Structure refinement, EPR, Specific magnetic heat and magnetic properties of ZnMnP2O7 diphosphate

Abstract

The structure of the diphosphate ZnMnP₂O₇ is determined on powder by the Rietveld method. It is of monoclinic symmetry C2/m. The cell parameters are: a = 6.6141(3) Å, b = 8.4366 (3) Å, c = 4.5305(2) Å and b= 103.948(2) °. The structural framework is built by MO₆ octahedron planes where M is a mixed site statistically occupied by Zn²⁺ and Mn²⁺ ions. These planes are parallel to the crystallographic plane (001) and are linked together by sheets of P₂O₇^4- groups.The value of the paramagnetic temperature Qp is -4 K, which proves that the interactions are antiferromagnetic . The magnetic specific heat of this compound has a symmetric maximum at T = 5.3 K less acute compared to that of Mn₂P₂O₇ of isotypic structure which is of ltype. This behavior change  can be explained by the interruption of three-dimensional interactions between Mn²⁺ ions which become limited to  2D order when 50% of these ions are replaced by Zn²⁺ ions.