Materials, Techniques, and Conservation of Historic Stained Glass “Grisailles”

A grisaille is a brown-blackish paint applied onto the inner surface of stained glass to draw the contours and details of the figures and to produce the effect of shades and volumes. Grisailles were traditionally made of finely ground oxides of iron but also of copper, zinc, lead, or manganese mixed with a flux such as lead ground glass and a binder and fixed onto the flat glass by firing. The grisailles have typical layer thickness varying between 10 and 100 µm and are formed by a complex mixture of pigment particles, crystalline, and amorphous reaction compounds, aging, and weathering compounds. The high brilliance, collimation, energy selection, and monochromacity of the SR beam are idea…

Ag/(Bi, Pb)-Sr-Ca-Cu-O superconducting tape processing: Solid state chemistry aspects

Abstract Different preparation methods have been used to obtain starting powders used in the fabrication of composite tapes by the powder-in-tube method. The effect of these distinct starting powders on the superconducting properties of Ag/Bi-Sr-Ca-Cu-O monofilament tapes has been investigated. The changes in the physical properties, including the critical current density at 77 K and ac magnetic susceptibility, and microstructure, using optical and electronic microscopy, have been analyzed in relation to the solid state reactions involved in the Bi 2 Sr 2 CaCu 2 O 8+δ and Bi 2 Sr 2 Ca 2 Cu 3 O 10+δ phase transformations.

Synthesis of new vanadium–chromium and chromium–molybdenum oxynitrides by direct ammonolysis of freeze-dried precursors

Interstitial vanadium–chromium and chromium–molybdenum oxynitrides in the solid solution series V1 − zCrz(OxNy) and Cr1 − zMoz(OxNy) (z = 0.0, 0.2, 0.4, 0.5, 0.6, 0.8, 1.0) have been obtained by direct ammonolysis of precursors resulting from the freeze-drying of aqueous solutions of the appropriate metal salts. A study of the influence of the preparative variables on the outcomes of this procedure is presented. Compounds in the V1 − zCrz(OxNy) series are prepared as single phases by nitridation at 1073 K, followed by fast cooling of the samples. Compounds in the Cr1 − zMoz(OxNy) series are prepared as nearly single phases by nitridation at different temperatures, optimized for each composi…

Laser ablation of a silicon target in chloroform: formation of multilayer graphite nanostructures

With the use of high-resolution transmission electron microscopy, selected area electron diffraction and x-ray photoelectron spectroscopy methods of analysis we show that the laser ablation of a Si target in chloroform (CHCl3) by nanosecond UV pulses (40 ns, 355 nm) results in the formation of about 50–80 nm core–shell nanoparticles with a polycrystalline core composed of small (5–10 nm) Si and SiC mono-crystallites, the core being coated by several layers of carbon with the structure of graphite (the shell). In addition, free carbon multilayer nanostructures (carbon nano-onions) are also found in the suspension. On the basis of a comparison with similar laser ablation experiments implement…

Synthesis of new molybdenum–tungsten, vanadium–tungsten and vanadium–molybdenum–tungsten oxynitrides from freeze-dried precursors

Abstract Interstitial molybdenum–tungsten, vanadium–tungsten and vanadium–molybdenum–tungsten oxynitrides in the solid solution series Mo1−zWz(OxNy) and V1−zWz(OxNy) (z=0, 0.2, 0.4, 0.5, 0.6, 0.8, 1), and V1−u−zMouWz(OxNy) (u, z=0.2, 0.33, 0.4, 0.6; u+z

X-ray diffraction line-broadening study on two vibrating, dry-milling procedures in kaolinites

Due to the great technological importance of the microstructure of kaolinite, characterizing its evolution during dry milling of kaolin and analyzing the microstructural information obtained from different methods were the main aims of this work. The microstructural alteration of kaolinite is evaluated by X-ray diffraction and electron microscopy methods, comparing the results obtained and analyzing the correlations between them. The Warren-Averbach and Voigt-function methods of X-ray diffraction microstructural analysis have been applied successfully to the study of the effects of two different, vibrating-cup dry-milling configurations in the microstructure of kaolinite from the reflection…

