Growth and thermodynamic characterization of pure and Er-doped KPb2Cl5

Centimeter-sized single crystals of pure and Er-doped KPb2Cl5 were successfully grown by the Bridgman-Stockbarger method using silica ampoules sealed under HCl gas. The phase transition that occurs at 255 °C (528.15 K) was characterized by differential scanning calorimetry and found not to entail mechanical breakdown of the crystals. The KPb2Cl5 volumic mass and specific heat functions were measured from ∼700 to 760 K and ∼120 to 760 K, respectively. An updated Ellingham diagram for chlorides aimed at choosing the crucible material, synthesis and crystal growth atmosphere, and starting products is proposed.