Some topical applications of plasma atomic spectrochemical methods for the analysis of ceramic powders

The scope of a number of plasma spectrochemical methods for the determination of the main components and impurities in ceramic powders is described. These methods meet the requirements for the analytical characterization of new structural and functional ceramics for modern industrial applications and electronic devices. For ceramic powders, spectrochemical analysis with direct methods as well as analysis subsequent to sample dissolution are discussed. Fusion is a powerful method for the dissolution of ZrO₂ ceramic powders, provided the fluxes are pure enough. For determinations in Al₂O₃, SiC and ZrO₂, it will be shown that ICP-MS is very useful. This is especially true for trace analysis after matrix removal. The latter can easily be performed on-line in the case of the analysis of Al₂O₃ powders. For direct analysis of ceramic powders, the direct insertion of samples into the plasma, spark and arc ablation, laser ablation, electrothermal vaporization and slurry nebulization are discussed. Particular attention is given to the direct analysis of ceramics in powder form (Al₂O₃, SiC, Si₃N₄, B₄, WC) using ICP-OES with slurry nebulization as well as with direct sample insertion (DSI) and with electrothermal vaporization (ETV). For the two latter methods, the use of chemical modifiers for volatile compound formation will be shown to be of great importance, and its features will be explained using thermochemical considerations.     

Some topical applications of plasma atomic spectrochemical methods for the analysis of ceramic powders

The scope of a number of plasma spectrochemical methods for the determination of the main components and impurities in ceramic powders is described. These methods meet the requirements for the analytical characterization of new structural and functional ceramics for modern industrial applications and electronic devices. For ceramic powders, spectrochemical analysis with direct methods as well as analysis subsequent to sample dissolution are discussed. Fusion is a powerful method for the dissolution of ZrO₂ ceramic powders, provided the fluxes are pure enough. For determinations in Al₂O₃, SiC and ZrO₂, it will be shown that ICP-MS is very useful. This is especially true for trace analysis after matrix removal. The latter can easily be performed on-line in the case of the analysis of Al₂O₃ powders. For direct analysis of ceramic powders, the direct insertion of samples into the plasma, spark and arc ablation, laser ablation, electrothermal vaporization and slurry nebulization are discussed. Particular attention is given to the direct analysis of ceramics in powder form (Al₂O₃, SiC, Si₃N₄, B₄, WC) using ICP-OES with slurry nebulization as well as with direct sample insertion (DSI) and with electrothermal vaporization (ETV). For the two latter methods, the use of chemical modifiers for volatile compound formation will be shown to be of great importance, and its features will be explained using thermochemical considerations. Received: 18 February 1998 / Revised: 13 May 1998 / Accepted: 9 June 1998     

Analysis of advanced ceramics and their basic products

Summary A review on the analysis of the most important ceramic materials and their basic substances is given. The importance of minor and trace elements in the bulk as well as their distribution on the microscale in both classes of substances is discussed by the example of Al₂O₃, AlN, TiO₂, Si₃N₄, SiO₂, SiC, Y₂O₃, ZrO₂-based and some other ceramics and of their basic substances. The state-of-the-art and trends of development in modern atomic spectrometric methods for bulk analysis of the basic substances subsequent to sample dissolution, such as plasma emission and mass spectrometry, but also of direct methods such as slurry nebulization for plasma spectrometry, inorganic mass spectrometry and X-ray spectrometry are discussed. Further, first approaches for the in-depth analysis of powders and trends in direct methods for compact ceramics based on laser evaporation as well as on electron and ion probe techniques are presented. The latter are illustrated with selected examples from the literature.

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Analyse von modernen keramischen Materialien und ihren Grundstoffen

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Dedicated to Prof. Dr. R. Neeb on the occasion of his 60th birthday     

Halbquantitative analyse durch messung der entfärbungs-zeit von tüpfelflecken

A rapid semiquantitative method is described based on measurement of the time required for decolorization of spotreactions on filter paper strips by suitable reagents, This very simple method yields results which are accurate to ± 10%. The method has been verified for several ions (Ag⁺, Pb²⁺, JO₃^-,Cu²⁺, CrO₄^2-). The utility of this method for the characterization and differentiation of filter papers is indicated.     

