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Role of Cu Substitute in AgGaTe2 in Structural Stabilities, Electronic Property, and High-Pressure Phase Transitions: A DFT Investigation

Year: 2025

Type: article

Abstract: High Resolution Image Download MS PowerPoint Slide The Cu–Ag–Ga–Te system has garnered significant attention due to its promising properties, including excellent photoelectric and thermoelectric characteristics. This study investigates the effects of substitutional Cu doping into AgGaTe 2 at a 1:1 ratio of Ag and Cu on the structural stabilities and electronic and mechanical properties using density functional theory (DFT) calculations. All calculated results are compared to those of AgGaTe 2 and CuGaTe 2 . We found that Cu 0.5 Ag 0.5 GaTe 2 is both dynamically and elastically stable. Mechanically, the bulk modulus ( B ) increases, while the shear ( G ) and Young’s ( E ) moduli decrease when subjected to Cu doping. The electronic band structure of Cu 0.5 Ag 0.5 GaTe 2 processes the direct band gap ( E g ) of 1.20 eV, which aligns between those of AgGaTe 2 (1.17 eV) and CuGaTe 2 (1.29 eV). The increase in band gap and the trend of mechanical behavior with higher Cu content are attributed to the stronger covalent bonding between Cu–Ag and Cu–Ga pairs compared to Ag–Ag and Ag–Ga pairs. Additionally, the high-pressure phase transitions of this material are explored up to 100 GPa. The first structural phase transition occurs at approximately 6 GPa, from the ambient phase ( I 4̅) to a tetragonal ( P 4/ mmm ) phase. This transition pressure is also intermediate between AgGaTe 2 (4 GPa) and CuGaTe 2 (8 GPa). Further high-pressure phase transitions, including those to the orthorhombic ( Pmm 2) and monoclinic ( Pm ) phases, are observed at about 36 and 55 GPa, respectively. These findings demonstrate that Cu 0.5 Ag 0.5 GaTe 2 exhibits consistent trends in the electronic band gap, mechanical properties, and high-pressure phase transitions relative to those of AgGaTe 2 and CuGaTe 2 . This study provides valuable insights into material engineering applications and enhances the understanding of substitutionally doped materials under high-pressure conditions.

Source: The Journal of Physical Chemistry C

DOI: 10.1021/acs.jpcc.5c01608

Authors: Iyarat Ounrit, Satchakorn Khammuang, Anan Udomkijmongkol, Sirinee Thasitha, Aparporn Sakulkalavek, Komsilp Kotmool

Institution: King Mongkut's Institute of Technology Ladkrabang

Language: English

Topic: Advanced Thermoelectric Materials and Devices

Subfield: Materials Chemistry

Field: Materials Science

Domain: Physical Sciences

Open Access status: hybrid

Estimated APC paid: $4,500

Funders: National Research Council of Thailand, King Mongkut's Institute of Technology Ladkrabang, Royal Golden Jubilee (RGJ) Ph.D. Programme, College of Advanced Manufacturing Innovation, King Mongkut’s Institute of Technology Ladkrabang