Electrical transport in light rare-earth orthochromites

Tripathi, A.K.; Lal, H. B.

doi:10.1007/bf00540784

Cited by 67 publications

(39 citation statements)

References 23 publications

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“…The activation energies estimated from the Arrhenius plots in accordance to the relation r dc T ð Þ ¼ A exp ÀE a =k BT ð Þ were 0.278, 0.258, 0.202, 0.220, and 0.223 eV for x(Co) = 0, 0.33, 0.5, 0.67 and 1, respectively and are in good agreement with the literature. 15,42 Activation energy also showed decreasing dependence with the increasing amount of cobalt in the structures, showing the lowest value for x = 0.5. According to the study of Subba Rao, 42 the energy bands associated with rare earth ions are not relevant to the electrical conduction in RCrO 3 .…”

Section: 41mentioning

confidence: 93%

“…15 Since the electrical conduction is directly connected to the energy bands of the B-cation in the structure, the changes in the conductivity are directly connected to the cobalt content. The explanation could be found in the electronic configuration of the two cations in the B-site, i.e., replacing of Cr 3+ (t 2g 3 e g 0 ) with Co 3+ (t 2g 6 e g 0 in low-spin state, S = 0).…”

Section: 41mentioning

confidence: 99%

“…[8][9][10] For GdCoO 3 , it was found to be a semiconductor at room temperature and that it undergoes semiconductor-tometal transition at 860 K. 11 The rare earth chromites are also interesting because of their relatively high electrical conductivity, resistance to oxidation, high melting points 12 and multiferroic properties observed in some chromites. 13,14 Moreover, GdCrO 3 , was reported to behave as a semiconductor in the temperature range of 300-1000 K. 15 However, there are limited data on perovskites containing both Co 3+ and Cr 3+ ions in B-position. Recently, we have reported on the electric properties of YCr 0.5 Co 0.5 O 3 .…”

Section: Introductionmentioning

confidence: 99%

“…It shows the presence of the grain boundaries which affect the electrical behavior of the structures. 15 The porosity of the pellets was calculated from the theoretical crystallographic 36 and the experimental density of the pellets and is in interval between 38% and 42%. The porosity slightly increases with increasing cobalt amount in perovskite structures (Table I).…”

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confidence: 99%

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Impedance and AC Conductivity of GdCr_1−xCo_xO₃ (x = 0, 0.33, 0.5, 0.67 and 1) Perovskites

et al. 2014

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Perovskite series GdCr 1 -x Co x O 3 (x = 0, 0.33, 0.5, 0.67 and 1) was obtained using a solution combustion method. The powder XRD was used for identification and structural characterization of the obtained perovskites. All compounds crystallize within the space group Pnma. The morphology of samples was studied using SEM. The impedance and AC conductivity of GdCr 1 -x Co x O 3 were studied using impedance spectroscopy in a frequency range from 10 Hz to 10 MHz and in temperature interval 297-337 K. Changes in electric modulus and DC conductivity, with increasing of the value of x in the structures, were observed. The AC conductivity obeyed the universal power law, r(x) = r(0) + Ax n and revealed semiconductor behavior. The calculated activation energies of existing processes varied with the cobalt content and applied frequency. The impedance spectra showed non-Debye behavior with a distribution of relaxation times for relaxation and conductive processes. The conduction mechanism for pure orthochromite and orthocobaltite was defined and two types of conduction were observed in the investigated temperature range for the complex perovskites. In order to explain the results, an equivalent circuit with fitted values of circuit components was proposed.