Oxygen Vacancy Engineering in Titanium Dioxide for Sodium Storage

Titanium dioxide (TiO₂) is a promising anode material for sodium-ion batteries (SIBs) due to its low cost, natural abundance, nontoxicity, and excellent electrochemical stability. Oxygen vacancies, the most common point defects in TiO₂, can dramatically influence the physical and chemical properties of TiO₂, including band structure, crystal structure and adsorption properties. Recent studies have demonstrated that oxygen-deficient TiO₂ can significantly enhance sodium storage performance. Considering the importance of oxygen vacancies in modifying the properties of TiO₂, the structural properties, common synthesis strategies, characterization techniques, as well as the contribution of oxygen-deficient TiO₂ on initial Coulombic efficiency, cyclic stability, rate performance for sodium storage are comprehensively described in this review. Finally, some perspectives on the challenge and future opportunities for the development of oxygen-deficient TiO₂ are proposed.     

CuII@PAA/PVC mesoporous fibers: A hybrid wedding as a high-performance versatile heterogeneous catalyst for A3, KA2, and decarboxylative A3 reactions

Efforts made on the development of a novel, simple, cost-effective, and efficient approach to fabricate a copper catalyst immobilized on mesoporous poly (acrylic acid)/poly (vinyl chloride) hybrid fibers (Cu^II@PAA/PVC) for versatile catalytic applications in A₃, KA₂, and decarboxylative A₃ couplings has been described in this present work. The characterization of the mesoporous hybrid fibers was well performed by BET, FTIR, SEM, EDX, XPS, and TGA techniques. The pore structure and surface area were calculated by using BET measurement analysis. The obtained mesoporous Cu^II@PAA/PVC fibers exert high catalytic performance in the synthesis of propargylamines via one-pot A₃, KA₂, and decarboxylative A₃ reactions over a series of substrates without employing expensive ligands or inert atmosphere. The active Cu²⁺ species chelating with carboxylate groups in PAA/PVC hybrid fibers plays a key role in the catalysis. Meanwhile, the unique mesoporous structure and fiber morphology facilitate a better mass transfer and enlarge its contact area with substrates in the course of a reaction. Moreover, the Cu²⁺–carboxylate chelation could suppress the leaching of active Cu²⁺ species from the catalyst and thus lead to the catalyst has excellent performance and good durability as well as reusability.     

Thermal and mineralogical investigations of historical ceramic

The selected sample for this study represents a piece of pavement ceramics from a private collection. The ceramic (approximately XVIIIth century) comes from Campania region, Naples province. A chemical, mineralogical and morphological characterization of a Campagna ceramic piece received from a particular collection has been performed. Inductively coupled plasma-atomic emission spectroscopy—(ICP-AES) was used for the determination of Al₂O₃, CaO, Fe₂O₃, K₂O, MgO, MnO, Na₂O, and TiO₂ as major constituents and Cu, Cr, Ni, Pb, and Zn as minor and trace selected elements. There is a very important characterization method used for the control of the reaction process and of the properties of the materials obtained. Physical and mineralogical analyses were made by using the thermal behavior (thermogravimetric analysis (TG) and differential thermal analysis (DTG)) and X-ray diffraction spectrometry for the mineralogical composition. The results of these analyses allow the establishment of conclusions about several aspects of their manufacture, the origin of the raw materials and their provenance (local or imported). They provide information supporting certain archeological hypothesis. The performed analysis revealed some very interesting characteristics: lower amount of silica and increased concentration of alumina, the presence of calcium in relatively low concentration (Ca-poor ceramic) and a mineralogical composition.     

Titanium dioxide nanoparticle coating of polymethacrylate-based chromatographic monoliths for phosphopetides enrichment

Metal oxide affinity chromatography has been one of the approaches for specific enrichment of phosphopeptides from complex samples, based on specific phosphopeptide adsorption forming bidentate chelates between phosphate anions and the surface of a metal oxide, such as TiO₂, ZrO₂, Fe₂O₃, and Al₂O₃. Due to convective mass transfer, flow-independent resolution and high dynamic binding capacity, monolith chromatographic supports have become important in studies where high resolution and selectivity are required. Here, we report the first synthesis and characterization of immobilisation of rutile TiO₂ nanoparticles onto organic monolithic chromatographic support (CIM-OH-TiO₂). We demonstrate the specificity of CIM-OH-TiO₂ column for enrichment of phosphopeptides by studying chromatographic separation of model phosphorylated and nonphosphorylated peptides as well as proving the phosphopeptide enrichment of digested bovine α-casein. The work described here opens the possibility for a faster, more selective enrichment of phosphopeptides from biological samples that will enable future advances in studying protein phosphorylation.     

