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High temperature sequestration of CO2 using lithium zirconates
2009-01-01
Equilibrium and kinetics of CO2 reaction with lithium zirconates synthesised by two different methods are reported. Considerably faster rates of high temperature reaction were obtained for the new material synthesised by a soft-chemistry route without the use of alkaline metal dopants, in comparison with the available literature data, with the highest rate 0.83wt%min-1. Lithium zirconate was found to be stable in consecutive forward-backward reaction cycles. Reaction rate dependency on the partial CO2 pressure was examined. The apparent slow reaction rates at Formula Not Shown are due to mass transfer limitations. Detailed analysis of the reverse reaction of decomposition of lithium carbonate-zirconia mixed matrix revealed complex three-step behaviour, which was associated with the transit...
Adhesive strength of new thermal barrier coatings of rare earth zirconates
2009-01-01
La2Zr2O7 (LZ) and La2(Zr0.7Ce0.3)2O7 (LZ7C3) as novel candidate materials for thermal barrier coatings (TBCs) were prepared by electron beam-physical vapor deposition (EB-PVD). The adhesive strength of the as-deposited LZ and LZ7C3 coatings were evaluated by transverse scratch test. Meanwhile, the factors affecting the critical load value were also investigated. The critical load value of LZ7C3 coating is larger than that of LZ coating, whereas both values of these two coatings are lower than that of the traditional coating material, i.e. 8wt% yttria stabilized zirconia (8YSZ). The micro-cracks formed in the scratch channel can partially release the stress in the coating and then enhance the adhesive strength of the coating. The width of the scratch channel and the surface spallation after...
2003-05-01
The 'Bataille' law gives orientations for nuclear waste management optimisation, which includes the partitioning of the most radio-toxic elements (the actinides and some fission products) in order to transmute them into less radio-toxic elements or to store for long term. For both applications a matrix with specific criteria is needed to incorporate the radionuclides. The aim of this work was the study of a potential matrix for the transmutation or the storage of actinides after their partitioning: pyrochlore zirconate, which general formula is A{sub 2}Zr{sub 2}O{sub 7}, where A is a lanthanide or a actinide. A fabrication process was developed leading to the production of neodymium zirconate with a density higher than 95 % of the theoretical density. The method of infiltration of active solution in an inactive precursor permitted to incorporate plutonium and uranium and to produce highly dense pellet with pyrochlore structure and general formula Nd{sub 1,57}Pu{sub 0,43}Zr{sub 2}O{sub 7+y}. Using three calorimetric techniques, the lanthanide zirconate heat capacity was measured in the temperature range [0.4 - 1400 K]. The thermal diffusivity of the neodymium zirconate was determined between 400 and 1400 K and its thermal conductivity was deduced in the same temperature range, yielding to the constant value of 1,33 W.m{sup -1}.s{sup -1}. Using this value, the thermal behaviour of a zirconate based fuel was numerically simulated. The radiation resistance of the neodymium zirconate was tested using ion implanted with several energy by accelerator in order to simulate fission products and alpha recoil atoms. Finally He ions were implanted in the matrix and their release was monitored using a Knudsen cell. Basis on all those results, it appears that pyrochlore zirconates could be used as inert matrix for the transmutation only as inclusions in composites. However, a complementary study of the compound behaviour against leaching is needed before to be able to conclude concerning it use as waste form for actinides storage. (author)
Molecular dynamics calculation of thermal expansion coefficient of a series of rare-earth zirconates
2009-01-01
To develop more reliable and stable thermal barrier coatings, low thermal conductivity materials with higher thermal expansion coefficients (TECs), like rare-earth zirconates (A2Zr2O7, A=La, Nd, Sm, Eu, Gd, Er, Yb and Lu), have been the focus of a great deal of attention in recent years. But the mechanisms underlying the values of TECs are still poorly understood. In this paper, the TECs of a series of rare-earth zirconates are calculated using molecular dynamics. Two typical crystal structures, pyrochlore and fluorite, are considered. By investigating the potential functions and the equilibrium-location deviations between the atoms, it is found that the Zr-O bond is the most important factor that determines the overall TECs, and the A-O bond plays a secondary role. However, O-O has little...
2009-01-01
Barium and strontium zirconates and niobates were prepared by means of an economic and ecologic aqueous solution-gel route with high compositional flexibility. The synthesis of precursor solutions and gels, and thermal analysis of the gels are presented. The crystallization of the different oxides was studied in situ using high-temperature X-ray diffraction measurements (HT-XRD). Zirconate crystallization was observed between 600degreeC and 700degreeC. Small amounts of Ba(II)- and Sr(II)-carbonate crystallized before the oxide did, and decomposed between 700degreeC and 800degreeC. More sensitive Fourier transform infrared spectra, showed that very small traces of carbonate remain at 900degreeC. The crystallization behavior of strontium niobates was strongly dependent on the Sr:Nb ratios, a...
2009-01-01
X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used to characterize NdxGd2-xZr2O7 (x=0, 0.6, 1.0, 1.4, and 2.0) solid solutions pressureless-sintered by using ceramic powders acquired by chemical-coprecipitation and calcination method. Heat capacity measurements were performed with a heat flux-type differential scanning calorimetry in the temperature range of 298.15-1050K. The heat capacity of NdxGd2-xZr2O7 solid solutions increases with increasing the concentration x of neodymium cations from x=0 to x=2.0 at identical temperature levels. At 298.15K, the heat capacities of Nd0.6Gd1.4Zr2O7, NdGdZr2O7 and Nd1.4Gd0.6Zr2O7 are 217, 220 and 224JK-1mol-1, respectively. Thermodynamic functions such as enthalpy increment, entropy and Gibbs energy functions were calculated from...
Preparation and properties of lithium silicates and zirconates ceramic blanket materials
1991-12-01
Three alternative methods for obtaining lithium compounds are compared - the synthesis of lithium orthosilicate and zirconates by sintering, the synthesis of hexalithium metasilicate from suspension, and low temperature plasma synthesis of lithium-enriched silicates. The present paper discuss the possibilities of obtaining ceramics discs using step-by-step heating and organic binders. The sintering process was computer controlled in order to fabricate ceramics with the desired properties. (orig.).
1987-01-01
Investigations of the reaction of Csl with excess ZrO/sub 2/ in various containers at 400-850/sup 0/C have successfully demonstrated the formation of Zrl/sub 4/ and Cs/sub 2/ZrO/sub 3/ in low yields (
X-ray spectra of some titanates and zirconates with the perovskite structure
1983-10-01
X-ray emission spectra of Ti, Zr and O in titanates of the ATiO/sub 3/ composition, where A=Cd, Ca, Sr, Pb, Ba, and in zirconates of the AZrO/sub 3/ composition, where A=Ca, Sr, Pb, Ba, are obtained. The spectra in oxides are compared with the spectra in the initial transition metals. For titanates, the similarity in the distribution of Ti occupied ds-states, and for zirconates, that of Zr p-states, is noted. The distribution of O p-states in all compounds considered is rather close.
Processing of antiferroelectric lead zirconates under hydrothermal conditions
2002-07-01
The hydrothermal conditions for the production of antiferroelectric PbZrO{sub 3} ceramics were theoretically studied by using a realistic thermodynamic model that predict optimized conditions of temperature, pressure, solution pH and input reagent concentrations. Experimental verification results showed that the thermodynamic calculations satisfactorily predict the synthesis conditions for which PbZrO{sub 3} are stable and can be obtained in a phase-pure form. (orig.)
Determination of strontium and lanthanum zirconates in YPSZ-LSM mixtures for SOFC
2008-01-01
Mixtures of 3% yttria- and partially-stabilized zirconia with LSMx (strontium-doped lanthanum manganite, x=0, 0.15 and 0.2) were prepared and heat treated at temperatures between 1000 and 1300degreeC to recreate the cathode-electrolyte interface interactions taking place during preparation and operation of solid oxide fuel cells (SOFC). Such interactions include the formation of La2Zr2O7 and SrZrO3, which are undesirable for SOFC. The effect of the manganese oxidation number on the mechanosynthesis of LSM during zirconate formation is also discussed. A quantitative analysis of zirconate formation by X-ray diffraction and Rietveld refinement was undertaken. Formation of lanthanum and strontium zirconates was completely avoided at temperatures as high as 1300degreeC by synthesizing lanthanum...
2008-01-01
The standard molar Gibbs free energies of formation of BaZrO3, and Ba2ZrO4 have been determined by solid-state galvanic cells involving a single crystal CaF2 as a solid-state electrolyte. The e.m.f. measurements were performed in the temperature range (1073 to 1273)K. The average values of the standard molar enthalpy and the standard molar entropy of formation in the temperature range covered by the e.m.f. measurements have been also estimated. The results have been compared with those obtained by other authors.
1996-06-19
This thesis aims to make a contribution to a better understanding of the chemical processes occurring during an ex-vessel MCCI accident with a western-type of nuclear reactor. Chosen is for a detailed thermochemical study of the silicates and zirconates of barium and strontium. In Chapter one a short introduction in the history of (research in) nuclear safety is given, followed by the state-of-the-art of molten core-concrete interactions in Chapter two. In both Chapters the role of chemical thermodynamics on this particular subject is dealt with. The experimental work on the silicates and zirconates of barium and strontium performed for this thesis, is described in the Chapters three, four, five, six, and parts of eight. In Chapter three the basis for all thermochemical measurements, the sample preparation is given. Because the sample preparation effects the accuracy of the thermodynamic measurements, a great deal of effort is spent in optimizing the synthesis of the silicates which resulted in the TEOS-method widely employed here. In the next Chapters the different thermochemical techniques used, are described: The low-temperature heat capacity measurements and the enthalpy increment measurements in Chapter four, the enthalpy-of-solution measurements in Chapter five, and measurements to determine the crystal structures in Chapter six. (orig.).
2007-07-25
The magmatic and metamorphic zircons were investigated with Raman spectrum microprobe analysis. We found notable differences between these two kinds of zircons exhibited by the variation trend of Raman peak intensity from core to rim of a crystal. In magmatic zircons, the intensity and the ratio H/W of Raman spectrum peaks gradually decrease from core to rim of a crystal, which is produced by an increase in metamictization degree and suggests an increase in U and Th concentrations from core to rim. In metamorphic zircons, there are two kinds of crystals according to their Raman spectra: the first group of zircons exhibits a variation trend opposite to those of magmatic zircons, tending to increase in the Raman peak intensity and H/W value from core to rim of a crystal, which is produced by a decrease in metamictization degree and indicates a decrease of U and Th concentrations from core to rim of a crystal. The second group of zircons exhibits no change in Raman peak intensity and H/W value through a crystal. The data of infrared and Raman spectra of these crystals show that they are well crystallized and have no lattice destruction induced by metamictization, and are thought to crystallize in high temperature stages of metamorphism. During these stages, the U and Th ions have been removed by metamorphic fluids from the parent rocks of these zircons. The other difference between magmatic and metamorphic zircons is the backgroun d level of their Raman spectra, which is high and sloped in magmatic zircons, but low and horizontal in metamorphic zircons. The differences between magmatic and metamorphic zircons can be used to identify the genesis of zircons and understand the origin and evolution history of their parent rocks.
