Nanoscale order in ZnS:(Cd, O)

A thermodynamic model of self-assembling of isoelectronic impurities in ZnS:(Cd, O) is presented. Self-assembling results in an occurrence of 1O4Cd tetrahedral clusters. The self-assembling conditions are derived by the minimum condition of the free energy of ZnS:(Cd, O) for Cd and oxygen in the dilute and ultra dilute limits, respectively. The occurrence of 1O4Cd clusters and the completion of self-assembling when all oxygen atoms are in clusters are results of the continuous phase transitions. The temperature of a self-assembling occurrence does not depend on oxygen content and is a function of Cd concentration. The fulfilled estimates show that at temperature of 300 °C all oxygen atoms should be in 1O4Cd clusters if Cd content is insignificantly larger than 1%.