Thermodynamic properties of nonstoichiometric H-Nb2 O5−x derived from a statistical model of its defect structure

Heat-Induced Phase Transformation of Three-Dimensional Nb3O7(OH) Superstructures: Effect of Atmosphere and Electron Beam

“…Neither of these patterns fit to the H-Nb 2 O 5 or Nb 3 O 7 (OH) crystal phase, and the phase variety of niobium oxide and its ability to accommodate reduction by crystallographic shear complicate the phase identification (the determined d-values are listed in SI, Table S2). 11,40,41,50 To address the question of the effect of the electron beam irradiation on the phase transformation further nanowires and networks which had not been illuminated during the in situ heating experiment are analyzed after being cooled down to room temperature. The investigation shows that in the absence of the electron beam a minimum temperature of 900 °C is required to initiate a phase transformation.…”

“…Neither of these patterns fit to the H-Nb 2 O 5 or Nb 3 O 7 (OH) crystal phase, and the phase variety of niobium oxide and its ability to accommodate reduction by crystallographic shear complicate the phase identification (the determined d -values are listed in SI, Table S2). ,,, …”

“…This is important as some niobium oxide polymorphs are reported to tolerate large deviation from stoichiometry. 11,40,41 In situ experiments carried out in a transmission electron microscope (TEM) are furthermore used to directly observe atomic scale phenomena.…”

“…In this work, the heat induced phase transformation of Nb 3 O 7 (OH) to H‑Nb 2 O 5 and the effect of annealing on the morphology of the superstructures are studied at the atomic scale as a function of pressure and atmosphere. This is important as some niobium oxide polymorphs are reported to tolerate large deviation from stoichiometry. ,, In situ experiments carried out in a transmission electron microscope (TEM) are furthermore used to directly observe atomic scale phenomena.…”

Micro‐Raman scattering in Nb2O5–TiO2 ceramics

“…It was proposed that the number and distribution of vacancies in the oxygen sublattice around the channels might precisely predict the phase transition in these materials. 4 As a result, the electrical and magnetic properties of Nb 2 O 5 were found to be strongly affected by small variations of oxygen vacancies or dopants. 5 -7 Micro-Raman spectroscopy is very useful in determining the effect of dopants in such structures because of the shorter coherence length and timescale of the phonons.…”