Kumar, N and Rao, CNR (1997) The nature of charge ordering in rare earth manganates and its strong dependence on the size of the A-site cations. In: Journal of Solid State Chemistry, 129 (2). pp. 363-366.
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Charge ordering in rare earth manganates of the type Ln(0.5)A(0.5)MnO(3) (Ln = rare earth, A = alkaline earth) is highly sensitive to the average radius of the A-site cations, [r(A)]. Tn the small [r(A)] regime (e.g., Y0.5Ca0.5MnO3), charge ordering occurs in the paramagnetic state, the transformation to an antiferromagnetic state occurring at still lower temperatures. At moderate [r(A)] values (e.g., Nd0.5Sr0.5MnO3), a ferromagnetic metallic state transforms to a charge-ordered antiferromagnetic state with cooling. These two distinct types of charge ordering and associated properties are explained in terms of the variation of the exchange couplings J(FM) and J(AFM) with [r(A)] and the invariance of the single-ion Jahn-Teller energy with [r(A)]. A qualitative temperature-[r(A)] phase diagram, consistent with the experimental observations, has been constructed to describe the properties of the manganates in the different [r(A)] regimes. (C) 1997 Academic Press.
|Item Type:||Editorials/Short Communications|
|Additional Information:||Copyright of this article belongs to Elsevier Science.|
|Date Deposited:||22 Jun 2011 06:34|
|Last Modified:||22 Jun 2011 06:34|
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