Polymer solution processing of (Bi, Pb)SrCaCuO

Abstract A simple polymer processing route to the 110 K phase (Bi, Pb) 2 Sr 2 Ca 2 Cu 3 O 10+δ superconductor has been developed. The influence of the polymer to metal starting ratio, as well as the sintering temperature and time on the quality of the resulting superconducting powders has been studied by XRD, a.c. susceptibility and resistivity measurements. Microstructure of ceramic compacts has been studied by SEM, and qualitatively analysed by EDS for compositional homogeneity. The results indicate that the polymer synthesis route described here may offer a good alternative to the conventional solid state preparation methods towards attaining homogeneous 110 K superconductor powder withi…

Fast synthesis of single-phased 110 K bismuth superconductor by freeze-drying of acetic precursors. Kinetic role of calcium and copper oxides

Abstract Although the usefulness of solution procedures to improve the synthesis of bismuth HTSC has been argued, an adequate control of the procedural variables has allowed us to isolate the 110 K phase as the only superconducting phase after such a short sintering time as 22 h. The precursors used have been freeze-dried powders resulting from acetic solutions containing excess Ca and Cu. TGA-DTA and XRD experiments have been performed to follow the subsequent solid-state reaction processes. The initial formation of a mixed bismuth-lead oxoacetate, as intermediate to (Bi 1− y Pb y ) 2 CuO 4 , and the presence of an excess of Ca 2 CuO 3 in the last reaction step are two of the main factors …

Fast Solution Precursor Synthesis of the 2223 Phase: the Role of Lead in the Reaction Pathway

ABSTRACTValuable mechanistic information, about the reaction pathway in the formation of the 2223 phase, has been obtained by the use of a solution synthesis route. The presence of lead in the starting mixture has remarkable effects on the nature and stability of the different intermediates: i) the grain size and morphology of Bi2CuO4 is severely changed, ii) calcium carbonate is partially decomposed to yield the calcium plumbate, iii) the 2201 phase results stabilized against the formation of the collapsed phase Bi17Sr16Cu7O49-δ, iv) the melting point of the intermediate 2212 is lowered by about 10 °C. All these effects, due to lead substitution, contribute to promote the formation of the …

Crystalline Microstructure of Corundum Fillers Determined from Powder X-Ray Diffraction Patterns

Transport and Diamagnetic Properties of 2:2:1:2 and 2:2:2:3 (Bi-Pb)-Sr-Ca-Cu-O Superconducting Materials

AbstractBismuth superconducting oriented fibers of the compositions 2:2:1:2: and 2:2:2:3 have been grown by the Laser Floating Zone (LFZ) method. Growth conditions have been optimized in order to improve the superconducting properties. The 108 K onset in susceptibility measurements (associated to the 2:2:2:3 phase) only appears well defined when starting from Sr-defective precursors.

Production of nanometer-size GaAs nanocristals by nanosecond laser ablation in liquid.

This paper reports the formation and characterization of spherical GaAs quantum dots obtained by nanosecond pulsed laser ablation in a liquid (ethanol or methanol). The produced bare GaAs nanoparticles demonstrate rather narrow size distribution which depends on the applied laser power density (from 4.25 to 13.9 J/cm 2 in our experiments) and is as low as 2.5 nm for the highest power used. The absolute value of the average diameter also decreases significantly, from 13.7 to 8.7 nm, as the laser power increases in this interval. Due to the narrow nanoparticle size dispersion achieved at the highest laser powers two absorption band edges are clearly distinguishable at about 1.72 and 3.15 eV w…

Vanadyl phosphate dihydrate, a solid acid: the role of water in VOPO4�2H2O and its sodium derivatives Na x (VIV x VV 1?x O)PO4�(2?x)H2O

Sodium-containing intercalates having as general formula Na x VOPOP4·(2−x)H2O (0.25≤x<0.50) have been obtained and characterized. Orthorhombic phases, which essentially maintain the structure of the layered oxide hydrate VOPO4·2H2O result. Intercalated sodium ions act as ‘pillars’. The presence of H3O+ ions in the parent VOPO4·2H2O and also in some reduced phases, is detected. The understanding of the structural role of the water molecules is advanced and the topotactic dehydration/rehydration processes are studied. The formation of a new metastable VOPO4·H2O phase is established.

