Rietveld refinements of a new solid solution Ba_(3−x)Sr_x(PO₄)₂ (0≤x≤3)

Abstract

Ba(3−x)Srx(PO4)2 orthophosphates (0≤x≤3) have been prepared by solid state reaction. The final temperature was 1000°C. The X-ray diffraction analyses show the existence of a continuous solid solution. Ba(3−x)Srx(PO4)2 orthophosphates (0≤x≤3) crystallize in the hexagonal system with the space group R3m. Their structure is based on a three-dimensional framework constructed of infinite layers of Ba1/Sr1O12 linked and parallel to infinite layers of Ba2/Sr2O10 polyhedra and PO4 tetrahedra.

Correlation between Raman wavenumbers and P?O bond lengths in crystalline inorganic phosphates

“…2. A trial bond length-stretching wavenumber trend is defined on the basis of a solid solution series (barium-strontium and strontium-calcium for orthophosphates 8,9,28 and calcium-cadmium for pyrophosphates 29 ) (see b in Tables 2 30 -48 and 3 29,49 -66 for explanation of initial assignments in each data set). 3.…”

“…Good spectral resolution in the case of Raman spectra was chosen to be limited to values better than 3 cm 1 . These data were supplemented by our experimental measurements on samples prepared by solid-state techniques and characterized by powder x-ray diffraction (Rietveld method) 8,9 and Raman spectroscopy. 10…”

“…The previous relationship for phosphates in aqueous solutions [Eqn (9)] was derived using a very limited number of compounds (though very well chosen, as, for example, with regular structure or with only one P-O bond). Although broad in their scope [Eqns (6), (7) and (9)] and very accurate for regular structures [especially Eqn (9)], these relationships do not take into account distortion observed within inorganic solid-state phosphates, because they use average values.…”

“…Although broad in their scope [Eqns (6), (7) and (9)] and very accurate for regular structures [especially Eqn (9)], these relationships do not take into account distortion observed within inorganic solid-state phosphates, because they use average values.…”

Crystal chemistry, Rietveld refinements and Raman spectroscopy studies of the new solid solution series: Ba3−xSrx(VO4)2 (0≤x≤3)

“…It is comprised of [Me (1) (VO 4 ) 2 ] 4− layers linked into a crystal network by Me 2+ (2) cations. Manoun et al and Popovic et al reported previously on the solid solution between isostructural phosphates substituting barium with strontium in Ba 3 (PO 4 ) 2 :Ba 3−x Sr x (PO 4 ) 2 [14,15]. Using Raman spectroscopy and X-ray diffraction techniques, the results showed continuous solid solutions.…”