ISSN print edition: 0366-6352 ISSN electronic edition: 1336-9075 Registr. No.: MK SR 9/7 Published monthly

Structural, optical, and vibrational behavior of V₂O₅-doped Li_0.5Na_0.5NbO₃ ceramics

Kamala Sujani Dasary, K. V. Ramesh, and A. V. N. Ramalingeswara Rao

Department of Physics, Andhra Christian College, Guntur, India

E-mail: ksdjntuk@gmail.com

Received: 14 February 2026  Accepted: 10 March 2026

Abstract:

Lead-free Li_0.5Na_0.5NbO₃ (LNN) ceramics doped with V₂O₅ (x = 0, 1, 3, 5, and 9 mol%) were synthesized using the conventional solid-state reaction method to investigate their structural, thermal, and optical properties. X-ray diffraction (XRD) analysis confirmed the formation of a single-phase orthorhombic perovskite structure for all compositions. A slight shift of diffraction peaks toward higher angles was observed with increasing V₂O₅ content, indicating successful substitution of V⁵⁺ (0.59 Å) at Nb⁵⁺ (0.64 Å) sites without the formation of secondary phases. Density measurements revealed improved densification with increasing dopant concentration, where the bulk density increased from 4.210 to 4.420 g cm⁻³. Differential scanning calorimetry (DSC) showed that the orthorhombic–tetragonal and tetragonal–cubic phase transition temperatures occur around ~ 460 °C, with slight shifts upon V₂O₅ incorporation, indicating modification of lattice stability. Optical studies using UV–Vis spectroscopy revealed a gradual reduction in the optical band gap from 3.365 to 3.152 eV, while the Urbach energy increased from 0.184 to 0.296 eV, suggesting the formation of localized defect states and increased structural disorder. FTIR and Raman spectroscopic analyses further confirmed changes in Nb–O vibrational modes and local lattice distortions caused by vanadium incorporation.

Keywords: Lead-free ceramics; Perovskite structure; Optical band gap; X-ray diffraction (XRD); Microstructure

Full paper is available at www.springerlink.com.

DOI: 10.1007/s11696-026-04802-9

Chemical Papers 80 (6) 6831–6844 (2026)