Low temperature dielectric studies of aluminum doped tin oxide nanoparticles

This study presents a facile sol-gel route for synthesizing pristine and Al-doped SnO2 nanoparticles. The phase purity of the synthesized nanoparticles was confirmed by powder X-ray diffraction (PXRD), revealing a tetragonal cassiterite structure for all samples. The crystallite size, determined by using the Scherrer equation and Willamson-Hall plot, ranged from 9.66 nm to 25.75 nm and exhibited an increasing trend with increasing doping concentration. Raman spectroscopy further corroborated this structural identification. The incorporation of aluminum (Al) into the tin oxide matrix was validated by energy-dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) analysis. UV-visible spectroscopy revealed a reduction in the bandgap from 3.6 eV to 3.2 eV upon Al doping, attributed to the decreasing lattice strain with increasing Al content and other underlying mechanisms. The dielectric properties, including dielectric constant, dielectric loss, and AC conductivity, were examined as a function of frequency and doping concentration within the temperature range of 100 K-400 K. These properties exhibited an increasing trend up to 6 % Al doping. Interestingly, the 8 % doped sample exhibited the lowest dielectric loss and the highest AC conductivity, making it a promising candidate for applications in high-frequency electronics, energy storage, and ferroelectric devices.