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By A. E. M. Warner

At the Copper Cliff Smelter, Inco Limited has extensive experience in converting primary smelting mattes over a broad range of nickel/copper ratios and compositions. In the past 35 years, technology developments at Inco have reduced the number of Peirce-Smith converters in Nickel/ Bulk (nickel-copper matte) service from 13 to the current 5. This paper will discuss: ? The performance and life of ?stretch? 13.7m shells versus conventional 10.7m converters. ? Process control and information system development from the early 1980?s to view converter aisle status on a continuous basis to the recent central control of the stretch shells. ? Nitrogen cooling of finishing matte from plant testing to implementation in the early 1990?s to replace the dedicated cooling converters. ? The impact on converting of changing the smelter flowsheet in the early 1990?s. ? A current program to develop a converting strategy for the future to address environmental issues and profitability.

Jan 1, 2005

By Jintao Gao, Zhancheng Guo, Chong Li

A new approach to enrich MFe and RO phase from the converter slag by super gravity was investigated. The samples obtained by the gravity coefficient G=600 and cooling rate V=5K/min from 1623K to 1373K appeared significant stratification and the MFe gathered at the bottom of sample. With the help of metallographic microscopy and X-ray diffraction, it is found that large quantity of white RO phase gathered at the lower part of the sample as the concentrate, with volume fraction appearing gradient distribution along the direction of super gravity, while the upper part was mainly composed of dicalcium silicate as the tailing. The mass fractions of the FeO, MgO and MnO in the concentrate are up to 40.46%, 6.9% and 3.91%, while that in the tailing are just 11.65%, 2.15% and 1.55%. The recovery ratios of FeO, MgO and MnO in the concentrate are 60.35%, 58.45% and 72.24%, respectively.

Jan 1, 2016

By Yeliz Demiraya, Onuralp Yucelb

"Production of strontium metal from its oxide was studied under the pressure of 1-5 mbar by methalothermic process. SrO with 99 % purity was used in the experiments. Effects of Al powder addition (100, 200, 300 % of stoichiometric ratio) and time were investigated on recovering of metallic strontium. Effects of BaO addition (100 %, 200 %, 300 %) was also investigated. The final residues were examined for their chemical composition. XRD, AAS and Flame Photometer were used for chemical analysis. More than 96 % of strontium metal recovery can be obtained.IntroductionStrontium is an element which is used in many advanced technology applications. Barium strontium titanat, strontium bismuth titanat, and strontium bismuth tantalat thin films are promising materials in ferroelectric and Schottky-based microelectronics technologies, especially for memory applications. Physical vapor deposition (PVD) techniques as magnetron sputtering, thermal evaporation and molecular beam epitaxy (MBE) are the most widely used methods for growth of these thin films [1-3]. In these techniques high-purity of Sr metal is used as evaporation sources and sputtering targets. Furthermore, metallic strontium is used as a ""getter"" in electron tubes, and as an alloying elements in aluminum alloys [4].The most used Sr compound is SrCO3 and widespread process used in production of SrCO3 is the hydrometallurgical carbonation of celestite. Although there are considerable amount of Selestite reserves, SrCO3 and strontinum metal are not being produced in Turkey, yet [5].Concentrated celestite (SrSO4) is conversed to SrCO3 in carbonate media. Black ash and direct conversion processes are currently used methods. There are many satisfactory studies about hydrometallurgical carbonation of celestite and decomposition of SrCO3 [6, 7]. Since strontium metal is produced from it’s oxide (SrO), SrCO3 needs to be decomposed to SrO."

