Synthesis of transparent tin-doped indium oxide (ITO)-containing glass-ceramic coating by the sol-gel route for UV/NIR-shielding

Transparent glass-ceramic containing tin-doped indium oxide nano-crystalline phase was synthesized using the sol-gel method. The prepared sol, which was based on sodium aluminoborosilicate glass composition, was applied on soda-lime-silicate glass substrate through the dip-coating technique. Developing such glass-ceramics can offer several advantages, including reducing the total cost of production, enhanced chemical durability and a low-temperature synthesis process. The thermal behavior of the dried gels was investigated using simultaneous thermal analysis (STA), to determine the decomposition temperature of the nitrate salts in the gel, its glass crystallization temperature, and finally to optimize the heat treatment regime and optical properties as well. UV–Vis–NIR spectroscopy of the coated samples after heat treatment at 500 °C for 10 h revealed high visible transparency (T>70%) while indicating significant UV/NIR shielding, i.e. near zero and 10 % transmission, respectively. Phase analysis and crystallization behavior studies were conducted using XRD and FE-SEM to evaluate the morphology and size of the precipitated crystallites. According to the results, the optimum heating program for ITO crystallization was heating temperature and soaking time of 500 °C and 10 h, respectively. The undesirable crystalline phase of InBO3 was precipitated as the main crystalline phase by increasing the heat treating temperature to 550 °C. Furthermore, the glass structure was studied using FTIR spectroscopy demonstrating a highly polymerized glassy network for the coating. The effect of the precursors-to-solvent ratio during the synthesis process on the final optical properties was also investigated.