A sol-gel process is described for preparation of crystalline lithium disilicate (Li2Si2O5) from tetraethylorthosilicate and lithium ethoxide. The glass network structure and crystallinity resulting from heat treatment at temperatures from 150 degrees to 900 degrees C were investigated by nuclear magnetic resonance, X-ray diffraction, and differential scanning calorimetry/thermogravimetric analysis. Q(3) structural units (SiO4 tetrahedra with three bridging oxygen atoms) formed in the amorphous gel at a low temperature (<= 150 degrees C) persist to elevated temperature (<= 500 degrees C) and directly transform to crystalline Li2Si2O5 at about 550 degrees C. The heating schedule slightly affects the crystalline phase transformation.