Square net distortion engineering in the ternary variants of titanium antimonide, Ti2−δMδSb (M = Zr, Hf)

The binary antimonide Ti2Sb crystallizes in a unique structure type, which may be considered as a distorted variant of the La2Sb structure type. The new ternary variants, Ti2−δMδSb (M = Zr, Hf) with δ < 0.85, were prepared by arc melting the elements in stoichiometric ratios. The ternaries crystallize in the body centered tetragonal space group I4/mmm, with lattice dimensions varying with δ and M, e.g. a = 3.977(1) Å and c = 15.011(2) Å for Ti1.5Zr0.5Sb (Z = 4). Single crystal structure investigations as well as powder X-ray profile refinements employing the Rietveld method and pair distribution function technique revealed, that with increasing δ the distortions lessen and finally disappear, as was predicted based on the Kleinke-Harbrecht structure map.