Low-temperature magnetic phase transition and dielectric relaxation mechanism in triclinic NiV2O6

Abstract

In the present work, we report the synthesis, structural characterization, and low-temperature magnetic and dielectric response of NiV₂O₆ prepared by solid-state techniques to explore its possible materials characteristics, magnetic phase transition, and dielectric relaxation mechanism. The Rietveld refinement of the X-ray diffraction (XRD) pattern of NiV₂O₆ reveals the single-phase triclinic crystal structure with space group P-1. The room temperature Raman spectra exhibit distinctive stretching, bending, and lattice vibrational modes of A_g and B_g in the wide spectrum range 50–900 cm⁻¹, corresponding to the triclinic structure of NiV₂O₆. It was observed from the high resolution field emission scanning electron microscopy (FESEM) images that the NiV₂O₆ particles are not agglomerated and uniformly distributed over space with an average particles sizes ∼ 1–6 µm and the elemental mapping with their atomic and weight percentages of Ni, Vi, and O was confirmed by energy dispersive X-ray spectroscopy (EDS). The Ni²⁺ (3d⁸) states and Ni²⁺–O–V⁵⁺–O–Ni²⁺ superexchange interactions confirmed by X-ray photoelectron (XPS) spectroscopy are mainly responsible for antiferromagnetic interaction in NiV₂O₆. The magnetization vs. temperature (M−T) graphs of NiV₂O₆ at a dc magnetic field of 100 Oe exhibit a paramagnetic to antiferromagnetic transition (T_N) at 16.3 K, and the inverse susceptibility fitted by Curie-Weiss law yielded a paramagnetic moment ∼ 3.25µ_B and Weiss constant${\theta }_{\mathrm{CW}}$ = -16.3 K. The magnetization vs. field (M−H) isotherm reveals the wavy curves at temperature 2 K, which suggests a metamagnetic transition up to the Neel temperature. The dielectric constant (ε_r) increases with temperature due to the contribution of dipolar or ionic polarization at various temperatures from 80 K to 325 K. The low-temperature magnetic transitions and dielectric relaxation behavior of NiV₂O₆ are attractive for several emerging technologies, such as quantum magnetism and spintronic devices, and cryogenic magnetic and dielectric sensors applications.