Thermodynamic Data for the (NaI–CeI3) and (CsI–CeI3) Systems in the Condensed and Gas Phases

Systems containing mixtures of alkali metal halides and lanthanide halides are widely used in metal halide discharge lamps. This work describes the derivation of thermochemical data for the gaseous and condensed phases of the (NaI–CeI3) and (CsI–CeI3) systems thus enabling the calculation of partial pressures above a liquid mixture at temperatures found in such lamps. Information on the thermodynamic data and phase diagrams for binary CeI3-containing systems are limited. Similarities in behaviour between various alkali metal halides with different halides across the lanthanide (Ln) series have been exploited to estimate missing parameters for the condensed phases. This has been augmented by abinitio quantum mechanics to derive thermodynamic properties for gas phase species.