The small polaron problem and optical effects in barium titanate

Gerthsen, P.; Groth, R. H.; Härdtl, Karl Heinz; Heese, D.; Reik, H.G.

doi:10.1016/0038-1098(65)90283-8

Cited by 46 publications

(9 citation statements)

References 13 publications

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“…supports the concept that the low energy Lorentz oscillator in the parameterization of e is associated with the small polaron hopping mechanism for conduction in amorphous VO x , in which case E 0 serves as the self-trapping energy. Such a mechanism has been proposed previously for other metaloxide semiconductors [33][34][35][36][37][38][39][40] and has been identified as variable range hopping conduction in pulsed dc sputtered VO x using low temperature electrical measurements. 41 Within a small polaron hopping model, the increase in the amplitude of the Lorentz oscillator and the associated carrier concentration with the decrease in q in Fig.…”

Section: Discussionmentioning

confidence: 67%

Electrical and optical properties of sputtered amorphous vanadium oxide thin films

Podraza

Gauntt

Motyka

et al. 2012

Journal of Applied Physics

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Articles you may be interested inMicrostructural evolution of thin film vanadium oxide prepared by pulsed-direct current magnetron sputtering J. Appl. Phys. 112, 093504 (2012); 10.1063/1.4759255 Enhanced electrical and noise properties of nanocomposite vanadium oxide thin films by reactive pulsed-dc magnetron sputtering Appl. Phys. Lett. 100, 262108 (2012); 10.1063/1.4731240 Process-structure-property correlations in pulsed dc reactive magnetron sputtered vanadium oxide thin films J. Vac. Sci. Technol. A 29, 061504 (2011); 10.1116/1.3636372 Vanadium oxide thin films for bolometric applications deposited by reactive pulsed dc sputtering J. Vac. Sci. Technol. A 27, 951 (2009); 10.1116/1.3119675Optical and electrical properties of sputtered vanadium oxide films Amorphous vanadium oxide (VO x ) is a component found in composite nanocrystalline VO x thin films. These types of composite films are used as thermistors in pulsed biased uncooled infrared imaging devices when containing face centered cubic vanadium monoxide phase crystallites, and substantial fractions of amorphous material in the composite are necessary to optimize device electrical properties. Similarly, optoelectronic devices exploiting the metal-to-semiconductor transition contain the room-temperature monoclinic or high-temperature (>68 C) rutile vanadium dioxide phase. Thin films of VO x exhibiting the metal-to-semiconductor transition are typically polycrystalline or nanocrystalline, implying that significant amounts of disordered, amorphous material is present at grain boundaries or surrounding the crystallites and can impact the overall optical or electronic properties of the film. The performance of thin film material for either application depends on both the nature of the crystalline and amorphous components, and in this work we seek to isolate and study amorphous VO x . VO x thin films were deposited by pulsed dc reactive magnetron sputtering to produce amorphous materials with oxygen contents !2, which were characterized electrically by temperature dependent current-voltage measurements and optically characterized by spectroscopic ellipsometry. Film resistivity, thermal activation energy, and complex dielectric function spectra from 0.75 to 6.0 eV were used to identify the impact of microstructural variations including composition and density. V C 2012 American Institute of Physics. [http://dx.

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Section: Discussionmentioning

confidence: 67%

Electrical and optical properties of sputtered amorphous vanadium oxide thin films

Podraza

Gauntt

Motyka

et al. 2012

Journal of Applied Physics

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“…Such a MIR absorption band was found in several well-studied materials, like cuprates, 32-36 manganites, 37-39 and nickelates. 32,37,40,41 Also several titanium oxides show the characteristic absorption feature of polarons in the MIR frequency range, [42][43][44][45][46] and also for LaTiO 3.41 such a picture had been suggested to explain the pronounced MIR band for E ʈ a. 14 For the manganites it was demonstrated that the MIR band is very sensitive to the application of chemical or external pressure, see, e.g., Refs.…”

Section: A Low-pressure Regime: P ͻ 15 Gpamentioning

confidence: 96%

Effect of pressure on the polarized infrared optical response of the quasi-one-dimensional conductorLaTiO3.41

et al. 2006

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The pressure-induced changes in the optical properties of the quasi-one-dimensional conductor LaTiO 3.41 were studied by polarization-dependent midinfrared microspectroscopy at room temperature. For the polarization of the incident radiation parallel to the conducting direction, the optical conductivity spectrum shows a pronounced midinfrared absorption band, exhibiting a shift to lower frequencies and an increase in oscillator strength with increasing pressure. On the basis of its pressure dependence, interpretations of the band in terms of electronic transitions and polaronic excitations are discussed. Distinct changes in the optical response near 15 GPa are in agreement with a recently reported pressure-induced structural phase transition and indicate the onset of a dimensional crossover in this highly anisotropic system.

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“…Small polarons generally play important roles in electronic and ionic transport, optical properties, and charge compensations. In BTO, it has been experimentally reported that small polarons would be the origin of the green luminescence [7][8][9], mid-near-infrared absorption, and blue coloration [10][11][12][13][14]. Especially, the transport of charged carriers has been attributed to hopping of small polarons in some studies [15][16][17][18][19].…”

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confidence: 99%

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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The small polaron problem and optical effects in barium titanate

Cited by 46 publications

References 13 publications

Electrical and optical properties of sputtered amorphous vanadium oxide thin films

Electrical and optical properties of sputtered amorphous vanadium oxide thin films

Effect of pressure on the polarized infrared optical response of the quasi-one-dimensional conductorLaTiO3.41

Stabilization of small polarons in BaTiO3 by local distortions

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