Temperature dependence of the optical parameters for potassium zinc chloride crystals doped with lithium ions

Temperature dependence of the optical parameters near the absorption edge of K2ZnCl4:yLi+crystals, where y = 0.00%, 0.34%, 0.86%, 0.94%, 1.13% and 1.29% is reported over the temperature range from 276 to 350 K. An analysis of the absorption spectrum reveals that the type of transition is the indirect allowed one. The absorption edge shifted towards lower energy with increasing temperature. As a necessity, the validity of the Urbach rule of the modified K2ZnCl4:yLi+ crystals has been checked. In the region of the absorption edge, the Urbach parameters, the temperature dependence of the optical energy gap and the steepness parameter were evaluated as functions of both temperature and y concentration.