Solid Cadmium Research Articles

INVESTIGATION OF CENTERING PROBLEM IN THE CADMIUM ZINC TELLURIDE (CZT) CARDIAC CAMERA

Introduction: Cadmium Zinc Telluride (CZT) Cardiac Cameras are a special SPECT cameras with solid state cadmium zinc telluride detectors. This diagnostic method applied in the evaluation of coronary artery disease is well designed for myocardial perfusion scintigraphy. Aim: CZT cardiac cameras have limited detector area. In patients who are morbidly obese or whose heart is not in its normal location in the body, the center of the heart and the isocenter of the device do not coincide. It is aim to investigate how these conditions affect the imaging performance of the CZT cardiac camera. Methods: A homogeneous and spherical ball with a diameter of 4 cm was used for the research. To be able to measure away from the center a wooden phantom with 8 cavities and a total length of 32 cm was designed. The center as reference point has been determined by matching the center of the device with the center of the sphere. For the next imaging, the image were taken by placing the spherical ball in the other cavities, respectively, without changing the center. Results: According to the results obtained, farther from the center, deviations from sphericity and differences in dose distribution were observed. Counts decreased by 1.5% in the 2nd position and 16% in the 3rd position relative to the center in the X-axis. A disaster area has been formed and the image area has been exited from the 4th imaging. Conclusion: It is very important to center the patient as much as possible, otherwise the doctor will misdiagnose.

Chemical Deposition of CdxPb1 – xS/CdyS Thin-Film Composite Structures

Thin films of CdxPb1 – xS (0 ≤ x ≤ 0.094) substitutional solid solutions of cubic structure B1 (space group Fm) were prepared by chemical deposition and characterized by X-ray diffraction, scanning electron microscopy, EDX elemental analysis, and Raman spectroscopy. Once the cadmium sulfate concentration in the batch reached some critical value (0.1 mol/L), the films formed involved two autonomous phases: CdxPb1 – xS substitutional solid solutions and hexagonal cadmium sulfide CdyS of structure В4 (space group P63mc). The method and its parameters as proposed are efficient for manufacturing heterostructures in the CdS–PbS system in one-pot deposition.

E-AlMgSi (Aldrey) aluminum conductive alloy with the solid state cadmium oxidation kinetics

In the development of new materials designed for use under particularly harsh conditions, the task of making them corrosion-resistant arises. The practical solution to this task correlates with knowledge in the field of high-temperature oxidation of metals and alloys. When using conductive aluminum alloys for the production of fine wires, such as winding wire, certain difficulties may arise due to their insufficient mechanical strength and inflection before breaking. The solution of modern technological problems is associated with the use of highly oxidation- resistant materials. As a consequence, the study of the interaction of oxygen with metals and alloys has become very important due to the widespread use of new materials with special physical and chemical properties. The E-AlMgSi (Aldrey) aluminum conductive alloy occupies a special place among others. The oxidation process of the alloys was studied under isothermal air atmosphere by thermogravimetric method with continuous fixation of the sample mass for 1 h at temperatures of 723, 773 and 823 K. The oxidation kinetics curves and the value dependencies of the specific mass increase of cadmium in the E-AlMgSi (Aldrey) alloy quantity, time and temperature were constructed on the experimental data basis. The processing of the quadratic kinetic curves of the oxidation of the alloys at the above temperatures has shown that the oxidation of the alloys obeys the hyperbolic dependence y = kxn, where the value of n varies from 1 to 4. The lg k dependence on 1/T for the alloy E-AlMgSi (Aldrey) with cadmium shows that the oxidation rate increases with temperature and cadmium content increasing.

