Verwey-type transition within the Pb3Rh7−xMnxO15 solid solution

A complete solid solution was found between isostructural Pb₃Mn₇O₁₅ and Pb₃Rh₇O₁₅. Single-crystals of two members of the solid solution Pb₃Rh_7−xMn_xO₁₅ (x=1.07 and 2.26) were grown and their crystal structures were determined. The Verwey-type transition for Pb₃Rh₇O₁₅ at 185 K remains with a 3% substitution of Mn for Rh but disappears with 4% substitution of Mn for Rh. The magnetic ordering temperature found for Pb₃Mn₇O₁₅ at about 70 K is maintained at a 43% substitution of Rh for Mn but has disappeared for 57% substitution of Rh for Mn. The unit cell volume of this layered structure contracts with increasing x for Pb₃Rh_7−xMn_xO₁₅ phases, but the structure actually expands in the direction perpendicular to the layers due to increased separation between the layers.