MAGNETIC-STRUCTURES OF THE 1D-ANTIFERROMAGNETIC FLUORIDES RB2MNF5 ANDRB2MNF5-CENTER-DOT-H2O

Magnetic structures of the chain-based pentafluoromanganates(III) Rb2M nF5 . H2O and Rb2MnF5 have been determined by means of neutron powder diffraction, Both compounds exhibit 3D antiferromagnetic order below T -N = 22.0(2) K and T-N = 26.0(5) K, respectively, Their identical magn etic structures are characterized by antiferromagnetic infinite chains of trans-corner connected octahedra [MnF4F2/2], with antiferromagneti c ordering between the closest chains, The magnetic moment modulus on the Jahn-Teller Mn3+ ion has been found to be 3.14(14) mu(B) and 3.30( 10) mu(B), for the hydrate and anhydrous compounds, respectively. Thes e relatively low values can be explained by a zero-spin reduction in a ntiferromagnetic low dimensional systems. The results are discussed in terms of relationships between structural and magnetic properties and compared with those obtained for others pentafluoromanganates (III). (C) 1996 Academic Press, Inc.