A Detailed Experimental and Theoretical Study of the Crystalline and Electronic Structure of BaHf(1-x)ZrxS3 Solid Solutions (0 ≤ x ≤ 1).

Solid solutions of the chalcogenide perovskites BaHfS₃ and BaZrS₃ are synthesized and studied in detail across the entire composition interval by X-ray diffraction, UV-vis spectroscopy, and theoretical calculations. The results obtained extend those previously obtained by the same authors in previous works, giving a deeper insight into the structure-electronic properties relationship of these materials. Furthermore, high-resolution synchrotron radiation powder X-ray diffraction data are obtained for pure BaHfS₃ and BaZrS₃. In particular, the analysis of a higher number of compositions reveals that the cell volume of the solid solutions decreases linearly with increasing Hf content, while the unit cell axes, though showing a decreasing behavior with increasing Hf content, do not show a well-defined trend. The bandgap values of the solid solutions show a more complex relationship with the composition and unit cell volume, that is, values of Hf/(Hf + Zr) ratio below 40% do not exert a significant influence on the bandgap value, which remains practically constant, and then it increases substantially up to reach the value for pure BaHfS₃. The comparison of the experimental data with density functional theory calculations reveals a satisfactory agreement.