Self‐Assembled Structures from Solid Cadmium(II) Acetate in Thiol/Ethanol Solutions: A Novel Type of Organic Chemical Garden

AbstractCadmium(II) acetate in tablet form, immersed in ethanol solutions with a high concentration of heptanethiol (30–80 mM), was able to develop self‐assembled sail‐shaped structures. The solution in which the self‐assembled structure is formed is totally organic (both solute and solvent), thus representing a unique case among organic Chemical Gardens. The constituting material for this new Chemical Garden (CG) is made of a single phase, namely a cadmium heptanethiolate with a microcrystalline structure consisting of a central cluster [CdnSn]. The morphological and structural features were studied using different techniques (SEM‐EDS, elemental analysis, ATR‐FTIR, 113Cd MAS NMR, XRPD). A crystalline cell for the Cd(II) heptanethiolate cluster was obtained that completely differs from that of the solid phase precipitated by mixing an ethanol solution of Cd(II) acetate with heptanethiol. It follows that the conditions under which the formation of Cd(II) heptanethiolate occurs (slowly from solid, quickly from solution) play a critical role in determining the nature and structure of the precipitating phase.

Luminescence Change of CdS and CdSe Quantum Dots on a Ag Film.

Enhanced luminescence of an emitter on a Ag film is usually ascribed to the resonant surface plasmons. In these studies, the solid cadmium sulfide (CdS) and cadmium selenide (CdSe) quantum dot/silver (QD/Ag) hybrids were prepared, and the luminescence characteristics of these QD/Ag hybrids were measured. It is found that the enhancement of the trap state emission (TSE) is related to the QD size. The TSE features of the annealed QD/Ag hybrids are insensitive to the morphology of the Ag film. We used the wet and dry methods to separate the QD and Ag components and found that the photoluminescence (PL) of the QD component was permanently changed from the initial state. The PL modification is ascribed to the Ag+ doping effect rather than the surface plasmons. This doping method uses pure Ag as the Ag+ ion source. In this case, though the CdS and CdSe QD/Ag hybrids are the solid state, the cation exchange between Ag+ and Cd2+ ions can still occur on the QD surface. Even a small amount of Ag can efficiently influence the luminescence of the QDs embedded in the poly(methyl methacrylate) matrix. A hypothetical model was proposed to explain the PL modification of the QD/Ag hybrid with and without annealing. Using this dry method for doping, the transparent luminescence label can be prepared easily, and the doped QDs can be further doped with Ag+ dopants.

Direct analysis of high-purity cadmium by electrothermal vaporization-inductively coupled plasma optical emission spectrometry

The paper presents the original technique of trace analysis of solid cadmium samples by the optical emission spectrometry with inductively coupled plasma in combination with the electrothermal vaporization (ETV-ICP-OES). The temperature program for heating ETV provides almost complete evaporation of cadmium (at 900 °C) and the subsequent vaporization of analytes when the temperature ETV rises up to 2400 °C. Separate vaporization of matrix and analytes provides reducing of spectral interferences, which ensures lower the limits of detection of the analytes (LODs). Evaluation of the analytical characteristics of the proposed technique shows that the ETV-ICP-OES allows us to reduce the detection limits of Al, Au, Be, Bi, Co, Cr, Fe, Ga, In, Mn, Ni, Re, Sn and V from 3 to 670 times compared with traditional ICP-OES analysis of 2% cadmium solutions. The accuracy of proposed technique was confirmed by analysis of cadmium samples by an independent ICP-MS technique and by addition and recovery experiment.

Basic cadmium salts as phase‐directing agent for the phase and morphology control of metal hydroxychlorides

Basic cadmium salts (CdOHCl and Cd(OH)NO3·H2O) were used as phase-directing agents to guide the phase development of various metal hydroxychlorides including Cu2(OH)3Cl, Co2(OH)3Cl, Zn5(OH)8Cl2(H2O), Sn3O(OH)2Cl3 and PbOHCl. The simple synthesis procedure includes only one step: solid basic cadmium salt was suspended in aqueous or ethanolic solution of metal salt for 6 h in ambient environment. The separated products from the solution had various morphologies such as sphere, bundle, sheet, hollow sphere and cube. The phase direction behaviour of basic cadmium salts can be attributed to their high reactivity, and most importantly to the structure similarity between basic cadmium salts and metal hydroxychlorides.