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Section: 41mentioning

confidence: 93%

Section: 41mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Impedance and AC Conductivity of GdCr_1−xCo_xO₃ (x = 0, 0.33, 0.5, 0.67 and 1) Perovskites

et al. 2014

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“…The substitution of the divalent alkaline arth metal ion for the trivalent lanthanum ion must lead either to an increase of the average valence state of the Cr ion or to a decrease of the content of O atoms in lanthanaum chromite to make the compound neutral. The conduction mechanism in lanthanum chromite is considered to have involved the Cr 4 ion [4]. Two different formulas have been suggested to describe the relationship between the electrical conductivity and the relative content of Cr 3 or Cr 4 ions in doped lanthanum chromite [4,5].…”

Section: Introductionmentioning

confidence: 99%

Valence State of the Chromium Ion and Electrical Conductivity of Ca-Doped Lanthanum Chromite

Zhang

Jia

1999

phys. stat. sol. (b)

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The valence state of the Cr ion in Ca‐doped lanthanum chromite compounds without or with oxygen deficiency has been calculated by means of a tight‐binding approximation on the basis of the EHMO approximation. The results indicate that the relative content of Cr4+ ions in La1—xCaxCrO3 will become larger with increasing x and the electrical conductivity is in proportion with the relative content of Cr4+ ions in the compound. The difference between some reported experimental results in the same compounds is mainly due to the different oxygen deficiency in the samples. Doping can lead not only to a splitting of the t2g and eg subbands from the Cr atom and a narrowing of the gap between the t2g subband from the Cr atom and 2p band from the O atom, but also leads to an increase of the relative content of the acceptor of Cr4+ ions and to an increasing number of holes in the band. A linear relationship between the elecrtrical conductivity and the relative Cr4+ ion content may be valid only for lanthanum chromite with a small amount of Ca.

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Calculation of chemical bond parameters in La1?xCaxCrO3 (0.0?x?0.3)

Zhang

1999

Int. J. Quant. Chem.

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ABSTRACT:The chemical bond parameters, that is, bond covalency, bond Ž susceptibility, and macroscopic linear susceptibility of La Ca CrO x s 0.0, 0.1, 0.2, 1yx x 3 . 0.3 has been calculated using a semiempirical method. This method is the generalization of the dielectric description theory proposed by Phillips, Van Vechten, Levine, and Ž . Tanaka PVLT . In the calculation of bond valence, two schemes were adopted. One is the Ž . bond valence sums BVS scheme, and the other is the equal-valence scheme. Both schemes suggest that for the title compounds bond covalency and bond susceptibility are mainly influenced by bond valence and are insensitive to the Ca doping level or structural change. Larger bond valences usually result in higher bond covalency and Ž bond susceptibility. The macroscopic linear susceptibility increases only slightly for BVS . scheme with the increasing Ca doping level.

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Electrical transport in light rare-earth orthochromites

Cited by 67 publications

References 23 publications

Impedance and AC Conductivity of GdCr_1−xCo_xO₃ (x = 0, 0.33, 0.5, 0.67 and 1) Perovskites

Impedance and AC Conductivity of GdCr_1−xCo_xO₃ (x = 0, 0.33, 0.5, 0.67 and 1) Perovskites

Valence State of the Chromium Ion and Electrical Conductivity of Ca-Doped Lanthanum Chromite

Calculation of chemical bond parameters in La1?xCaxCrO3 (0.0?x?0.3)

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Electrical transport in light rare-earth orthochromites

Cited by 67 publications

References 23 publications

Impedance and AC Conductivity of GdCr1−xCoxO3 (x = 0, 0.33, 0.5, 0.67 and 1) Perovskites

Impedance and AC Conductivity of GdCr1−xCoxO3 (x = 0, 0.33, 0.5, 0.67 and 1) Perovskites

Valence State of the Chromium Ion and Electrical Conductivity of Ca-Doped Lanthanum Chromite

Calculation of chemical bond parameters in La1?xCaxCrO3 (0.0?x?0.3)

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Impedance and AC Conductivity of GdCr_1−xCo_xO₃ (x = 0, 0.33, 0.5, 0.67 and 1) Perovskites

Impedance and AC Conductivity of GdCr_1−xCo_xO₃ (x = 0, 0.33, 0.5, 0.67 and 1) Perovskites