Jan 1, 2011

By D. Valic

In 1997, 9.2 million tonnes of mined, recoverable copper was produced, of which, 1.8 million tonnes or 19.4% was produced by leaching, solvent extraction and electrowinning. The amount of copper produced by this method grew faster than those attained from concentrate smelting, signifying the growing importance of this low-cost production method. Statistical experimental design, unlike traditional approaches, allows for proper distribution of experiments within the boundaries of factors being studied such that the number of experiments required to develop a sound relationship between the factors and a response is minimized. In the past, very little use has been made of statistical experimental design in copper electrowinning studies. Traditional one- variable-at-a-time approaches are widely employed for this purpose. The present study employs a factorial experimental design to relate current efficiency with current density (180 and 300 A/m2), copper concentration (25 and 65 gL), and temperature (40 and 60 °C). Pure synthetic electrolyte with a constant acid concentration of 180 g/L was used throughout the study. The designed study produced a linear relationship where the independent variables of current density, copper concentration, and temperature, and their interactions, were found statistically significant. It was shown that current efficiency could not solely be used as a predictor of copper cathode quality. The quality of the deposit is difficult to be incorporated into a model or relation. It was determined that other measures, such as cathode morphology and crystal structure should be considered. This was done through XRD and SEM analysis.

Jan 1, 1999

By J. C. Huyhua

The effect or various oxidants on gold and silver dissolution in thiourea solutions (0.05 M in H2SO4) was studied using the rotating disc technique, a.t 2s c and 600 rpm. These studies were carried out at constant (4:1) initial molar ratio or thiourea to oxidant concentrations, to produce 50 % thiourea. oxidation. The initial dissolution rate of gold was approximately four times higher in the presence. of ferric sulfate (5.37 x 10-3mg cm-2 s-1) than in the presence of hydrogen peroxide (H2O2), potassium persultate (K2S2O3), or monopersulfa.te (KHS06). The dissolution rates for silver were considerably lower than gold for the same oxidants. Oxidation of thiourea in the presence of peroxygen and persulta.te compounds is a. fast reaction and it is completed in less than ten minutes. On the other hand, the oxidation or thiourea with? ferric.sulfate is slow, yielding a second-order reaction rate constant k = 6.09 I mol-1 h-1. Sulfur formation in the ferric thiourea system begins when ferric ion reduction approaches to completion. With hydrogen peroxide, sulfur is observed at lower thiourea concentration than ferric. Suifate. The presence of a large excess or free thiourea i.e., s to 20 % thiourea oxidation) retards sulfur formation and maintains favorable dissolution rates. Finally, carbon-in-leach experiments indicate that thiourea solutions a.re stable for several days, with ferric sulfate or hydrogen peroxide. The dissolution rates of gold and silver doubles in the presence or activated carbon when hydrogen peroxide is used as oxidant.

Jan 1, 1989

By Valerio Viti

In High Pressure Die Casting a molten metal is injected through a thin gate into the cast cavity. High injection pressures and high gate velocities create atomization phenomena which can negatively affect the final quality of the cast. In order to control atomization process it is essential to understand the atomization patterns and the two-phase flowfield that exist at the gate exit. In the present work, 2D numerical simulations of the flow of molten Magnesium through a high aspect-ratio rectangular gate are performed using a water analogue for an open and closed cavity. The numerical simulations made use of VOF-type (Eulerian) physical models and Lagrangian models. Further, a sub-grid scale model was implemented that, in conjunction with VOF-type equations can efficiently predict the general atomization pattern without the need for high-resolution grids. The numerical results were compared to experimental data for validation.

Jan 1, 2006

By Albert Wraith, Thomas Price, Wayne Boyd, Skip (I. E. ) Hills, Cameron Harris

Most Peirce-Smith converters inject air through tuyeres, with nitrogen representing the majority of gas passing through the process. The nitrogen controls the temperature of the vessel by carrying away heat from the reactions, both globally and locally at the tuyere tip. However, nitrogen adds energy to the bath and contributes to splashing and limits the blowing rate. High oxygen smelting has made streams of gas containing high concentrations of sulphur dioxide commonplace, which can be used to substitute SO2 for nitrogen and drastically changes Peirce- Smith converting (and all other smelting/converting processes as well). Less SO2 is required to carry away the same quantity of heat, which allows higher concentrations of oxygen and leads to the possibility of increased production. The paper investigates this substitution, its impact on converter productivity, and on the remainder of the plant. 181