Solid contact cadmium ion-selective electrode based on ionic liquid and carbon nanotubes

A new type of cadmium ion-selective electrode with solid contact with the implementation of multi-walled carbon nanotubes (MWCNTs) as the ion-to-electron transducer and ionic liquid: 1-butyl-3-methylimidazolium hexafluorophosphate (BMImPF6) as a lipophilic ionic additive was reported. The proposed electrode exhibits low detection limit and short response time but has stable, reproducible and reversible potential. The presence of the interfacial water film was evaluated by the potentiometric water layer test and electrical properties of the membrane were studied by electrochemical impedance spectroscopy.

High pressure and temperature structure of liquid and solid Cd: implications for the melting curve of Cd

The structure of cadmium was characterized in both the solid and liquid forms at pressures to 10 GPa using in situ x-ray diffraction measurements in a resistively heated diamond anvil cell. The distorted hexagonal structure of solid cadmium persists at high pressures and temperatures, with anomalously large c/a ratio of Cd becoming larger as the melting curve is approached. The measured structure factor S(Q) for the melt reveals that the cadmium atoms are spaced about 0.6 Angstroms apart. The melt structure remains notably constant with increasing pressure, with the first peak in the structure factor remaining mildly asymmetric, in accord with the persistence of an anisotropic bonding environment within the liquid. Evolution of powder diffraction patterns up to the temperature of melting revealed the stability of the ambient-pressure hcp structure up to a pressure of 10 GPa. The melting curve has a positive Clausius–Clapeyron slope, and its slope is in good agreement with data from other techniques. We find deviations in the melting curve from Lindemann law type behavior for pressures above 1 GPa.

Investigation on the electrochemical behavior of neodymium chloride at W, Al and Cd electrodes in molten LiCl-KCl eutectic

Electrochemical behavior of neodymium (III) ion was studied in LiCl-KCl eutectic melt in the temperature range 723-798K on inert tungsten electrode using various transient electrochemical techniques such as cyclic voltammetry, convolution voltammetry, chronopotentiometry and square wave voltammetry. The reduction of Nd(III) ion to Nd metal on tungsten electrode takes place in two steps- Nd(III)/Nd(II) and Nd(II)/Nd(0). The diffusion coefficient of Nd(III) and Nd (II) ions were determined. Reduction of Nd(III) to Nd(II) showed reversible electrode behavior and that for Nd(II) to Nd metal followed the quasi-reversible behavior. Heterogeneous rate constant for the reduction, Nd(II)/Nd(0) was estimated from the convoluted voltammograms. The apparent standard electrode potentials,ENd(III)/Nd(II)*, ENd(II)/Nd(0)* and ENd(III)/Nd(0)* were estimated from the cyclic voltammograms.The electrode behavior of Nd(III) ion on solid aluminium electrode and liquid cadmium electrode was studied by cyclic voltammetry. Under-potential reduction of Nd(III) ion takes place on Al and Cd cathodes in a single step with three electron transfer. The apparent standard electrode potentials, ENd(III)/Nd(Al)* and ENd(III)/Nd(Cd)* were estimated for different temperatures in the range 698-773K. The formation of intermetallics, Al11Nd3 and Cd11Nd were studied from open circuit potential measurement on Al and Cd film electrode respectively. The Gibbs energy of formation for these intermetallics was evaluated. The activity of neodymium in Al/Cd, the excess Gibbs energy and the activity coefficient of neodymium in Al/Cd were estimated from the open circuit potential measurement. SEM-EDX analysis and the XRD pattern of the electro-deposit revealed the formation of Al11Nd3 and Cd11Nd on Al and Cd cathodes respectively.

