Síntese de cristais de HgI2 por evaporação isotérmica de solvente através da análise dos diagramas de Ostwald-Miers

Abstract

In this research, crystals of mercury iodide (HgI2), with millimetric dimensions, were obtained through the technique of Isothermal Solvent Evaporation (ISE), making use of acetone and ethyl ether as solvents, at controlled temperatures. In addition, crystals were also grown, using these same solvents, together with N,N-dimethylformamide (DMF). There is a great interest in semiconductor materials with high atomic number and wide-bandgap, for applications such as ionizing radiation detectors at room temperature, using the direct detection method. Materials such as HgI2, PbI2, TlBr and CdTe are photoconductors and are examples of devices that present these conditions. HgI2has a band gap of 2.13 eV, a mass density of 6.36 g/cm3 and a high atomic number (ZHg=80, ZI=53). Along with the isothermal solvent evaporation technique, experiments were carried out to determine the metastable region of the Ostwald-Miers diagram during the crystallization process from seven different HgI2 solutions. The samples were separated into groups, where parameters such as temperature, concentration, volume, and solvent nature were changed for a better understanding of them. The growth of HgI2 crystals was associated with Ostwald-Miers diagrams for each solvent used. The final regular crystal had a length of roughly 4.0 mm and was obtained using both solvents, ethyl ether and acetone. Crystal growth mechanisms will be discussed, along with electrical transport measurements.