In Situ Synthesis Kinetics of Salicylic Acid Terbium Complexes in Sol-Gel Derived Host Materials

In situ synthesis kinetics of salicylic acid terbium complexes in sol-gel derived host materials has been investigated. With the increase of the heat treatment time, the broad excitation band in the excitation spectra of the salicylic acid and terbium chloride co-doped gel glass was formed gradually and the luminescence intensity increased gradually, which indicated the gradual synthesis of the salicylic acid terbium complexes in the gel glass during the heat treatment. In situ synthesis reactions of the salicylic acid terbium complexes in 90°C, 120°C, 150°C were found to be second-order reactions, and can be described by the integrated rate equation: \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document} $$\frac{1}{{(1 - x)}} - 1 = ak_2 t$$ \end{document}, where x is the fractional concentration of the synthesized complex and t the reaction time. According to Arrhenius equation, the activation energy of in situ synthesis of the salicylic acid terbium complexes in the gel glasses was calculated to be 46.39 KJ/mol.