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Localized versus collective behaviour of d-electrons in transition metal oxide systems of perovskite systems

Journal Article:

Abstract

The behavior of d-electrons in perovskites of the type LnZO/sub 3/ (Z = trivalent transition metal ion and Ln = rare earth or yttrium) depends on the spin configuration of the transition metal ion. LaTiO/sub 3/ and LaNiO/sub 3/ with low-spin transition metal ions (S = 1/2) are metallic while LaCrO/sub 3/, LnMnO/sub 3/ and LnFeO/sub 3/ with high-spin ions are poor semiconductors exhibiting localized behavior of d-electrons. In rare earth cobaltites, the cobalt ions are present mainly in the diamagnetic low-spin Co /sup III/ state at low temperatures. The Co/sup III/ ions transform to high-spin Co/sup 3 +/ ions with increase in temperature. At higher temperatures, there is electron-transfer from Co/sup 3 +/ to Co/sup III/ions producing intermetallic states. Spin-state transitions are seen in these cobaltites in the range 150-870/sup 0/K. At high temperatures, the cobaltites show evidence for localized-itinerant electron transitions. In La/sub 1-x/ Sr/sub x/CoO/sub 3/ there is onset of ferromagnetism at x > 0.125, at which point there is a structural dicontinuity and electrons become itinerant. The composition with x = 0.5 is metallic and T/sub c/ = 230/sup 0/K. The ferromagnetic component in La/sub 1-x/Sr/sub x/ CoO/sub 3/ increases with x in the range 0.125-0.50.  More>>
Authors:
Rao, C N.R. [1] 
  1. Indian Inst. of Tech., Kanpur
Publication Date:
Dec 01, 1974
Product Type:
Journal Article
Reference Number:
EDB-76-036944
Resource Relation:
Journal Name: J. Indian Chem. Soc.; (India); Journal Volume: 51:12; Other Information: 26 refs., 11 figs
Subject:
37 INORGANIC, ORGANIC, PHYSICAL AND ANALYTICAL CHEMISTRY; GADOLINIUM COMPOUNDS; ELECTRONIC STRUCTURE; LANTHANUM COMPOUNDS; NEODYMIUM COMPOUNDS; ELECTRON TRANSFER; ELECTRONS; FERROMAGNETISM; MAGNETISM; MOESSBAUER EFFECT; OXIDES; PEROVSKITE; SPIN; TRANSITION ELEMENT COMPOUNDS; ALKALINE EARTH METAL COMPOUNDS; ANGULAR MOMENTUM; CALCIUM COMPOUNDS; CALCIUM OXIDES; CHALCOGENIDES; ELEMENTARY PARTICLES; FERMIONS; LEPTONS; MINERALS; OXYGEN COMPOUNDS; PARTICLE PROPERTIES; PEROVSKITES; RARE EARTH COMPOUNDS; TITANIUM COMPOUNDS; TITANIUM OXIDES; 400201* - Chemical & Physicochemical Properties
OSTI ID:
7366340
Country of Origin:
India
Language:
English
Other Identifying Numbers:
Journal ID: CODEN: JICSA
Submitting Site:
INIS
Size:
Pages: 979-987
Announcement Date:

Journal Article:

Citation Formats

Rao, C N.R. Localized versus collective behaviour of d-electrons in transition metal oxide systems of perovskite systems. India: N. p., 1974. Web.
Rao, C N.R. Localized versus collective behaviour of d-electrons in transition metal oxide systems of perovskite systems. India.
Rao, C N.R. 1974. "Localized versus collective behaviour of d-electrons in transition metal oxide systems of perovskite systems." India.
@misc{etde_7366340,
title = {Localized versus collective behaviour of d-electrons in transition metal oxide systems of perovskite systems}
author = {Rao, C N.R.}
abstractNote = {The behavior of d-electrons in perovskites of the type LnZO/sub 3/ (Z = trivalent transition metal ion and Ln = rare earth or yttrium) depends on the spin configuration of the transition metal ion. LaTiO/sub 3/ and LaNiO/sub 3/ with low-spin transition metal ions (S = 1/2) are metallic while LaCrO/sub 3/, LnMnO/sub 3/ and LnFeO/sub 3/ with high-spin ions are poor semiconductors exhibiting localized behavior of d-electrons. In rare earth cobaltites, the cobalt ions are present mainly in the diamagnetic low-spin Co /sup III/ state at low temperatures. The Co/sup III/ ions transform to high-spin Co/sup 3 +/ ions with increase in temperature. At higher temperatures, there is electron-transfer from Co/sup 3 +/ to Co/sup III/ions producing intermetallic states. Spin-state transitions are seen in these cobaltites in the range 150-870/sup 0/K. At high temperatures, the cobaltites show evidence for localized-itinerant electron transitions. In La/sub 1-x/ Sr/sub x/CoO/sub 3/ there is onset of ferromagnetism at x > 0.125, at which point there is a structural dicontinuity and electrons become itinerant. The composition with x = 0.5 is metallic and T/sub c/ = 230/sup 0/K. The ferromagnetic component in La/sub 1-x/Sr/sub x/ CoO/sub 3/ increases with x in the range 0.125-0.50. Catalytic properties of rare earth cobaltites appear to be related to the spin state equilibria. (auth)}
journal = {J. Indian Chem. Soc.; (India)}
volume = {51:12}
journal type = {AC}
place = {India}
year = {1974}
month = {Dec}
}