Linear combination of atomic orbitals approximation in nanocrystalline yittria-stabilized zirconia synthesized by citrate-nitrate gel combustion process

Nanocrystalline yittria-stabilized zirconia (YSZ) compounds with yittria concentration varying between 8 and 12 mol% have been synthesized by gel combustion method followed by heat treatment at 550 degrees C. The YSZs are found to posses stable face centered cubic structure at room temperature by X-ray diffractometry. The lattice parameter 'a' showed an increasing trend with increasing concentration of yittria. The crystallite size estimated by Scherrer method was in the range of 7-10 nm. Band gap studies showed an increasing trend with increasing yittria concentration and are found to be consistent with respective lattice parameters following the tight binding approximation or linear combination of atomic orbitals approximation.