Crystal chemistry, X-ray diffraction reference patterns, and bandgap studies for (BaxSr1–x)2CoWO6 (x = 0.1, 0.2, 0.3, 0.5, 0.7, and 0.9)

X-ray reference powder patterns and structures have been determined for a series of cobalt- and tungsten-containing cubic alkaline-earth perovskites, (Ba x Sr 1– x ) 2 CoWO 6 ( x = 0.1, 0.2, 0.3, 0.5, 0.7, and 0.9). The structure of the end members of the series, Sr 2 CoWO 6 and Ba 2 CoWO 6 , were tetragonal and cubic, respectively, agreeing with the literature data. From Rietveld refinements, it was found that when x = 0.1 and 0.2, the structure was tetragonal I 4/ m ( a = 5.60481(6) and 5.62305(11) Å and c = 7.97989(12) and 7.9847(2) Å, respectively; Z = 2). When x > 0.2, the structure was cubic ( Fm $\bar{3}$ m , No. 225; Z = 4) (from x = 0.3 to 0.9, a increases from 7.98399(13) to 8.08871(10) Å). This tetragonal series of compounds exhibit the characteristics of a distorted double-perovskite structure. The bond valence sum values for the alkaline-earth (Ba, Sr) sites in all (Ba x Sr 1− x ) 2 CoWO 6 members are greater than the ideal value of 2.0, indicating over-bonding situation, whereas for the W sites, as x increases, a change from under-bonding to slightly over-bonding situation was observed. Density functional theory calculations revealed that while Sr 2 CoWO 6 is a semiconductor, Ba 2 CoWO 6 and SrBaCoWO 6 are half-metals. Powder X-ray diffraction patterns of this series of compounds (Ba x Sr 1− x ) 2 CoWO 6 , with x = 0.1, 0.2, 0.3, 0.5, 0.7, and 0.9, have been submitted to be included in the Powder Diffraction File.