Phase equilibria in the quasiternary system Ag2Se–CdSe–In2Se3

Ivashchenko, I. A.; Zmiy, O. F.; Olekseyuk, I. D.

doi:10.30970/cma1.0065

Cited by 5 publications

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“…For the endmembers, they generally agree well with literature values (850−860 °C for AgGaSe 2 , 846 °C for orthorhombic LiGaSe 2 , 787 °C for AgInSe 2 , and 904 °C for LiInSe 2 ). 15,18,48,49 For Li x Ag 1−x GaSe 2 , the melting point stays within a relatively narrow range, in agreement with previous observations (850 ± 50 °C), 18 but it maximizes near x = 0.75. It is interesting that the tetragonal form of LiGaSe 2 also melts congruently, given that it is presumed to be metastable relative to the orthorhombic form.…”

Section: Opticalsupporting

confidence: 90%

Structure and Optical Properties of Li_xAg_1–xGaSe₂ and Li_xAg_1–xInSe₂

et al. 2023

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Complete substitution of Li atoms for Ag atoms in AgGaSe2 and AgInSe2 was achieved, resulting in the solid solutions Li x Ag1–x GaSe2 and Li x Ag1–x InSe2. The detailed crystal structures were determined by single-crystal X-ray diffraction and solid-state 7Li nuclear magnetic resonance spectroscopy, which confirm that Li atoms occupy unique sites and disorder only with Ag atoms. The tetragonal CuFeS2-type structure (space group I4̅2d) was retained within the entirety of the Ga-containing solid solution Li x Ag1–x GaSe2, which is noteworthy because the end-member LiGaSe2 normally adopts the orthorhombic β-NaFeO2-type structure (space group Pna21). These structures are closely related, being superstructures of the cubic sphalerite and hexagonal wurtzite prototypes adopted by diamond-like semiconductors. For the In-containing solid solution Li x Ag1–x InSe2, the structure transforms from the tetragonal to orthorhombic forms as the Li content increases past x = 0.50. The optical band gaps increase gradually with higher Li content, from 1.8 to 3.4 eV in Li x Ag1–x GaSe2 and from 1.2 to 2.5 eV in Li x Ag1–x InSe2, enabling control to desired values, while the second harmonic generation responses become stronger or are similar to those of benchmark infrared nonlinear optical materials such as AgGaS2. All members of these solid solutions remain congruently melting at accessible temperatures between 800 and 900 °C. Electronic structure calculations support the linear trends seen in the optical band gaps and confirm the mostly ionic character present in Li–Se bonds, in contrast to the more covalent character in Ga–Se or In–Se bonds.

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