WEAK FERROMAGNETISM AND FRAMEWORK SWITCHING IN KMnHP3O10

摘要

Polycrystalline KMnHP3O10 has been prepared from solution. It adopts a triclinically distorted variant of the RbMnHP3O10 structure and an approximate structure refinement has been obtained from powder neutron diffraction data (space group P1, a=7.102(2), b=7.234(1), c=9.109(2) angstroms, alpha=72.176(8), beta=73.762(9), gamma=70.642(12) degrees at 2 K). A magnetic ordering transition is observed at 15 K, below which KMnHP3O10 displays weak ferromagnetism with a net moment of approx 0.3 mu B per Mn ion showing that the true structural symmetry may be P1. The magnetic structure has an ax2bx2c supercell and is more complex than that of the Rb and Cs analogues, due to a switching of the Jahn-Teller distortions of the MnO6 octahedra. 13 refs.