Radiation dose and positive predictive value of revascularisation with low dose myocardialperfusion scintigraphy compared with computed tomography coronary angiography

Background: To evaluate the radiation dose and positive predictive value (PPV) of the need for revascularisation of contemporary (low dose) Myocardial Perfusion Scintigraphy (MPS) compared with Computed Tomography Coronary Angiography (CTCA).Methods: We consecutively reviewed 314 MPS and 221 CTCA studies performed at our hospital in 2013. Stress/Rest MPS studies were performed with exercise and/or adenosine using Sestamibi Tc99m and a solid state Cadmium Zinc Telluride gamma camera. CTCA was performed using a 256 slice CT. Radiation exposure was measured in milisievert (mSv). Positive tests leading to invasive coronary angiography were used to determine the PPV of the need for revascularisation.Results: For demographics see table 1. The main indication for tests in both cohorts was chest pain (>75%). Patients undergoing MPS were older, more likely to have diabetes, and had worse renal function compared with CTCA (p< 0.01).Table 1MPSCTCAP valueAge (years)66.09 ± 43.5353.00 ± 13.79<0.01eGFR73.42 ± 19.2484.04 ± 9.55<0.01Diabetes111/314 (35%)49/221(22%)0.001Radiation (mSv)6.80 ± 2.075.64 ± 3.29<0.01PPV21/41 (51%)21/26 (80%)0.02 Open table in a new tab 41/314 (13%) MPS and 26/221 (11%) CTCA patients proceeded to have coronary angiography. There was a small but statistically significant reduction in radiation dose for CTCA compared with MPS (p< 0.01). CTCA was significantly better at predicting the need for revascularisation compared with MPS (PPV 80% vs 51%, p: 0.02).Conclusions: Despite lower than usual dose MPS utilising contemporary techniques, radiation dose remained lower with CTCA. CTCA had a higher PPV of the need for revascularisation compared with MPS in our non-randomised evaluation. Background: To evaluate the radiation dose and positive predictive value (PPV) of the need for revascularisation of contemporary (low dose) Myocardial Perfusion Scintigraphy (MPS) compared with Computed Tomography Coronary Angiography (CTCA). Methods: We consecutively reviewed 314 MPS and 221 CTCA studies performed at our hospital in 2013. Stress/Rest MPS studies were performed with exercise and/or adenosine using Sestamibi Tc99m and a solid state Cadmium Zinc Telluride gamma camera. CTCA was performed using a 256 slice CT. Radiation exposure was measured in milisievert (mSv). Positive tests leading to invasive coronary angiography were used to determine the PPV of the need for revascularisation. Results: For demographics see table 1. The main indication for tests in both cohorts was chest pain (>75%). Patients undergoing MPS were older, more likely to have diabetes, and had worse renal function compared with CTCA (p< 0.01). 41/314 (13%) MPS and 26/221 (11%) CTCA patients proceeded to have coronary angiography. There was a small but statistically significant reduction in radiation dose for CTCA compared with MPS (p< 0.01). CTCA was significantly better at predicting the need for revascularisation compared with MPS (PPV 80% vs 51%, p: 0.02). Conclusions: Despite lower than usual dose MPS utilising contemporary techniques, radiation dose remained lower with CTCA. CTCA had a higher PPV of the need for revascularisation compared with MPS in our non-randomised evaluation. CSANZ NZ AbstractsHeart, Lung and CirculationVol. 23Preview Full-Text PDF

Co-operativity in a nanocrystalline solid-state transition

Co-operativity is a remarkable phenomenon mostly seen in biology, where initial reaction events significantly alter the propensity of subsequent reaction events, giving rise to a nonlinear tightly regulated synergistic response. Here we have found unique evidence of atomic level co-operativity in an inorganic material. A thousand-atom nanocrystal (NC) of the inorganic solid cadmium selenide exhibits strong positive co-operativity in its reaction with copper ions. A NC doped with a few copper impurities becomes highly prone to be doped even further, driving an abrupt transition of the entire NC to the copper selenide phase, as manifested by a strongly sigmoidal response in optical spectroscopy and electron diffraction measurements. The examples presented here suggest that cooperative phenomena may have an important role in the solid state, especially in the nucleation of new chemical phases, crystal growth, and other materials' transformations.

