Electrical properties of NbO and NbO2

Temperature independent Seebeck coefficient through quantum confinement modulation in amorphous Nb-O/Ni-Ta-O multilayers

“…−25 μV K −1 . This is similar to or a slight improvement over cubic NbO at elevated temperatures [7,9], but it is striking that the Seebeck coefficient is constant over a wide temperature range, which resembles the behavior of functionally graded or segmented crystalline bulk thermoelectrics [27][28][29][30][31]. However, it is possible to synthesize amorphous multilayers on any kind of substrates, especially temperature sensitive substrates, such as polymers.…”

“…It is catalytically active with CH 4 [5] as well as CO and CO 2 [6] in the gas phase, but it is not known what occurs on its solid surfaces. In addition, NbO possesses the Seebeck coefficient in the range of −10 to −25 µV K −1 at 1000 K [7,8]. By filling the 1b vacant Wyckoff sites with N, its Seebeck coefficient can attain −70 µV K −1 at 800 K [9].…”

Metal-Insulator Transition in Niobium Dioxide Thin Films

“…[57] NbO 2 exhibits a negative Seebeck coefficient, indicating a n-type semiconductor. The magnitude of Seebeck coefficient is on the order of ⇠10 3 µV/K at room temperature and decreases to ⇠10 2 µV/K around 1000 K. [9,57,60] All properties summarized above were obtained from bulk NbO 2 samples, and transport characterization on NbO 2 thin films is still very limited. Only recent study on epitaxial NbO 2 thin films on sapphire substrates by Wong et al showed an activation energy for conduction of ⇠ 0.16 eV between 300 K and 400 K. [24] 2.3 Metal insulator transition (MIT)…”

“…O + 2e 0 respectively using Kröger-Vink notations. [60] The resultant electrons can be localized near niobium ions, resulting in Nb (4 y)+ ions nearby and introducing multiple donor levels within the band gap.…”

“…Oxygen content is deficient in S1 while excessive in other samples. The predominant type of point defects and therefore dependence of physical properties on oxygen content are different, which is discussed briefly below referring to some early studies on bulk NbO 2 and on VO 2 thin films [60,[100][101][102]. In deposited NbO 2 films, increased amount of point defects can be introduced by nonstoichiometry due to variation or dynamic fluctuation of deposition conditions.…”