Growing crystals and studying structure and electronic properties of Cu 2 ZnGe(S х Se 1-x ) 4 compositions.

Single crystals of Cu ₂ ZnGeSe ₄ and Cu ₂ ZnGeS ₄ solid solutions were developed and successfully obtained using the chemical vapor transfer method, with iodine acting as a transporter. The structure, compositional dependences of lattice parameters, pycnometric and X-ray densities and microhardness were determined. The chemical composition determined by the X-ray microanalysis satisfactorily corresponds to the nominal one with a tolerance of ±5 %. The XRD analysis showed that all the obtained compounds and their solid solutions have unit cell described by tetragonal symmetry. The attice parameters were found to be а  = 5.342 ± 0.005 Å, с  = 10.51 ± 0.01 Å for the Сu ₂ ZnGeS ₄ compound and а  = 5.607 ± 0.005 Å, с  = 11.04 ± 0.01 Å for the Cu ₂ ZnGeSe ₄ , respectively. Structural studies confirmed the validity of the Vegard's law in relation to the obtained samples. The pycnometric densities of ∼4.28 g/cm ³ for the Cu ₂ ZnGeS ₄ and ∼5.46 g/cm ³ for the Cu ₂ ZnGeSe ₄ were found to be slightly less than their X-ray densities of ∼4.32 g/cm ³ and ∼5.52 g/cm ³ , respectively. The maximum microhardness of ∼398 kg/mm ² for these solid solutions corresponds to x  = 0.60. The melt point of the solid solutions increases from ∼1180 °C for the Сu ₂ ZnGeSe ₄ up to ∼1400 °C for the Сu ₂ ZnGeS ₄ . Based on X-ray fluorescence analysis and DTA data, the phase diagram of the Cu ₂ ZnGeSe ₄ -Cu ₂ ZnGeS ₄ system was constructed. Analysis of the obtained diagram indicates its first type according to Rozbom's classification.
Competing Interests: The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
(© 2023 The Authors.)