Thermal Decomposition of Indium(III) Hydroxide Prepared by the Microwave‐Assisted Hydrothermal Method

Abstract

Cubic‐shaped In(OH)3 particles with average size of 0.348 μm were precipitated from a mixed aqueous solution of InCl3 and urea by a microwave‐assisted hydrothermal method. The kinetics and mechanisms of the thermal decomposition of the sample were investigated by means of thermoanalytical measurements under three different modes of temperature program, complemented by several physicochemical techniques. No intermediate compound was found during the course of thermal decomposition from cubic‐In(OH)3 to cubic‐In2O3. Distinguished induction period for the thermal decomposition was identified as one of the most characteristic kinetic phenomena of the present reaction, together with the crack formation on the surface product layer during the second half of the reaction. The kinetic rate behavior of the reaction was characterized physicogeometrically as the surface nucleation and subsequent advancement of the established reaction interface inward toward the center of the reactant particle, where the apparent activation energies for the surface nucleation and advancement of the reaction interface were estimated as 257 and 140 kJ/mol, respectively.