Niobium oxide prepared by sol–gel using powder coconut water

Niobium oxides are presently very important materials for electronic device applications. In this work, a new approach, using the proteic sol–gel route, was used to prepare niobium pentoxide powders. This approach uses powdered coconut water (PCW) for the powders production. The obtained powders, with an amorphous structure, were heat-treated at different temperatures and their structural and morphological properties were studied and related to their dielectric properties. Dielectric measurements as a function of frequency (100 Hz–1 MHz) and temperature (200–400 K) were performed. The heat-treatment promotes the formation of crystalline structures, mainly Nb₂O₅ with orthorhombic structure, which transforms to monoclinic with treatments at 1000 °C. The formation of CaNb₂O₆ and NaNbO₃ crystallites, in the samples treated at 800 and 1000 °C is related to the PCW base composition. The samples revealed a quasi-independence of the dielectric constant with temperature and frequency, presenting a \(\varepsilon^{\prime}\) ≈ 70 and tan ≈ 0.006, at room temperature and 100 kHz.