Abstract
Solid solutions Nd2MnMn(Mn4−xSbx)O12, belonging to the A-site columnar-ordered quadruple perovskite subfamily A2A′A″B4O12 and prepared by a high-pressure, high-temperature method at about 6 GPa and about 1700 K, were investigated in a compositional range of 0.2 ≤ x ≤ 2.0. Crystal structures were studied using synchrotron powder X-ray diffraction. Two regions with different cation orders in the B sublattice were found: a narrow region of 0.8 ≤ x ≤ 1.0 had a B-site disordered structure with space group P42/nmc (No. 137), and a wider region of 1.6 ≤ x ≤ 2.0 had a B-site rock-salt-ordered structure with space group P42/n (No. 86). Small anti-site disorder of Nd and Mn was detected among the A, A′, and A″ sites. In the B-site rock-salt-ordered structures, one B site was solely occupied by Mn, the second B′ site had a mixture of Sb and Mn (for x < 2). The samples showed complex magnetic behavior with two ferrimagnetic transitions. TC1 monotonically increased (from 66 K to 75 K) and TC2 was almost constant (about 6–7 K) for 0.8 ≤ x ≤ 1.0. TC1 monotonically decreased (from 77 K to 63 K) and TC2 monotonically increased (from 19 K to 39 K) for 1.6 ≤ x ≤ 2.0. There was evidence for the third magnetic transition in the 1.7 ≤ x ≤ 2.0 samples, and TC3 increased from 13 K to 20 K with increasing x.
Published Version
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