Effects of the A-site cation number on the properties of Ln5/8M3/8MnO3 manganites

The properties of manganites can be tuned by changing the doping level x in Ln(1-x)M(x)MnO(3). A second mechanism allows tuning of magnetic and electronic properties, for fixed x values, by varying the average A-cation radius, < r(A)>. Moreover, for fixed x and <r(A)> values, the changes in the A-cation size variance, e, also modify the ferromagnetic and metal-insulator-transition temperatures. Here, we investigate the influence of the number of A-site cations on Ln(5/8)M(3/8)MnO(3) manganites, where x, < r(A) > and sigma(2) values are kept constant, and in the absence of phase separation phenomena. We have found that the number of cation species at the A site (N-A) has a strong influence on the width of the ferromagnetic and metal-insulator transitions, and a small influence on the average transition temperature. This behavior is opposite to that observed for increasing values of the variance sigma(2) in manganites, with the same x and <r(A)> values, where average transition temperatures are strongly reduced. (C)2010 Elsevier Inc. All rights reserved.