Method of Forming and Controlling Morphology of Cracks in Silicon Dioxide Film

A method of forming and controlling morphology of cracks in silicon dioxide film, the method comprising:

• preparing a silicon dioxide precursor solution, wherein the silicon dioxide precursor solution comprises a solvent, a precursor of silicon dioxide, a precursor of metal oxide nanocrystals, water, and an acid as a catalyst;
• coating the silicon dioxide precursor solution onto a substrate;
• drying the silicon dioxide precursor solution atop the substrate in ambient air, with blown air, and/or with blown nitrogen at a drying temperature between about 20° C. to 100° C. for drying times between 1 minute to 24 hours to form a silicon dioxide film having uniformly dispersed metal oxide nanocrystals, wherein shorter drying times yield substantially spherical, ball shaped metal oxide nanocrystals and wherein longer drying times yield rod shaped and disc shaped metal oxide nanocrystals;
• and
• thermally treating the silicon dioxide film at a thermally treating temperature between about 60° C. to 500° C. for thermally treating times between 1 minute to 24 hours to form a cracked mesh of silicon dioxide film, wherein approximately two cracks are initiated from each rod shaped metal oxide nanocrystal, wherein approximately three to four cracks are initiated from each substantially spherical, ball shaped metal oxide nanocrystal, and wherein approximately four or more cracks are initiated from each disc shaped metal oxide nanocrystal.