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Effect of the sintering temperature on the properties of nanocrystalline Ca1−x Sm x MnO3 (0≤ x ≤0.4) powders

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Title: Effect of the sintering temperature on the properties of nanocrystalline Ca1−x Sm x MnO3 (0≤ x ≤0.4) powders
Authors: Matos, I.1, Sério, S.2, Lopes, M.E.3, Nunes, M.R.4, Jorge, M.E. Melo4 mdjorge@fc.ul.pt
Source: Journal of Alloys & Compounds. Oct2011, Vol. 509 Issue 40, p9617-9626. 10p.
Subjects: Sintering, Temperature effect, Nanocrystals, Annealing of metals, Crystal growth, Phase transitions, Semiconductors, Chemical bonds, Rietveld refinement, Electric properties of metals
Abstract: Abstract: Nanocrystalline Ca1−x Sm x MnO3 (0≤ x ≤0.4) manganites were prepared by a soft chemical method (Pechini method) followed by auto-combustion and sintering in air at 1073 or 1473K. Single-phase powders with general composition Ca1−x Sm x MnO3 were obtained after 18h annealing. The particle and grain sizes of the substituted Sm-manganites did not exhibit variation with samarium content, but increase with increasing the sintering temperature. All manganites show two active IR vibrational modes near 400 and 600cm−1 characteristic of the BO6 octahedron vibrations. For the samples sintered at T s =1473K, the partial substitution of calcium by samarium in the CaMnO3 phase induces a marked decrease in the electrical resistivity, in the temperature range of 300–900K, and at the same time a metal-to-insulator transition occurs; for T s =1073K all the samples present semiconductor behaviour. With the increase of the annealing temperature the grain size increases and a metal–semiconductor transition appears. The results can be ascribed to the Mn4+/Mn3+ ratio and particle grain size. The effects of particle size on the electrical properties can be attributed to the domain status, changes in the Mn–O–Mn bond angle and Mn–O bond length. [Copyright &y& Elsevier]
Copyright of Journal of Alloys & Compounds is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database: Engineering Source
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Header DbId: egs
DbLabel: Engineering Source
An: 65226282
AccessLevel: 6
PubType: Academic Journal
PubTypeId: academicJournal
PreciseRelevancyScore: 0
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  Data: Effect of the sintering temperature on the properties of nanocrystalline Ca<subscript>1−x </subscript>Sm<subscript> x </subscript>MnO<subscript>3</subscript> (0≤ x ≤0.4) powders
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  Data: <searchLink fieldCode="AR" term="%22Matos%2C+I%2E%22">Matos, I.</searchLink><relatesTo>1</relatesTo><br /><searchLink fieldCode="AR" term="%22Sério%2C+S%2E%22">Sério, S.</searchLink><relatesTo>2</relatesTo><br /><searchLink fieldCode="AR" term="%22Lopes%2C+M%2EE%2E%22">Lopes, M.E.</searchLink><relatesTo>3</relatesTo><br /><searchLink fieldCode="AR" term="%22Nunes%2C+M%2ER%2E%22">Nunes, M.R.</searchLink><relatesTo>4</relatesTo><br /><searchLink fieldCode="AR" term="%22Jorge%2C+M%2EE%2E+Melo%22">Jorge, M.E. Melo</searchLink><relatesTo>4</relatesTo><i> mdjorge@fc.ul.pt</i>
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  Data: <searchLink fieldCode="JN" term="%22Journal+of+Alloys+%26+Compounds%22">Journal of Alloys & Compounds</searchLink>. Oct2011, Vol. 509 Issue 40, p9617-9626. 10p.
– Name: Subject
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  Data: <searchLink fieldCode="DE" term="%22Sintering%22">Sintering</searchLink><br /><searchLink fieldCode="DE" term="%22Temperature+effect%22">Temperature effect</searchLink><br /><searchLink fieldCode="DE" term="%22Nanocrystals%22">Nanocrystals</searchLink><br /><searchLink fieldCode="DE" term="%22Annealing+of+metals%22">Annealing of metals</searchLink><br /><searchLink fieldCode="DE" term="%22Crystal+growth%22">Crystal growth</searchLink><br /><searchLink fieldCode="DE" term="%22Phase+transitions%22">Phase transitions</searchLink><br /><searchLink fieldCode="DE" term="%22Semiconductors%22">Semiconductors</searchLink><br /><searchLink fieldCode="DE" term="%22Chemical+bonds%22">Chemical bonds</searchLink><br /><searchLink fieldCode="DE" term="%22Rietveld+refinement%22">Rietveld refinement</searchLink><br /><searchLink fieldCode="DE" term="%22Electric+properties+of+metals%22">Electric properties of metals</searchLink>
– Name: Abstract
  Label: Abstract
  Group: Ab
  Data: Abstract: Nanocrystalline Ca1−x Sm x MnO3 (0≤ x ≤0.4) manganites were prepared by a soft chemical method (Pechini method) followed by auto-combustion and sintering in air at 1073 or 1473K. Single-phase powders with general composition Ca1−x Sm x MnO3 were obtained after 18h annealing. The particle and grain sizes of the substituted Sm-manganites did not exhibit variation with samarium content, but increase with increasing the sintering temperature. All manganites show two active IR vibrational modes near 400 and 600cm−1 characteristic of the BO6 octahedron vibrations. For the samples sintered at T s =1473K, the partial substitution of calcium by samarium in the CaMnO3 phase induces a marked decrease in the electrical resistivity, in the temperature range of 300–900K, and at the same time a metal-to-insulator transition occurs; for T s =1073K all the samples present semiconductor behaviour. With the increase of the annealing temperature the grain size increases and a metal–semiconductor transition appears. The results can be ascribed to the Mn4+/Mn3+ ratio and particle grain size. The effects of particle size on the electrical properties can be attributed to the domain status, changes in the Mn–O–Mn bond angle and Mn–O bond length. [Copyright &y& Elsevier]
– Name: AbstractSuppliedCopyright
  Label:
  Group: Ab
  Data: <i>Copyright of Journal of Alloys & Compounds is the property of Elsevier B.V. and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract.</i> (Copyright applies to all Abstracts.)
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RecordInfo BibRecord:
  BibEntity:
    Identifiers:
      – Type: doi
        Value: 10.1016/j.jallcom.2011.07.032
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      – Code: eng
        Text: English
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      Pagination:
        PageCount: 10
        StartPage: 9617
    Subjects:
      – SubjectFull: Sintering
        Type: general
      – SubjectFull: Temperature effect
        Type: general
      – SubjectFull: Nanocrystals
        Type: general
      – SubjectFull: Annealing of metals
        Type: general
      – SubjectFull: Crystal growth
        Type: general
      – SubjectFull: Phase transitions
        Type: general
      – SubjectFull: Semiconductors
        Type: general
      – SubjectFull: Chemical bonds
        Type: general
      – SubjectFull: Rietveld refinement
        Type: general
      – SubjectFull: Electric properties of metals
        Type: general
    Titles:
      – TitleFull: Effect of the sintering temperature on the properties of nanocrystalline Ca1−x Sm x MnO3 (0≤ x ≤0.4) powders
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            NameFull: Matos, I.
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            NameFull: Sério, S.
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            NameFull: Lopes, M.E.
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            NameFull: Jorge, M.E. Melo
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            – D: 06
              M: 10
              Text: Oct2011
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              Y: 2011
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              Value: 509
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