Study of titanium phosphate gels and their application to the synthesis of KTiOPO4 films

Abstract

Phosphoric acid esters PO(OR)_3–x(OH)_x(with 0<x<3 and R = Et, Bu, Prⁱ, 2-methylbutane) have been studied as precursors for polycondensation reactions with titanium alkoxides. These precursors are easily synthesized by reaction of P₂O₅ with alcohols. Both the POH : Ti ratio and the hydrolysis ratio (H₂O : Ti) have an effect on the condensation and gelation. Also, thermolysis of phosphate esters of tertiary alcohols causes the in situ generation of free H₃PO₄ and the condensation of titanium phosphate. The precursors and the colloidal solutions have been characterized through ³¹P nuclear magnetic resonance (NMR) and dynamic light scattering. The use of these colloidal solutions for the thin-film synthesis of KTiOPO₄ is demonstrated.