Superconducting, surface and anomalous electron transport properties of BaNbO3−x films

Gasparov, V. A.; Ermolov, S.N.; Khassanov, S. S.; Струкова, Г. К.; Gasparov, L. V.; Wang, H.S.; Li, Q.; Schnider, M.; Richter, W.; Glaser, E.; Schmidl, F.; Seidel, P.; Brandt, B. L.

doi:10.1016/s0921-4526(99)02468-0

Cited by 10 publications

(11 citation statements)

References 3 publications

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“…This leads to a rather low zero temperature value of H c2 (0) = 0.1 T (ξ(0) = 570Å) which is significantly smaller than for MgB 2 (18 T ) 15 . Such a linear H c2 (T) dependence is characteristic for 2D superconductors16 and was also observed in MgB 2 15 wires and BaNbO 3−x films17,18 . The results of extended study of the H c2 (T)…”

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confidence: 54%

Electron transport in diborides: Observation of superconductivity in ZrB2

et al. 2001

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We report on syntheses and electron transport properties of polycrystalline samples of diborides (AB 2 ) with different transition metals atoms (A=Zr,Nb,Ta). The temperature dependence of resistivity, ρ(T ), and ac susceptibility of these samples reveal superconducting transition of ZrB 2 with T c = 5.5 K, while NbB 2 and TaB 2 have been observed nonsuperconducting up to 0.37 K. H c2 (T) is linear in temperature below T c , leading to a rather low H c2 (0) = 0.1 T . At T close to T c H c2 (T) demonstrates a downward curvature. We conclude that these diborides as well as MgB 2 samples behaves like a simple metals in the normal state with usual Bloch-Grüneisen temperature dependence of resistivity and with Debye temperatures: 280 K, 460 K and 440 K, for ZrB 2 , NbB 2 and MgB 2 , respectively, rather than T 2 and T 3 as previously reported for MgB 2 .

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confidence: 54%

Electron transport in diborides: Observation of superconductivity in ZrB2

et al. 2001

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“…Figure a shows a typical survey spectrum, indicating that the as-synthesized samples contain Ba, Nb, and O, which accords with the EDS results (Figure d), and the C 1s peak is probably attributed to the adventitious hydrocarbon from the XPS instrument itself. Figure b gives the XPS spectrum of the core levels of Ba 3d 5/2 and Ba 3d 3/2 to be approximately 779.8 and 795.6 eV, indicating the +2 valence of Ba, which are in perfect agreement with the literature. ,, The separation between Ba 3d 5/2 and Ba 3d 3/2 is 15.8 eV, and the FWHM of Ba 3d 5/2 and Ba 3d 3/2 is 1.73 and 2.05 eV, respectively, which are consistent with the literature . The Nb 3d level spectrum after linear background subtraction is presented in Figure c.…”

Section: Resultssupporting

confidence: 86%

“…The total magnetic moment induced by the defect of V O1 2+ – V O5 2+ is about 0.942 μB, which matches the weak magnetism in the experiment. Since the calculated structure contains two oxygen vacancies with the chemical formula of the defect structure of BaNbO 2.75 , this concentration of oxygen vacancies matches the laboratorial result, BaNbO x , x = 2.2–2.4 …”

Section: Resultssupporting

confidence: 72%

“…From ref , it is known that the UV irradiation can generate oxygen vacancy in the sample, so here, we remove one oxygen atom (O2 in Figure a) based on the defect of V O1 2+ – V O5 2+ . The calculated structure contains three oxygen vacancies, indicating that the chemical formula of the defect structure is BaNbO 2.62 , which matches the laboratorial result, BaNbO X , X = 2.2–2.4 . The total magnetic moment changes from 0.942 to 1.76 μB.…”

Section: Resultssupporting

confidence: 71%

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Defect-Induced and UV-Irradiation-Enhanced Ferromagnetism in Cubic Barium Niobate

Guo

Hao

2013

J. Phys. Chem. C

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Optical and magnetic properties of the perovskite barium niobate (BaNbO3) nanocubes are investigated before and after UV irradiation. The energy gap changes from 3.94 to 3.88 eV, and light absorption ability increases after UV irradiation. The X-ray photoelectron spectroscopy (XPS) spectra reveal that the BaNbO3 nanocubes contain oxygen vacancy. The BaNbO3 nanocubes show weak ferromagnetism, but the saturation magnetization is enhanced from 4.34 × 10–3 to 6.60 × 10–3 emu/g after UV irradiation. The calculations indicate that the ferromagnetism is due to two +2 charge oxygen vacancies (V O1 2+ – V O5 2+) which cause unpaired electrons around the oxygen vacancy occupying the d state of the nearest-neighbor Nb atom. The total magnetic moment increases from 0.942 to 1.76 μB owing to an increase of the concentration of the oxygen vacancy in BaNbO3. The theoretical consequence well matches the laboratorial result.

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“…The ligand ( t 2g antibonding) state, in particular, was affected by T r . Therefore, the O 2p and ligand ( t 2g antibonding) states both increased in intensity and shifted to lower binding energies as T r increased in Figures (a) and S11, and S12. − The band structure around the ligand ( t 2g bonding) widened for T r2 . In addition, an Urbach tail appeared at the band edge, as shown in Figure (c).…”

mentioning

confidence: 95%

Electronic Structure and Thermoelectric Properties of Highly Oriented Ba₂NaNb₅O₁₅ Reduced Ceramics

Kakemoto

2019

ACS Appl. Electron. Mater.

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Often, thermoelectric (TE) materials cannot realize energy harvesting at ∼200 °C. If a fine structure arranged oxide TE material could convert electricity from waste heat, its TE application potential is increased. We report a dimensionless figure of merit (ZT) with low thermal conductivity (κ) ≈ 200 °C of highly oriented n-type Ba2NaNb5O15 (BNN) reduced ceramics, prepared to investigate orientation on transport and thermal dynamics. ZT and κmin for BNN were evaluated to be 0.1 and a surprisingly small 0.2 W/mK, respectively, at ∼200 °C using the Harman method. TE properties of BNN were discussed in terms of transport and thermal dynamics considering electronic structure, small polaron, and anomalies with calculations.

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Superconducting, surface and anomalous electron transport properties of BaNbO3−x films

Cited by 10 publications

References 3 publications

Electron transport in diborides: Observation of superconductivity in ZrB2

Electron transport in diborides: Observation of superconductivity in ZrB2

Defect-Induced and UV-Irradiation-Enhanced Ferromagnetism in Cubic Barium Niobate

Electronic Structure and Thermoelectric Properties of Highly Oriented Ba₂NaNb₅O₁₅ Reduced Ceramics

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Superconducting, surface and anomalous electron transport properties of BaNbO3−x films

Cited by 10 publications

References 3 publications

Electron transport in diborides: Observation of superconductivity in ZrB2

Electron transport in diborides: Observation of superconductivity in ZrB2

Defect-Induced and UV-Irradiation-Enhanced Ferromagnetism in Cubic Barium Niobate

Electronic Structure and Thermoelectric Properties of Highly Oriented Ba2NaNb5O15 Reduced Ceramics

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Electronic Structure and Thermoelectric Properties of Highly Oriented Ba₂NaNb₅O₁₅ Reduced Ceramics