High temperature transport properties of co-substituted Ca1−xLnxMn1−xNbxO3 (Ln = Yb, Lu; 0.02 ≤ x ≤ 0.08)
IR@NAL: CSIR-National Aerospace Laboratories, Bangalore
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| Title |
High temperature transport properties of co-substituted Ca1−xLnxMn1−xNbxO3 (Ln = Yb, Lu; 0.02 ≤ x ≤ 0.08)
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| Creator |
Nag, Abanti
Bose , Rapaka SC |
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| Subject |
Chemistry and Materials (General)
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| Description |
The co-substituted Ca1�xLnxMn1�xNbxO3 (Ln = Yb, Lu; 0.02 � x � 0.08) are synthesized by solid-state reaction and the electronic transport properties are investigated. Rietveld refinement confirms the formation of single phase orthorhombic structure with gradual increase of cell parameters with doping level. The electronic transport properties such as Seebeck coefficient and electrical resistivity decrease with increasing the dopant concentration for both the co-substituted compositions. All the compositions of Ca1�xLnxMn1�xNbxO3 show nonmetal-like temperature dependence of resistivity; whereas metal-like
temperature dependence of thermopower. This inconsistency is explained by the formation of oxygen vacancy associated defect centres that originates from partial reduction of Mn4+ to Mn3+ due to cosubstitution. The defect centres act as extrinsic carriers and cause additional contribution to the entropy of the system, leading to increase of Seebeck coefficient as a function of temperature. The transport
mechanism of charge carriers is explained in the framework of Mott’s small polaron hopping mechanism.
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| Publisher |
Elsevier
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| Date |
2016-02
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| Type |
Journal Article
PeerReviewed |
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| Format |
application/pdf
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| Identifier |
http://nal-ir.nal.res.in/12459/1/ja728POST.pdf
Nag, Abanti and Bose , Rapaka SC (2016) High temperature transport properties of co-substituted Ca1−xLnxMn1−xNbxO3 (Ln = Yb, Lu; 0.02 ≤ x ≤ 0.08). Materials Research Bulletin, 74 . pp. 41-49. ISSN 0025-5408 |
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| Relation |
http://dx.doi.org/10.1016/j.materresbull.2015.10.016
http://nal-ir.nal.res.in/12459/ |
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