J. Phys. IV France 123 (2005) 241-244
Structural, luminescent and magnetic studies of Mn(HPO4).3H2OA. Larrañaga1, J.L. Mesa2, J.L. Pizarro1, R. Olazcuaga3, F. Guillen3, M.I. Arriortua1 and T. Rojo2
1 Departamento de Mineralogía-Petrología, Facultad de Ciencia y Tecnologia, Universidad del País Vasco, Apdo. 644, 48080 Bilbao, Spain
2 Departamento de Química Inorgánica, Facultad de Ciencia y Tecnologia, Universidad del País Vasco, 48080 Bilbao, Spain
3 Institut de Chimie de la Matière Condensée de Bordeaux, 33608 Pessac, France
The Mn(HPO4).3H2O compound has been synthesized from a mixture of manganese(II) chloride tetrahydrate, phosphoric acid and water at pH=6. The compound was characterized from X-ray powder diffraction data by means of the Rietveld method. Its crystal structure consists of layers constructed from isolated MnO6 octahedra linked by the PO4 tetrahedra anions giving rise to chains. The thermogravimetric study indicates that the compound is stable up to 100 C. The IR spectrum confirms the presence of hydrogenphosphate anion. The Dq and Racah parameters have been calculated from the luminescent spectra of the Mn(II) cations. The magnetic measurements indicate the presence of mainly antiferromagnetic interactions with a weak ferromagnetism intrinsic to the compound below 7.9 K.
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