Interface energy of solid cadmium (Cd) phase in the Cd-Pb (Cadmium-Lead) binary alloy

The grain boundary groove shapes for the Cadmium (Cd) phase in equilibrium with the Lead (Pb)-Cd eutectic liquid were obtained with radial heat flow apparatus. From the obtained grain boundary groove shapes, the Gibbs-Thomson coefficient, solid-liquid and grain boundary energy for the Cd phase in equilibrium with the Pb-Cd eutectic liquid were determined to be (8.35 ± 0.41) x 10-8 Km, (128.00 ± 12.8) × 10-3 Jm-2 and (239.33 ± 26.32) × 10−3 Jm-2, respectively. The thermal conductivities of the solid and liquid phases at the eutectic composition and temperature were also measured by using radial heat flow and Bridgman-type directional growth apparatus, respectively. Key words: Crystal growth, phase equilibria, thermal conductivity, Gibbs-Thomson coefficient, grain boundary energy.

Enhanced Light Absorption in Textured Metal Organic Chemical Vapour Deposited (MOCVD) CdO Thin Films

ABSTRACTThe Single Solid Source precursor Cadmium Acetylacetonate, Cd[C5H7O2]2 was prepared and Cadmium Oxide thin films were deposited on Sodalime glass substrate using Metal Organic Chemical Vapour Deposition (MOCVD) technique at deposition temperature of 420 oC The films were characterized using Scanning Electron Microscopy (SEM) with Energy Dispersive XRay (EDX) facility attached to it, X-Ray Diffractometry (XRD) and UV-visible spectrometry. SEM micrographs showed the formation of textured surface with identifiable cubic and hexagonal structures, having average grain size greater than 1 μm. XRD studies indicated the formation of polycrystalline cubic CdO phase with preferred orientation in (111) plane. A direct optical band gap of 2.10 eV was obtained from the analysis of the UV-visible spectrum with an enhanced light absorption in 750 – 1000 nm spectrum range. This enhancement is as a result of light trapping by the textured crystalline structure.

IUPAC-NIST Solubility Data Series. 92. Metal Carbonates. Part 1. Solubility and Related Thermodynamic Quantities of Cadmium(II) Carbonate in Aqueous Systems

This paper, devoted to cadmium(II) carbonate, is the first in a series dedicated to the solubility of compounds relevant to mobility of metals in the environment. Here, we present compilations and critical evaluation of the experimental solubility data for cadmium(II) carbonate, otavite, in aqueous ternary and higher-order systems. The solubility of cadmium(II) carbonate depends on temperature, carbon dioxide partial pressure, pH, the presence of complexing ions, and ionic strength of the solution. Papers referring to solubility of cadmium(II) carbonate have been published since 1901; the thorough search of the literature in this field covered the period from 1901 through 2009. The compilation of the available experimental data is introduced with a critical evaluation. The evaluation of the experimental data considers the possible correlation between the data obtained under similar experimental conditions of temperature, carbon dioxide partial pressure, electrolyte, and ionic strength. Those experiments where the solid phase was well identified and the interactions between the electrolyte and the dissolved cadmium(II) ion were considered practically negligible were used to determine the thermodynamic properties of the solid cadmium(II) carbonate. Recommended values for the thermodynamic quantities are lg*Kps0∘ = 6.11 ± 0.10, ΔfG°(CdCO3, cr, 298.15 K) = −(674.3 ± 0.6) kJ mol−1, ΔfH°(CdCO3, cr, 298.15 K) = −(752.2 ± 0.8) kJ mol−1, S°(CdCO3, cr, 298.15 K) = (103.9 ± 0.2) J K−1 mol−1.

