Preparation, Characterization, and Evaluation of Humidity-Dependent Electrical Properties of Undoped and Niobium Oxide-Doped TiO₂ : WO₃ Mixed Powders

Abstract

e study of selective metal oxide-based binary/ternary systems has received increasing interest in recent years due to the possibility of producing e cient new ceramic materials for relative humidity (RH) detection, given the superior properties of the mixed compounds in comparison with pristine ones. e aim of this work was focused on preparation and characterization of non-doped and Nb 2 O 5 -doped TiO 2 : WO 3 pair (in the pellet form) and evaluation of corresponding humidity-dependent electrical properties. e microstructure of the samples was analyzed from scanning electron microscopy, X-ray di raction patterns, Raman spectra, BET surface area analysis, and porosimetry. e electrical characterization was obtained from impedance spectroscopy (100 Hz to 40 MHz) in the 10-100% RH range. e results showed that adequate doping levels of Nb 2 O 5 introduce important advantages due to the atomic substitution of Ti by Nb atoms in highly doped structures with di erent levels of porosity and grain sizes. ese aspects introduced a key role in the excursion (one order of magnitude) in the bulk resistance and grain boundary resistance, which characterizes these composite ceramics as a promising platform for RH identi cation.

Electrochemical Characterization of Novel Polyantimonic-Acid-Based Proton Conductors for Low- and Intermediate-Temperature Fuel Cells

“…The grain conductivity remained unchanged, being ~5 × 10 −2 S/cm for both binder contents. The results are supported not only by unit cell shrinkage and Sb-O bond length decreases according to XRD and Raman spectroscopy (i.e., holes and windows size decrease slightly in the anionic skeleton where ion carriers are accommodated), but also by literature previous reports [13,39,42], and previous studies by the authors [53][54][55]: together, this entirely underwrites the considered circuit model. Based on the presented membrane properties, the authors believe that they are undoubtedly strong candidates to be used in high-efficiency fuel cells in the near future.…”

Effect of Nb5+ and In3+ Ions on Moisture Sensitivity of Electrospun Titanium/Tungsten Oxide Nanostructures: Microstructural Characterization and Electrical Response

“…The combined use of titanium dioxide (TiO 2 ) and tungsten trioxide (WO 3 ) with selective dopants such as Zn 2+ , Cu 2+ , Nb 5+ and V 5+ ions, in volumetric pellets arrangement, has been studied for the development of more efficient MMO sensors [9][10][11]. While WO 3 interacts superficially with TiO 2 , which increases both the thermal/structural stability and the conductivity of the system, the dopants increase the degree of adsorption of water molecules, resulting in an excellent sensitivity to RH variations.…”