2008-01-01
A novel ceramic fiber processing method by gelation of Na-alginate, a natural in noxious polymer, is reported. The ion exchange reaction between Na and Ca, and associated gelation process is utilized to fabricate lead zirconate titanate piezoelectric ceramic fibers using a Na-alginate based ceramic suspension. Effects of solid loading, viscosity of the starting sodium alginate and its amount in the slurry, and the chelator content were investigated as main parameters in obtaining uniform, dense fibers. Slurries with 64 wt% solid loading containing 1.0-1.5 wt% low or 0.5 wt% medium viscosity Na-alginate and 0.25-1.0 wt% chelator resulted in dense fibers with uniform shapes and dimensions. Electrical measurements taken from pellets prepared from reprocessed slurry and fibers indicate a decrease in the properties with increasing Na-alginate content of the slurry. ... >>
Review of the recent x-ray and neutron powder diffraction studies on lead zirconate titanate
2006-03-06
The issues related to the structure refinement of Pb(Zr$_x$Ti$_{1-x}$)O$_3$ (PZT) solid solutions are discussed. Particular attention is paid on the modelling of the co-existing phases in the vicinity of the morphotropic phase boundary (MPB), where local symmetry is often significantly lower than the average symmetry. As recent studies reveal, two-phase co-existence in the vicinity of the MPB is a thermodynamical necessity. Significantly different structural models for PZT with $x$ in the vicinity of the MPB have recently been published. Structural models, based on x-ray, neutron and electron diffraction studies, are reviewed and two essentially different approaches were identified: (i) a method where space group symmetry was decreased untill the features due to the local distortions were 'modelled' and (ii) a method where the highest space group symmetry compatible with the powder diffraction data was used together with a model for a local disorder. Related to the method (ii), the essential features of a model taking the $hkl$-dependent line broadening into account are summarized. The underlying theme is to consider how local regions, with symmetry lower than the average symmetry, should be modelled. Method (i) often introduces unjustified structural parameters and should be avoided. By studying the temperature and composition dependence of the structural parameters (and phase fractions in the case of the two phase samples) one can further test the proposed models. The connection between the structure and piezoelectric properties, with emphasis on the co-existence of the rhombohedral and monoclinic phases, is discussed in light of the recent first-principles computational studies. Also problems connected to sample preparation and data collection are pointed out.
2006-08-28
The results of the first investigations of the process of local decomposition of lead-lanthanum zirconate-titanate solid solution in the vicinity of the interphase boundaries separating domains of coexisting ferroelectric and antiferroelectric phases are presented. The solid solution with the composition: 6 at% of La, 73 at% of Zr, and 27 at% of Ti is considered. The kinetics of the local decomposition of this solid solution in the process of aging of samples quenched down to room temperature from the paraelectric phase is studied. The mechanisms that define the kinetics of the process of establishment of the equilibrium state of coexisting domains of ferroelectric and antiferroelectric phases are discussed.
Fixed points of zircon automorphisms
2007-03-16
A zircon is a poset in which every principal order ideal is finite and equipped with a so-called special matching. We prove that the subposet induced by the fixed points of any automorphism of a zircon is itself a zircon. This provides a natural context in which to view recent results on Bruhat orders on twisted involutions in Coxeter groups.
2007-07-25
Zircon can crystallize in a wide range of physical and chemical conditions. At the same time, it has very high stability and durability. Therefore zircon can grow and survive in a variety of geological processes. In addition, the diffusivity of chemical compositions in its crystal is very low. Consequently, we can trace back the evolution history of the planetary materials containing zircon by zircon U-Th-Pb geochronology and geochemistry studies. However, this depends on our ability to decipher its genesis, namely magmatic or metamorphic origins. In this paper, magmatic and metamorphic zircons were found from plagioclase-amphibolite samples. Their geneses have been determined by zircon morphology, chemical composition zonations and geological field setting combined with their zircon U-Th-Pb ages. We have found obvious differences in micro-scale Raman spectra between these magmatic and metamorphic zircons. The magmatic zircons exhibit a high sloping background in their Raman spectra, but the metamorphic zircons exhibit a low horizontal background in their Raman spectra, which suggest that the magmatic zircons may contain a much higher concentration of fluorescent impurities than the metamorphic zircons. Moreover, reverse variation trends in Raman spectrum peak intensities from core to rim of a crystal between the magmatic and metamorphic zircons have been found. We think that this can be attributed to their reverse chemical com position zonations. These differences can be used to distinguish magmatic and metamorphic zircons.
Vapor deposited samarium zirconate thermal barrier coatings
2009-01-01
The rare earth zirconates (M2Zr2O7, M=La→Gd) have a low intrinsic thermal conductivity and high temperature phase stability making them attractive candidates for thermal barrier coating applications. An electron-beam evaporation, directed-vapor deposition (EB-DVD) technique has been used to investigate the synthesis of Sm2Zr2O7 (SZO) coatings and to explore the relationships between the deposition conditions and the coating composition, structure, texture, pore morphology, and thermal conductivity. The coatings exhibited significant fluctuations in composition because of differences in the vapor pressures of the constituent oxides and had a metastable fluorite structure because kinetic limitations hindered the cation ordering needed to form the equilibrium pyrochlore structure. The growt...
Two Trends of Composition Variation of Zircons and Their Significance in Origin Discrimination
2007-07-25
Zircon can crystallize in a wide range of physical and chemical conditions. At the same time, it has very high stability and durability. Therefore zircon can grow and survive in a variety of geological processes. In addition, the diffusivity of chemical compositions in its crystal is very low. Consequently, we can trace back the evolution history of the planetary materials containing zircon by zircon U-Th-Pb geochronology and geochemistry studies. However, this depends on our ability to decipher its genesis,namely magmatic or metamorphic origins. In this paper, we have found that there are obvious differences between magmatic and metamorphic zircons in their chemical composition zonations. The magmatic zircons exhibit composition zonation of increasing HfO2, and (UO2 + ThO2) content and decreasing ZrO2/HfO2 ratio and ZrO2 content from inner to outer parts within each growth zone or from core to rim of a crysta1. The metamorphic zircons exhibit compositional variation trend opposite to that of magmatic (igneous) zircons,tending to decrease in HfO2, (UO2+ ThO2) and increase in ZrO2/HfO2 ratio and ZrO2 from core to rim of a crystal. These chemical composition variation trends are thought to be controlled by the crystal chemical features of ions themselves and the evolution trends of magmatism and metamorphism respectively, and can be used to identify the genesis of zircons. Their morphological features are also discussed.
Thermophysical Properties of Complex Rare-Earth Zirconate Ceramic for Thermal Barrier Coatings
2008-01-01
Two complex rare-earth zirconates (La0.4Sm0.5Yb0.1)2(Zr0.7Ce0.4)2O7.4 and (Sr0.1La0.3Sm0.5Yb0.1)2(Zr0.7Ce0.4)2O7.3 for thermal barrier coatings (TBCs) were synthesized by the coprecipitation method. Their phase composition, microstructure, and thermophysical properties were investigated. X-ray diffractometry results revealed that single-phase (La0.4Sm0.5Yb0.1)2(Zr0.7Ce0.4)2O7.4 and (Sr0.1La0.3Sm0.5Yb0.1)2(Zr0.7Ce0.4)2O7.3 with pyrochlore structure were prepared, and the scanning electron microscopy results showed that the microstructures of the products were dense and no other phases existed among the grains. With the temperature increasing, the thermal expansion coefficient (CTE) of the ceramics increased, while the thermal conductivity decreased. The results indicated that the CTE of (Sr...
Potentiometric determination of the Gibbs energies of formation of SrZrO{sub 3} and BaZrO{sub 3}
1995-08-01
The Gibbs free energies of formation of strontium and barium zirconates have been determined in the temperature range 960 to 1,210 K using electrochemical cells incorporating the respective alkaline-earth fluoride single crystals as solid electrolytes. Pure strontium and barium monoxides were used in the reference electrodes. During measurements on barium zirconate, the oxygen partial pressure in the gas phase over the electrodes was maintained at a low value of 18.7 Pa to minimize the solubility of barium peroxide in the monoxide phase. Strontium zirconate was found to undergo a phase transition from orthorhombic perovskite (o) with space group Cmcm; D{sub 2h}{sup 17} to tetragonal perovskite (t). Barium zirconate doe3s not appear to undergo a phase transition in the temperature range of measurement. It has the cubic perovskite (c) structure. The standard free energies of formation of the zirconates from their component binary oxides AO (A = Sr, Ba) with rock salt (rs) and ZrO{sub 2} with monoclinic (m) structures can be expressed by the relations described herein. The results of this study are in reasonable agreement with calorimetric measurements reported in the literature. Systematic trends in the stability of alkaline-earth zirconates having the stoichiometry AZrO{sub 3} are discussed. Both strontium and barium zirconates are formed in the fuel pins of nuclear reactors under normal operating conditions of temperature and oxygen chemical potential. High-temperature thermodynamic properties of the compounds are therefore needed for the evaluation of fuel-fission product interactions and are relevant to nuclear technology.
Compounds of rare-earth elements
1985-01-01
In this monograph information on zirconates, hafnates, niobates, tantalates, and antimonates of rare-earth elements is set forth according to the following order: phase diagrams, methods of obtaining the compounds, structure, and physical chemical properties. The monograph is intended for specialists in the fields of inorganic and physical chemistry, crystal chemistry and several areas of materials sciences. 100 tables.
Thermodynamic analysis for high burn-up fuel internal chemistry. 2
1998-09-01
Thermodynamic calculations with the computer program SOLGASMIX-PV have been performed for the chemical states expected in irradiated fast breeder reactor (FBR) fuels containing transuranium (TRU) elements. The analysis shows that A (alkali and alkaline-earth)-molybdates exist, but neither A-uranates nor A-zirconates are formed in FBR fuel pellets irradiated to high burn-up. And increase of oxygen potential in irradiated FBR fuel is ascribed to growing amount of rare earth, noble metal and TRU elements. (author)
Heat capacities and enthalpy increments of the metazirconates of calcium, strontium and barium
1996-03-25
The enthalpy increments of CaZrO{sub 3}(s) and SrZrO{sub 3}(s) have been measured by drop calorimetry from 475.6 to 845.6 K, and from 474.4 to 906.5 K, respectively. Some additional enthalpy increment measurements on BaZrO{sub 3}(s) have been performed from 804.3 to 899.30 K. The results are compared with other measurements on CaZrO{sub 3}(s), SrZrO{sub 3}(s) and BaZrO{sub 3}(s), and these are discussed critically. The heat capacity functions up to 2000 K for the three zirconates are presented
Phase formation along the PO 4 3â /Zr = 1.5â2.0 section of the ZrO(NO3)2-KF-H3PO4-H2O) system
2008-01-01
The phase composition of precipitates at 20°C along the PO 4 3â /Zr = 1.5â2.0 section at KF/Zr = 1â5 (mol/mol) of the ZrO(NO3)2-H3PO4-KF-H2O system has been investigated. Phases in these precipitates have been identified by X-ray powder diffraction, crystal-optical, chemical, and thermal analyses and by IR spectroscopy. The previously known potassium zirconates K3ZrF7 and K2ZrF6 have been revealed, and crystalline fluorophosphate zirconate K3Zr3F3(HPO4)3(PO4)2 and a phosphate nitrate of unknown formula have been obtained for the first time.