Jan 1, 2009

By Xin Zhang, Mengqi Li, Hongxu Li, Xinrong Zhang, Hao Bai, Ning Li

"Organic Rankin Cycle (ORC) is an effective technology to transform low-grade energy resource into electricity. In this paper, based on thermodynamic principle, considering the waste heat resource lower than 120°C, thermodynamic properties of ORC with working fluids ofR245fa, mixed R21/R245fa and mixed Rl52a/R245fa were assessed. The results show that high evaporation temperature contributes to improved system performance. The Rankine Cycle that uses R21/R245fa can increase net cycle output, thermal efficiency and exergy efficiency by 3.02%, 2.35%, and 4.44%,respectively, as compared to that with pure R245fa. When using Rl52a/R245fa as working fluid, the net cycle output can increase by 3.83% at most, while the thermal efficiency decreases by 8.7%. These results indicate that R21/R245fa has a good advantage in improving the cycle thermodynamic performance.IntroductionOrganic Rankine cycle is usually used for low temperature power generation, and is applied to the conversion of geothermal energy, low-temperature solar energy, ocean thermal energy and industrial low-temperature waste heat etc. Traditional Rankine cycle is quite mature already, however, organic working fluids would affect significantly the general efficiency of the entire thermodynamic system. Thus, selection of proper working fluids and development of new highperformance cycle is becoming important."

Jan 1, 2013

By Jun Deng, Daohong Wu, Zhicheng Cao, Jingkun Tang, Luxing Feng, Xun Xue

The effect of reducing temperature, H2/CO mole ratio, and reduction gas flow rate on the metallization rate of oxide pellets were investigated at laboratory scale, with ludwigite iron concentrate used as raw materials. The reducing temperature varied from 850 to 950 °C, the H2/CO mole ratio changed from 1.5 to 4.5, the range of reduction gas flow rate was from 2 to 5 L/min. The results indicate that the metallization degree of pellets increase with increase of the temperature, H2/CO mole ratio, and gas flow rate. However, after temperature rises to 850 °C, metallization degree increases slowly. The effect of H2/CO on the metallization degree is not very obviously with the ratio of H2/CO increasing from 1.5 to 4.5. When the gas flow rate was increased from 2 to 3 L/min, the metallization degree increased greatly from 72.2 to 92.1%. In the flow range from 3 to 5 L/min, the metallization degree was increased slowly. The results obtained could be useful for comprehensive utilization of ludwigite iron concentrate by gas-based direct reduction method.

Mar 1, 2017

By Jie Li, Thomas A. Rawdanowicz, W. J. Collis, S. Venkatraman, S. Iyer

"InSb being the lowest band gap. material amongst the 111-V semiconductors with low effective mass has long attracted research interest, due to its potential application in far infrared devices and for high speed circuit elements. In this paper, we report, for the first time, Te-doping of InSb on GaAs substrate using SnTe doping source with molecular beam epitaxy (MBE) technique and its electrical characterization. The undoped epilayers are n-type in the temperature range of 10 K to 300 K investigated. The room temperature (RT) mobility as high as 64,810 cm2/V·s (1.9x1016 cm-3) have been measured on a 4.8 µm thick epilayer. Sn Te doping at different doping levels were investigated. 5. 7 µm thick doped layers with RT carrier concentrations ranging from 2x1016 cm-3 to 3.2x1018 cm-3 with corresponding full width at half maximum (FWHM) of x-ray (400) rocking curve varying from 170-200 arc-seconds have been achieved. The Hall mobility of 20,000 cm2/V·s at 1.3xl018 cm-3 carrier concentration was obtained indicating that SnTe is a good candidate as source material for n-type doping of InSb.IntroductionThe thin films of InSb and InSb-based alloys have found considerable interest because of potential applications in III-V semiconductor-based infrared optoelectronic devices1• In addition, the advantage of the small effective mass and the consequent high mobility can be utilized in high frequency and high-speed circuit devices2 InSb can also be used in magnetoresistive sensors for position sensing3. Epitaxial InSb films grown by MBE may be doped n-type with Si or Sn, or with the group VI elements, namely, S, Se, or Te. Of the group VI elements, Te may be advantageous because of its relatively low vapor pressure. However, the vapor pressure is high enough to have sufficient memory effect during MBE growth. Hence different telluride compounds such as GaTe45, PbTe6 and Sb2Te37 have been used as the dopant source for Sb-based compounds. SnTe has also been used as a successful n-type dopant in the MBE growth ofGaSb8 But, to our knowledge, there is no report on the investigation of SnTe doping of InSb. In this paper, we report the first doping characteristics of SnTe in InSb layers grown on GaAs substrate."

