Síntese e caracterização de M2+NBb2O6 (M2+ = Mg, Ca, Sr, Ba) com estrutura tipo perovskita, obtidos por moagem de alta energia e com potencial para aplicação como eletrólito sólido em dispositivos de armazenamento de energia e sensores eletroquímicos

Abstract

The growing energy demand and the environmental impacts of petroleum are driving the search for economically and environmentally viable alternatives, which, however, depend on efficient energy storage systems. Batteries and supercapacitors have stood out in this context. Electrolytes are fundamental components in these types of devices. Solid electrolytes have gained attention due to their safety and stability, although they still face challenges related to ionic conductivity, manufacturing, and cost. In this scenario, perovskite-type structures, particularly those based on niobium, appear promising, although they are still underexplored for this application. This study presents the synthesis of alkaline earth metal niobates (MgNb2O6, CaNb2O6, SrNb2O6 and BaNb2O6) via high-energy ball milling, with potential application as solid electrolytes. X-ray diffraction, Rietveld refinement, and Raman spectroscopy analyses confirmed the predominant formation of the desired crystalline phase after 3 hours of synthesis. Structural and electrochemical analyses revealed crystallite sizes ranging from 11 to 47 nm, optical bandgaps between 2.71 and 3.45 eV, and ionic conductivity ranging from 1.96x10-6 to 2.8x10-5 S/cm. Morphological analysis showed the formation of irregular particle agglomerates ranging from submicron to micron scale. Thermogravimetric analyses revealed a recrystallization temperature range between 400 and 700°C, with structural stability. The adopted approach proved effective for obtaining niobates with potential for application as electrolytes in batteries, supercapacitors, and electrochemical sensors. In this work, the synthesized niobates are specifically explored as sensors for detecting lead (Pb2+) and cadmium (Cd2+) ions.