Proton conductivity and phase composition in BaZr{sub 0.9}Y{sub 0.1}O{sub 3-{delta}}
2004-03-15
In order to evaluate the feasibility of fuel cells with proton conducting solid-electrolyte ceramics, the proton conductivity of sintered samples of BaZr{sub 0.9}Y{sub 0.1}O{sub 3-{delta}} was measured with impedance spectroscopy. The processing parameters and stoichiometry strongly affect the proton conductivity of the material. Considerable analogy has been shown between doped cerates and doped zirconates.
2007-01-01
Formal [3+2] cycloaddition reactions between the bis-sulfonium zirconocene-ate dimer 1a and methylpropiolate, benzaldehyde and carbon disulfide afforded stable zwitterionic phosphonium zirconocene-ate complexes 2-4, respectively, with two orthocondensed five-membered heterocycles. X-ray crystal structure of 4 has been determined. Elemental chalcogens (S, Se, Te) gave rise also to a new variety of five-coordinate zirconium(IV) complexes (5-7) by a formal [3+1] cycloaddition reaction. In these bicyclic zirconates, sulfur is included in a five-membered ring while the second chalcogen is in a four-membered one.
1981-11-01
The precipitations of alkaline-earth metal hydroxoberyllates and zincates, hydroxochromates(III), ferrates(III), aluminates and gallates, hydroxotitanates, zirconates and stannates(IV) and hydroxoantimonates(V) from different aqueous solutions are surveyed. The relevant ionic equilibria (hydroxoanion formation, precipitation of hydroxosalts, amphoteric metal hydroxides and alkaline-earth metal hydroxides) that may influence these precipitations are examined. The crystalline phases precipitated from different systems are tabulated and precipitation mechanisms are analysed.
LSM-YSZ Reactions in Different Atmospheres
2009-01-01
The influences of the oxygen partial pressure and the LSM/YSZ ratio on the LSM-YSZ interface reactions at 1,000 °C were investigated. Both pellets and diffusion couples were employed in the study. The equilibrium thermodynamics of the LSM-YSZ reactions was clarified based on the pellet study-powder reaction. LSM reacts differently with YSZ in different atmospheres. In air, m-ZrO2 (monoclinic) is formed; while in N2, SrZrO3 and/or La2Zr2O7 are formed depending on the initial LSM/YSZ ratio. The reactions are reversible with varying P(O2) i.e. treating the sample in air after the heat treatment in N2 results in a decomposition of the formed La- and Sr-zirconates. The de-stabilisation of the LSM-YSZ interface under long-term annealing at 1,000 °C originates mainly from the inter-diffusion across the interface. Under reduced P(O2), the Mn diffusion from LSM into YSZ is enhanced. High P(O2) (0.21 atm) promotes the m-ZrO2 formation.
Thermal conductivity of plasma sprayed Sm2Zr2O7 coatings
2010-01-01
Rare-earth zirconates with a pyrochlore structure have been developed for potential application in thermal barrier coating systems to further improve the performance and durability of gas turbines. The Sm2Zr2O7 (abbreviated as SZ) powder was synthesized by solid state reaction and then deposited by air plasma spraying. The phase stability, microstructure and thermal conductivity of SZ and 8wt% Y2O3 stabilized zirconia (8YSZ) coatings were investigated. The X-ray diffraction results indicated that the crystal structure of the as-sprayed SZ coatings was defect-fluorite, and after heat treating at 1200^oC for 50h, it started to transform to pyrochlore, and the content of pyrochlore increased with increase in temperature of the heat treatment. The thermal conductivities of SZ coatings were sig...
2008-01-01
Fine-particle rare-earth metal zirconates Ln2Zr2O7 (Ln=La, Nd, Sm, Dy, Er) with cubic structure were prepared by stearic acid method. Zirconium nitrate and rare-earth nitrate were as raw materials, and stearic acid was used as solvent and dispersant. The as-prepared Ln2Zr2O7 nanocrystals were characterized by XRD, FT-IR, TEM and HRTEM. The results showed that the preparation temperature was lowered (from 1500degreeC to 800degreeC) and the reaction time was shortened (from at least 10h to 5h) by stearic acid method, compared with transitional solid-state method. The photocatalytic activity of Ln2Zr2O7 nanocrystals was evaluated by the photocatalytic degradation of methyl orange. With the increase of the atomic number, the photocatalytic activity trend of obtained Ln2Zr2O7 (Ln=La, Nd, Sm, Dy...
2008-01-01
Two lanthanide zirconates Ln2Zr2O7 (Ln=La and Nd) with pyrochlore structures were prepared by solid-state reaction at a relatively low temperature. The as-prepared Ln2Zr2O7 nanocrystals were characterized by XRD, FT-IR, TEM, HRTEM, EDS and BET. The as-obtained nanocrystals were composed of square-like particles with the average size of 20-50nm. The interplanar distances of d222 and d440 measured from the HRTEM images for La2Zr2O7 nanocrystals were 0.303nm and 0.185nm, respectively, coinciding with the theoretical values. The interplanar distance of d222 for Nd2Zr2O7 was 0.307nm. The La2Zr2O7 and Nd2Zr2O7 nanocrystals gave a relatively high value in surface area of 11.33m2/g and 3.48m2/g, respectively. Moreover, the photocatalytic activity was measured and the photodegraded amount of methyl...
2009-01-01
Thermodynamic simulations are performed in all areas of materials processing because of the advances that have taken place in computer software for complex non-ideal calculations, together with the increasing availability of evaluated data for different phases. In the present work, a thermodynamic model of electrolytic solutions was applied to determine the reaction conditions favoring the hydrothermal synthesis of the following electroceramics: zinc ferrites, sodium niobates, and lead zirconates. Stability and yield diagrams were constructed relating the equilibrium concentration of all of the aqueous and solid species as functions of temperature, pressure, pH, and input reagent concentrations. The theoretical predictions avoided the empirical trial-and-error method of synthesis and were ...
NOVEL CERAMIC MEMBRANE FOR HIGH TEMPERATURE CARBON DIOXIDE SEPARATION
2001-09-01
The Objective of this research program is to develop a dense, non porous ceramic membrane for separation of carbon dioxide from flue gas at high temperatures (400-600 C). The research has been focused on addressing several fundamental issues of lithium zirconate (Li{sub 2}ZrO{sub 3}). In the 2nd half research, we conducted various kinds of experiments to understand the CO{sub 2} sorption/desorption mechanism on the pure and modified Li{sub 2}ZrO{sub 3} with the help of TGA, DSC TGA and XRD. DSC TGA results suggest that the melting of Li/K carbonates mixture may play an important role in rapid CO{sub 2} sorption in the case of modified lithium zirconate. The CO{sub 2} desorption experiments show that CO{sub 2} desorption from the modified lithium zirconate follows the same mechanism as that from the pure lithium zirconate. This is different from the CO{sub 2} adsorption on the pure and modified lithium zirconates.
2007-01-01
We have synthesized a variety of alkali-metal and ammonium fluorosulfatometallates (titanates, zirconates, and hafnates). The alkali fluorosulfatozirconates and fluorosulfatohafnates have been shown to exhibit efficient roentgenoluminescence (RL) in the UV through visible spectral region, with a maximum at 390â440 nm. Their RL spectra depend significantly on their composition (cation, anion, and water content), coordination of KF and K2SO4, and relative amounts of fluorine and SO4 groups. We have examined the effect of heat treatment on the RL of these compounds. The rubidium and cesium fluorosulfatozirconates Rb3Zr2F9SO4 · 2H2O, Cs2ZrF2(SO4)2 · 2H2O, Cs8Zr4F2(SO4)11 · 16H2O, and Cs2ZrF4SO4 offer the most efficient RL.
Tricolor luminescence in rare earth doped CaZrO3 perovskite oxides
2009-01-01
Intense tricolor photoluminescence under ultraviolet excitation was observed from Eu-Mg codoped CaZrO3 and Tb-Mg codoped CaZrO3. The RGB tricolor was obtained from a single host lattice of perovskite-type CaZrO3 by just varying a doped rare earth ion and its concentration. Red luminescence was observed in Eu-Mg codoped CaZrO3, and green and blue luminescence was observed in Tb-Mg codoped CaZrO3. The color of the luminescence in Tb-Mg codoped CaZrO3 changed with Tb concentration due to the cross relaxation in Tb ions; green color was seen at high concentration and blue color at low concentration. In comparison with other perovskite host lattices, these zirconates showed more intense luminescence than hafnates and stannates. In addition, Mg codoping with the rare earth ions markedly increase...
2008-01-01
Detailed X-ray diffraction (XRD) analysis of two different Sr-doped LaFeO3 cathodes, YSZ electrolyte and two Sm/Gd-doped CeO2 interlayer and their mixtures were used to evaluate the formation of undesired secondary reaction compounds. The analysis of room temperature X-ray diffraction data of the mixtures indicates the crystallization of strontium and/or lanthanum zirconates between the cathode and the electrolyte materials and no detected reaction between the cathode and the interlayer materials. For all the ferrite mixtures a significant shift in the diffraction peaks is observed, which is the result of the unit cell volume expansion and contraction of the cathode (LSF) structures mixed with electrolyte (YSZ), and with interlayers (SDC, GDC), respectively. On the other hand, a complete s...
A method to remove Ammonia using a Proton-Conducting Ceramic Membrane
1999-09-22
An apparatus and method for decomposing NH{sub 3}. A fluid containing NH{sub 3} is passed in contact with a tubular membrane that is a homogeneous mixture of a ceramic and a first metal, with the ceramic being selected from one or more of a cerate having the formula of M' Ce{sub 1-x} M''O{sub 3-{delta}}, zirconates having the formula M'Zr{sub 1-x} M''3-{delta}, stannates having the formula M'Sn{sub 1-x}M''O{sub 3}-{delta}, where M' is a group IIA metal, M'' is a dopant metal of one or more of Ca, Y, Yb, In, Nd, Gd or mixtures thereof and {delta} is a variable depending on the concentration of dopant and is in the range of from 0.001 to 0.5, the first metal is a group VIII or group IB element selected from the group consisting of Pt, Ag, Pd, Fe, Co, Cr, Mn, V, Ni, Au, Cu, Rh, Ru and mixtures thereof. The tubular membrane has a catalytic metal on the side thereof in contact with the fluid containing NH{sub 3} which is effective to cause NH{sub 3} to decompose to N{sub 2} and H{sub 2}. When the H{sub 2} contacts the membrane, H{sup +} ions are formed which pass through the membrane driving the NH{sub 3} decomposition toward completion.
