New Gd(3+) and Mn(2+)-Co-Doped Scheelite-Type Ceramics—Their Structural, Optical and Magnetic Properties

New Gd(3+)- and Mn(2+)-co-doped calcium molybdato-tungstates with the chemical formula of Ca(1−3x−y)Mn(y)▯(x)Gd(2x)(MoO(4))(1−3x)(WO(4))(3x) (labeled later as CaMnGdMoWO), where ▯ denotes vacant sites in the crystal lattice, 0 < x ≤ 0.2500 and y = 0.0200 as well as 0 < y ≤ 0.0667 and x = 0.1667 were successfully synthesized by high-temperature solid-state reaction method and combustion route. Obtained ceramic materials crystallize in scheelite-type structure with space group I4(1)/a. Morphological features and grain sizes of powders under study were investigated by SEM technique. Spectroscopic studies within the UV-vis spectral range were carried out to estimate the direct band gap (E(g)) and Urbach energy (E(U)) of obtained powders. EPR studies confirmed the existence of two types of magnetic objects, i.e., Mn(2+) and Gd(3+) ions, and significant antiferromagnetic (AFM) interactions among them.