X-ray absorption fine structure study of manganese compounds

Nanocrystalline manganese dihydrogen phosphate dihydrate Mn(H2PO4)2·2H2O and its decomposition product (Mn2P4O12) obtained by simple precipitation route

“…Additional, manganese phosphates are among the widest spread minerals in the class of phosphates [7,8]. Several manganese (III) phosphates such as MnP 3 O 9 [9], MnPO 4 ·H 2 O [10], MnPO 4 [11], MnHP 2 O 7 [12] and Mn 3 (PO 4 ) 3 [13] are known. Manganese in the oxidation states +2 is observed in MnP 4 O 11 [14], Mn 2 P 4 O 12 [15], Mn 2 P 2 O 7 [15], ␤-Mn 3 (PO 4 ) 2 [16] and Mn 2 P 2 O 7 ·2H 2 O [17], Mn(H 2 PO 4 ) 2 ·2H 2 O [18], etc.…”

“…·2H 2 O obtained from MnCO 3 -H 3 PO4 and Mn(c)-H 3 PO 4 system, respectively. The corresponding observed weight losses are 0.78,11.41, 8.84, 3.42% and 6.34, 5.14, 8.83, 2.99% by mass, which correspond to 0.13, 1.83, 1.41, 0.55 and 1.01, 0.82, 1.41, 0.49 mol of water for Mn(H 2 PO 4 ) 2 ·2H 2 O obtained from MnCO 3 -H 3 PO 4 and Mn(c)-H 3 PO 4 systems, respectively. The DTA curves of Mn(H 2 PO 4 ) 2 ·2H 2 O obtained from MnCO 3 -H 3 PO 4 and Mn(c)-H 3 PO 4 are slightly different in each temperature regions.…”

Preparation and structural characterization of ferromagneticMn5Si3CSürgers1, Gajdzik2, Fischer3 et al. 2003Phys. Rev. B320250View full textAdd to dashboardCite

“…A mixing of the of p-like and d-like states was also derived from calculations of the partial local densities of electron states. 17 The main absorption edge at A is different for the films compared to pure Mn as expected due to the different electronic structure. This edge is caused by transitions from the 1s state into the continuum of p-like states in the conduction band.…”

“…This would cause the presence of two Mn II 2ϩ and four Mn II 3ϩ ions surrounding each C Ϫ4 ion in Mn 5 Si 3 C x and could lead to a double exchange stabilizing ferromagnetic order similar to the colossal magnetoresistance alloys. 2 [17][18][19] In general, with increasing oxidation state of Mn the K edge shifts by about 3-5 eV/ valence to higher energies. For the Mn 5 Si 3 C 0.75 films an average valence change of 0.3 would shift the Mn K edge by 0.9-1.5 eV, which should be easily observable in the spectra.…”

“…X-ray-absorption spectroscopy Figure 8 shows the x-ray absorption, i.e., fluorescence yield, normalized to the intensity well above the discontinuity vs photon energy E. The preedge at a, originating from electronic transitions from the 1s core level into the d states of the conduction band, is preserved for all samples in agreement with previous near-edge data of several Mn compounds. 17 Although these transitions are forbidden by dipole selection rules, the states are accessible due to s-p-d hybridization. A mixing of the of p-like and d-like states was also derived from calculations of the partial local densities of electron states.…”