First principles Candu fuel model and validation experimentation
2007-01-01
Many modeling projects on nuclear fuel rest on a quantitative understanding of the co-existing phases at various stages of burnup. Since the various fission products have considerably different abilities to chemically associate with oxygen, and the O/M ratio is slowly changing as well, the chemical potential (generally expressed as an equivalent oxygen partial pressure) is a function of burnup. Concurrently, well-recognized small fractions of new phases such as inert gas, noble metals, zirconates, etc. also develop. To further complicate matters, the dominant UO2 fuel phase may be non-stoichiometric and most of minor phases have a variable composition dependent on temperature and possible contact with the coolant in the event of a sheathing defect. A Thermodynamic Fuel Model to predict the phases in partially burned Candu nuclear fuel containing many major ... >>
http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=117467
Inherited zircons in Cenozoic sedimentary and igneous rocks of East Java range in age from Archean to Cenozoic. Thedistribution of zircons reveals two different basement types at depth. The igneous rocks of the Early Cenozoic arc, found along thesoutheast coast, contain only Archean to Cambrian zircons. In contrast, clastic rocks of north and west of East Java containCretaceous zircons, which are not found in the arc rocks to the south. The presence of Cretaceous zircons supports previousinterpretations that much of East Java is underlain by arc and ophiolitic rocks, accreted to the Southeast Asian margin duringCretaceous subduction. However, such accreted material cannot account for the older zircons. The age populations of Archean toCambrian zircons in the arc rocks are similar to Gondwana crust. We interpret the East Java Early Cenozoic arc to be underlain by acontinental fragment of Gondwana origin and not Cretaceous material as previously suggested. Melts rising through the crust,feeding the Early Cenozoic arc, picked up the ancient zircons through assimilation or partial melting. We suggest a WesternAustralian origin for the fragment, which rifted from Australia during the Mesozoic and collided with Southeast Asia, resulting inthe termination of Cretaceous subduction. Continental crust was therefore present at depth beneath the arc in south Java whenCenozoic subduction began in the Eocene. 2007 Elsevier B.V. All rights reserved. Publisher: Department of Applied Geology Other identifier: PUB-SE-DAG-NET-44058
Electrolytic preparation of high dielectric thin films
Electrolytic formation techniques for high dielectric materials in thin films - barium salts - titanate, zirconate, and niobate
http://hdl.handle.net/1959.14/64944
U–Pb isotopic ages and Hf isotope compositions by laser microprobe ICPMS and MC-ICPMS can be useful in identifying detrital zircons derived from juvenile continental sources. Hf isotopes in detrital zircons from modern river deposits in Brazil, Australia, India and the Ukraine show evidence for production of juvenile crust at about 2.5 Ga. However, if detrital zircon populations in the 2.4–2.2 Ga time window are representative of the proportion of juvenile crust in their primary sources, they yield little evidence for significant volumes of juvenile crust of this age. Hf isotopic compositions of detrital zircons from the Ukraine and eastern Australia also record production of juvenile continental crust between 1.65 and 1.40 Ga. Zircons from granitoids in south-central Laurentia and in western Brazil have EHf(T) values that fall near the depleted mantle growth curve recording production of juvenile continental crust in these regions between 1.5 and 1.3 Ga. Although Hf isotope compositions of detrital zircons can be useful in identifying detrital zircons derived from juvenile continental sources, the results do not necessarily equate to the volume of juvenile continental crust produced during specific time intervals.59 page(s) Publisher: Elsevier Science Relation: Precambrian research, Vol. 139, Issue 1-2, p.42-100; 10.1016/j.precamres.2005.04.006 Other identifier: ISSN:0301-9268; mq-rm-2005002236 Language: eng
http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=19482
Quantitative microstructural analysis of zircon using electron backscatter diffraction (EBSD) requires a comparison of empirically collected electron backscatter patterns with theoretical patterns or ?match units? derived from known crystallographic parameters. There are 23 possible crystallographic data sets for zircon, and associated match units, derived from natural and synthetic zircon and from theoretical calculations over a range of pressures and different rare earth element (REE) compositions. A systematic assessment of these match units has been undertaken by EBSD analysis of each of four zircons from a range of geological environments combined with principal components analysis and self-organizing map networks. Comparison of the different match units shows a systematic relationship across all samples that is related to changes in unit cell dimensions associated with pressure and compositional variations. Systematic variations in the data generated from 96 EBSD maps, each comprising 10,000 electron backscatter patterns, indicate that match units associated with increasing pressure or REE dopants yield poorer quality EBSD data. The match units from low pressure, undoped, natural zircon consistently yield the best EBSD results, and are recommended for natural zircon EBSD studies irrespective of the zircon source or U content. The results provide a clear strategy for optimizing the acquisition and analysis of EBSD data from zircon from both crustal and mantle sources. In addition, the developed approach to match unit analysis may be applied to all other crystalline materials, potentially optimizing EBSD analyses from a range of materials. Publisher: Department of Applied Geology Other identifier: PUB-SE-DAG-SMR-42210; EPR-2626
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SHRIMP U-Pb ages have been obtained for zircon in granitic gneisses from the aureole of the Rogaland anorthosite-norite intrusive complex, both from the ultrahigh temperature (UHT; >900 C pigeonite-in) zone and from outside the hypersthene-in isograd. Magmatic and metamorphic segments of composite zircon were characterised on the basis of electron backscattered electron and cathodoluminescenceimages plus trace element analysis. A sample from outside the UHT zone has magmatic cores with an age of 1034 + or- 7 Ma (2r, n= 8) and 1052 + or - 5 Ma (1r, n=1) overgrown by M1 metamorphic rims giving ages between 1020 + or- 7 and 1007 + or - 5 Ma. In contrast, samples from the UHT zone exhibitfour major age groups: (1) magmatic cores yielding ages over 1500 Ma (2) magmatic cores giving ages of 1034 + or - 13 Ma (2r, n=4) and 1056 + or - 10 Ma (1r, n=1) (3) metamorphic overgrowths ranging in age between 1017 + or - 6 Ma and 992 + or - 7 Ma (1r) corresponding to the regional M1 Sveconorwegiangranulite facies metamorphism, and (4) overgrowths corresponding to M2 UHTcontact metamorphism giving values of 922 + or - 14 Ma (2r, n=6). Recrystallized areas in zircon from both areas define a furtherage group at 974 + or - 13 Ma (2r, n=4). This study presents the first evidence from Rogaland for newgrowth of zircon resulting from UHT contact metamorphism. More importantly, it shows the survival of magmatic and regional metamorphic zircon relics in rocks that experienced a thermal overprint of c.950 C for at least 1 Myr. Magmatic and different metamorphic zones in the same zircon are sharply bounded and preserve original crystallization age information, a result inconsistent with some experimental data on Pb diffusion in zircon which predict measurable Pb diffusion under suchconditions. The implication is that resetting of zircon ages by diffusion during M2 was negligible in thesedry granulite facies rocks. Imaging and Th/U-Y systematics indicate that the main processes affecting zircon were dissolution-reprecipitation in a closed system and solid-state recrystallization during andsoon after M1. Publisher: Department of Imaging and Applied Physics Other identifier: PUB-ESC-DAP-SA-14629
http://hdl.handle.net/1959.14/66567
A detailed in situ isotopic (U–Pb, Lu–Hf) and geochemical study of zircon populations in a composite sequence of foliated to massive Cambro-Ordovician intrusions in the Deep Freeze Range (North Victoria Land, Antarctica), has highlighted great complexity in zircon systematics. Zircons in deformed granitoids and tonalites display complex internal textures, a wide spread of concordant U–Pb ages (between 522 and 435 Ma) and unusual trace-element compositions (anomalous enrichment of light rare earth elements, U, Th and Y) within single zircon grains. In contrast, zircons from undeformed samples display a limited range of U–Pb ages and trace-element compositions. Zircons from all age and textural populations in most of the deformed and undeformed samples show a relatively narrow range of ∊Hf values, suggesting that the Lu–Hf system remained undisturbed. Inferred emplacement ages cover a time interval of about 30 Myr: from 508 to 493 Ma for the oldest strongly foliated synkinematic Howard Peaks megacrystic monzogranites and high-K calc-alkaline mafic to intermediate rocks of the ‘Corner Tonalite’ unit; from about 489 to 481 Ma for the younger massive shoshonitic mafic dyke suite and the high-K calc-alkaline Keinath granite. The observed isotopic and chemical variations in zircon are attributed to a sub-solidus recrystallization under hydrous conditions and varying temperature, in a setting characterized by a transpressional to extensional stress regime.38 page(s) Publisher: Oxford University Press Relation: Journal of petrology, Vol. 48, Issue 2, p.327-364; 10.1093/petrology/egl064 Other identifier: ISSN:1460-2415; mq-rm-2007001014 Language: eng
http://hdl.handle.net/1959.14/67159
