Controlled co-precipitation synthesis of Gd and Mn doped zinc tungstate: insights into structural, optical, magnetic behavior, and dielectric properties

Abstract

Gadolinium and manganese-doped zinc tungstate (ZnWO₄: Gd & ZnWO₄: Mn (1 at%)) nanocrystals were successfully prepared using a simple co-precipitation method. The structural, morphological, and chemical properties of the materials were thoroughly investigated using X-ray diffraction (XRD), scanning/transmission electron microscopy (SEM/TEM), and energy dispersive X-ray (EDX) analysis. The crystallite sizes of the Gd-doped and Mn-doped samples were 46 nm and 59 nm, respectively. XRD analysis confirmed that both samples exhibited a single monoclinic phase crystal structure. The Gd-doping resulted in a more uniform particle size distribution and smoother surface morphology, which could enhance the optical and magnetic properties of the material. In contrast, Mn-doping led to the formation of more agglomerated particles with a rougher texture, potentially affecting the specific surface area and its interaction with external fields. SEM/TEM images also revealed an increase in average particle size with the Mn dopant. Optical properties, as measured by diffuse reflectance spectroscopy (DRS), showed a band gap of 3.79 eV for ZnWO₄: Gd and 3.40 eV for ZnWO₄: Mn. Magnetic measurements indicated enhanced magnetic properties for ZnWO₄: Mn compared to both pure ZnWO₄ and ZnWO₄: Gd. The dielectric properties, including the dielectric constant (εr), dielectric loss (tan δ), and AC conductivity, were studied over a frequency range from 100 Hz to 3 MHz at room temperature. The reduced coercivity observed in the Mn-doped sample suggests improved performance for potential applications in transformers, windings, and magnetic storage devices, where reduced core loss and enhanced efficiency are key requirements.This study not only enhances the understanding of the influence of Gd and Mn doping on ZnWO₄ properties but also opens up new possibilities for the development of multifunctional materials for advanced technological applications.

Graphical Abstract