Jan 1, 1998

Mineralogical and metallurgical scoping testwork were carried out to investigate the production of separate, marketable gold and platinum concentrates. The study utilized a flotation concentrate assaying approximately 5 wt% gold and 5 grams per tonne platinum. The gold-platinum mineralization was recovered from a placer deposit. Optical microscopy and scanning electron microscopy with energy dispersive x-ray analysis identified gold as zoned Au- Ag and Au-Ag-Cu alloys. Platinum primarily occurred as weakly zoned, variably magnetic Pt- Pd-Fe alloys. A combination of gravity and magnetic separations resulted in a gold concentrate grading 86.9 wt% Au (and 9.lwt% Ag) and a separate platinum concentrate grading 400 g/t Pt with recoveries of 94.5% and 96.7%, respectively. Magnetohydrostatic separation (MHS) using the Magstream 200 Separator indicated promising results.

Jan 1, 1994

By Mostafa O. El-Bealy

"To estimate the interdendritic cracking tendency in casting processes, a new model for interdendritic cracking criteria has been proposed. The model combines a concept of the alloying element effect on the interdendritic strain generation and therefore on the susceptibility of interdendritic cracking phenomena. A susceptibility of interdendritic cracking is modeled by using El-Bealy's interdendritic cracking susceptibility function ""BJCSF' and the opening displacement between the dendrites ""EIA "". These concepts are modeled based on the previous experimental observations and ElBealy' approach. The model is implemented numerically for a one-dimensional model problem with some similarities to the casting of steel. The variation of some key parameters that are known to influence the frequency and severity of the interdendritic cracking is then studied.I. INTRODUCTIONInterdendritic cracking ""hot tearing"" commonly encountered in both ferrous and nonferrous castings (1,2]. It is generally believed that interdendritic cracks start to nucleate and develop in the interdendritic strain region within the mushy zone [l-5]. The interdendritic strain region is then definitely coherent, but continuous films of liquid still exit (4,5]. This distinguishes interdendritic cracks from cold cracks forming during the casting process after complete solidification (6,7].Much effort has been put into the understanding of the interdendritic cracking phenomena, and several theories have been proposed. Fellini [8] stated that interdendritic crack ""hot tear"" will result if the material is subjected to too high of accumulated strain within so called vulnerable part of the solidification interval. Kinosita et. al. [9] and Campbell (10] also emphasized the role of tensile stresses in the forming of interdendritic cracks. Most interdendritic cracks criteria simply consider the size of solidification interval, stating that solidification range is associated with a lager interdendritic cracking susceptibility than a short range. Clyne and Davies (11] formulated a more refined such criteria based upon the time spent in different regimes of the solidification interval. They defined a vulnerable region in which thin continuous films of interdendritic liquid exist, and the permeability is low. When thermal strains are induced in this region, the film is not able to sustain the stresses, and an interdendritic crack will form."

