La:ZnO nanoparticles: an investigation on structural, optical, and microwave properties

Abstract

This paper presents the utilization of ethylene glycol monomethyl ether (EGME) during the synthesis of ZnO and La:ZnO with two tasks as a solvent and a fuel source within the gel combustion technique. The use of EGME for this purpose provides one-step production of the nanoparticles (NPs) and saves a considerable amount of time. The detailed characterization of the nanoparticles was carried out by X-ray diffractometer (XRD), scanning electron microscope (SEM), particle size analyzer, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), and Vector Network Analyzer (VNA) measurements, respectively. The NPs exhibited a hexagonal wurtzite structure with good crystallinity and a porous spongy morphology. The photoluminescence emission maxima of the synthesized NPs appeared at 500, 560, and 676 nm, upon excitation by the 372 nm of excitation. La:ZnO NPs showed significantly better photoluminescent characteristics than La-free ZnO forms. When excited at the same wavelength, La-free ZnO, 3%, and 7% La:ZnO exhibited 92, 45, and 35 μs average decay times, respectively. Finally, the microwave properties of the relative complex permittivity and permeability characteristics were also investigated and discussed in detail, which were derived from the scattering parameters of S11 and S21 in the X band regime.