Laser-pulse melting of calcium oxide and some peculiarities of its high-temperature behavior

The study aims to address and overcome the existing hurdles and challenges in measuring the melting temperature of calcium oxide (CaO). Despite numerous experiments of this kind in the past, the exact melting point (MP) of CaO still remains quite uncertain due to three factors associated with it: a high melting temperature, an optical semitransparency, and a high vapor pressure in the vicinity of the melting point. The method used in the present study is based on the laser-pulse heating with CO₂- and Nd:YAG-lasers. It was designed specifically to eliminate the possible ambiguity due to variance in absorbance in the specimen bulk. Temperature measurements were performed with advanced multichannel pyrometry combined with probe laser reflectometry. Subsequently, this technique allowed to determine both the melting and the solidification points of CaO. The final measurement of the melting point amounted to 3160 ± 10 K.