Jan 1, 2001

By Somayeh Dashti, Ehsan Vahidi, Fereshteh Rashchi

"The main goals in zinc electrowinning process are decreasing of power consumption and increasing of current efficiency. In this study, the electrowinning of zinc in the presence of different additives in electrolyte were established and Arabic Gum, Gelatine, sodium lauryl sulphate and l-hexyl-3-methylimidazolium hydrogen sulfate in the five levels using Taguchi method was examined. In our previous researches, using orthogonal array, effect of zinc electrowinning parameters such as anode type, current density, sulphuric acid concentration, temperature and zinc ion concentration was studied and the optimized conditions for zinc electrowinning was obtained. Anode composition: Pb-Ag 0.5%-Sn2%-Sb1%, current density (A/m2):500, acid concentration (g/1):165, temperature: 60°C, zinc ion concentration (g/1):70. The main goals in zinc electrowinning process are decreasing of power consumption and increasing of current efficiency. ln this research, the effect of four additives: Gum Arabic, Gelatine, sodium lauryl sulphate and an organic material in the four levels with Taguchi method was examined. ln fact the effect of electrolyte environment and determining the best electrolyte under the optimized conditions is the main aim of this study.IntroductionDue to its low cost and abundance, zinc is widely used in the production of brass, galvanized steel, sacrificed anodes and primary and secondary batteries [I]. Some 80% of world primary zinc production is derived via roast-leach-electrowinning processes [2-4]. In the electrowinning process to both improve final product quality and current efficiency the leachate should be purified [5].To produce zinc a current method is to extractit from acidic zinc sulphate solutions by electrolysis with aluminum cathodes and insoluble lead-based anodes [6]. Though the electrolytic processing of zinc has been performed for many years, there are still current efficiency problems in the cathodic process. These low efficiencies (88- 93%) have a serious impact on the costs associated with the energy consumption. On the other hand, these low efficiencies increase energy consumption and decrease the quality of the surface morphology [7- 8]."

Jan 1, 2012

By Akihide Hosokawa

The void growth and coalescence in model materials involving a pre-existing three dimensional void array (i.e. multiple layers of a void array) was studied by X-ray computed tomography (XCT) coupled with in situ tensile deformation. To reduce the recording time, a new technique called fast tomography was employed. The model materials used in this paper were fabricated by the combination of an ultra-short pulsed laser machining system and a diffusion bonding technique, and two different types of arrays were prepared namely, FCC 1 and FCC 2 type array. This methodology allowed the authors to capture the entire process of growth and coalescence events of a void array embedded in the metal matrix. The failures in the both materials involved internal necking and shear localization. One of the highlights of this paper is that the plastic strain at the onset of void coalescence was measured for each model material. These values are in fact the adequate values to be compared with the coalescence strain predicted by existing void coalescence models such as the Brown and Embury model, the Thomason model and the Pardoen and Hutchinson model. The comparison suggested that the Brown and Embury model underestimated the coalescence in neither of the current model materials, while the Thomason model and the Pardoen and Hutchinson model showed a quite good agreement with the result for FCC 1 material. On the other hand the result from FCC 2 material agreed with none of the models probably due to the geometry of the void array that is not compatible with the existing models.

Jan 1, 2010

By Dhanesh Chandra

Long term stability studies were conducted on four variants of LaNi5; 10,000 hydriding/dehydriding cycles were used to evaluate their suitability for a metal hydride cooling system. Thermodynamic and structural studies were conducted to determine changes in these materials during cycling test period. The hydrogen sorption properties of LaNi5.2, and Lao 9Gd0.1Ni5 and LaNi4.75In0.27 were seriously degraded during the tests but the LaNi4.8Sn0.22 hydride was virtually unaffected. Hydride isotherms were measured at the beginning and at intervals through out the test period to observe the nature and extent of damage degradation in the sorption properties. X-ray diffraction studies of the alloys (LaNi5.2, LaO.9Gd0.1Ni5 LaNi4 8Sn0.22) and their respective hydride, before and after test, provided insight with regards to the observed changes in the hydride properties. Electron microscopic studies were also conducted to evaluate the changes in particle sizes.