This paper reports new developments in in situ U–Pb zircon geochronology using 266 and 213 nm laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS). Standard spot ablation (spot diameters 40–80 μm) was employed, with no sampling strategies employed specifically to minimise elemental fractionation. Instead, He ablation gas and carefully replicated ablation conditions were employed to maintain constant ablation-related elemental fractionation of Pb and U between analyses. Combining these strategies with calibration on a new zircon standard (GJ-1) allows elemental fractionation and instrumental mass bias to be corrected efficiently, and accurate ²⁰⁶Pb/²³⁸U and ²⁰⁷Pb/²³⁵U ratios to be measured with short-term precision (2 r.s.d.) of 1.9% and 3.0%, respectively. Long-term precision (2 r.s.d.) of the technique (266 nm ablation), based on 355 analyses of the 91500 zircon (1065 Ma) standard over more than a year, was 3.8%, 4.0% and 1.4% for the ²⁰⁶Pb/²³⁸U, ²⁰⁷Pb/²³⁵U and ²⁰⁷Pb/²⁰⁶Pb ratios, respectively. Long-term precision (2 r.s.d.) for the ²⁰⁶Pb/²³⁸U, ²⁰⁷Pb/²³⁵U and ²⁰⁷Pb/²⁰⁶Pb ratios of the Mud Tank zircon (732 Ma) was 3.9%, 4.1% and 1.7%, respectively (359 analyses). Selective integration of time-resolved signals was used to minimise the effect of Pb loss and common Pb enrichments on the measured ages. The precision and accuracy of our data compare very favourably with those obtained using more involved procedures to correct or minimise ablation- and ICP-MS-induced biases. 213 nm laser ablation produced comparable precision to 266 nm ablation using generally smaller spot sizes (40–50 vs. 60–80 μm), and offered significant advantages in terms of ablation duration and stability, particularly for small zircons (<60 μm). For the 91500 zircon, but not the Mud Tank zircon, 213 nm ablation also produced significantly older and more accurate Pb/U ages. This suggests that shorter wavelength ablation may have reduced a matrix-dependent elemental fractionation difference between sample and standard. The accuracy and precision of the technique for young zircons are demonstrated by analysis of three zircon populations ranging in age from 417 to 7 Ma. In each case, the zircons have yielded concordant ages or common Pb discordia which give concordia intercept ages that are in agreement with independently determined ages for the same samples. Application of Tera–Wasserburg diagrams [Earth Planet. Sci. Lett. 14 (1972) 281] was found to be the most useful approach to handling common Pb contributions that were not removed by selective integration of signals.23 page(s) Publisher: Elsevier Science Relation: Chemical geology, Vol. 211, Issue 1-2, p.47-69; 10.1016/j.chemgeo.2004.06.017 Other identifier: ISSN:1872-6836; mq-rm-2004020685 Language: eng
http://hdl.handle.net/1959.14/65587
Field relations and whole-rock geochemistry indicate that magma mixing has been important in the genesis of the late Mesozoic I-type igneous complexes at Pingtan and Tonglu in SE China. Morphological and trace-element studies of zircon populations in rocks from each of these complexes have defined several distinct growth stages [Mineral. Mag. (2001)]. In-situ LAM-MC-ICPMS microanalysis shows large variations in ¹⁷⁶Hf/¹⁷⁷Hf (up to 15 εHf units) between zircons of different growth stages within a single rock, and between zones within single zircon grains (up to 9 εHfHf units). These variations suggest that each of the observed magmas in both complexes developed through hybridisation of ≥2 magmas with different sources. Although this mixing has produced similar Sr and Nd isotopic compositions in the different rock types of each complex, the zircons have functioned as “tape recorders” and have preserved details of the assembly of the different magmas. In the Tonglu complex the most primitive magma is a mafic monzonite (preserved as enclaves), whose isotopic composition suggests derivation from the lower crust; rhyodacites, rhyolites and quartz diorites reflect the mixing of the monzonite with ≥2 more felsic magmas, derived from older crustal materials. In the Pingtan complex, zircons in a quartz diorite enclave suggest mixing between a crustal magma and a more primitive mantle-derived component. Zircons from granites and granodiorite enclaves indicate mixing between the quartz diorite and more felsic melts with lower ¹⁷⁶Hf/¹⁷⁷Hf. Major changes in ¹⁷⁶Hf/¹⁷⁷Hf correlate with discontinuous changes in the trace-element composition and morphology of the zircons, in particular the development of sector zoning that suggests rapid disequilibrium crystallisation. We suggest that the magma mixing recorded by the changes in ¹⁷⁶Hf/¹⁷⁷Hf occurred during transport in magma conduits. The in-situ analysis of Hf-isotopic stratigraphy in zircons is a new and powerful tool for the detailed study of magma generation processes.33 page(s) Publisher: Elsevier Relation: Lithos, Vol. 61, Issue 3-4, p.237-269; 0.1016/S0024-4937(02)00082-8 Other identifier: ISSN:1872-6143; mq-rm-2002014634 Language: eng
Energetics of intrinsic point defects in ZrSiO$_4$
2004-10-28
Using first principles calculations we have studied the formation energies, electron and hole affinities, and electronic levels of intrinsic point defects in zircon. The atomic structures of charged interstitials, vacancies, Frenkel pairs and anti-site defects are obtained. The limit of high concentration of point defects, relevant for the use of this material in nuclear waste immobilization, was studied with a variable lattice relaxation that can simulate the swelling induced by radiation damage. The limit of low concentration of defects is simulated with larger cells and fixed lattice parameters. Using known band offset values at the interface of zircon with silicon, we analyze the foreseeable effect of the defects on the electronic properties of zircon used as gate in metal-oxide-semiconductor devices.
http://hdl.handle.net/1959.14/68165
The first in situ Hf and U-Pb isotope analyses of zircon separates from Mesozoic granites in southern Tibet identify a significant, previously unknown stage of magmatism. Igneous zircons (n = 34) from a granite within the Gangdese batholith show a weighted mean ²⁰⁶Pb/²³⁸U age of 188.1 ± 1.4 Ma and εHf(T) (the parts in 10⁴ deviation of initial Hf isotope ratios between the zircon sample and the chondritic reservoir) values between +10.4 and +16.8, suggesting predominantly Early Jurassic intrusive activity with a juvenile mantle contribution. Of 40 inherited zircons from two Cretaceous S-type granites in the northern magmatic belt, 23 delineate a slightly older ²⁰⁶Pb/²³⁸U age cluster between 188 and 210 Ma. These zircons have εHf(T) values from −3.9 to −13.7, yielding crustal Hf model ages from ca. 1.4 to 2.1 Ga, suggesting a major episode of crustal growth in Proterozoic time and remelting of this crust in Early Jurassic time. Combining these with literature data, we interpret the Jurassic Gangdese magmatism as an early product of the Neo-Tethyan subduction that played a long-lasting role in the tectonic evolution of southern Tibet prior to the India-Asia collision.4 page(s) Publisher: Geological Society of America Relation: Geology, Vol. 34, Issue 9, p.745-748; 10.1130/G22725.1 Other identifier: ISSN:0091-7613; mq-rm-2006000157 Language: eng
http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=118154
Geochemical and geochronological studies of zircon are commonly supplemented by cathodoluminescence (CL) imaging because it provides a means of recognizing different generations of zircon growth at high-spatial resolution. Crystal-plastic deformation of zircon can have significant effects on zircon geochemistry. Detailed analyses from electron backscatter diffraction mapping combined with panchromatic CL imaging and hyperspectral CL mapping of several crystal-plastically deformed grains from different geological settings are used to establish the relationships between crystal-plastic deformation and CL in zircon. Results show a strong spatial association between deformation microstructures and CL response that lead to modification of CL that commonly cross-cuts primary zoning. Variable contributions from two fundamental deformation-related processes result in a variety of CL characteristics: A defect control on panchromatic CL intensity, particularly at low-angle (subgrain) boundaries; and changes in spectral CL response due to deformation-related modification of CL-active REE geochemistry. A framework is provided for the recognition of deformation-related microstructures using CL and the usefulness of CL imaging in the discrimination of these microstructures is critically evaluated. Publisher: Department of Applied Geology Other identifier: PUB-SE-DAG-NET-48266
http://espace.library.curtin.edu.au:80/R/?func=dbin-jump-full&object_id=20072
Avast sequence of quartz-rich sandstonewas deposited overNorth Africa and Arabia during Early Palaeozoic times, in the aftermath of Neoproterozoic Pan-African orogeny and the amalgamation of Gondwana. This rock sequence forms a relatively thin sheet (1-3 km thick) that was transported over a very gentle slope and deposited over a huge area. The sense of transport indicates unroofing of Gondwana terranes but the exact provenance of the siliciclastic deposit remains unclear. Detrital zircons from Cambrian arkoses that immediately overlie the Neoproterozoic Arabian-Nubian Shield in Israel and Jordan yielded Neoproterozoic U-Pb ages (900-530 Ma), suggesting derivation from a proximal source such as the Arabian-Nubian Shield. A minor fraction of earliest Neoproterozoic and older age zircons was also detected. Upward in the section, the proportion of old zircons increases and reaches a maximum (40%) in the Ordovician strata of Jordan. The major earliest Neoproterozoic and older age groups detected are 0.95-1.1, 1.8-1.9 and 2.65-2.7 Ga, among which the 0.95-1.1 Ga group is ubiquitous and makes up as much as 27% in the Ordovician of Jordan, indicating it is a prominent component of the detrital zircon age spectra of northeast Gondwana. The pattern of zircon ages obtained in the present work reflects progressive blanketing of the northern Arabian-Nubian Shield by Cambrian?Ordovician sediments and an increasing contribution from a more distal source, possibly south of the Arabian-Nubian Shield. The significant changes in the zircon age signal reflect many hundreds of kilometres of southward migration of the provenance. Publisher: John de Laeter Centre for Mass Spectrometry (COE) Other identifier: EPR-1507
Phonocardiograph microphone is rugged and moistureproof
Microphone used as a phonocardiograph transducer monitors small amplitude audio signals in the presence of large shock loads and high humidity. It contains a lead zirconate-lead titanate piezoelectric plate encapsulated in a ...
http://hdl.handle.net/1959.14/68168
A database of > 600 analyses of the zircon “standard” Harvard 91500 shows considerable heterogeneity in ¹⁷⁶Hf/¹⁷⁷Hf; the distribution is essentially bimodal with major peaks at 0.282284 ± 22 and 0.282330 ± 29 (2σ). Although the zircon shows a wide range of ¹⁷⁶Yb/¹⁷⁷Hf and ¹⁷⁶Lu/¹⁷⁷Hf, there is no correlation of ¹⁷⁶Hf/¹⁷⁷Hf with either parameter. This isotopic heterogeneity limits the degree to which 91500 can be used to evaluate the precision or accuracy of different treatments of mass bias and overlap corrections for in situ analysis of Hf-isotope compositions in zircons, or differences between solution and in situ data.6 page(s) Publisher: Elsevier Science Relation: Chemical geology, Vol. 233, Issue 3-4, p.358-363; 10.1016/j.chemgeo.2006.03.007 Other identifier: ISSN:0009-2541; mq-rm-2006000150 Language: eng
Dielectric measurements of selected ceramics at microwave frequencies
Dielectric measurements of strontium titanate and lead titanate zirconate ceramics are conducted at microwave frequencies using a cylindrical resonant cavity in the TE(sub 011) mode. The perturbations of the electric field ...
