| Autor: |
Escobal, Jaione, L. Mesa, José, L. Pizarro, José, Lezama, Luis, Olazcuaga, Roger, Rojo, Teófilo |
| Zdroj: |
Journal of Materials Chemistry; October 1999, Vol. 9 Issue: 10 p2691-2695, 5p |
| Abstrakt: |
Ba(MnPO4)2·H2O has been prepared by hydrothermal synthesis and characterized by spectroscopic and magnetic techniques. Its crystal structure has been solved from X-ray powder diffraction data by using direct methods and refined with the Rietveld method. The compound crystallizes in the monoclinic system in the C2 space group with unit cell parameters, a = 9.457(1), b = 4.984(1), c = 8.346(1) Å and β = 92.07(1)°. The structure consists of a two-dimensional network of MnO6 octahedra, linked by phosphate anions and water molecules, which form chains along the |010| direction. The luminescence properties of Mn(II) in the compound are studied and the values of Dq and Racah parameters B and C have been calculated. The EPR spectra recorded on a polycrystalline sample at different temperatures show isotropic signals with g-values of 2.0. The intensity of the EPR signals increases with decreasing temperature down to 45 4;K and at lower temperatures rapidly decreases. Magnetic measurements show the presence of antiferromagnetic interactions. An analysis of the magnetic behaviour was carried out considering a theoretical model for antiferromagnetic chains with spin S = 5/2. Similar values for the J-exchange parameter inside the chains (J/k = –2.0 4;K) and for the J′-exchange parameter between neighbouring chains (zJ′/k = –2.0 4;K) are observed. These results suggest that the compound can be considered as a non-regular two-dimensional magnetic system. |
| Databáze: |
Supplemental Index |
| Externí odkaz: |
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