Thermal analysis of phase transitions in perovskite electroceramics

Perovskite oxide ceramics have found wide applications in energy storage capacitors, electromechanical transducers, and infrared imaging devices due to their unique dielectric, piezoelectric, pyroelectric, and ferroelectric properties. These functional properties are intimately related to the complex displacive phase transitions that readily occur. In this study, these solid–solid phase transitions are characterized with dielectric measurements, dynamic mechanical analysis, thermomechanical analysis, and differential scanning calorimetry in an antiferroelectric lead-containing composition, Pb_0.99Nb_0.02[(Zr_0.57Sn_0.43)_0.92Ti_0.08]_0.98O₃, and in a relaxor ferrielectric lead-free composition, (Bi_1/2Na_1/2)_0.93Ba_0.07TiO₃. The (Bi_1/2Na_1/2)_0.93Ba_0.07TiO₃ ceramic develops strong piezoelectricity through electric field-induced phase transitions during the poling process. The combined thermal analysis techniques clearly reveal the differences in unpoled and poled ceramics.     

Liquid chromatographic characterization of the deoxyribonucleoside-5’-phosphates and deoxyribonucleoside-3’,5’-bisphosphates obtained by32P-postlabeling of DNA

Summary The use of high-performance liquid chromatography (HPLC) for the characterization of the adducts formed by the³²P-postlabeling of DNA is described. Adducts formed from the reaction of DNA with small molecules are characterized as deoxyribonucleoside-5′-monophosphates. Adducts formed from the reaction of DNA with larger molecules are characterized as 3′,5′-bisphosphates. In either case, good separations are obtained for adducts, other than methyl, by conventional reversed-phase chromatography using a C₁₈ column. Ion-exchange chromatography can be used in selected circumstances where reversed-phase techniques are not successful. Using sample concentration techniques, sensitivities are achievable which make this technique applicable toin vivo situations.     

Mechanochemistry for Energy Materials: Impact of High-Energy Milling on Chemical,Electric and Thermal Transport Properties of Chalcopyrite CuFeS2 Nanoparticles

Chalcopyrite CuFeS₂, a semiconductor with applications in chemical sector and energy conversion engineering, was synthetized in a planetary mill from elemental precursors. The synthesis is environmentally friendly, waste-free and inexpensive. The synthesized nano-powders were characterized by XRD, SEM, EDX, BET and UV/Vis techniques, tests of chemical reactivity and, namely, thermoelectric performance of sintered ceramics followed. The crystallite size of ∼13 nm and the strain of ∼17 were calculated for CuFeS₂ powders milled for 60, 120, 180 and 240 min, respectively. The evolution of characteristic band gaps, Eg, and the rate constant of leaching, k, of nano-powders are corroborated by the universal evolution of the parameter S_BET/X (S_BET-specific surface area, X-crystallinity) introduced for complex characterization of mechanochemically activated solids in various fields such as chemical engineering and/or energy conversion. The focus on non-doped semiconducting CuFeS₂ enabled to assess the role of impurities, which critically and often negatively influence the thermoelectric properties.     

NASICON结构的锂离子导电微晶玻璃结构与电导率

通过对LixAlx-1Ge3-x(PO4)3(x=1.1～1.9)锂离子导电玻璃的差示量热扫描(DSC)数据,结合XRD及其Rietveld精修、FESEM和交流阻抗等测试方法,研究了该系微晶玻璃的物相组成、主晶相晶胞参数变化情况、微观结构形貌、锂离子电导率和电化学窗口等。结果表明:LixAlx-1Ge3-x(PO4)3(x=1.1～1.9)锂离子导电微晶玻璃析出导电主晶相为LiGe2(PO4)3。当x=1.5时,由于导电主晶相LiGe2(PO4)3晶粒充分长大、分布均匀,晶界清晰,LAGP导电微晶玻璃的室温电导率最高(可达5.3×10-4 S.cm-1),电化学窗口为7.2V,可以满足全固态锂离子电池对电解质高室温电导率和宽电化学窗口的应用要求。     

