K. The UV-visible diffuse reflectance measurements for the differentmembers of the series Li₃(Li_1.5xFe_3−(x+1.5x)Te_x)O₆, (0.1 ≤ 𝑥 ≤ 1.0) show the expected shifts in their absorptionedges based on the increasing amount of Fe³⁺ions starting from 𝑥 = 1.0 member to 𝑥 = 0.1 member