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Title: Origin of the solid solution in the LiInSe{sub 2}–In{sub 2}Se{sub 3} system

Techniques of bulk and local analyses were used to characterize the melt-grown single crystals of LiInSe{sub 2}, where yellow matrix coexists together with extended red areas distributed irregularly. Bulk chemical analysis showed that the average stoichiometry of yellow matrix is close to ideal 1:1:2, but red areas are enriched with In{sub 2}Se{sub 3}. An excess In{sub 2}Se{sub 3} is incorporated coherently into the crystal lattice of LiInSe{sub 2}, forming the substitution solid solution with the general formula (Li{sub 1−3x}In{sub x}⎕{sub 2})InSe{sub 2} and changing the color from yellow to red. The test crystals with the 50–55% content of In{sub 2}Se{sub 3} were found by the X-ray analysis to be single phase. The differential dissolution technique, measuring the spatial variation of the composition with high resolution, demonstrated that the single phase crystals in the LiInSe{sub 2}–In{sub 2}Se{sub 3} system might be grown only in a very narrow range close to stoichiometric. Being supersaturated, the heterovalent solid solution phases decompose in the course of cooling, and the concentration micro-heterogeneity occurs in the matrix as the coherent (or incoherent) inclusions of two different types, practically pure selenides of lithium and indium. The origin and scale of the micro-heterogeneity determining the physical properties ofmore » LiInSe{sub 2} are discussed as a starting point for the development of physicochemical foundations for growing high quality optical crystals. - Graphical abstract: Differential dissolution technique applied for detection of dispersive precipitates in as-grown LiInSe{sub 2} single crystals: kinetic curves of the phase dissolution: F is the main phase Li{sub 0.96}In{sub 1.01}Se{sub 2} (98.9%), secondary minor phases Li{sub 2}Se (0.1%), In{sub 2}Se{sub 3} (0.9%). - Highlights: • Phase purity of crystals Li{sub 1−3x}In{sub 1+x}Se{sub 2} was examined by a new stoichiographic method. • Breakup of the metastable solid solution with temperature drop was detected. • Dispersive precipitates Li–Se and In–Se of low content result from the breakup. • A crucial role of the precipitates in optical properties of the crystals is shown. • Conditions are given how to grow stoichiometric and single-phase crystals.« less
Authors:
 [1] ;  [2] ;  [3]
  1. Nikolaev Institute of Inorganic Chemistry, Siberian Branch of the Russian Academy of Sciences, Novosibirsk 630090 (Russian Federation)
  2. Boreskov Institute of Catalysis, Siberian Branch of the Russian Academy of Sciences, Novosibirsk 630090 (Russian Federation)
  3. Institute of Geology and Mineralogy, Siberian Branch of the Russian Academy of Sciences, Novosibirsk 630090 (Russian Federation)
Publication Date:
OSTI Identifier:
22451115
Resource Type:
Journal Article
Resource Relation:
Journal Name: Journal of Solid State Chemistry; Journal Volume: 220; Other Information: Copyright (c) 2014 Elsevier Science B.V., Amsterdam, The Netherlands, All rights reserved.; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; CHEMICAL ANALYSIS; CRYSTAL LATTICES; DETECTION; DISSOLUTION; INCLUSIONS; INDIUM SELENIDES; LITHIUM; LITHIUM SELENIDES; MONOCRYSTALS; PRECIPITATION; SOLID SOLUTIONS; X RADIATION