Structural and Dielectric Properties of Al-Doped ZnO Nanoparticles for High-Frequency Applications

This study reports the synthesis of 5% Al-doped zinc oxide (ZnO) nanoparticles using the sol-gel method, followed by a comprehensive analysis of their structural and dielectric properties. X-ray diffraction (XRD) confirmed a hexagonal wurtzite structure with lattice parameters a = 3.277 Å and c = 5.257 Å, indicating successful Al³⁺ incorporation without impurity phases. Dielectric relaxation spectroscopy (DRS) revealed a low real permittivity (ε' ≈ 0.97–1.0) and an extremely low dielectric loss (ε'' ≈ 10⁻¹³ to 10⁻¹²) over 400 kHz to 800 kHz and 88 K to 220 K, showcasing excellent insulating properties. The nanoparticles, with a crystallite size of 20–30 nm, exhibited structural stability and minimal lattice strain. These properties suggest potential applications in high-frequency electronic devices and capacitors. This work provides a detailed understanding of Al-doped ZnO nanoparticles, highlighting their suitability for advanced dielectric applications.