Synthesis of Complex Cesium Lead Bromide Glass Ceramics: Role of Thermal Plasma

The present work reports on the results of the synthesis and study of complex cesium lead bromide glass ceramics using classical heating and thermal plasma. The role of the substrate in the thermal plasma-assisted processes of growth has been disclosed. For reference, powder samples of these bromides were also synthesized. X-ray diffraction (XRD) revealed the presence of many material phases in all the samples except for the glass ceramics grown in a furnace using classical methods. The dominant phase was Cs4PbBr6 in most cases. However, CsPbBr3 was also present in some samples. Exotic phases such as solid Br2, metallic Cs (which dominates in one of the glass ceramic samples), and Cs4Pb9 were also observed. This indicates cesium segregation during the samples' growth and excess cesium in metallic form within the samples. The existence of CsPbBr3 quantum dots within or among the Cs4PbBr6 nanocrystals has been confirmed by photoluminescence (PL) measurements. Electron paramagnetic resonance (EPR) revealed the existence of Cs0-Cs0 dimers in a type of quantum dot undergoing a phase transition at 10 K.