A one-step synthesis of rare-earth phosphate–borosilicate glass composites

Abstract

REPO4–BG composites synthesized by a new 1-step method were investigated and were found to be similar to the composite made by the traditional 2-step method.

A Novel Approach for the Quantification of Different Inorganic and Organic Phosphorus Compounds in Environmental Samples by P L2,3-Edge X-ray Absorption Near-Edge Structure (XANES) Spectroscopy

“…Baseline correction was the most fundamental part of the analysis, and to the best of our knowledge, the confounding effect of Si on the shape of P L 2,3 -edge XANES spectra has been overlooked in previous studies where both elements are present. , In this study, we confirm that Si can cause distortion of the P L 2,3 -edge XANES spectrum if significant proportions of Si are present in the sample, because of the proximity of both edges (see Figure S1 in the Supporting Information). Moreover, comparing the spectrum of phytic acid and phytic acid diluted in quartz reveals that the nonlinear background of the diluted phytic acid P L 2,3 -edge XANES spectrum is at least partly caused by interference of the Si L-edges (see Figure S1).…”

“…However, when probing the K-edge, the speciation of organic P forms is difficult or even impossible, because of the lack of distinguishable spectral features among different organic reference compounds at the P K-edge. , By contrast, P XANES spectroscopy at the L 2,3 -edge seems to be more promising, because the L 2,3 -edge spectra of different organic and inorganic P forms are characterized by more potentially distinguishable spectral features . Although investigations using P L 2,3 -edge XANES spectroscopy have been performed, it has been mainly in the field of materials science ,,,,− and only a few were dedicated to environmentally related samples. ,, The latter can be explained by the high P concentration (>3 mg g –1 ) required to record the P L 2,3 -edge spectra, compared to the P K-edge (0.1 mg g –1 ) spectra, because of lower excitation probabilities at lower excitation energies . Furthermore, spectral data evaluation so far has been mainly restricted to visual comparisons with reference compounds, instead of quantitative data evaluation by e.g., linear combination fitting (LCF), as often used in P K-edge XANES data evaluation. − This is mostly due to difficulties in spectral data treatment, namely, regarding a correct deconvolution of an oftentimes nonlinear background originating from excitations of other matrix elements, low-energy electrons, and sample charging which complicates spectrum normalization and thus subsequent fitting of spectra.…”

Crystallization of Rare-Earth Phosphate-Borosilicate Glass Composites Synthesized by a One-Step Coprecipitation Method

“…The SEM/EDX analysis of 40 wt % CePO 4 –BG [Ce­(III)] and 40 wt % CePO 4 –BG [Ce­(IV)] suggested some incorporation of Ce and P cations within the glass matrix, although no change in local coordination environment of P can be observed based on P L 2,3 -edge XANES spectra from these materials. This behavior was also observed in YPO 4 –BG composite materials, which definitively showed Y and P cations incorporated in the borosilicate glass matrix …”

“…This is because nagelschmidtite was observed to form within CePO 4 −BG composite materials (Figure 6) as well as in a previous study of LaPO 4 − BG composite materials synthesized by a one-step ceramic method. 50 There was a small amount of nagelschmidtite crystallites observed in the SEM image, but no nagelschmidtite peaks were present in the powder XRD pattern from LaPO 4 − BG composite materials. The XRD peaks belonging to nagelshmidtite were most likely obscured by the background and not observed by powder XRD due to the large difference in the concentration and electron density within the lattice planes between LaPO 4 and nagelschmidtite.…”

“…was also observed in YPO 4 −BG composite materials, which definitively showed Y and P cations incorporated in the borosilicate glass matrix. 50 Figure 9c shows the P L 2,3 -edge XANES spectra collected from the CePO 4 [Ce(IV)], 40 wt % CePO 4 −BG [Ce(III)], and 40 wt % CePO 4 −BG [Ce(IV)] composite materials annealed at 900 and 700 °C. The spectrum from the 40 wt % CePO 4 −BG [Ce(III)] composite material annealed at 900 and 700 °C was observed to possess a more intense peak at ∼141.5 eV when compared to the P L 2,3 -edge XANES spectrum from CePO 4 [Ce(IV)] (Figure 9).…”