Coupled In/Te and Ni/vacancy ordering and the modulated crystal structure of a B8 type, Ni{sub 3{+-}}{sub x}In{sub 1-y}Te{sub 2+y} solid solution phase
- Research School of Chemistry, Australian National University, Science Road, Canberra, ACT 0200 (Australia)
- Inst. Materialkemi, Angstroemlaboratoriet, Box 538, S-752 21 Uppsala (Sweden)
The commensurate superstructures of a NiAs/Ni{sub 2}In type parent structure, Ni{sub 3.32}InTe{sub 2} and Ni{sub 3.12}In{sub 0.86}Te{sub 2.14} (q={gamma}[0 0 1]{sup *}, {gamma}=2/3) as well as one dimensionally incommensurate structure of Ni{sub 3}InTe{sub 2} ({gamma}=0.71) were refined from neutron powder diffraction data (R{sub wp}=4.77%, 4.53% and 4.91% for the three structures, respectively, at 298 K). The commensurate structures were refined in the P6{sub 3}/mmc space group (c=3c{sub NiAs}). The stacking sequence at the hcp array is -In/Te/Te/- and the trigonal bipyramidal site within the In layer, Ni(2), is partially occupied while it is empty in the Te layers. The octahedral position in between the In and Te layers, Ni(1a), is fully occupied while the octahedral position in between two adjacent Te layers, Ni(1b), is partially occupied. With decreasing In and Ni content, the modulation wave vector, {gamma}, was found to increase continuously until {gamma}=1. From this, crenel functions to describe the whole homogeneity range of the solid solution were constructed with the length of the atomic domains {delta}{sup Te}={gamma} (and hence {delta}{sup In}={delta}{sup Ni}=1-{gamma}) and {delta}{sup Ni(1b)}={gamma}/2 (and hence {delta}{sup Ni(1a)}=1-{gamma}/2) which were then used for the refinement of the incommensurate structure of Ni{sub 3}InTe{sub 2}. The corresponding effect in real space is that the single In layers separating double layers of Te occur less frequent when {gamma} in increasing until at {gamma}=1 the CdI{sub 2} type structure of Ni{sub 1+x}Te{sub 2} is reached. - Graphical abstract: The crystal structure of Ni{sub 3.31}InTe{sub 2} is a superstructure of the NiAs type structure with q={gamma}[0 0 1]{sup *}, {gamma}=2/3. The -In/Te/Te/- stacking sequence at the hcp array can be described with a crenel function with the length of the atomic domains {delta}{sup Te}={gamma} and {delta}{sup In}=1-{gamma}. With decreasing In and Ni content, the modulation wave vector, {gamma}, increases continuously until {gamma}=1. The corresponding effect in real space is that the In layers separating double layers of Te occur less frequently until at {gamma}=1 the CdI{sub 2} type structure of Ni{sub 1+x}Te{sub 2} is reached.
- OSTI ID:
- 21049503
- Journal Information:
- Journal of Solid State Chemistry, Vol. 180, Issue 10; Other Information: DOI: 10.1016/j.jssc.2007.07.020; PII: S0022-4596(07)00281-2; Copyright (c) 2007 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved; Country of input: International Atomic Energy Agency (IAEA); ISSN 0022-4596
- Country of Publication:
- United States
- Language:
- English
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