Conduction states in oxide perovskites:  Three manifestations of<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msup><mml:mrow><mml:mi mathvariant="normal">Ti</mml:mi></mml:mrow><mml:mrow><mml:mn>3</mml:mn><mml:mo>+</mml:mo></mml:mrow></mml:msup></mml:mrow></mml:math>Jahn-Teller polarons in barium titanate

Lenjer, S.; Schirmer, O. F.; Hesse, H.; Kool, Th. W.

doi:10.1103/physrevb.66.165106

Cited by 108 publications

(75 citation statements)

References 29 publications

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“…The charge transfer occurring from one ͓TiO 5 ͔ to one ͓TiO 6 ͔ cluster creates electron and hole polarons that can be designed as JahnTeller bipolarons. They have already been evidenced by means of electron paramagnetic resonance measurements in pure BaTiO 3 monocrystal 34 or by theoretical calculations where they were considered as point defects. 35,36 Stashans et al announced that they had to be expected for perovskitetype titanates.…”

Section: Resultsmentioning

confidence: 99%

Room-temperature photoluminescence ofBaTiO3: Joint experimental and theoretical study

et al. 2005

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Strong photoluminescent emission has been measured at room temperature for noncrystalline BaTiO 3 ͑BT͒ perovskite powders. A joint experimental and theoretical study has been carried out to rationalize this phenomenon. From the experimental side, BT powder samples have been synthesized following a soft chemical processing, their crystal structure has been confirmed by x-ray data and the corresponding photoluminescence ͑PL͒ properties have been measured. Only the structurally disordered samples present PL at room temperature. From the theoretical side, first-principles quantum-mechanical techniques, based on density-functional theory at the B3LYP level, have been employed to study the electronic structure of crystalline ͑BT-c͒ and asymmetric ͑BT-a͒ models. Theoretical and experimental results are found to be consistent and their confrontation leads to an interpretation of the PL apparition at room temperature in the structurally disordered powders.

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Section: Resultsmentioning

confidence: 99%

Room-temperature photoluminescence ofBaTiO3: Joint experimental and theoretical study

et al. 2005

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“…Therefore, the distorted models ͑ST-f, ST-m, and ST-fm͒ can also be seen as a crystalline model like a Jahn-Teller distortion. 53 The direct observation of oxygen vacancies is difficult, but spectroscopic studies of doped and annealed crystals indicate the presence of these vacancies. 54,55 EPR spectroscopy is an excellent tool for identifying and qualitatively monitoring complex oxygen vacancies that modify the electronic and ionic conductivities or grain boundary properties.…”

Section: Resultsmentioning

confidence: 99%

Structural conditions that leads to photoluminescence emission in SrTiO3: An experimental and theoretical approach

Longo

Figueiredo

Lázaro

et al. 2008

Journal of Applied Physics

159

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• ͒ vacancies were identified in disordered SrTiO 3 powders prepared by the polymeric precursor method, based on experimental measurements by x-ray absorption near edge structure spectroscopy. The paramagnetic complex states of ͓TiO 5 · V O • ͔ and ͓SrO 11 · V O • ͔ with unpaired electrons were confirmed by electron paramagnetic resonance spectroscopy. The disordered powders showed strong photoluminescence at room temperature. Structural defects of disordered powders, in terms of band diagram, density of states, and electronic charges, were interpreted using high-level quantum mechanical calculations in the density functional framework. The four periodic models used here were consistent with the experimental data and explained the presence of photoluminescence.

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“…Different strength of electronphonon coupling in n-type SrTiO 3 and BaTiO 3 have been invoked to classify these materials into the large and small polaron categories, respectively. [4][5][6][7] The origin of the different nature of the electron-phonon interactions in these two compounds is not clear, however, especially considering very similar lattice constants and identical valence electronic structure.…”

Section: Introductionmentioning

confidence: 99%

Doping and temperature-dependent optical properties of oxygen-reducedBaTiO3−δ

et al. 2010

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We report on optical properties of reduced BaTiO 3−δ at different doping levels including insulating and metallic samples. In all the samples, including metallic one, we observe structural phase transitions from the changes of the infrared active phonon modes. Metallic ground state is confirmed by the Drude-type low-frequency optical reflectance. Similar to SrTiO 3−δ we find that the mid-infrared absorption band in BaTiO 3−δ appears and grows with an increase in the oxygen vacancy concentration. Upon decrease in temperature from 300 K, the mid-infrared band shifts slightly to higher frequency and evolves into two bands: the existing band and a new and smaller band at lower frequency. The appearance of the new and smaller band seems to be correlated with the structural phase transitions.

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Conduction states in oxide perovskites: Three manifestations ofTi3+Jahn-Teller polarons in barium titanate

Cited by 108 publications

References 29 publications

Room-temperature photoluminescence ofBaTiO3: Joint experimental and theoretical study

Room-temperature photoluminescence ofBaTiO3: Joint experimental and theoretical study

Structural conditions that leads to photoluminescence emission in SrTiO3: An experimental and theoretical approach

Doping and temperature-dependent optical properties of oxygen-reducedBaTiO3−δ

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