http://hdl.handle.net/1959.14/67900
In situ laser ablation inductively coupled plasma mass spectrometry analysis of trace elements, U-Pb ages and Hf isotopic compositions of magmatic zircon from I- and S-type granitoids from the Lachlan Fold Belt (Berridale adamellite and Kosciusko tonalite) and New England Fold Belt (Dundee rhyodacite ignimbrite), Eastern Australia, is combined with detailed studies of crystal morphology to model petrogenetic processes. The presented examples demonstrate that changes in zircon morphology, within single grains and between populations, generally correlate with changes in trace element and Hf-isotope signatures, reflecting the mixing of magmas and changes in the composition of the magma through mingling processes and progressive crystallization. The zircon data show that the I-type Kosciusko tonalite was derived from a single source of crusta lorigin, whereas the S-type Berridale adamellite had two distinct sources including a significant I-type magma contribution. Complex morphology and Hf isotope variations in zircon grains indicate a moderate contribution from a crustal component in the genesis of the I-type Dundee rhyodacite. The integration of data on morphology, trace elements and Hf isotope variations in zircon populations provides a tool for the detailed analysis of the evolution of individual igneous rocks; it offers new insights into the contributions of different source rocks and the importance of magma mixing in granite petro-genesis. Such information is rarely obtainable from the analysis of bulk rocks.25 page(s) Publisher: Oxford University Press Relation: Journal of petrology, Vol. 47, Issue 2, p.329-353; 10.1093/petrology/egi077 Other identifier: ISSN:1460-2415; mq-rm-2006000108 Language: eng
http://handle.unsw.edu.au/1959.4/41327
Preserving the anatase phase of TiO2 is of interest due to the photocatalytic activity of this phase, which is generally considered superior to rutile Ti02 due to a higher surface area. The retardation of the anatase to rutile transition through the use of low cost dopants, zircon and bauxite, was investigated. Pressed powder compacts of anatase TiO2 doped with varying levels of bauxite and zircon powders were fired at 1025°C for durations of 2, 3 and 4 hours. X-ray diffraction analysis, Scanning electron microscopy, Energy dispersive X-ray spectroscopy and Raman spectroscopy were used to evaluate the effect these dopants have on the transition to rutile. It was found that both zircon and bauxite retard the transition to rutile in the solid state. Increasing the level of bauxite dopant consistently increases the preservation of the anatase phase. It was found that at levels of bauxite doping over 5 wt%, over 90% of the anatase phase is retained through 2 hour firing cycles. Using EDS, zircon particles were observed to nucleate elongated prismatic rutile grains. Whilst XRD analysis showed that the addition of zircon has a marked effect on retarding the overall transition of anatase to rutile, increasing levels of this dopant over 2.5% brings about a reduction in preserved anatase, probably due to increased rutile nucleation. Findings showed Samples doped with 2.5% ZrSi04 retained approximately 95% anatase through 2 hour firing cycles. Publisher: Awarded by:University of New South Wales. Materials Science & Engineering Relation: SHELF:T/2008/83 (Ask at Level 2 Information Desk, UNSW Library) Other identifier: unsworks:5515 Language: EN Rights: Copyright Hanaor Dorian Amir Henry.; http://unsworks.unsw.edu.au/copyright
http://hdl.handle.net/1959.14/66566
The Gungwania and Talala kimberlitic pipes on the Kundelungu Plateau (Katanga, SE Congo) have been used as drillholes, to obtain crustal zircons for a study of crustal evolution in the region and to constrain the age of the basement and the sedimentary provenance of the Katangan Supergroup. Two hundred and twenty-nine zircon grains were analysed for U–Pb ages and Hf-isotope compositions. Juvenile Mesoarchean (~3.4–3.3 Ga) crust in the region underwent recycling during Neoarchean and Paleoproterozoic time. The Paleoproterozoic event involved little production of juvenile crust, and this Paleoproterozoic crust was recycled during Mesoproterozoic and Neoproterozoic time. Both the Mesoproterozoic and Neoproterozoic were characterised by bimodal magmatism reflecting extension, linked with the break up of Rodinia and the opening of the Katangan basin, and the development of juvenile crust. Detailed studies of the external morphology of the zircons in different age groups suggest that the basement beneath the Kundelungu region is predominantly Paleoproterozoic in age; other zircon populations may be derived from the Katangan sediments. The absence of any zircons younger than 560 Ma supports deposition of the Biano Subgroup, which hosts the kimberlites, during the Pan-African Lufilian orogeny. The Archean Congo and Zimbabwe cratons, the Paleoproterozoic Ubendian Belt (Bangweulu Block), the Paleo-to-Mesoproterozoic Irumide Belt, the Mesoproterozoic Kibaran Belt and the Choma Kalomo Block may all have contributed material to the sediments of the Katangan Supergroup.31 page(s) Publisher: Elsevier Relation: Precambrian research, Vol. 156, Issue 3-4, p.195-225; 10.1016/j.precamres.2007.04.002 Other identifier: ISSN:0301-9268; mq-rm-2007001078 Language: eng
http://hdl.handle.net/1959.14/65627
The Pingtan and Tonglu igneous complexes in SE China are typical of the calc-alkaline series developed at active continental margins. These two complexes are dominated by felsic rocks, temporally and spatially associated with minor mafic rocks. Morphological and trace-element studies of zircon populations in rocks from each of these complexes show that the zircon populations may be divided into 3 - 4 distinct growth stages, characterized by different distributions of morphological indices (Ipr, Ipy and Iel), and different contents of the substituting elements (Hf, U, Th, Y and P). The four growth stages recognized in the zircons are believed to have formed successively in the magma chamber, during the emplacement, and in the early and later stages of magma consolidation, respectively. All four stages are recognized in the plutonic Pingtan complex, whereas the stages 3 and 4 are less developed in the volcanic/subvolcanic Tonglu complex. Based on the chemistry and morphology of the different zircon populations of the Pingtan and Tonglu complexes, it is suggested that basaltic magmas underplating at the boundary between crust and mantle caused partial melting of the mid-lower crust and produced granitoid magmas. Subsequently, mixing between magmas was important.17 page(s) Publisher: Mineralogical Society Relation: Mineralogical magazine, Vol. 66, Issue 2, p.235-251; 10.1180/0026461026620025 Other identifier: ISSN:1471-8022; mq-rm-2002014321 Language: eng
http://hdl.handle.net/2440/13632
In order to draw attention to the effectiveness of the single-grain evaporation technique of Pb-Pb zircon dating, this method has been applied to the Charleston Granite, a Mesoproterozoic granitoid from the South Australian Gawler Craton. The granite has previously been dated by both conventional and SHRIMP U-Pb techniques permitting comparison of the relative advantages of all three techniques. The date obtained by the evaporation technique for the crystallisation of the main magmatic phase of zircon was 1581 ± 4 Ma (2σ) which is the same within error as the SHRIMP result of 1585 ± 5 Ma (2σ). Other identifier: Australian Journal of Earth Sciences, 1996; 43 (2):133-137; 0812-0099; 0019965608; 10.1080/08120099608728242 Language: en_US
http://hdl.handle.net/1959.14/66569
The use of in situ Hf-isotope analysis of zircon allows a more detailed evaluation of magma-generation processes than the analysis of whole-rock isotopic systems, and is a powerful tool for studying crustal evolution. Detrital zircon grains have been analysed by in situ LAM-ICPMS and LAM-MC-ICPMS for U-Pb ages, trace element patterns and Hf-isotope composition to evaluate patterns of magma genesis and crustal evolution in the central part of the Precambrian Georgetown Inlier, North Queensland, Australia. Archean zircons and low ∊Hf in Proterozoic and Phanerozoic magmatic zircons provide direct evidence for the existence of Archean crustal components in the Georgetown Inlier, although the surface geology is dominated by Mesoproterozoic basement rocks and Palaeozoic granitoids. Crustal evolution in the Georgetown Inlier has involved at least three stages of heating and granitoid magmatism, possibly associated with basaltic magma underplating and/or overplating (1545–1585 Ma, 420 Ma and 340 Ma). In general, granitoids with high ∊Hf are typical of the Percyvale area, closest to the Phanerozoic Tasman Fold Belt, and may reflect thinner and younger crust. Granitoids with less radiogenic Hf-isotope compositions are typical of the Einasleigh and Mount Surprise areas in the central part of the Inlier, and may reflect the presence of older and thicker crust. The most significant juvenile additions to the crust after Archean time occurred in the Einasleigh and Mount Surprise areas during Mesoproterozoic time and in the Percyvale area during Carboniferous time. In the Mount Surprise area, resorbed zircon cores of Mesoproterozoic age are overgrown by magmatic rims of Siluro–Devonian age. Similarities in the Hf-isotope composition of core-rim pairs suggest that the large range in ∊Hf observed in zircons from Siluro–Devonian granitoids reflects remelting of a heterogeneous 1545–1585 Ma old crust, rather than mixing between juvenile and crustal sources. Crustal remelting has been the main process responsible for the production of granitoid magmas in the Georgetown Inlier. However, minor addition of mantle-derived material may have occurred during both Mesoproterozoic and Carboniferous time. Similarities and differences in the crustal evolution of the Mt Isa, Broken Hill and Georgetown blocks suggest that the Proterozoic history of the Australian continental margin involved the accretion and subsequent dispersal of individual, originally Archean, microcontinents.21 page(s) Publisher: Elsevier Relation: Chemical geology, Vol. 245, Issue 3-4, p.198-218; 10.1016/j.chemgeo.2007.08.001 Other identifier: ISSN:0009-2541; mq-rm-2007001013 Language: eng
2003-07-12
Structural, magnetic and ferromagnetic resonance characterization studies have been performed on lay-ered ferromagnetic-ferroelectric oxides that show strong magnetoelectric coupling. The samples contained thick films of ferrites or substituted lanthanum manganites for the ferromagnetic phase and lead zirconate titanate for the ferroelectric phase, and were sintered high temperatures. Results indicate defect free ferrites, but deterioration of manganite parameters due to diffusion at the interface and accounts for poor magnetoelectric coupling in manganite-PZT samples.
High-Pressure Induced Structural Phase Transition in CaCrO4: Evidence from Raman Scattering Studies
2005-06-06
Raman spectroscopic studies have been carried out on CaCrO4 under pressure up to 26GPa at ambient temperature. The Raman spectra showed CaCrO4 experienced a continuous structural phase transition started at near 6GPa, and finished at about 10GPa. It is found that the high-pressure phase could be quenched to ambient conditions. Pressure dependence of the Raman peaks suggested there existed four pressure regions related to different structural characters. We discussed these characters and inferred that the nonreversible structural transition in CaCrO4, most likely was from a zircon-type (I41/amd) ambient phase to a scheelite-type high pressure structure (I41/a).