Jan 1, 1989

By R. G. Reddy

Industrial copper reverberatory furnace slags were treated by high temperature techniques (sulfide and carbothermic reduction) to recover copper in alloy or matte phase at 1473K. Recovery was investigated for the condi¬tions of varying amounts of metallic sulfide, carbon and CaO additions. The results showed that recovery of copper increased with increasing amounts of carbon addition, and also is strongly dependent on the initial concentration of copper in the slags. Copper recovery for both carbothermic reduction and sulfide treatment were modeled with linear relationships as follows: for carbothermic reduction (%Cu recovery) = 9.0 (%Cu in slag)initial 73.8 and for sulfide (%Cu recovery) = 7.1 (%Cu in slag)initial 82.2 Higher copper recovery was obtained with sulfide treatment than with carbothermic reduction of slags.

Jan 1, 1983

By P. A. Olubambi1

Representative samples of the hydrothermal vein deposits of the bulk complex sulphide ore deposit, 10 km south of Ishiagu, in Ebonyin State, South Eastern part of Nigeria were collected from two small scale mining companies. The samples were mixed and successively crushed in a jaw crusher and cone crusher, and ground in a rod mill. Characterization was carried out with SEM, EDX, XRD, XRF and ICP-OES. Mineralogical analysis revealed the presence of sphalerite, galena, siderite, pyrite, quartz and chalcopyrite. X-ray Diffractometry showed that sphalerite mineral in the ore occurs as sphalerite ferrous with varied percentage of Zn and Fe within the various sizes while chalcopyrite occurs as a chalcopyrite group mineral with chemical formula Cu2MnSnS4. Results of the elemental analysis showed variations in elemental composition within the different sizes.

Jan 1, 2006

By Ehsan Vahidi, Fereshteh Rashchi, Ataollah Babakhani, Alireza Zakeri

"The synergistic effect of Cyanex 302 on solvent extraction of nickel and cadmium from sulfate solution with D2EHPA diluted in kerosene was investigated with the aim of increasing separation efficiency. Experiments were carried out within a pH range of 0.1-5.0 using sole D2EHPA and D2EHPA-Cyanex 302 mixtures in different ratios. Increasing Cyanex 302 to D2EHPA ratios in the organic phase caused a left shifting of the extraction isotherm of cadmium and a right shifting of the extraction isotherm of nickel. As a result, optimum separation was found with a Cyanex 302 to D2EHPA ratio of 0.1M:0.5M. In the present system, effect of a modifying reagent such as TBP was studied. The influence of various diluents including kerosene and carbon tetrachloride was also investigated.IntroductionBatteries are popular sources of portable energy. Ni-Cd batteries are manufactured in two main groups of small domestic cells and large industrial batteries with 80% being in domestic use. Ni-Cd cells have various uses, for example in cordless electric utensils, cordless telephones, airplane engine starters, and communicational distribution systems [1].Depleted Ni-Cd batteries are classified as hazardous waste since nickel and cadmium are heavy metals and suspected carcinogens. Given the risk associated with uncontrolled disposal, directions for issuing legislation on disposal and recycling of used batteries have been made in industrialized countries [2]. Recycling of Ni-Cd batteries is important from both economic and environmental points of view. Different methods have been used for recycling these wastes through pyrometallurgy [3], biotechnology [4,5], and hydrometallurgy [1,2].Due to the advantages of hydrometallurgical processes, several studies have been implemented on leaching and solvent extraction (SX) of the used Ni-Cd batteries. Leaching of batteries is usually done in sulfate or chloride media; while solvent extraction has been used in different extractants: two-stage solvent extraction by D2EHPA and Cyanex 272 [6]. Solvent extraction of Cd from leach solutions has been studied using various extractants; Cyanex 301 [1], D2EHPA [7], Cyanex 302 [8], Cyanex 923 [9], Cyanex 272, Tops 99, PC88A [10]. Application of phosphorus based extractants for the solvent extraction studies of Ni such as TOPS 99 [11], D2EHPA [12], Cyanex 272 [2], has been investigated. Separation of Cd(ll), Ni(II), and Co(ll) from chloride leach liquor of spent batteries [13], were explored in the earlier studies. Cd extraction with D2EHPA involves co-extraction of both Ni and Co [14], which causes issues in the separation process efficiency."

