Influence of Al3+, Ga3+, and In3+ substitution on the structural, microstructural and dielectric characteristics of ZnS nanoparticles

Trivalent metal cations modified polycrystalline ZnS nanoparticles, Zn0.95X0.05S (X = Al3+, Ga3+, & In3+) NPs, were synthesized using co-precipitation technique and their physicochemical investigations were carried out. Structural analysis revealed that all the compositions display cubic crystallinity having Fm3‾m space group as evident from Rietveld refinement technique. The average crystallite size evaluated using Williamson-Hall plot was found to be 4.75 nm, 5.17 nm, and 5.76 nm for Zn0.95Al0.05S NPs, Zn0.95Ga0.05S NPs, and Zn0.95In0.05S NPs respectively. Microstructural studies depicted the nanoscale formation of nanoparticles with uniform grain distribution where the average grain size was observed between 38.2 nm and 45.4 nm. FT-IR spectra analysis confirmed the formation of Zn0.95Al0.05S, Zn0.95Ga0.05S, and Zn0.95In0.05S NPs with high frequency stretching vibrations about 465 cm−1 and 654 cm−1, belonging to the weak and strong edge of elemental regions. The value of the dielectric constant in the lower frequency region was found to be maximum (27.2) for Zn0.95In0.05S NPs and least (17.8) for Zn0.95Al0.05S NPs. It was observed that ac conductivity increases sharply with the increasing frequency of the applied electric field. The measured values of ac conductivity at 1 kHz for Zn0.95Al0.05S NPs, Zn0.95Ga0.05S NPs, and Zn0.95In0.05S NPs were found to be 5.06 × 10−7 Ω−1cm−1, 1.24 × 10−6 Ω−1cm−1, and 1.28 × 10−6 Ω−1cm−1, respectively.