Effects of Heating Rate on the Nucleation, Growth, and Transformation of InOOH and In₂O₃ via Solvothermal Reactions

A solvothermal reaction is generally considered to be governed by the chemical and thermodynamic parameters. Yet, the effects of heating rate on the nucleation and growth of the target materials within solvothermal processes have been rarely reported. In this work, taking the solvothermally synthesized InOOH/In₂O₃ as the sample system we intend to illustrate that the heating rate plays an important role in the nucleation, growth, and transformation in solvothermal reactions. It is shown that with the heating rate changing from 4 to 8 °C/min, the initial nucleation temperature for ultrathin InOOH nanowires drops greatly from 160 to 120 °C. At a heating rate of 4 °C/min, the transformation from InOOH nanowires to In₂O₃ nanocubes in the one-step solvothermal system begins at 170 °C and completes at 210 °C. While at a heating rate of 8 °C/min, the transformation begins at 130 °C and completes at 180 °C. It is also found that heating rate may trigger different growth mechanisms in the solvothermal system and subsequently influence the microstructure of the products. Thus, it is anticipated that controlling the heating rate may be a potential route to tailor the morphology, microstructure, and even the properties of materials via solvothermal processes