Optical properties of the <i>d</i>-band perovskites

Wolfram, T.; Ellialtıoğlu, Şinasi

doi:10.1017/cbo9780511541292.008

Cited by 38 publications

(53 citation statements)

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“…25 Hence, the band width of the r-band is substantially larger than that of p -band; therefore, one can consider that only the e g electrons are able to move close to the Fermi level. Consequently, for a number of perovskites, the t 2g states are localized while the e g states form r-conduction bands; 26 LaNiO 3 with filled t 2g states and a single electron in the e g band is an example. 12 So in case of LaCo(Ni)O 3 , the conduction band is also made up of e g electrons of Ni and Co ions, as has been described for similar system.…”

Section: B Electrical Resistivitymentioning

confidence: 99%

Electronic structure and electrical transport properties of LaCo1−xNixO3 (0 ≤ x ≤0.5)

Kumar

Shukla

et al. 2013

Journal of Applied Physics

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The structural analysis of LaCo1−xNixO3 (0 ≤ x ≤ 0.5) samples assures single phase rhombohedral structure with space-group R3¯c. Electronic structure of these samples has been studied by x-ray absorption near edge spectroscopy (XANES) at K-edge of O, Ni, Co and M5,4 edge of La. These studies confirm the trivalent state of Co/Ni and La in all the compositions. Upon substitution of the Ni at the Co site in LaCoO3, the O K-edge spectra show a feature about 1.2 eV lower than that of LaCoO3. This feature keeps on growing as the concentration of the Ni is increasing. This is consistent with our resistivity data which shows drastic decrease in resistivity with the Ni substitution. The resistivity data have been analyzed using Arrhenius and Efros-Shklovski's type variable range hopping models in different temperature ranges. The activation energy decreases and localization length increases systematically with increase in the Ni concentration. Observed features have been explained on the basis of change in charge-carrier density with substitution. The disorder-induced localization of carriers is found to govern conduction mechanism and resistivity behavior in substituted sample.

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Section: B Electrical Resistivitymentioning

confidence: 99%

Electronic structure and electrical transport properties of LaCo1−xNixO3 (0 ≤ x ≤0.5)

Kumar

Shukla

et al. 2013

Journal of Applied Physics

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“…19 Hence the p-d hybridization is crucial in describing the observed magnetism in the above systems. [20][21][22][23][24][25] The common feature for dilute magnetic semiconductors and defect based magnetism in oxide materials is the density of charge carriers.…”

Section: Introductionmentioning

confidence: 99%

Magnetic and nonlinear optical properties of BaTiO3 nanoparticles

et al. 2015

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In our earlier studies the BaTiO3 samples were processed at higher temperatures like 1000oC and explained the observed magnetism in it. It is found that the charge transfer effects are playing crucial role in explaining the observed ferromagnetism in it. In the present work the samples were processed at lower temperatures like 650oC-800oC. The carrier densities in these particles were estimated to be ∼ 1019-1020/cm3 range. The band gap is in the range of 2.53eV to 3.2eV. It is observed that magnetization increased with band gap narrowing. The higher band gap narrowed particles exhibited increased magnetization with a higher carrier density of 1.23×1020/cm3 near to the Mott critical density. This hint the exchange interactions between the carriers play a dominant role in deciding the magnetic properties of these particles. The increase in charge carrier density in this undoped BaTiO3 is because of oxygen defects only. The oxygen vacancy will introduce electrons in the system and hence more charge carriers means more oxygen defects in the system and increases the exchange interactions between Ti3+, Ti4+, hence high magnetic moment. The coercivity is increased from 23 nm to 31 nm and then decreased again for higher particle size of 54 nm. These particles do not show photoluminescence property and hence it hints the absence of uniformly distributed distorted [TiO5]-[TiO6] clusters formation and charge transfer between them. Whereas these charge transfer effects are vital in explaining the observed magnetism in high temperature processed samples. Thus the variation of magnetic properties like magnetization, coercivity with band gap narrowing, particle size and charge carrier density reveals the super paramagnetic nature of BaTiO3 nanoparticles. The nonlinear optical coefficients extracted from Z-scan studies suggest that these are potential candidates for optical imaging and signal processing applications.

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“…Polar solids crystallizing in a perovskite structure have received much interest because of their particular structural and electronic properties [1][2][3][4][5]. Electronic and/or spin correlations in such materials give rise to charge ordering, ferroelectricity, superconductivity, ferromagnetism and other phenomena.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast structural dynamics of perovskite superlattices

et al. 2009

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Femtosecond x-ray diffraction provides direct insight into the ultrafast reversible lattice dynamics of materials with a perovskite structure. Superlattice (SL) structures consisting of a sequence of nanometer-thick layer pairs allow for optically inducing a tailored stress profile that drives the lattice motions and for limiting the influence of strain propagation on the observed dynamics. We demonstrate this concept in a series of diffraction experiments with femtosecond time resolution, giving detailed information on the ultrafast lattice dynamics of ferroelectric and ferromagnetic superlattices. Anharmonically coupled lattice motions in a SrRuO 3 /PbZr 0.2 Ti 0.8 O 3 (SRO/PZT) SL lead to a switch-off of the electric polarizations on a time scale of the order of 1 ps. Ultrafast magnetostriction of photoexcited SRO layers is demonstrated in a SRO/SrTiO 3 (STO) SL.

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Optical properties of the d-band perovskites

Cited by 38 publications

References 0 publications

Electronic structure and electrical transport properties of LaCo1−xNixO3 (0 ≤ x ≤0.5)

Electronic structure and electrical transport properties of LaCo1−xNixO3 (0 ≤ x ≤0.5)

Magnetic and nonlinear optical properties of BaTiO3 nanoparticles

Ultrafast structural dynamics of perovskite superlattices

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