Desenvolvimento e estudo de materiais baseados em AgNbO3 para armazenamento de energia

Abstract

Because of the high toxicity and environment concerns promoted by lead-based materials, the exploration of alternative lead-free compounds is becoming nowadays an evolving research field. As a result, a series of lead-free materials, which exhibit high energy storage densities, have been recently developed, from which the lead niobate (AgNbO3 – AN) system stands out. In this context, the objective of the present work was conducted to the synthesis of pure and doped Ag(1–3x)LaxNbO3-based ceramics, considering different lanthanum (La) concentrations, where x = 0; 0,005; 0,010 e 0,015, obtained via the conventional solid-state reaction method. The structural properties have been systematically investigated at room temperature by the X-ray diffraction (XRD) technique and Raman spectroscopy. The XRD result confirmed the formation of a single-phase with orthorhombic symmetry, without secondary phases. The Raman spectra analyses revealed structural modification with the inclusion of the doping element, with respect to the pure AgNbO3 system, showing additional modes in the highest wavenumbers range (570−758 cm–1). Additional information was provided by the refinement Rietveld method, as well as the Williamson-Hall analysis, from which detailed structural and microstructural characteristics were analyzed as a function of lanthanum concentration. Additional microstructural characteristics were performed using the scanning electron microscopy (SEM) technique, revealing homogeneous microstructures and grain-sizes on a micrometric scale (um), uniformly distributed for all studied compositions.