Y3Al5O12:Tb3+ phosphor was prepared by using a sol-gel method and the process of particle growth was investigated by X-ray diffraction, scanning electron microscopy, particle size, and Brunauer-Emmett-Teller surface area measurements. As-dried Y3Al5O12:Tb3+ precursor is amorphous bulk. After heating above 800 degrees C, the samples become polycrystalline powders. The low-temperature heated sample (e.g., 900 degrees C) has a porous texture with large particle size (> 10 mu m). When the samples are heated at higher temperatures (e.g., 1100 degrees C), the pores become larger and the grains start to appear. When the samples are heated at 1400 degrees C, the large-size particles break into small particles (similar to 1 mu m), which are actually agglomerated particles by even smaller grains (in submicrometer scale). Under the excitations of the low-voltage cathode ray (< 1500 V), the phosphor prepared in this sol-gel method has brighter cathodoluminescent intensity than the commercial phosphor. (c) 2007 The Electrochemical Society.