The Fourier Transform Infrared (FT-IR) spectroscopy is by far known to be a useful technique for qualitative and quantitative analysis of asbestos in bulk samples, since all asbestos species exhibit intense absorption...The Fourier Transform Infrared (FT-IR) spectroscopy is by far known to be a useful technique for qualitative and quantitative analysis of asbestos in bulk samples, since all asbestos species exhibit intense absorption peaks in the 4000 - 400 cm-1 region of the infrared spectrum. In the present work, we compare the accuracy and precision of two analytical procedures (the Linear Calibration Curve Method and the Method of Addition) for the quantitative determination of asbestos in a host matrix. We have found that, providing careful samples preparation, both techniques quantify the asbestos content at the level of few micrograms with good precision. Due to less expensive equipment requirements and shorter analysis time, FT-IR can be a competitive analytical technique in the characterization of asbestos containing material with the respect to diffractometry or electron microscopy.展开更多
The present study has been conducted to contribute,once and for all,filling the lack of structural information for the whole class of rare earth(RE)carbonates owning the tengerite-(Y)structure.A complete structural ch...The present study has been conducted to contribute,once and for all,filling the lack of structural information for the whole class of rare earth(RE)carbonates owning the tengerite-(Y)structure.A complete structural characterization,carried out by Rietveld refinement of X-ray powder diffraction(XRD)data,was comparatively performed for the first time on several hydrated RE carbonates,having the general chemical formula RE_(2)(CO_(3))_(3)·χH_(2)O,RE=Y,Gd,Tb,Dy,Ho and Er.All samples share the same space group and lattice parameters similar to tengerite-(Y);the structures are also closely related,consisting in all cases of a three-dimensional framework of nine-fold coordinated RE atom polyhedral,linked together by carbonate ions.In addition to relatively minor changes in fractional coordinates of atom sites and corresponding interatomic distances,the only perceivable difference lies in the lattice parameters affected by the ionic radius of RE^(3+).However,in the case of Er,which has the lowest cationic radius among the analyzed RE,the stabilization of tengerite structure is at its limit condition,because the carbonate groups are heavily distorted.Furthermore,FT-IR and Raman spectra confirm the main structural features obtained by Rietveld refinements.The observed morphology of the various samples is almost the same,being characterized by the presence of bidimensional rod-like particles grouped in agglomerates,typical of tengerite crystals,thus indicating that the crystallization mechanism occurring during the hydrothermal synthesis is the same,irrespective of the involved RE cation.展开更多
文摘The Fourier Transform Infrared (FT-IR) spectroscopy is by far known to be a useful technique for qualitative and quantitative analysis of asbestos in bulk samples, since all asbestos species exhibit intense absorption peaks in the 4000 - 400 cm-1 region of the infrared spectrum. In the present work, we compare the accuracy and precision of two analytical procedures (the Linear Calibration Curve Method and the Method of Addition) for the quantitative determination of asbestos in a host matrix. We have found that, providing careful samples preparation, both techniques quantify the asbestos content at the level of few micrograms with good precision. Due to less expensive equipment requirements and shorter analysis time, FT-IR can be a competitive analytical technique in the characterization of asbestos containing material with the respect to diffractometry or electron microscopy.
文摘The present study has been conducted to contribute,once and for all,filling the lack of structural information for the whole class of rare earth(RE)carbonates owning the tengerite-(Y)structure.A complete structural characterization,carried out by Rietveld refinement of X-ray powder diffraction(XRD)data,was comparatively performed for the first time on several hydrated RE carbonates,having the general chemical formula RE_(2)(CO_(3))_(3)·χH_(2)O,RE=Y,Gd,Tb,Dy,Ho and Er.All samples share the same space group and lattice parameters similar to tengerite-(Y);the structures are also closely related,consisting in all cases of a three-dimensional framework of nine-fold coordinated RE atom polyhedral,linked together by carbonate ions.In addition to relatively minor changes in fractional coordinates of atom sites and corresponding interatomic distances,the only perceivable difference lies in the lattice parameters affected by the ionic radius of RE^(3+).However,in the case of Er,which has the lowest cationic radius among the analyzed RE,the stabilization of tengerite structure is at its limit condition,because the carbonate groups are heavily distorted.Furthermore,FT-IR and Raman spectra confirm the main structural features obtained by Rietveld refinements.The observed morphology of the various samples is almost the same,being characterized by the presence of bidimensional rod-like particles grouped in agglomerates,typical of tengerite crystals,thus indicating that the crystallization mechanism occurring during the hydrothermal synthesis is the same,irrespective of the involved RE cation.
