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J. Korean Ceram. Soc. > Volume 62(5); 2025 > Article
Journal of the Korean Ceramic Society 2025;62(5): 1002-1012.
doi: https://doi.org/10.1007/s43207-025-00519-9
Structural phase transition and optoelectronic properties of lead-free AgNb1-xTaxO3 (x = 0, 0.5 and 1) perovskite systems
Mian Abdul Wahab1,2, Hidayat Ullah Khan3, Iftikhar Ahmad1,2, Amir Ullah4, Zahid Ali1,2
1Department of Physics, University of Malakand, Chakdara, Dir (Lower), 18800, Pakistan
2Center for Computational Materials Science, University of Malakand, Chakdara, Dir (Lower), 18800, Pakistan
3Department of Physics, University of Peshawar, Peshawar, 25120, Pakistan
4Department of Physics, Islamia College, Peshawar, 25120, Pakistan
Correspondence  Zahid Ali ,Email: zahidf82@gmail.com
Received: February 4, 2025; Revised: May 8, 2025   Accepted: May 22, 2025.  Published online: June 7, 2025.
ABSTRACT
Crystal phases Pbcm (monoclinic), Cmcm (orthorhombic), P4/mbm (tetragonal) and Pm3m (cubic) of the perovskite AgNbO3; Pm3m (cubic) of AgNb0.5Ta0.5O3; and R3c (rhombohedral), P2/m (monoclinic), Cmcm (orthorhombic), P4/mbm (tetragonal) and Pm3m (cubic) of AgTaO3 have been studied using DFT. To investigate stable crystal phases, cohesive energies and formation enthalpy are calculated demonstrating that P4/mbm, Pm3m and P2/m are the stable phases of AgNbO3, AgNb0.5Ta0.5O3 and AgTaO3 respectively. The electronic properties are examined through the mBJ exchange potential in their stable structural phases reveal that allAgNb1-xTaxO3 (x = 0, 0.5 and 1) perovskites are direct band gap semiconductors with energy gaps of 1.686, 1.973 and 2.1 eV respectively. Previous studies reported an indirect band gap of 2.97 eV for AgTaO3. These systems are semiconductors with ideal band gaps, leading to a wide array of applications including dielectric and photocatalytic devices. The optoelectronic properties of these compounds suggest that they are promising candidates for optical devices such as LEDs, photodiodes, quantum wells and solar cells in the visible region of the electromagnetic spectrum.
Key words: Density functional theory · Perovskites · Cohesive energy · Formation enthalpy · Optoelectronic properties · Electronic devices
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