Crystal chemistry, single crystal X-ray structure and magnetism of nickel manganese pyrophosphate

A study of the crystal chemistry of the Ni2 − xMnxP2O7 systems in powder form, 0 ≤ x ≤ 2, has revealed the existence of three solid solutions. When x < 0.10, the solution is isostructural with low temperature form, α-Ni2P2O7. When 0.10 ≤ x ≤ 0.40, the structure of the solid solution is similar to that of σ-Ni2P2O7. When 0.60 ≤ x ≤ 2, a form similar to β-Ni2P2O7 (or Mn2P2O7) is seen. The single crystal structure of material corresponding to x = 0.816 has been determined in monoclinic space group Cm, a = 6.557(3), b = 8.738(5), c = 4.498(3), β = 103.24(1) °, V = 240.6(2)Å3, Z = 2, RRw = 3.85.3% and shows a structural deformation of the parent lattice. The system shows antiferromagnetic interactions at low temperature.