2009-01-01
X-Ray diffraction investigations were made of high-quality epitaxial thin films of the ferroelectric material lead zirconate titanate, PbZr0.2Ti0.8O3 (PZT), grown by pulsed laser deposition (PLD). Layers from 7 to 200 nm in thickness were studied, deposited on a 30 nm SrRuO3 (SRO) electrode on a [001] oriented SrTiO3 (STO) substrate. The out-of-plane lattice parameters of the PZT films were measured by high-resolution X-ray diffraction using CuKalpha1 radiation. A significant enhancement of the c lattice parameter with film thickness was observed, the maximum value of 4.25 Aa reached in the 30-50 nm thick films. For film thicknesses greater than 100 nm, the c lattice parameter is relaxed, towards the bulk value of 4.13 Aa at this composition. The in-plane lattice parameters were ... >>
Piezoelectric Pb(Zr,Ti)O3 Nano fibers Produced By Electro spinning Process
2008-01-01
Lead zirconate titanate (PZT) is the most widely used piezoelectric material in ultrasonic transducers, non-volatile random access memory devices, microelectromechanical devices, sensor and actuator applications. In this study, PZT nanofibers were obtained by electrospinning method using a sol-gel based solution and polyvinyl pyrrolidone (PVP) polymer. Effect of electrospinning parameters such as. The applied electric field (E=1.2-1.7 kV/cm), polymer content and the aging of the precursor solution were investigated. PVP content of lower than 22wt% was found to lead to electrospray coating of nanosize beads. Annealing regime (T=600-700 degree heating rate=0.5-5 degree/min) was another crucial parameter on the sintered morphology of the nanofiber mats. X-ray diffraction (XRD) pattern of the annealed PZT fibers exhibited no preferred orientation and a pure ... >>
Characterization and Operation of PZT Ceramic Filters on Gamma-Radiation Environment
2009-01-01
The present paper deals with thc gamma-ray effects on the electrical characteristics of ferroelectric materials used as an electronic frequency filters. After the recall of main observations, mechanisms are analyzed and proposed to take into account the effects in Lead-Zirconate-Titanate (PZT) based materials. In this concern, a wide frequency range samples, extends from 400 k Hz up to 6.5 MHz, were chosen for studying their frequency response and related terminologies, dynamic characteristics, and equivalent circuits. In general, for all samples, a shift on the frequency values was recorded, where the values of the center frequency, resonance frequency and anti-resonance frequency were shown to be shifted. The observed shift is mainly due to the noticed changes on the equivalent circuit elements of the devices, where a pronounced shift on the values of ... >>
2003-07-13
Thick film layered magnetoelectric composites consisting of ferromagnetic and ferroelectric phases have been synthesized with nickel ferrite (NFO), cobalt ferrite (CFO), La0.7Sr0.3MnO3 (LSMO), or La0.7Ca0.3MnO3 (LCMO) and lead zirconate titanate (PZT). Structural, magnetic and ferromagnetic resonance characterization shows evidence for defect free ferrites, but deterioration of manganite parameters. The resistivity and dielectric constants are smaller than expected values. The magnetoelectric effect (ME) is stronger in ferrite-PZT than in manganite-PZT. The ME voltage coefficient aE at room temperature is the highest in NFO-PZT and the smallest for LCMO-PZT. The transverse ME effect is an order of magnitude stronger than the longitudinal effect. The magnitude of aE correlates well with magnetic permeability for the ferrites.
Deposition of highly (111)-oriented PZT thin films by using metal organic chemical deposition
Lead zirconate titanate (PZT) thin films have been grown on Pt/Ta/SiNx/Si substrates by using metal organic chemical vapor deposition with Pb(C sub 2 H sub 5) sub 4 , Zr(O-t-C sub 4 H sub 9) sub 4 , and Ti(O-i-C sub 3 H sub 7) sub 4 as source materials and O sub 2 as an oxidizing gas. The Zr fraction in the thin films was controlled by varying the flow rate of the Zr source material. The crystal structure and the electrical properties were investigated as functions of the composition. X-ray diffraction analysis showed that at a certain range of Zr fraction, highly (111)-oriented PZT thin films with no pyrochlore phases were deposited. On the other hand, at low Zr fractions, there were peaks from Pb-oxide phases. At high Zr fractions, peaks from pyrochlore phase were seen. The films also showed good electrical properties, such as a high dielectric constant of more than 1200 and a low coercive voltage of 1.35 V.
http://hdl.handle.net/1959.14/64775
The genesis of intermediate-silicic intrusive rocks and their enclaves in Tongling are closely related to Fe, Cu mineralization, which may provide petrologic information on lithospheric dynamics in this region. Tongguanshan quartz diorite and its enclaves, representatives of the Mesozoic intermediate-silicic intrusive rocks in the Tongling area, were studied using approaches of petrography, electron microprobe mineral chemistry and the LA-ICPMS zircon U-Pb dating. The chemical compositions of pyroxene and amphibole in pyroxene-amphibole cumulate, quartz-diorite host rock from Tongguanshan show correlative variations. The Al contents of the minerals in pyroxene-amphibole cumulate are higher than those in the host rocks, indicating that the cumulate crystals were crystallized before the emplacement of host magma. The consistent mineral chemical compositions between the Tongguanshan quartz diorite and the microgranular diorite enclave indicate that the enclave and host rock were crystallized under similar conditions and therefore are closely genetically related. The LA-ICPMS zircon U-Pb dating suggests that the crystallization age of Tongguanshan quartz diorite is 137.5±1.1 Ma, consistent with the previous dates by different methods. However, the present U-Pb dating also revealed the presence of late-Archean relict cores, demonstrating that older lower crustal materials were involved in the generation of Mesozoic magmatic rocks in this area. Furthermore, the dating results show that the crystallization age of the microgranular diorite enclave is 137.5 ± 2.4 Ma, the same as the crystallization age of the host magma. By integrating the previous Sr-Nd-Pb isotope data, it is also discussed the petrogenesis of quartz diorite and its enclaves in Tongguanshan.10 page(s) Publisher: Science in China Press Relation: Chinese science bulletin, Vol. 49, Issue 19, p.2073-2082; 10.1360/04wd0137 Other identifier: ISSN:1001-6538; mq-rm-2004020879 Language: eng
2006-04-19
This paper contains results of investigations of inhomogeneous states caused by the coexistence of ferroelectric and antiferroelectric phases in lead-zirconate-titanate based solid solutions. The domains of ferroelectric and antiferroelectric phases with sizes of the order of 20 to 30 nm coexist in the bulk of the samples due to a small difference in the free energies of the phases. The coherent character of interphase boundaries leads to the concentration of elastic stresses along these boundaries. Elastic stresses cause the local decomposition of the solid solution due to the circumstance that equivalent positions of the crystal lattice are occupied by ions with different sizes. Larger ions are driven out into domains with larger crystal cell parameters and smaller ions are pushed into domains with smaller parameters of the crystal cell. The sizes of segregates formed in this way are of the order 8 to 15 nm.
Construction of a PZT Sensor Network for Low and Hypervelocity Impact Detection
2005-01-10
Orbital debris is a constraint on the long-term health of any spacecraft and must be considered during mission planning. Varying mechanisms have been proposed to quantify the problem. Assessment of orbital debris employing ground-based methods such as radar can help determine where debris clouds are located as well as their density or orbital trajectory. Such data is invaluable to computer simulations and can allow predictions of the debris environment over specific time periods [1]. Accurate in-situ data is essential as well with various types of sensors designed to detect orbital debris impacts employed on space missions since the 1950's [2]. One of the most common of these is the PZT (piezoelectric lead zirconate titanate) which is often used in-situ to measure the momentum of a particle at the time of impact. This paper will discuss a multiple PZT sensor system capable of determining both impactor momentum and location currently in development within CASPER.
High-pressure structural study of the scheelite tungstates CaWO4 and SrWO4
2005-04-06
Angle-dispersive x-ray diffraction (ADXRD) and x-ray absorption near edge structure (XANES) measurements have been performed in the AWO4 tungstates CaWO4 and SrWO4 under high pressure up to approximately 20 GPa. Similar phase transitions and phase transition pressures have been observed for both tungstates using the two techniques in the studied pressure range. Both materials are found to undergo a pressure-induced scheelite-to-fergusonite phase transition under sufficiently hydrostatic conditions. Our results are compared to those found previously in the literature and supported by ab initio total energy calculations. From the total energy calculations we have also predicted a second phase transition from the fergusonite structure to a new structure identified as Cmca. Finally, a linear relationship between the charge density in the AO8 polyhedra of ABO4 scheelite-related structures and the bulk modulus is discussed and used to predict the bulk modulus of other materials, like zircon.
The annealing induced extraordinary properties of SI based ZNO film grown by RF sputtering
2007-11-29
Pb(Zr0.52Ti0.48)O3 (PZT) thin films were in situ deposited by pulsed laser deposition (PLD) on Pt/Ti/SiO2/Si substrates using a template layer derived by sol-gel method. A 0.1-$\mu$m-thick PZT layer with (111) or (100)-preferred orientation was first deposited onto Pt/Ti/SiO2/Si substrates using the sol-gel method, and than a PZT layer with thickness of 1$\mu$m was in situ deposited by PLD on the above-mentioned PZT layer. The crystalline phases and the preferred orientations of the PZT films were investigated by X-ray diffraction analysis. Surface and cross-sectional morphologies were observed by scanning electron microscopy and transmission electron microscopy. The electrical properties of the films were evaluated by measuring their P-E hysteresis loops and dielectric constants. The preferred orientation of the films can be controlled using the template layer derived by the sol-gel method. The deposition temperature required to obtain the perovskite phase in this process is approximately 460 degrees C, and is significantly lower than that in the case of direct film deposition by PLD on the Pt/Ti/SiO2/Si substrates. Keywords: lead zirconate titanate (PZT), thin film, sol-gel method, laser ablation, electrical properties
Liquid Density Sensing Using Resonant Flexural Plate Wave Device with Sol-Gel PZT Thin Films
2008-02-22
This paper presents the design, fabrication and preliminary experimental results of a flexure plate wave (FPW) resonator using sol-gel derived lead zirconate titanates (PZT) thin films. The resonator adopts a two-port structure with reflecting grates on the composite membrane of PZT and SiNx. The design of the reflecting grate is derived from a SAW resonator model using COM theory to produce a sharp resonant peak. The comparison between the mass and the viscosity effects from the theoretical expression illustrates the applications and the constraints of the proposed device in liquid sensing. Multiple coatings of sol-gel derived PZT films are adopted because of the cost advantage and the high electromechanical coupling effect over other piezoelectric films. The fabrication issues of the proposed material structure are addressed. Theoretical estimations of the mass and the viscosity effects are compared with the experimental results. The resonant frequency has a good linear correlation with the density of low viscosity liquids, which demonstrate the feasibility of the proposed device.
