A novel two-dimensional mercury antimony telluride: Low temperature synthesis and characterization of RbHgSbTe₃

RbHgSbTe₃ (I), a novel two-dimensional quaternary mercury antimony telluride, was synthesized via an unconventional low-temperature route. Single crystals of I were grown at 180°C from solvothermal reactions using ethylenediamine as solvent. The crystal structure of I was determined by X-ray diffraction methods. The structure belongs to the orthorhombic crystal system, space group Cmcm (no. 63), a = 4.590 (2) Å, b = 15.745 (4) Å, c = 11.737 (2) Å, Z = 4. The crystal structure of this compound consists of two-dimensional layers of _∞²[HgSbTe₃^- ] with Rb⁺ counterions located between the layers. Optical studies performed on the powder samples of I suggested that the compound is a narrow-gap semiconductor. A band-gap of 0.2 e V was estimated from its diffuse reflectance spectrum.