Electrical conductivity of similarly doped BaTiO3 single crystals and ceramics in the rhombohedral phase

Gillot, C.; Michenaud, Jean-Pierre

doi:10.1016/0038-1098(94)90955-5

Cited by 10 publications

(7 citation statements)

References 6 publications

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“…For example, the positive temperature coefficient resistivity effect is commonly observed in polycrystals but not in single crystals. In general, the small polaron's hopping model fits well the observed thermally activated conductivity especially in the rhombohedral phase [14,[45][46][47]. The deep pinning level at 0.3 eV in the R model is consistent with this hopping scenario at low temperature [ Fig.…”

Section: O and Ti −supporting

confidence: 67%

“…Consequently, the STEs are found to be energetically favorable in both phases compared with delocalized carrier electrons. Our results are in contrast to previous theoretical studies that used the centrosymmetric cubic model but reasonably explain some experimental observations such as green luminescence [7][8][9] and small polaron hopping conductivity at low temperatures [14,[45][46][47]. This discussion is extendable to other d 0 perovskite oxides.…”

Section: O and Ti −supporting

confidence: 59%

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Stabilization of small polarons in BaTiO3 by local distortions

Tsunoda

Kumagai

Oba

2019

Phys. Rev. Materials

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Small polarons and point defects in BaTiO 3 are investigated using hybrid functional calculations. Based on the experimentally-confirmed order-disorder-type phase transitions, Ti displacements along 111 directions are included in the cubic model. We reveal that the self-trapped electrons at Ti sites are stable in both rhombohedral and cubic BaTiO 3 and the Ti off-centering, which introduces antibonding hybridization between lowest-lying Ti-3d and O-2p orbitals at the conduction band minimum, is essential for stabilizing the self-trapped electrons. Our calculations are in contrast to previous theoretical studies, even qualitatively, but reasonably consistent with the long-standing experimentally-observed small polarons in BaTiO 3. This finding may explain why self-trapped electrons are not stable in SrTiO 3 but are in BaTiO 3 from the symmetry viewpoint.

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Section: O and Ti −supporting

confidence: 67%

Section: O and Ti −supporting

confidence: 59%

Stabilization of small polarons in BaTiO3 by local distortions

Tsunoda

Kumagai

Oba

2019

Phys. Rev. Materials

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“…That is, the coexistence of conductivity and ferroelectricity is shown by many experiments. Several results indicate that oxygenvacancy-or impurity-doped conducting BaTiO 3 single crystals undergo structural phase transitions and the critical temperature of these phase transitions is almost unchanged by conductance [38][39][40][41][42]. Here, the change of electron/hole mobility and the optical absorption is the indication of the band structure, and therefore, the crystallographic structure.…”

Section: Experimental Evidencementioning

confidence: 92%

“…In particular, Nb-doped BaTiO 3 single crystals are conductive also at cryogenic temperature. Nonetheless, the temperature dependence of the conductance indicates that evident abrupt Downloaded by [University of Saskatchewan Library] at 09:11 03 October 2012 structural phase transitions exist at all the critical temperatures same as those of insulating single crystals [41,42].…”

Section: Experimental Evidencementioning

confidence: 95%

Examination of Long-Range Electrostatic Interaction for Ferroelectricity in View of Intrinsic Free Electrons/Holes at Polarization Discontinuities

Watanabe

2012

Ferroelectrics

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“…The evolution of M'' shows that with increasing temperature the maxima (peaks) shift to higher frequencies, which indicates that charge carriers become thermally stimulated with increasing temperature, resulting in a gradual movement (in other words: increasing temperature trigger faster ionic activity, which results in the peak shifting towards higher frequencies). The shorten the period and increase of the relaxation frequency, suggesting the presence of a temperature-dependent thermally activated relaxation process, dominated by the charge carrier hopping mechanism [52]. In the low-frequency interval below the maximum of M''(f), carriers can hop from one site to another site (i.e., long-distance hopping exists).…”

Section: Complex Impedance Spectroscopy Analysismentioning

confidence: 95%

Characterization of Na0.5Bi0.5TiO3 Single Crystals by X-ray Diffraction, Scanning Electron Microscopy, X-ray Photoelectron Spectroscopy, Optical Absorption, Electric and Thermoelectric Properties Studies

J.Suchanicz,

Kluczewska-Chmielarz,

Jagło

et al. 2024

Preprint

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High-quality and large-size single crystals of lead-free Na0.5Bi0.5TiO3 were grown using the Czo-chralski technique. The crystals had pure perovskite structure with rhombohedral symmetry and were translucent in the visible and near infrared spectral ranges recorded in the interval 350-1050 nm. The energy gaps determined from the X-ray photoelectron spectroscopy (XPS) and optical measurements were approximately 2.92 eV. The current-voltage characteristics, depolarization current, dc (σdc) and ac (σac) electrical conductivity, and Seebeck coefficient of the crystals were investigated. The frequency/temperature-dependent electrical properties were also measured and analyzed through complex impedance spectroscopy. An overlapping reversible insulator-metal transition (resistive switching) on nanoscales, caused by the electric field, was detected. This was the first time that most of these investigations were performed for this material. The following conductivity mechanisms of NBT single crystals were identified: (i) quasi-free electron and hole conduction and hopping-charges mechanism at low temperatures, (ii) small polaron conductivity in the middle temperature range, and (iii) a significant contribution of the oxygen vacancies to conductivity in the high temperature range. The activation energy values determined from the conductivity data, the imaginary part of the electric impedance and the modulus indicate that the relaxation process in the high-temperature range is attributable to both single and double ionized oxygen vacancies, in combination with the hopping of electrons between Ti4+ and Ti3+. P-type electrical conductivity was also found. These discoveries create new possibilities of reducing the electrical conductivity of NBT and improving the process of effectively poling this material. The density of the electronic states was investigated using an ab initio method. The energy gap cal-culated for NBT (R3c) was 2.8 eV, and is well comparable to those determined from XPS and optical measurements. Our results indicate the possibility of tuning material properties by inten-tionally creating non-stoichiometry/structural defects (oxygen vacancies, cation excess and cation deficiency).

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Electrical conductivity of similarly doped BaTiO3 single crystals and ceramics in the rhombohedral phase

Cited by 10 publications

References 6 publications

Stabilization of small polarons in BaTiO3 by local distortions

Stabilization of small polarons in BaTiO3 by local distortions

Examination of Long-Range Electrostatic Interaction for Ferroelectricity in View of Intrinsic Free Electrons/Holes at Polarization Discontinuities

Characterization of Na<sub>0.5</sub>Bi<sub>0.5</sub>TiO<sub>3</sub> Single Crystals by X-ray Diffraction, Scanning Electron Microscopy, X-ray Photoelectron Spectroscopy, Optical Absorption, Electric and Thermoelectric Properties Studies

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