Thermodynamic assessment of the Ga–Se–Te system

Liu, Yuheng; Dou, Zhichao; Enoki, Masanori; Oyama, Yutaka; Ohtani, Hiroshi

doi:10.1016/j.calphad.2020.102206

Cited by 4 publications

(3 citation statements)

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“…On the other hand, it is well-known that γ-Ga 2 S 3 is a HT phase with a DZ structure that is isostructural with α-Ga 2 Se 3 and β-Ga 2 Te 3 ,,− and that in the case of Ga 2 Se 3 this DZ phase has also been observed at LT (α-Ga 2 Se 3 ). Additionally, DZ structures have been obtained in several decompressed ternary A Ga 2 X 4 ( A = Zn, Cd, Hg; X = S, Se) OVCs. , To investigate whether γ-Ga 2 S 3 might have a DZ structure, we have plotted in Figure c the RS spectra of DZ γ- and α′-Ga 2 S 3 , DZ- and DC-CdGa 2 S 4 , DZ α-Ga 2 Se 3 , and DZ- and DC-CdGa 2 Se 4 .…”

Section: Resultsmentioning

confidence: 99%

“…Note that we have not included the DZ phase in Figure S5 because of the fractional occupation of the cation positions in this phase makes it difficult to simulate this structure. However, we consider that the DZ phase must be a metastable structure competitive in energy with the α′ phase since this phase has been also observed in Ga 2 Se 3 and Ga 2 Te 3 at RC. ,,− …”

Section: Resultsmentioning

confidence: 99%

“…The ortho phase has been predicted to be much less stable than the mono phase. ,, Regarding the DZ structure, the α (γ) structure of Ga 2 Se 3 has been reported at LT (HT) with a lattice parameter of 5.4222 (5.463 Å). , This result suggests that both phases are the same one, being that the lattice parameter was affected by thermal expansion. On the other hand, the temperature phase diagram of Ga 2 Te 3 only shows β-Ga 2 Te 3 with a DZ structure. − However, α-Ga 2 Te 3 (hereinafter, ortho-α-Ga 2 Te 3 ) with a vacancy-ordered α-II-In 2 Te 3 -like structure has been crystallized by varying Ga/Te ratios at HT. , …”

Section: Introductionmentioning

confidence: 99%

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High-Pressure Synthesis of β- and α-In₂Se₃-Like Structures in Ga₂S₃

et al. 2022

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The synthesis of polymorphs of α′-Ga 2 S 3 at room temperature on compression/decompression is studied from a joint experimental and theoretical point of view to reveal the nature of their crystalline structures. The results of Raman scattering and X-ray diffraction measurements on these polymorphs have been analyzed supported by theoretical ab initio simulations. On compression, α′-Ga 2 S 3 undergoes a phase transition above 16 GPa to β′-Ga 2 S 3 with a tetradymite-like (R-3m) structure, isostructural with β-In 2 Se 3 . On decompression, β′-Ga 2 S 3 undergoes a phase transition below 9.0 GPa to φ-Ga 2 S 3 , which is isostructural with α-In 2 Se 3 (R3m). Raman signatures of symmetry breaking as well as clear structural differences between the pressure dependence of the unit-cell volume per formula unit, zero-pressure axial compressibilities, bulk modulus, and their first pressure derivative between β′-Ga 2 S 3 and φ-Ga 2 S 3 have allowed us to determine the R3m nature of φ-Ga 2 S 3 . The observation of the R3m phase is also supported by theoretical total energy ab initio simulations. This result unveils a pressure-induced paraelectricferroelectric R-3m-to-R3m transition, like the theoretically predicted temperature-induced transition in several III−VI B 2 X 3 compounds, which could find use in technological applications. Finally, φ-Ga 2 S 3 undergoes a phase transition below 1.0 GPa to γ-Ga 2 S 3 with a disordered zincblende (F-43m) phase, isostructural with α-Ga 2 Se 3 and remains metastable at room conditions. Since the disordered zincblende phase of Ga 2 X 3 chalcogenides has also been found upon decompression in AGa 2 X 4 chalcogenides, we discuss the relation between the pressure-induced phase transitions of both Ga 2 X 3 and AGa 2 X 4 compounds.

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