Soil emissivity and reflectance spectra measurements

We present an analysis of the laboratory reflectance and emissivity spectra of 11 soil samples collected on different field campaigns carried out over a diverse suite of test sites in Europe, North Africa, and South America from 2002 to 2008. Hemispherical reflectance spectra were measured from 2.0 to 14 microm with a Fourier transform infrared spectrometer, and x-ray diffraction analysis (XRD) was used to determine the mineralogical phases of the soil samples. Emissivity spectra were obtained from the hemispherical reflectance measurements using Kirchhoff's law and compared with in situ radiance measurements obtained with a CIMEL Electronique CE312-2 thermal radiometer and converted to emi…

A novel method of nanocrystal fabrication based on laser ablation in liquid environment

Abstract Metal nanoparticles can be prepared by a novel technique that consists of the laser ablation of a solid target immersed in a water solution of a metal salt. Silicon was chosen as the most adequate target to synthesize silver and gold nanoparticles from a water solution of either AgNO3 or HAuCl4. The influence of both the silver nitrate concentrations and the irradiation time of the Si target on the optical properties of the Au and Ag nanoparticles have been investigated. The crystalline nature of the metal nanoparticles has been determined by X-ray diffraction (XRD). Average size and particle size distribution have been measured by means of TEM. The absorbance spectra show the char…

Pd2Mo3N: a new molybdenum bimetallic interstitial nitride

The molybdenum bimetallic nitride Pd2Mo3N has been synthesized by ammonolysis of the stoichiometric mixture of low sized pure oxide crystallites (2PdO/3MoO3) as resulting from low temperature thermal decomposition of precursor powders obtained by freeze-drying of aqueous solutions of the appropriate metal salts. This compound has been characterized by elemental analysis, energy dispersive analysis of X-rays, X-ray diffraction, scanning electron microscopy (field emision) and thermogravimetry under oxygen atmosphere. Pd2Mo3N crystallizes in the cubic space group P4132 (no. 213) (Pd2Mo3N, a = 6.81770(3) A, Z = 4), and presents the unusual filled β-manganese structure. It is stable under oxyge…

(Bi,Pb)2Sr2Ca2Cu3O10+δ superconductor composites: Ceramics vs. fibers

Abstract Well characterized (Bi, Pb) 2 Sr 2 Ca 2 Cu 3 O 10+δ superconductor powder has been used to prepare superconductor-glass, -metal and -alloy composites through solid state reaction method. A recently developed Laser Floating Zone (LFZ) apparatus has been used to transform the ceramic precursors into oriented fibers. The diamagnetic properties have been studied by a.c. susceptibility. The microstructure of fibers has been studied by SEM and compared with that of the original ceramic precursors. XRD has been used to study phase composition on representative composite samples and fibers. The results indicate some potential for the 2223-Ag composite, which displays improved diamagnetic p…

Laser floating zone growth of textured Ag/(Bi,Pb)SrCaCuO superconductors

A new improved synthesis of the 110 K bismuth superconducting phase: freeze-drying of acetic solutions

Abstract Metastability has greatly hindered the separated synthesis of the high-temperature superconducting phases represented as (Bi1−x, Pbx)2Sr2Can−1CunO4 + 2n (n = 2, 2-2-1-2, Tc≈80 K, and n = 3, 2-2-2-3, Tc≈110 K). By careful control of the synthetic variables, it becomes possible to obtain the 110 K phase as the only superconducting one through processing of freeze-dried acetic solutions. This technique leads to homogeneously sized (5–10 μm) micaceous platelets of the superconducting material.

