Transition Metal-Gallium Ordering in HfCoGa2 and HfNiGa2
نویسندگان
چکیده
The gallides HfCoGa2 and HfNiGa2 were synthesized by arc-melting of the elements and subsequent annealing in glassy carbon crucibles. Their structures have been reinvestigated by X-ray diffraction on powders and single crystals: I4mm, a = 1222.4(1), c = 812.0(1) pm, wR2 = 0.0766, 1464 F2 values, 64 variables, BASF = 0.41(2) for HfCoGa2 and a = 1224.0(2), c = 809.3(2) pm, wR2 = 0.0609, 1499 F2 values, 63 variables for HfNiGa2. In contrast to a previous investigation (Dopov. Akad. Nauk Ukr. RSR, Ser. A, 51 (1988)) we observe a fully ordered arrangement of the transition metal and gallium atoms. The crystal chemistry of these gallides is briefly discussed.
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