Characterization, sintering and dielectric properties of nanocrystalline zinc oxide prepared by a citric acid-based combustion route

Nanosized zinc oxide has been synthesized through a novel single step solution combustion route using citric acid as fuel. The X-ray diffraction (XRD) analysis revealed that the synthesized ZnO nanopowder has the pure wurtzite structure. The phase purity of the nanopowder has been confirmed using differential thermal analysis (DTA), thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FT-IR). The morphology and crystalline size of the as-prepared nanopowder characterized by scanning electron microscopy (SEM) and transmission electron microscopy (TEM) revealed that the powder consisted of a mixture of nanoparticles and nanorods. The nanocrystalline ZnO could be sintered to ∼97% of the theoretical density at 1200 °C in 4 h. The dielectric constant (εr) and dielectric loss (εi) of sintered ZnO pellets at 5 MHz were 1.38 and 9×10−2, respectively, at room temperature.

Research highlights
► Nanocrystalline ZnO has been successfully synthesized through combustion route, without any calcination step.
► Nanoparticles of ZnO obtained by the present combustion method were sintered to 97% of the theoretical density at 1200 °C for 4 h.
► Dielectric studies on the sintered pellet suggest that ZnO behaves as a conductor at high temperature.
► To the best of our knowledge, it is the first attempt in the literature to study the sintering and dielectric behavior of phase pure ZnO nanocrystals synthesized by a single step combustion route.