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Journal of thermal analysis

, Volume 48, Issue 4, pp 819–834 | Cite as

Reactivity of oxalates of La(III), Ba(II) and Cu(II) in ternary mixtures

  • L. Bapat
  • G. N. Natu
  • M. Bhide
  • J. Kher
Article

Abstract

Composites of cuprates of La(III) and Ba(II) were obtained by decomposing mixtures of oxalates of La(III), Ba(II) and Cu(II) prepared in 1∶1∶1 and 1∶2∶3 mol proportions respectively and sintering the oxide products at 1173 K. Reactions studied by TG, DTA and XRD techniques revealed the following features: (i) Decomposition of oxalates of La(III) and Ba(II) is drastically affected in mixtures. Decomposition temperature of organic part in the former (1∶1∶1) is shifted by ∼100 K while that of BaCO3 in the case of latter (1∶2∶3) is shifted by ∼400 K towards lower temperature side. (ii) All exothermic peaks on DTA traces of both the mixtures are allotted to the decomposition of oxalates to Cu2O, La2O2CO3 and BaCO3 phases while endothermic peaks around 863 and 1083 K are assigned for BaCuO2 and La2CuO4 phases respectively in the case of former (1∶1∶1) and endothermic peaks at about 1068, 1136 and 1213 K are correlated with BaCuO2, a composite of La2O3, La2CuO4 and La0.5Ba0.5CuO3−δ (δ→0.5) phases and LaBa2Cu3O7−δ (δ→0) phase respectively in the case of latter (1∶2∶3) and (iii) Lines of all cuprate compounds appear in XRD patterns of those samples preheated at temperatures ≥873 K. The following reaction is proposed in the case of 1∶2∶3 mixture:

Keywords

composites of cuprates DTA mixture of oxalates TG XRD 

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Copyright information

© Wiley Heyden Ltd., Chichester and Akadémiai Kiadó, Budapest 1997

Authors and Affiliations

  • L. Bapat
    • 1
  • G. N. Natu
    • 2
  • M. Bhide
    • 1
  • J. Kher
    • 1
  1. 1.Department of ChemistryN. Wadia CollegePune
  2. 2.Department of ChemistryUniversity of PoonaPuneIndia

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