Sol-Gel Synthesis and Optical Studies of Rare Earth and Transition Metal Ions Doped Nanocrystalline Aluminum and Yttrium Oxides

The paper reviews the studies of sol-gel produced nanocrystalline -Al₂O₃ and cubic Y₂O₃ doped with RE³⁺ and TM³⁺ ions. The effects of spatial confinement (on nanometer scale) in optical properties of sol-gel produced insulating nanocrystalline oxide materials doped with rare earth and transition metal ions are discussed. The experimental studies showed that in insulators these effects are mostly connected with the changes in the vibrational spectrum and the increased role of the surface in nanocrystals. The transformations between the crystalline forms of Al₂O₃ and the properties of doped corundum ceramics are studied. The methods of sol-gel synthesis of highly dispersed nanocrystalline -Al₂O₃ and cubic Y₂O₃ doped with RE³⁺ and TM³⁺ ions in wide range of concentrations are described. It is shown that optical techniques are useful for characterization of sol-gel produced materials.     

Direct hydroxylation of benzene to phenol by supported vanadium substitution polyoxometalates using H<Subscript>2</Subscript>O<Subscript>2</Subscript> as oxidant

A practical method for the direct hydroxylation of benzene to phenol catalyzed by supported vanadium-substituted polyoxometalates using H₂O₂ as an oxidant is described. Three vanadium-doped polyoxometalate Na₂H₃PMo₁₀V₂O₄₀·xH₂O catalysts were designed and prepared through support on graphitic carbon nitride (g-C₃N₄), montmorillonite, and activated carbon and named as CN-PMoV₂, M-PMoV₂, and C-PMoV₂, respectively. Their characterization was elucidated through the Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA), inductively coupled plasma-atomic emission spectrometry (ICP-AES) and scanning electron microscopy (SEM). This heterogeneous catalyst demonstrated promising activity in the hydroxylation of benzene to phenol with H₂O₂. Especially, CN-PMoV₂ catalyst was highly active and selective even under mild conditions. Moreover, CN-PMoV₂ catalyst still has a certain catalytic effect even after three instances of repeated use.     

Methodology for uranium compounds characterization applied to biomedical monitoring

Chronic exposure to uranium compounds led to the development of a methodology in order to characterize those compounds. This methodology, based on the recommendation of the I.C.R.P,¹ involves three main steps: the measurement of the uranium concentration and the particle size distribution at workstations; the characterization of the industrial compound, i.e. its physico-chemical properties; and the study of in-vitro solubility using chemical and cellular tests. Different methods for uranium analysis are presented. Results and comments on UF₄, UO₃, U₃O₈, UO₂ and U+UO₂ are given.     

Determination of soluble ions and elements in ambient air suspended particulate matter: Inter-technique comparison of XRF, IC and ICP for sample-by-sample quality control

In this paper, we describe a validation procedure for chemical fractionation analysis of elements (Al, As, Ba, Ca, Cd, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, S, Sb, Si, Sr, Ti and V) and soluble ions (Cl⁻, NO₃⁻, SO₄²⁻, Na⁺, NH₄⁺, Mg²⁺, Ca²⁺) in suspended particulate matter (PM). The procedure applies three distinct measurement techniques (XRF, IC and ICP-OES) to the analysis of individual samples. The techniques used generate different outputs at different stages in the procedure. This makes it possible to identify the contributions of specific parameters to measurement uncertainty. On this basis, we propose a scheme for controlling the analytical quality of data from individual samples in which inter-technique comparisons is used in the same way many analytical methods use surrogates. We apply this scheme to about 310 samples of PM₁₀ and PM_2.5 identifying and assessing the main factors contributing to measurement uncertainty. This procedure successfully resolved a number of difficulties frequently encountered during the analysis of PM, including lack of appropriate reference materials and the low reliability of alternative techniques of quality control. The results demonstrate the critical importance of sample treatment prior to destructive analysis by IC and ICP.     

