Unusual broadening of the NIR luminescence of Er3+-doped Nb2O5 nanocrystals embedded in silica host: Preparation and their structural and spectroscopic study for photonics applications

Annealing-free synthesis of carbonaceous Nb2O5 microspheres by flame thermal method and enhanced photocatalytic activity for hydrogen evolution

“…8 exhibits the Raman spectra for the as-prepared Nb 2 O 5 before and after annealing. A large background with several weak peaks from 1000 to 1500 cm À1 in correlation with small vibrations of carbonate bonds was observed for the carbonaceous Nb 2 O 5 microspheres (a), compared to the strong characteristic vibrational mode (695 cm À1 ) of Nb-O symmetric stretching for the annealed Nb 2 O 5 samples (b) [51]. The large background in the Raman spectroscopy suggested amorphous carbon species dispersing on the surface of carbonaceous Nb 2 O 5 microspheres as shown in the mapping photo (Fig.…”

Hybrid systems based on metal oxide and nanocarbons: electronic properties and applications for photocatalysis

“…[Soares et al 2011] Moreover, the band at 125cm -1 corresponds to optical vibrations of the hexagonal phase and indicates a highly ordered crystal structure. [Aquino et al 2014] In addition, Figure A.5b shows the Raman spectra of Ta2O5 nanoparticles and nanofibres annealed at 700ºC/10h and in the same frequency range than the niobium oxide spectra. The…”

Desenvolvimento de materiais nanoestruturados à base de SiO2-Nb2O5 preparados por uma nova rota sol-gel com aplicações em fotônica

“…Em trabalhos anteriores de nosso grupo foi verificado que os alcóxidos utilizados como precursores na preparação de materiais dopados com íons TR por sol-gel foram muito sensíveis à hidrólise FERRARI et al, 2012;AQUINO, 2013;AQUINO et al, 2014;AQUINO et al, 2016). Alquier et al (ALQUIER et al, 1986) também reportaram a dificuldade em se preparar géis de pentóxido de nióbio devido à rápida hidrólise do precursor etóxido de nióbio.…”

“…A caracterização óptica dos guias de onda planares 70Si-30Nb codopados com , 1975;NOWAK e ZIOLEK, 1999;AQUINO et al, 2014). A intensidade dos picos em 23° e 29° aumentou da amostra Nb20 até a Nb40, onde outros picos também referentes à fase T podem ser notados.…”