Mild hydrothermal synthesis, isomorphous substitution, crystal structure characterization and magnetic properties of BaMP2O7 (M = Mn, Cu)

Abstract At mild hydrothermal conditions triclinic modifications of BaMP 2 O 7 (M = Mn and/or Cu) have been succeeded. The method offers cheap, one step, impurity free and chemical flexible fabrication of family of metal phosphates that are potential low-dimensional quantum magnets. Partial isomorphous substitution of the Mn 2+ by Cu 2+ resulted into mixed-metal solid that has been structurally and magnetically characterized. Rietveld refinement study confirmed the structures and revealed the influence of transition metal substitution. The temperature-dependent magnetic measurements revealed that the system is paramagnetic in almost all temperature range and an apparent antiferromagnetic phase transition occurs around 5 K. Using the Curie–Weiss law, a Curie–Weiss temperature, θ P  = −11.0 K, and a Curie constant C  = 3.39 emu K mol −1 was obtained. The small negative θ P value and the χT behavior as a function of temperature reveal a weak antiferromagnetic interaction between the Cu 2+ /Mn 2+ magnetic centers.