Nanocrystalline GdAlO₃: XPS, EPR and magnetic susceptibility studies

Abstract

Nanocrystalline gadolinium monoaluminate (GdAlO₃) has been synthesized by sol–gel method after sintering the precursor gel at 950°C. The microstructural features have been proved by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy-dispersive X-ray analysis (EDX). The XRD pattern confirms the formation of single-phase GdAlO₃ while EDX shows that this nanomaterial is stoichiometric; the average size of the nanoparticles is 40 nm. X-ray photoelectron spectroscopy (XPS) has been used to study the chemical composition and bonding in the as-prepared samples. The binding energies of core-level electrons in Gd, Al and O in GdAlO₃ nanopowder have been found slightly shifted compared to the corresponding values of the same elements. The electron paramagnetic resonance (EPR) spectra at 9.23 GHz (X-band) and different temperatures indicate the existence of magnetically concentrated solid containing Gd³⁺ ions. Nèel temperature, T _N =3.993 K, effective Bohr magneton number, μ _eff=8.18, and constant of magnetic exchange interaction, J _ex=−0.069 cm⁻¹, have been determined from DC magnetic susceptibilities measured in the range 2–300 K.