Experimental and Density Functional Theory Study of the Structural, Optical, and Electronic Properties of La₂NiMnO₆ and Nd₂NiMnO₆ Double Perovskite Ceramics

Authors

• Mahmoud S. Alkathy
• Anibal Thiago Bezerra
• Person Pereira Neves
• Mariama Rebello de Sousa Dias, University of RichmondFollow
• Alexandre José Gualdi
• Marco Daldin Teodoro
• Valmo R. Mastelaro
• José A. Eiras

DOI

10.1021/acsaenm.6c00567

Author ORCID Identifier

Mariama Rebello de Sousa:  https://orcid.org/0000-0001-9090-0018 

Abstract

Despite extensive study of La₂NiMnO₆ double perovskites, a systematic understanding of the effects of A-site rare-earth substitution on coupled structural, electronic, and optical properties remains lacking. Here, we provide the first integrated experimental-computational comparison of La₂NiMnO₆ (LaNMO) and Nd₂NiMnO₆ (NdNMO), establishing quantitative structure–property relationships. Rietveld refinement demonstrates that Nd³⁺ substitution amplifies MnO₆ and NiO₆ octahedral distortions 5-fold (Δd_Mn: 4.69 × 10^–4 to 23.9 × 10^–4; Δd_Ni: 1.18 × 10^–4 to 5.91 × 10^–4), reduces Mn–O–Ni bond angles from 162.6° to 159.4°, and decreases grain size by 19% (1.29 to 1.04 μm), while preserving monoclinic P2₁/n B-site ordering. Quantitative XPS reveals composition-dependent defect engineering, with oxygen-vacancy concentrations of 40.6% (LaNMO) versus 29.7% (NdNMO) and mixed Ni²⁺/Ni³⁺ and Mn³⁺/Mn⁴⁺ valence states. Importantly, spin-polarized DFT confirms the broadening of the optical band gap from 1.21 to 1.32 eV (9%) by A-site modification. Photoluminescence deconvolution reveals three emission bands (425, 470, and 530 nm for LaNMO), which show a consistent blue shift upon Nd inclusion (425, 466, and 514 nm) that is directly correlated with higher distortion and defect states. DFT studies indicate a decrease in the tolerance factor (0.97 to 0.94) and a rise in carrier mass (m_h: 1.60 to 4.25 m₀; electron: 3.80 to 6.15 m₀), implying increased localization. This work establishes the first quantitative framework demonstrating that rare-earth A-site downsizing systematically tunes electronic structure, stabilizes ferromagnetic insulating states with adjustable narrow band gaps (1.2–1.3 eV), and modulates defect-engineered emission, providing rational design principles for Re₂NiMnO₆ double perovskites in solar cells, photocatalysis, and optoelectronics.

Document Type

Article

Publication Date

7-10-2026

Publisher Statement

This article is licensed under CC-BY 4.0

Open Access - Creative Commons CC BY 4.0

Recommended Citation

Mahmoud S. Alkathy, Anibal Thiago Bezerra, Person Pereira Neves, Mariama Rebello Sousa Dias, Alexandre José Gualdi, Marcio Daldin Teodoro, Valmor R. Mastelaro, José A. Eiras; Experimental and Density Functional Theory Study of the Structural, Optical, and Electronic Properties of La₂NiMnO₆ and Nd₂NiMnO₆ Double Perovskite Ceramics. ACS Appl. Eng. Mater. 24 July 2026; 4 (7): 3985–4001. https://doi.org/10.1021/acsaenm.6c00567