Structural, optical, luminescent and magnetic properties of Gd2O3 nanoparticles: A comparative study on the effect of different green fuels in the sol–gel synthesis tactics

Abstract

In this study, five samples of Gd2O3 NPs (size range: 4–33 nm) were synthesized by five different green facile and diverse natural products acting as reducing & stabilizing agents such as: fresh juices of sugarcane, lemon, tomato & orange fruits and citric acid via self combustion sol–gel tactics. Powder X-ray diffraction (PXRD), High resolution transmission electron microscopy (HRTEM), Fourier transform infrared (FTIR) and Raman analysis affirmed cubic-C type crystal structure of Gd2O3 NPs prepared using citric acid, lemon juice and sugarcane juice. Mixed cubic and monoclinic phases were observed in Gd2O3 NPs prepared using tomato and orange juices. Notably, NPs of Gd2O3 in quantum dot regime (size: 6 ± 2 nm) were produced in the fresh sugarcane juice mediated synthesis protocol. Fresh lemon juice and sugarcane juice were appeared to be the most efficient green fuel for producing quality samples of Gd2O3 NPs. Optical absorption studies showed that bandgap in these Gd2O3 NPs is strongly dependent on the preparation protocol and type of green fuel. Interestingly, highest and lowest band gap of 4.91 eV and 4.43 eV were obtained for Gd2O3 NPs fabricated with orange and lemon juices, respectively. Photoluminescence (PL) and electron spin resonance (ESR) analysis affirmed formation of Schottky and Frenkel surface defects along with self trapped excitons and oxygen vacancies in these Gd2O3 NPs. Paramagnetic character of these Gd2O3 NPs at 300 K is validated by dc-magnetization and ESR studies. Present study demonstrated that microstructural, optical absorption and photoluminescence properties of Gd2O3 NPs can be easily customized by choice of natural products in the synthesis tactics.