Magneto-Structural Correlations in μ-Halo Bridged Copper(II) Chains

To design synthetic pathways to systems of desired properties is a growing challenge for inorganic chemist. Our current interest in this area is focused on copper(II) chemistry. Besides to advance in the understanding of the factors determining the conformation around copper(II) in the solid state, we intend to gain insight into the chemical and structural effects that govern exchange coupling interactions in condensed species. In this context, we have approached the synthesis and characterization of a wide set of pentacoordinated Cu(LIII)XY complexes (LIII=tridentate ligand, X=coordinating anion, Y=coordinating or non-coordinating anion) showing a great structural diversity (including mono…

Structural study of NaNdGa4S8, a luminescent material with low-concentration quenching

Abstract Single-crystal X-ray diffraction analysis and optical investigations of NaNdGa 4 S 8 show that Nd 3+ ions are essentially distributed in two of the three square antiprismatic sites of a CaGa 2 S 4 -type lattice. The NdS 8 polyhedra are isolated (minimum NdNd distance: 6.07 A) so the interactions responsible for concentration quenching of the luminescence are considerably reduced

The Influence of Morphological Aspects in the Reaction Pathway and Superconductive Properties of Bi2223-Ca2CuO3 Ceramic Composites

ABSTRACTA variation of the solid-state matrix technique has been developed as a procedure for the preparation of 2223 bismuth superconducting phases [(Bi,Pb)2Sr2Ca1-nCunO4+2n, n=3]. The adequate processing of samples of nominal compositions 2223+x 0021, obtained both by this procedure and by the polymer matrix method, has allowed the modification of the microstructure of the calcium copper excess, with no noticeable change in that of the 2223 grains. The study of the phase evolution in the processing of the samples has shown that the formation rate of the 2223 phase is faster when the particle size of the calcium cuprate is smaller. A dependence of the intergranular superconducting properti…

Polymer-matrix route to (Bi, Pb)2Sr2Ca2Cu3O10+δ: The role of Ca2CuO3☆

Abstract The use of polyethylenimine as active matrix agent has provided a fast synthesis method for (Bi, Pb)2Sr2Ca2Cu3O10+δ, starting from aqueous acetic solutions combined with careful control of the procedural variables. The 110 K phase is obtained as the only superconducting phase after sintering in air during 42 h at 860°C. This technique yields homogeneously sized, large (ca. 20 μm) platelets of the superconducting material. The presence of an excess of calcium and copper over the stoichiometric requirements accelerates the formation of the superconducting phase. This excess, which appears in the resulting material as Ca2CuO3, influences the superconducting properties, other than Tc, …

Submicrometer CaCuO2 and Ca2CuO3 particles from bimetallic formate precursors

Abstract CaCuO2 and Ca2CuO3 are readily obtained by thermal decomposition of two new calcium and copper formates, CaCu(HCOO)4 and Ca2Cu(HCOO)6. These chemical-precursor based syntheses, while overcoming problems related to the stoichiometry of the final products, involve very short diffusion path lengths. This, in turn, results in soft treatments yielding pure phases constituted by submicrometer (≈0.4 μm) homogeneous particles.

Silicon Nanocrystals Produced by Nanosecond Laser Ablation in an Organic Liquid

Small (3−5 nm in diameter following HRTEM images) Si nanocrystals were produced in a two-stage process including (1) nanosecond laser ablation of a Si target in an organic liquid (chloroform) that results in formation of big composite polycrystalline particles (about 20−100 nm average diameter) and (2) ultrasonic post-treatment of Si nanoparticles in the presence of HF. The post-treatment is responsible for disintegration of the composite Si particles, release of small individual nanocrystals, and reduction of their size due to HF-induced etching of Si oxide. The downshift and broadening of the ∼520 cm−1 Raman phonon band of the small Si nanocrystals with respect to the bulk Si Raman band i…

Laser Floating Zone Growth: Overview, Singular Materials, Broad Applications, and Future Perspectives

This article belongs to the Special Issue Laser-Induced Crystallization.