Search results for "Zirconi"
showing 10 items of 413 documents
Adsorption mechanism of arsenate by zirconyl-functionalized activated carbon
2007
Arsenate [As(V)] and arsenite [As(III)] sorption at the solid-water interface of activated carbon impregnated with zirconyl nitrate (Zr-AC) was investigated using X-ray absorption spectroscopy (XAS) and surface complexation modeling. The XAS data at the Zr K-edge suggest that the structure of the zirconyl nitrate coating is built from chains of edge-sharing ZrO8 trigonal dodecahedra bound to each other through two double hydroxyl bridges. The 8-fold coordination of each Zr atom is completed by four O atoms, which share a bit less than the two theoretically possible bidentate nitrate groups. On impregnation, two of the O atoms may lose their nitrate group and be transformed to hydroxyl group…
Simultaneous determinations of zirconium, hafnium, yttrium and lanthanides in seawater according to a co-precipitation technique onto iron-hydroxide.
2013
Very low concentrations (pg mL(-1) or sub-pg mL(-1) level) along with the high salinity are the main problems in determining trace metal contents in seawater. This problem is mainly considered for investigations of naturally occurring YLOID (Y and Lanthanides) and Zr and Hf in order to provide precise and accurate results. The inductively coupled plasma mass spectrometry (ICP-MS), both in high and low resolution, offers many advantages including simultaneous analyses of all elements and their quantitative determination with detection limits of the order of pg mL(-1). However in the analysis of YLOID in seawater, a better determination needs an efficient combination of ICP-MS measurement wit…
Analysis of insoluble silicate: Decomposition with molten sodium hydroxide and determination of Zr(IV) with chloranilic acid in medium-strong acid
1983
A rapid, accurate and precise method for the determination of zirconium in silicates is proposed. Insoluble or sparingly soluble samples are decomposed by means of molten sodium hydroxide. Chloranilic acid is employed as reagent for the spectrophotometric determination of Zr(IV). The limit of detection is 1.2×10−7 M and the relative standard deviation is 0.24%.
CCDC 635011: Experimental Crystal Structure Determination
2008
Related Article: M.Sanz, M.E.G.Mosquera, T.Cuenca, C.R.de Arellano, M.Schormann, M.Bochmann|2007|Polyhedron|26|5339|doi:10.1016/j.poly.2007.08.001
High-pressure structural, elastic, and thermodynamic properties of zircon-type HoPO4 and TmPO4
2017
[EN] Zircon-type holmium phosphate (HoPO4) and thulium phosphate (TmPO4) have been studied by single-crystal x-ray diffraction and ab initio calculations. We report on the influence of pressure on the crystal structure, and on the elastic and thermodynamic properties. The equation of state for both compounds is accurately determined. We have also obtained information on the polyhedral compressibility which is used to explain the anisotropic axial compressibility and the bulk compressibility. Both compounds are ductile and more resistive to volume compression than to shear deformation at all pressures. Furthermore, the elastic anisotropy is enhanced upon compression. Finally, the calculation…
Study of plastic deformation modes in zirconium by color image analysis
2004
Abstract Twinning, as a deformation mode, is a complement to slip. This paper deals with the study from a qualitative point of view, as well as from a quantitative one. Besides techniques widely used in materials science studies such as electron backscattered diffraction (EBSD) or X-ray diffraction (XRD), colour image analysis technique are presented here. Its results manage to confirm or complete the ones obtained, thanks to others methods.
Elastic Properties of Barium Zirconate Titanate Ceramics
2011
In the paper the influence of zirconium admixture on the structure and material constants of polycrystalline ferroelectric materials BaZrxTi1-xO3 (BZT) was examined. The barium zirconate titanate samples were prepared by a conventional solid state reaction method. A single phase with perovskite structure of the samples, was identified by an X-Ray diffraction technique at room temperature. The performed EDS study revealed that the samples were perfectly sintered and the material was chemically homogeneous. The dependence of shear modulus G on sample composition is similar to the respective dependence of Young's modulus E, whereas the Poisson's ratio ν decreases with the increase in zirconium…
Differential scanning calorimetry investigation of phase transition in $BaZr_{x}Ti_{1-x}O_{3}$
2009
ABSTRACT Lead-free BaZrxTi1-xO3 (x = 0; 0.025; 0.125) ceramics have been obtained by a conventional method. A single-phase perovskite structure of the ceramics was identified by the X-ray diffraction method. EDS analysis, performed for the individual grains of the tested sample, showed a good homogeneous distribution of all elements throughout the grains. The thermal behaviour of BaZrxTi1-xO3 (x = 0; 0.025; 0.125) ceramics was studied using the Differential Scanning Calorimetry (DSC). Measurements showed the influence of Zr addition on the character of phase transition in the BaTiO3 structure. The results were compared with these ones obtained for pure BaTiO3.
Zirconia implant abutments: A review
2009
Objectives: An increasing aesthetic demand within developed populations conducted to the fabrication of metalfree restorations and to a wide use of ceramic materials, due to its excellent characteristics of biocompatibility and aesthetics. With the incessant increase of commercial labels involved in this technological advance, a review is imposed on ceramic abutments, specifically on zirconia. We made a search of articles of peer-reviewed Journals in PubMed/ Medline, crossing the terms ?Dental Abutments?, ?Dental Porcelain? and ?Zirconia?. The review was divided by subtopics: zirconia physical and mechanical properties, precision fit in the implant-abutment interface, zirconia abutments str…
The Role of Zr in the High-Temperature Oxidation of Fe<sub>3</sub>Al
2008
The paper describes an examination of the effect of the addition of zirconium as a third element on the heat-resisting properties and explains the high temperature oxidation mechanism of Fe3Al intermetallic compounds. The Fe3Al and Fe3Al-0,05Zr specimens have been isothermally oxidized in the temperature range of 1173-1473 K in synthetic air for 100 hrs. The formed oxide layer, about 1,5-2 μm thick, was Al2O3. An examination of the cross-sectioned scales by SEM-EDS showed that the alumina layer consisted of a small inner columnar layer and an outer equiaxed grain layer. Additionally, very fine (50-150 nm) oxide grains rich in Zr, further identified as ZrO2, were found across the alumina sca…