Jan 1, 2012

By Huayi Yin, Wang. Dihua, Wei Xiao, Xuhui Mao, Diyong Tang

"The world production of crude steel reached 1.55 billion tons in 2012,which generated ~2.5 billion tons of CO2. Electrochemical metallurgy especially through high temperature molten salt electrolysis with renewable electricity stands for a great opportunity for producing “green” metals. In recent years, electrolytic production of iron without emission of CO2 in different molten salt systems has been reported. A cost-affordable inert anode is the key to produce acceptable eco-friendly iron by the novel molten salt electrolysis processes. Based on the authors’ research, this paper will discuss iron production by molten salt electrolysis using a nickel alloy inert anode. On the other hand, the paper also covers a novel molten salt CO2 capture and electrochemical transformation (MSCC-ET) process, in which CO2 is effectively converted to value-added carbon and oxygen in a molten bath using a cost-affordable nonconsumable SnO2 anode.1. IntroductionEnergy and materials are cornerstones to support the development of human society. The traditional primary metal production, especially iron and steel, and electricity production are mainly based on the reactions between carbon (coal) and oxygen (represented by equations (1) and (2) respectively), which produce huge amount of CO2.MxOy + 0.5y C = x M + 0.5y CO2 (g) + Q1 ( 1 )C + O2 (g) = CO2 (g) + Q2 ( 2 )In 2012, the world production of crude steel reached 1.55 billion tons, of which 46.3 %, ~0.7165 billion tons were produced in China. Based on the average level of 1.7t CO2 emission per ton steel, more than 1 billion tons of CO2 generated from steel industry in China in the year. Besides the iron and steel industry, thermal power plant leads the CO2 emission in both USA and China. The total consumed electricity in China increased to 4959 billion kWh in 2012, ~70% of it was from coal fired power plant. The average CO2 emission for electricity production in the typical thermal power plant in China is around 0.78 kg kWh-1. It accounts for ~ 3.868 billion tons of CO2 emission from thermal power plant in 2012 in China."

Jan 1, 2014

By Shadia J. Ikhmayies

"Cadmium sulfide (CdS) in the form of thin films is an interesting material because it has a large variety of applications ranging from photovoltaic to luminescent devices. N-type CdS is usually used as a window layer in the heterojunction CdS/CdTe thin film solar cells. A review of the photoluminescence (PL) spectra ofn-type CdS thin films prepared by different techniques was performed. The effects of different dopants and impurities and the effects of temperature and deposition parameters on the PL spectra were discussed. Annealing in different atmospheres causes the changes in material structure and phase change from cubic to hexagonal phase which can be detected through the variations in the PL spectra. CdCh heat treatment improves the cystallinity of the films and enhances the exciton peaks and the green band in the PL spectra.IntroductionThin CdS films deserve attention because their expected gap emission lies very close to the highest sensitivity of the human eye. Thus, one might assume that thin CdS films are an appealing host for photonic devices [ l]. They have been used in a lot of applications including electronic and optoelectronic devices [2]. Thin films ofn-type CdS are widely used as a window layer in heterojunction solar cells such as CdS/CdTe solar cells. Doped and undoped CdS thin films can be obtained by different techniques such as; spray pyrolysis (SP) [3], chemical bath deposition (CBD) [2, 4], pulsed laser deposition [5, 6, 7], laser ablation [l], thermal evaporation [8].Several experimental techniques have been used in order to study semiconductor defects. In particular, photoluminescence (PL) has been shown as a powerful and sensitive tool in examining the crystal quality of polycrystalline thin films. PL can be used in the detection of defects which are radiative active. These defects can also act as traps in the transport of carriers [9]. The photoluminescence (PL) of thin film CdS is strongly influenced by the unbalanced stoichiometry, which is typical for CdS and is in general evoked by a Cd surplus. With increasing Cd content, the emission spectra move far below the gap to the red spectral range. Besides stoichiometry problems, independent of the material deposited, the PL properties of thin films depend on surface features and the influence of the interface between the film material and the substrate [10]."

Jan 1, 2013