Experimental and DFT investigation of Gd3 + /Tm3+ and Al3+ co-doping effects on HoCrO3 orthochromites

Authors

• Jolaikha Sultana, College of Arts & Sciences
• Jemma R. DeFeo, Buffalo State University
• Rajiv K. Chouhan, Iowa State University
• Yenugonda Venkateswara, Buffalo State University
• Arjun K. Pathak, Buffalo State University
• Sanjay R. Mishra, College of Arts & Sciences

Abstract

This study examines the effects of rare-earth (Gd³⁺, Tm³⁺) and nonmagnetic Al³⁺ co-doping on the structural, magnetic, and magnetocaloric properties of HoCrO3-based perovskites. Compounds Ho0.67Gd0.33CrO3, Ho0.67Gd0.33Cr0.5Al0.5O3, Ho0.67Tm0.33CrO3, and Ho0.67Tm0.33Cr0.5Al0.5O3 were synthesized by a sol–gel autocombustion method and confirmed by XRD to crystallize in an orthorhombic Pbnm structure. Gd³⁺ substitution expanded the lattice, while Tm³⁺ and Al³⁺ reduced it. DFT study identified the G-type antiferromagnetic configuration as the most stable for all doped systems, with Al³⁺ substitution significantly reducing the AFM–FM energy gap. Magnetization data showed decreasing transition temperatures from 150.8 K (Ho0.67Gd0.33CrO3) to 120.0 K (Ho0.67Gd0.33Cr0.5Al0.5O3) and from 133.8 K (Ho0.67Tm0.33CrO3) to 113.2 K (Ho0.67Tm0.33Cr0.5O3). The maximum magnetic entropy change (−ΔSₘ) reached 11.41 J/kg·K at 5 T for Ho0.67Gd0.33Cr0.5Al0.5O3, exceeding that of HoCrO3 (6.47 J/kg·K). These enhancements highlight Gd/Tm- and Al-co-doped HoCrO3 as promising candidates for low-temperature magnetic refrigeration.

Publication Title

Journal of Alloys and Compounds

Recommended Citation

Sultana, J., DeFeo, J., Chouhan, R., Venkateswara, Y., Pathak, A., & Mishra, S. (2026). Experimental and DFT investigation of Gd3 + /Tm3+ and Al3+ co-doping effects on HoCrO3 orthochromites. Journal of Alloys and Compounds, 1070 https://doi.org/10.1016/j.jallcom.2026.188701