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 1-3 x - y Mn y ▯ x Gd 2 x (MoO 4 ) 1-3 x (WO 4 ) 3 x (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 I 4 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.