On the synthesis, characterization and magnetic properties of two new phases discovered in the PbO-Fe2O3-P2O5 system
Language
en
Article de revue
This item was published in
Journal of Solid State Chemistry. 2013, vol. 202, p. 85-92
Elsevier
English Abstract
The PbFe3O(PO4)3 powder compound was studied by means of X-ray diffraction (XRD) from 300 to 6 K, electron-probe microanalysis (EPMA) coupled with wavelength dispersion spectroscopy (WDS), calorimetric (DSC and specific ...Read more >
The PbFe3O(PO4)3 powder compound was studied by means of X-ray diffraction (XRD) from 300 to 6 K, electron-probe microanalysis (EPMA) coupled with wavelength dispersion spectroscopy (WDS), calorimetric (DSC and specific heat) and magnetic properties measurements. Magnetization, magnetic susceptibility and specific heat measurements carried out on PbFe3O(PO4)3 powders firmly establish a series of three ferromagnetic (FM)-like second order phase transitions spanned over the 32-8 K temperature range. Discrepancies between magnetization and specific heat data obtained in PbFe3O(PO4)3 powders and single crystals are highlighted. A first extraction of the critical exponents (β,γ,δ) was performed by ac magnetic susceptibility in both PbFe3O(PO4)3 powders and single crystals and the values were found to be consistent with mean-field theory. Further exploration of the PbO-Fe2O3-P2O5 system led to the discovery of a new langbeinite phase, Pb1.5Fe2(PO4)3, the crystal structure of which was solved by room temperature single crystal XRD (P213, Z=4, a=9.7831(2) Å). This phase does not undergo any structural phase transition down to 6 K nor any kind of long range ordering down to 2 K.Read less <
English Keywords
X-ray diffraction
Phosphates
Phase transitions
Ferrimagnetism
Specific heat
Raman spectroscopy
Origin
Hal imported