Dipolar and magnetic order in Sr(Mn 1/2 Nb 1/2 )O 3

Abstract

A polycrystalline sample of Sr(Mn_1/2Nb_1/2)O₃ (SMNO) was synthesised via the solid-state reaction method, confirming a single-phase perovskite structure. Room-temperature XRD analysis revealed a tetragonal crystal system. Micro-Raman spectroscopy exhibited broad peaks, suggesting the presence of a vibrational band and ferroelectric characteristics. Dielectric properties were investigated over a broad frequency (100–1 MHz) and temperature (24–360°C) range, revealing strong low-frequency dispersion, a very high dielectric constant and loss (∼6). A broad permittivity peak was observed at 280°C across all measured frequencies. The frequency and temperature dependence of the ac conductivity (σ_ac) suggest a thermally activated relaxation mechanism. Impedance spectroscopy indicated that the dielectric and conductive properties of the material arise from the contributions of bulk, grain boundaries and electrode effects. Magnetic measurements identified an antiferromagnetic transition at 41 K, co-existing with a low-temperature ferromagnetic phase. The growing demand for miniaturised and versatile electronic components drives our strong interest in developing dielectric ceramics. These materials are critical for applications such as capacitors, sensors, actuators and transducers.