Isolation and characterization of kurstakin and surfactin isoforms produced by Enterobacter cloacae C3 strain

In this work, the extraction, structural analysis, and identification as well as antimicrobial, anti‐adhesive, and antibiofilm activities of lipopeptides produced by Enterobacter cloacae C3 strain were studied. A combination of chromatographic and spectroscopic techniques offers opportunities for a better characterization of the biosurfactant structure. Thin layer chromatography (TLC) and HPLC for amino acid composition determination are used. Efficient spectroscopic techniques have been utilized for investigations on the biochemical structure of biosurfactants, such as Fourier transform infrared (FT‐IR) spectroscopy and mass spectrometry analysis. This is the first work describing the production of different isoforms belonging to kurstakin and surfactin families by E cloacae strain. Three kurstakin homologues differing by the fatty acid chain length from C₁₀ to C₁₂ were detected. The spectrum of lipopeptides belonging to surfactin family contains various isoforms differing by the fatty acid chain length as well as the amino acids at positions four and seven. Lipopeptide C3 extract exhibited important antibacterial activity against Gram‐positive and Gram‐negative bacteria, antifungal activity, and interesting anti‐adhesive and disruptive properties against biofilm formation by human pathogenic bacterial strains: Salmonella typhimurium, Klebsiella pneumoniae, Staphylococcus aureus, Bacillus cereus, and Candida albicans.     

晶种协同廉价有机模板导向合成高纯度MCM-49沸石

采用廉价低毒性的环己胺（CHA）作为有机模板剂,并合理添加少量MCM-49沸石晶种,在静态水热条件下成功合成了高纯度MCM-49沸石.研究了起始凝胶组成（如Al₂O₃/SiO₂,H₂O/SiO₂,CHA/SiO₂,晶种/SiO₂,Na₂O/SiO₂）、晶化温度和时间等因素对合成MCM-49沸石的影响.通过XRD、SEM、N₂吸附、固体²⁷Al和²⁹Si MAS NMR等手段表征产物,结果表明合成的MCM-49沸石具有良好的结晶度、均匀的晶体尺寸、高比表面积和纯的四配位Al³⁺物种.热重差热分析（TG-DTA）和固体¹³C MAS NMR表征结果证实CHA是作为模板剂填充在沸石产物的孔道内.这种合成MCM-49的方法具有廉价和低毒性的特点,对其产业应用有潜在的重要价值.     

Raman spectroscopic studies on the structure of materials, specially of glasses, ceramics, films and fibres

A survey is given of applications of Raman spectroscopy in materials characterization. The following topics are covered: Analytical characterization of glasses in the system PbO-B₂O₃ and of glasses and ceramics in the system SrO-B₂O₃-Al₂O₃-TiO₂; investigation and discussion of the so-called Boson peak in the Raman spectra of glasses; Raman spectra obtained with a microscope attachment of carbonaceous materials to study the orientation of graphite planes in films and fibres.     

Fluoride optical nanoceramics

The methods for preparation of highly transparent optical ceramics based on simple and complex fluoride compounds of elements of the first, second, and third Group in the Periodical system are considered. The use of precursors as nanopowders and processes of their self-assembling on heating results in maximally homogeneous, transparent, and mechanically strong ceramics. The resulting calcium fluoride ceramics possess optical losses of 10⁻²–10⁻³ cm⁻¹ at 1.06 μm and shock resistance characterized by the fracture toughness K _1C = 4.7±0.3 MPa m^1/2 (for comparison, for a calcium fluoride single crystal K _1C = 1.5±0.15 MPa m^1/2). Regularities of the chemistry of fluoride nanopowders were considered in comparison with the oxide nanopowders: the fluorides are prone to hydrolysis, and powder nanoparticles precipitated from aqueous solutions have complex and heterogeneous (over the volume) chemical composition. The spectral luminescence properties of the ceramics activated by rare-earth metals (Ce³⁺, Nd³⁺, Er³⁺, Yb³⁺) or containing active color centers are presented. The generation properties of the lithium fluoride ceramics with the color centers and the ternary Ca-Sr-Yb fluoride during diode laser pumping are describe Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 863–872, May, 2008.