Estudo da capacidade de complexação e sua relação com algumas variáveis ambientais em cinco represas do Rio Tietê/Brasil

The copper and cadmium complexation properties in natural sediment suspensions of reservoirs of the Tiete River were studied using the solid membrane copper and cadmium ion-selective electrodes. The complexation and the average conditional stability constants were determined under equilibrium conditions at pH=6.00 ± 0.05 in a medium of 1.0 mol L-1 sodium nitrate, using the Scatchard method. The copper and cadmium electrodes presented Nernstian behavior from 1x10-6 to 1x10-3 mol L-1 of total metal concentration. Scatchard graphs suggest two classes of binding sites for both metals. A multivariate study was done to correlate the reservoirs and the variables: complexation properties, size, total organic carbon, volatile acid sulfide, EII and pH.

Development of the HEFT and NuSTAR focusing telescopes

Hard X-ray/soft gamma-ray astrophysics is on the verge of a major advance with the practical realization of technologies capable of efficiently focusing X-rays above 10 keV. Hard X-ray focusing telescopes can achieve orders of magnitude improvements in sensitivity compared to the instruments based on coded apertures and collimated detectors that have traditionally been employed in this energy band. Compact focal planes enable high-performance detectors with good spectral resolution to be employed in efficient, low-background configurations. We have developed multilayer coated grazing incidence optics and solid state Cadmium Zinc Telluride focal plane systems for the High Energy Focusing Telescope (HEFT) balloon-borne experiment, and for the Nuclear Spectroscopic Telescope Array (NuSTAR) Small Explorer satellite. In this paper we describe the technologies, telescope designs, and performance of both experiments.

Preparation and Thermal Transformations of a Hydrous Cadmium Diphosphate Ammine Complex

A solid hydrous cadmium diphosphate ammine complex of composition Cd2P2O7 · 3.0NH3 · 4.5H2O is prepared, and its thermal transformations during constant-rate and quasi-isothermal heating are studied using chemical analysis, paper chromatography, and x-ray diffraction. The results are used to establish the mechanisms of the transformations.

Investigation of zinc dissolution and cadmium precipitation rates in a Cd2+/Zn cementation system

In this paper, an investigation of the Cd2+/Zn cementation system is attempted through a semi-theoretical approach, correlating the rates of zinc dissolution and cadmium precipitation under various conditions. Two series of experiments were carried out using zinc in the form of sticks and dust, respectively, while cadmium ions were dissolved as sulphates. The parameters examined were temperature (25–50°C), additives (H2SO4, NH4OH, Na2SO4), stirring speed (200–600 rpm), initial Cd2+ concentration and granulometric size of zinc dust (0·78–1·84 mm). In the second group of tests, continuous recording of pH change versus time was carried out. Total dissolved solids curves versus pH were constructed for each experiment showing solid cadmium to be the only precipitated phase, and mass balances for the two elements were evaluated for all tests. To account for the sampling position in the reactor, a new concept, the normalisation coefficient, is introduced and evaluated, correlating the species' concentrations in the system. Also time expansion was taken into account and equilibrium constants were evaluated. Based on the above, a correlation equation between the rates of zinc dissolution and cadmium precipitation is derived theoretically and it is confirmed by the experimental results. This analysis demonstrated the important role of pH for the system kinetics and the considerable effect obtained using normalisation coefficient on the experimental data. The plots of the normalised Cd2+ concentrations in the solution versus Zn2+ dissolved, verify the proposed linear dependence between the rates of cadmium precipitation and zinc dissolution.

Cadmium under high pressure and high temperature conditions

In this work liquid and solid cadmium has been investigated in a wide pressure and temperature range in order to provide new information about structure and transitions occurring in this metal. X-ray absorption, single-energy temperature scans and energy scanning x-ray diffraction data were collected in a 25–600 °C temperature and 0–5.8 GPa pressure range, exploiting the setup available at the ESRF-BM29 beam-line. Clear changes in the absorption spectra (measured at cadmium K-edge) and in the diffraction patterns, associated with the solid-liquid transition, allowed us to obtain an accurate measurement of the melting curve as a function of pressure. The structural data are compared with the few available calculations and x-ray scattering data on molten Cd at ambient pressure. High pressure data on liquid cadmium are reported for the first time and are essential to shed some light on the changes of the local structure induced by pressure.