This chapter presents typical mid-IR (MIR) and near-IR (NIR) spectra of different clay mineral families and discusses how basic information on crystal chemistry can be derived. MIR spectroscopy has been applied to clay minerals studies since the early 1960s, but in more recent decades NIR spectroscopy has become more commonly applied to the study of clay minerals. These complementary techniques provide information concerning their structure, ordering or chemical composition, including different types of isomorphous substitutions within clay mineral species. The emphasis is on interpretation of the MIR and NIR spectra of selected representative specimens of the main clay mineral groups, based on the well-known work of V.C. Farmer and on more recent published literature.

IR Spectra of Clay Minerals

Assessment of hand-held Raman instrumentation for in situ screening for potentially counterfeit artesunate antimalarial tablets by FT-Raman spectroscopy and direct ionization mass spectrometry

Al doped nanostructured zinc oxide thin films (thickness, 165 ± 5 nm) on silica glass were prepared from zinc acetate based solutions of varying dopant content (0 to 10 at% with respect to Zn). X-ray diffraction confirmed the presence of nanocrystalline hexagonal ZnO. On increasing the doping level, we observed a change in ZnO morphology (spherical, hexagon and plate-shaped) under field emission scanning and transmission electron microscopes and a gradual decrease of ZnO crystallite size (14.0 to ∼10 nm) vis-a-vis an enhancement of direct band gap energy of the films. Root mean square film surface roughness and chemical state of elements were studied by atomic force microscopy and X-ray photoelectron spectroscopy respectively. In addition to common intrinsic defects in ZnO, a defect (designated as D˙ZA, appearing as a paramagnetic singly negatively charged oxygen vacancy) was identified up to 4% doping from the appearance of photoluminescence emission at 398 nm and measurement of paramagnetic property of the films. Film photocatalytic activity towards Rhodamine 6G dye decomposition was performed under UV (254 nm) irradiation and the film with 4% doping (A4ZO) showed the highest value of first order decomposition rate constant. On increasing Al content, the trend of change of defect concentration (oxygen vacancies) analyzed by Raman spectra was found to be identical with the dye photodecomposition activity (PA) of the films. A major role of DZA˙ towards the PA was explored under visible light. We proposed the reaction mechanism of PA based on the experimental results. The A4ZO would be expected to decompose micro-organisms under visible light.

Influence of Al doping on microstructural, optical and photocatalytic properties of sol–gel based nanostructured zinc oxide films on glass

Composites of poly(vinylidene fluoride-co-hexafluoro propylene) (PVdF-HFP) incorporating 10 wt % bis(trifluoromethane)sulfonimide lithium salt (LiTFSI) and 10 wt % particles of nanoparticulate silica (nm-SiO2), nanoparticulate titania (nm-TiO2), and fumed silica (f-SiO2) were prepared by electrospinning. These membranes served as host matrix for the preparation of composite polymer electrolytes (CPEs) following activation with lithium sulfur battery electrolyte comprising 50/50 (vol %) dioxolane/dimethoxyethane with 1 M LiTFSI and 0.1 M LiNO3. The membranes consist of layers of fibers with average fiber diameter of 0.1–0.2 μm. CPEs with f-SiO2 exhibited higher ionic conductivity with a maximum of 1.3 × 10–3 S cm–1 at 25 °C obtained with 10 wt % filler compositions. The optimum CPE based on PVdF-HFP with 10 wt % f-SiO2 exhibited enhanced charge–discharge performance in Li-S cells at room-temperature eliminating polysulfide migration, delivering initial specific capacity of 895 mAh g–1 at 0.1 C-rate and a v...

Novel Composite Polymer Electrolytes of PVdF-HFP Derived by Electrospinning with Enhanced Li-Ion Conductivities for Rechargeable Lithium–Sulfur Batteries

Spectroscopic characterization of natural chrysotile

Minerals from Macedonia. Part XIX. Vibrational spectroscopy as identificational tool for some sheet silicate minerals

Vibrational (infrared and Raman) spectra of the sheet silicate minerals: biotite, K(Mg,Fe 2+ ) 3 AlSiO 10 (OH,F) 2 ; muscovite, KAl 2 (Si 3 Al) 10 (OH,F) 2 ; phlogopite, KMg 3 (Si 3 Al)O 10 (F,OH) 2 and sheridanite (clinochlore), (Mg,Al) 6 (Si,Al) 4 O 10 (OH) 8 , collected from various localities within the Republic of Macedonia, were described and interpreted. The above-mentioned minerals showed IR spectral similarities in the region bellow 1200 cm -1 mainly due to their common structural characteristics. In general, the bands appearing in the 1100-900 cm -1 spectral region were assigned to v(Si-O-Si) modes, whereas most of the lower-frequency bands were interpreted as either 8(OH) or δ(Si-O-Si) vibrations. The similarities between the Raman spectra (1200-100 cm -1 ) were less pronounced indicating that Raman technique is more sensitive to compositional changes. The results were compared to the literature data for the analogous species originating from all over the world. The authenticity of the samples was checked by powder XRD and chemical composition determined by X-ray microprobe analysis.

Violeta Sontevska

Papers

Minerals from Macedonia. Part XIX. Vibrational spectroscopy as identificational tool for some sheet silicate minerals

Minerals From Macedonia. XXI. Vibrational Spectroscopy as Identificational Tool for Some Phyllosilicate Minerals