Microscopic description of the evolution of the local structure and an evaluation of the chemical pressure concept in a solid solution

Mukherjee, Soham and Nag, Angshuman and Kocevski, Vancho and Santra, Pralay K and Balasubramanian, Mahalingam and Chattopadhyay, Soma and Shibata, Tomohiro and Schaefers, Franz and Rusz, Jan and Gerard, Celine and Eriksson, Olle and Segre, CU and Sarma, DD (2014) Microscopic description of the evolution of the local structure and an evaluation of the chemical pressure concept in a solid solution. In: PHYSICAL REVIEW B, 89 (22).

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Abstract

Extended x-ray absorption fine-structure studies have been performed at the Zn K and Cd K edges for a series of solid solutions of wurtzite Zn1-xCdxS samples with x = 0.0, 0.1, 0.25, 0.5, 0.75, and 1.0, where the lattice parameter as a function of x evolves according to the well-known Vegard's law. In conjunction with extensive, large-scale first-principles electronic structure calculations with full geometry optimizations, these results establish that the percentage variation in the nearest-neighbor bond distances are lower by nearly an order of magnitude compared to what would be expected on the basis of lattice parameter variation, seriously undermining the chemical pressure concept. With experimental results that allow us to probe up to the third coordination shell distances, we provide a direct description of how the local structure, apparently inconsistent with the global structure, evolves very rapidly with interatomic distances to become consistent with it. We show that the basic features of this structural evolution with the composition can be visualized with nearly invariant Zn-S-4 and Cd-S-4 tetrahedral units retaining their structural integrity, while the tilts between these tetrahedral building blocks change with composition to conform to the changing lattice parameters according to the Vegard's law within a relatively short length scale. These results underline the limits of applicability of the chemical pressure concept that has been a favored tool of experimentalists to control physical properties of a large variety of condensed matter systems.

Item Type:	Journal Article
Publication:	PHYSICAL REVIEW B
Publisher:	AMER PHYSICAL SOC
Additional Information:	copyright for this article belongs to AMER PHYSICAL SOC, USA
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	19 Aug 2014 10:51
Last Modified:	19 Aug 2014 10:51
URI:	http://eprints.iisc.ac.in/id/eprint/49589

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