Two new titanium molybdenum arsenides: Ti2MoAs2 and Ti3MoAs3, ternary substitution variants of V3As2 and β-V4As3 |
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Authors: | Abdeljalil Assoud |
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Institution: | Department of Chemistry, University of Waterloo, Waterloo, Ont., Canada N2L 3G1 |
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Abstract: | The title compounds were prepared by arc-melting pre-annealed mixtures of Ti, Mo, and As. Both Ti2MoAs2 and Ti3MoAs3 adopt structures formed by the corresponding binary vanadium arsenides, V3As2 and β-V4As3. Ti2MoAs2 crystallizes in the tetragonal space group P4/m, with a=9.706(4) Å, c=3.451(2) Å, V=325.1(3) Å3 (Z=4), and Ti3MoAs3 in the monoclinic space group C2/m, with a=14.107(3) Å, b=3.5148(7) Å, c=9.522(2) Å, β=100.66(3)°, V=464.0(2) Å3 (Z=4). In both cases, the metal atoms form infinite chains of trans edge-condensed octahedra, and the As atoms are located in (capped) trigonal prismatic voids. While most metal atom sites exhibit mixed Ti/Mo occupancies, the Mo atoms prefer the sites with more metal atom and fewer As atom neighbors. Ti2MoAs2 and Ti3MoAs3 are metallic entropy-stabilized materials that decompose upon annealing at intermediate temperatures. |
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Keywords: | Crystal structure Electronic structure Mixed occupancies Arsenide |
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