Raman Spectroscopy of Potassium Titanates: Their Synthesis,Hydrolytic Reactions,and Thermal Stability

Abstract

The majority of the potassium titanates described in the literature were synthesized, and their Raman spectra recorded. The identity of the compounds K₂TiO₃, K₂Ti₂O₅, K₂Ti₄O₉, K₂Ti₆O₁₃, and K₂Ti₈O₁₇ was confirmed by x-ray diffraction. Raman spectroscopy was then used to study the hydrolysis, under different conditions, of K₂Ti₂O₅ and of K₂Ti₄O₉. On drying of the hydrolysis products, the following species were found to form: K₂(H₂O)_0.66 Ti₈O₁₆(OH)₂, K_1.33(H₂O)_0.33Ti₄O_8.33(OH)_0.67, and H₂Ti₈O₁₇. On ignition at temperatures of 500–600°C these species converted, respectively, to K₂Ti₈O₁₇, K₂Ti₆O₁₃, and TiO₂(B). Raman spectroscopy was used to establish that (1) K₆Ti₄O₁₁ consists of a mixture of K₂TiO₃ and a new compound K₄Ti₃O₈; (2) K₂Ti₃O₇ consists of a mixture of K₂Ti₂O₅ and K₂Ti₄O₉, and (3) K₂Ti₅O₁₁ consists of a mixture of K₂Ti₄O₉ and K₂Ti₆O₁₃. The temperature of decomposition and the identity of the products of the thermal decomposition of K₂Ti₈O_l7, K₂Ti₄O₉, K₂Ti₂O₅, and K₄Ti₃O₈ were determined by Raman spectroscopy. The XRD data of the newly identified compounds are reported.