On Site Raman Analysis of Iznik Pottery Glazes and Pigments
2006-12-14
On site Raman analyses were performed at the Mus\'{e}e national de C\'{e}ramique, S\`{e}vres, France, on rare Iznik (former Nicaea) pottery produced from ~1480 to ~1620. A comparison is made with a series of shards. The town of production of these potteries was highly disputed in the 80's and many questions still remain. The potential of glaze on-site analyses as a classification/datating tool is evaluated. The structure of the silicate glaze does not change with the sample (index of polymerisation ~ 0.5-0.8, indicating a lead silicate composition; characteristic Si-O stretching mode doublet at \~985 and 1030-1050 cm-1). By contrast the corresponding signature of most of the "K\"{u}tahya" wares peaks at ~1070-1090 cm-1. The lowest index is measured for a brilliant overglazed red bole, according to a lower temperature of (post)firing. The different crystalline phases identified in the glaze are -quartz, haematite, spinel, cassiterite, uvarovite garnet and zircon. White colour arises from -quartz slip in most samples studied. Cassiterite (SnO2) opacifier is only present in some early blue-and-white ceramics (Master of the Knots and Baba Nakkas style, ca. 1510-1530) and we do not have other evidence of its intentional use as an opacifier. Intentional addition of tin oxide is likely for colour lightening in some red, blue and in clear green boles. At least two types of red glazes and two types of Cr-containing green pigments are evidenced.
http://hdl.handle.net/2440/16491
Copyright © 2005 Geological Society of LondonUntil recently it has been widely accepted that protoliths to metasediments of the Harts Range Metamorphic Complex (central Australia) were deposited prior to c. 1.75 Ga and form part of the Palaeoproterozoic Arunta Inlier. However, new sensitive high-resolution ion microprobe U–Pb analyses of detrital zircon, together with recently published data, suggest that they were deposited coeval with c. 545–520 Ma sediments from the adjacent, little metamorphosed Neoproterozoic to Palaeozoic Centralian Superbasin. Protoliths of the Harts Range Metamorphic Complex were deposited in the Irindina sub-basin, an early- to mid-Cambrian rift located between the present-day Amadeus and Georgina Basin remnants of the Centralian Superbasin. Deposition occurred during a widespread and long-lived interval of extension in parts of central Australia associated with eruption of the voluminous Kalkarinji Continental Flood Basalts. The Harts Range Metamorphic Complex was metamorphosed to upper amphibolite- to granulite-facies conditions within c. 40 Ma of deposition of its sedimentary protoliths.Ian S. Buick, Martin Hand, Ian S. Williams, Jo Mawby, Jodie A. Miller & Robert S. Nicoll Publisher: Geological Society Other identifier: Journal of the Geological Society, 2005; 162 (5):777-787; 0016-7649; 0020050988; 10.1144/0016-764904-044 Language: en
Science and technology with nuclear tracks in solids
Fission track dating has greatly expanded its usefulness to geology over the last 40 years. It is central to thermochronology—the use of shortened fission tracks to decipher the thermal history, movement, and provenance of rocks. When combined with other indicators, such as zircon color and (U–Th)/He, a range of temperatures from C to C can be studied. Combining fission track analysis with cosmogenic nuclide decay rates, one can study landscape development and denudation of passive margins. Technological applications have expanded from biological filters, radon mapping, and dosimetry to the use of ion track microtechnology in microlithography, micromachining by ion track etching, microscopic field emission tips, magnetic nanowires as magnetoresistive sensors, microfluidic devices, physiology of ion channels in single cells, and so on. In nuclear and particle physics, relatively insensitive glass detectors have been almost single-handedly responsible for our knowledge of cluster radioactivity, and plastic track detectors together with automated measuring systems have been used at the Bevalac, Brookhaven, CERN, and GSI, mainly to study fragmentation of high-energy heavy nuclei. Almost everything we know about the ultraheavy cosmic rays has been learned using Lexan on the Long Duration Exposure Facility and BP-1 phosphate glass on the Mir Station. New topics include development of calorimetric aerogels capable of measuring kinetic energies of hypervelocity interstellar and interplanetary dust grains in space and research on identification of strains of Bacillus spores by measurements of their size and swelling rates when humidified.
http://hdl.handle.net/1959.14/66427
In the Jiangnan orogen, a clear angular unconformity between the Precambrian basement sequences and the overlying Neoproterozoic sedimentary strata (e.g. the Danzhou/Banxi Group, younger than ca. 800 Ma) marks the collisional orogenesis (the Jinning orogeny) between the Yangtze and Cathaysia Blocks. In contrast to the upright, open folds in the Danzhou/Banxi Group, the basement sequences were deformed into high-angle tight linear and isoclinal overturned folds. It has been previously accepted that the basement sequences are of Mesoproterozoic age. However, LA-ICP–MS U–Pb dating of detrital zircons suggests that the maximum depositional age of the basement sedimentary rocks in the western part of the Jiangnan orogen (i.e. the Sibao/Lengjiaxi Group) is ca. 860 Ma. This provides a lower limit for the assembly of the Yangtze and Cathaysia Blocks. Consequently, there may be no significant (ca. 200 Ma) early Neoproterozoic sedimentary hiatus in South China. These data, combined with published dates on orogeny-related igneous rocks in the Jiangnan orogen, indicate that the Jinning orogeny took place at 860–800 Ma, significantly younger than the typical Grenvillian orogeny at 1.3–1.0 Ga. The Sibao/Lengjiaxi Group may have been deposited in a foreland basin. The Yangtze Block and the arc terrains that resulted from the early subduction along the Jiangnan orogen might be the two main source regions for the sedimentary rocks.15 page(s) Publisher: Elsevier BV Relation: Precambrian research, Vol. 159, Issue 1-2, p.117-131; 10.1016/j.precamres.2007.06.005 Other identifier: ISSN:0301-9268; mq-rm-2007001169 Language: eng
axion: Axion - Java Database - News
The Axion news feed is on hiatus, yet Axion is still being actively developed. ... Better late than never, it's the Axion database project's October 2003 ...
A small, fast, SQL and JDBC compliant relational database engine written in and for the Java programming language. [Open source, BSD License]
One of the greatest obstacles with the fluorozirconate ZBLAN (ZrF4-BaF2-LaF3-AIF3-NaF) is the problem of devitrification. Fluoride glasses have a narrow working range and the viscosity is a strong function of temperature. ...
2007-01-01
The aim of this thesis was to obtain a consistent set of thermodynamic data for the Cu-Pb-Zr-Ti-O system, by means of the CALPHAD method, and then to calculate phase equilibria and chemical potential diagrams. The thermodynamic properties were described using the compound energy formalism (CEF) as well as the substitutional solution model for various solid phases and the associate model for the liquid phase, while the Redlich-Kister series were used to account for the interactions between species. Associate solution model adopted for the description of the liquid phase in the multicomponent Cu-Pb-Zr-Ti-O system was found to be superior for calculating the relevant phase equilibria in comparison with the twosublattice ionic model, although both models can be successfully applied to the binary systems (Zr-O, Ti-O, Cu-O, Pb-O). The ternary compound ... >>
[Fe sub 7 sub 5 sub . sub 5 Zr sub 8 sub . sub 3 N sub 1 sub 6 sub . sub 2 (800 A)/SiO sub 2 (250 A)] sub 1 sub 0 multilayer thin films were fabricated by using an rf magnetron reactive sputtering method. The saturation magnetic flux density and the coercive force were measured as functions of the annealing temperature. The effective permeability at high frequencies and the thermal stability were also examined. The magnetic properties of the [Fe sub 7 sub 5 sub . sub 5 Zr sub 8 sub . sub 3 N sub 1 sub 6 sub . sub 2 (800 A)/SiO sub 2 (250 A)] sub 1 sub 0 multilayer thin films showed a saturation flux density of 1.08 T, a coercive force of 0.41 Oe, and an effective permeability of about 4000 at 1 MHz. The observed good magnetic softness is attributed to the prohibition of the growth of alpha-Fe grains due to the precipitation of nanocrystalline ZrN particles. The sizes of the alpha-Fe grains and the nanocrystalline ZrN particles were 40 approx 50 A and 10 approx 15 A, respectively. The effective permeability of a FeZrN single-layer film decreased rapidly when the frequency exceeded 5 MHz. On the contrary, the effective permeability of a multilayer film was around 2200 up to a frequency of 40 MHz.
2009-01-01
The relative permittivity of O-cresol Novolac epoxy resin/(Ba0.9Sr0.1)(Ti0.9Zr0.1)O3 (epoxy/BSTZ) composites with various contents of BSTZ ceramic powder was measured at 10 kHz to 1 MHz. As the content of BSTZ ceramic powder increases from 0 to 70 wt%, the permittivity increases from 5.72 to 25.23. Four different mixing rules are used to predict the variation of permittivity of epoxy/BSTZ composites, and the Lichtenecker equation fits the measured results. The permittivity of epoxy/BSTZ composites slightly increases as the measured temperature increases, and is unchanged when the measured temperatures are higher than the Curie temperature of BSTZ ceramic. This research proves that we can develop the epoxy/BSTZ composites with characteristics of stable temperature and frequency dependence. (orig.)
The Effects of a Magnetic Field on the Crystallization of a Fluorozirconate Glass
An axial magnetic field of 0.1T was applied to ZrF4-BaF2-LaF3-AlF3-NaF (ZBLAN) fibers during heating to the glass crystallization temperature. Scanning electron microscopy and x-ray diffraction were used to identify crystal ...
High vacuum deposition techniques for fabricating thin film capacitors
Protective coating of phosphate-bonded zirconia for regeneratively cooled thrust chambers
Piezoelectric acoustoconductors SAW on the basis of Pb(ZrTi)O{sub 3}
1994-12-31
Short communication. 1 fig., 2 tabs.
Montreal Axion - Wikipedia, the free encyclopedia
The Montreal Axion are a National Women's Hockey League team located in Montreal, Quebec, Canada. v ? d ? e · Sports teams based in the province of Quebec, ...
2008-01-01
It is established that the piezoceramic materials based on 0.41PNN-0.23PZ-0.36PT solid solutions can be produced using a liquid-phase sintering procedure at temperatures 960--11000C. It is found that introducing micro additives causes of parameters of a crystal lattice to change and a phase transition temperature to grow. A perspective use of 0.41PNN-0.23PZ-0.36PT ceramics for creation on its basis of functional elements of multilayered devices is shown. (authors)
2009-01-01
(Pb0.97L0.02)(Zr0.95Ti0.05)O3 (PLZT) antiferroelectric thick films with (100) and (110) orientation were fabricated on platinum and LaNiO3-buffered silicon substrates through a modified sol-gel process. It was demonstrated that the PLZT thick films with (110) preferred orientation had an enhanced electric-field-induced strain, by 77% as compared to the films with (100) orientation. Also, the antiferroelectric-ferroelectric switching field for the PLZT thick films with (110) orientation was 200 kV/cm, which was much lower than that (256 kV/cm) of the (100) oriented films. Moreover, the fatigue behavior of the PLZT thick films on LaNiO3 electrodes was much better than that of the films on platinum electrodes. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) ... >>
Hf- and Zr-based alkaline earth perovskite dielectrics for memory applications
2009-01-01
We investigate a group of Hf- and Zr-based dielectrics crystallizing in the cubic perovskite structure for memory applications. The dielectrics are deposited in the form of thin layers (
Fabrication and test of inorganic/organic separators
Completion of testing and failure analysis of MDC 40 Ahr silver zinc cells containing largely inorganic separators was accomplished. The results showed that the wet stand and cycle life objectives of the silver zinc cell ...
Efeito de íons aliovalentes nas propriedades elétricas de céria dopada com ítria
2008-01-01
Full Text Available
Bimorph piezoelectric device functions as flapper valve
Flapper valve using a bimorph piezoelectric ceramic bender converts an electrical input into a pneumatic output signal capable of operating fluidic logic elements in a decoder and display system.
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Axion Project Incubation Status - Apache Incubator
For general project status, see the Axion project website. ... The axion project never moved to the ASF from tigris.org. 2003-12-19: The Apache Incubator ...
Axion - Wikipedia, the free encyclopedia
The axion is a hypothetical elementary particle postulated by Peccei-Quinn theory in 1977 to resolve the strong-CP problem in quantum chromodynamics (QCD). ...
A pre-edge analysis of Ti K-edge XANES spectra of photo luminescent PZT powder
2009-01-01
(No abstract available)
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