Effect of Ca2+ site substitution on structural, optical, electrical and magnetic properties in Nd3+ and Mn2+-co-doped calcium molybdato-tungstates

摘要

? 2022 Elsevier Ltd and Techna Group S.r.l.Ca1-3x-yMny[]xNd2x(MoO4)1-3x(WO4)3x molybdato-tungstates (? denotes vacant sites) were successfully synthesized by high-temperature solid-state reaction. New materials crystallize in scheelite-type structure within whole homogeneity range of solid solution (x ≤ 0.2000 and y = 0.0200). Morphological features and particle size distribution were investigated by SEM and laser diffraction methods, respectively. Spectroscopic measurements in the UV–vis range was carried out to determine optical direct band gap (Eg), Urbach energy (EU) and confirmation of structural disorder. Refractive index (n) was calculated using four different models. Magnetic studies revealed paramagnetic behavior with long-range ferrimagnetic and short-range antiferromagnetic interactions. New materials showed weak n-type electrical conductivity and thermoelectric power factor (S2σ) that strongly depends on Nd3+ ions content. Dielectric parameters, i.e. relative permittivity (εr) and energy loss (tanδ) are insignificantly dependent on Nd3+ ions concentration. These effects were considered in terms of structural defects, thermal activation of charge carriers, and the Maxwell–Wagner polarization.