Thermal Decomposition of Copper(I) Thiocarbamide Chloride Hemihydrate

Two combinations of simultaneous thermoanalytical techniques (TG+DTA and TG+EGA) were used to study the thermal decomposition of the title compound in order to gain a better insight into the spray pyrolytic processes leading to Cu2-xS and CuInS2 thin films. After dehydration a complex sequence of reactions starts above 220°C leading through several intermediates to the formation of CuO in air at 1000°C. In an inert atmosphere Cu2S is formed which in helium above 800°C partly decomposes to Cu. XRD and FTIR were used to identify the intermediate solid phases which in air included CuCl, Cu2OSO4, Cu2OCl2 and CuSO4. EGA-FTIR confirmed the complex reaction mechanism with NH3, HCl, H2O, COS, CO2 and some HCN as main gaseous products under oxidative conditions. This revised version was published online in July 2006 with corrections to the Cover Date.     

A Thermoanalytical Study of Copper(I) Thiocarbamide Compounds

Hydrated isostructural 1:3 complexes of copper(I) chloride and bromide with thiourea were synthesised and their thermal decomposition studied by simultaneous TG/DTA complemented by ex situ FTIR and XRD studies. The decomposition of Cu(tu)₃Cl·H₂O is initiated by dehydration around 100°C, followed by a total multi-step degradation of the structure in the temperature range of 200–600°C. The counter ion has some influence on the temperatures and composition of the solid residue. The results were compared with those obtained with the 1:1 complex Cu(tu)Cl·1/2H₂O. This revised version was published online in August 2006 with corrections to the Cover Date.     

Useful and accessible organometallic precursors for preparation of zinc sulfide and indium sulfide thin films via solution pyrolysis (printing) method

Polycrystalline β-zinc sulfide thin films were prepared by solution pyrolysis of an ethylzinc isopropylthiolate–zinc bis(dibutyldithiocarbamate) combined precursor (EtZnSiPr–Zn(S₂CNnBu₂)₂) in chloroform solution on glass or silicon(111) substrates at 300°C. Homogeneous but amorphous indium sulfide thin films were obtained from butylindium bis(isopropylthiolate) (nBuInSiPr₂) in P-xylene on these substrates at 300°C similarly. The sulfide thin films obtained were characterized by means of X-ray photoelectron spectroscopy (XPS), X-ray fluorescence Microanalysis, scanning electron microscopy (SEM) and optical band gap measurements.     

The morphological,optical and electrical properties of SnO2:F thin films prepared by spray pyrolysis

Combining the spray pyrolysis and the sol–gel techniques gives the possibility to produce Fluorine doped Tin oxide (SnO₂:F) thin films. Transparent conducting SnO₂:F thin films have been deposited on glass substrates by the spray pyrolysis technique. This technique for the fabrication of SnO₂:F filmsby combining sol–gel process and the spray pyrolysis technique ispresented in this paper. The Sol–gel precursors have been successfully prepared using SnCl₂·5H₂O and (Ac)F₃. The structural, electrical, and optical properties of these films were investigated. The high resolution transmission electron microscopy (HRTEM) and selected area diffraction (SAD) patterns of SnO₂:F films show that the gel films lead to a tetragonal structure. The X‐ray diffraction pattern of the films deposited at substrate temperature 530° , the orientation of the films was predominantly [110]. In addition, the surface chemical components were also examined by X‐ray photoelectron spectroscopy (XPS) showing the SnO₂:F deposited with the atomic concentration ratios Sn/F 1.82:1. The minimum sheet resistance was 50 Ω and average transmission in the visible wavelength range of 300 to 800 nm was 87.25%. Copyright © 2008 John Wiley & Sons, Ltd.     

Facile synthesis of spray pyrolyzed ZnO/NiO nanocomposites thin films

Abstract

This study reviews ZnO, NiO, and ZnO/NiO nanocomposites thin films deposition using the Spray Pyrolysis Technique (S.P.T). The thin films were deposited onto ordinary glass substrates heated at 500?°C from aqueous solutions of zinc chloride and nickel chloride precursors dissolved in distilled water. The structural, morphological, and optical properties of the ZnO, NiO, and ZnO/NiO thin films have been studied by X-ray diffraction, scanning electron microscopy, Raman spectroscopies, and so on. The optical band gaps are 3.3 and 3.5?eV for ZnO and NiO thin films, respectively obtained by UV–Vis spectroscopy. However, the optical band gaps of ZnO/NiO nanocomposites thin films, are noticeable out of the range (3.4–3.64?eV).     

Growth of semiconducting iron sulfide thin films by chemical vapor deposition from air-stable single-source metal organic precursor for photovoltaic application

Semiconducting nanostructured iron sulfide thin films were prepared by aerosol chemical vapor deposition at 673 and 723?K from newly synthesized iron complex of dithiocarbo-1,2,3,4-tetrahydroquinoline [Fe(S₂CNC₉H₁₀)₂]. The degree of film surface roughness was determined by atomic force microscopy. The nature of the deposited thin films formed was determined by a combination of EDX analysis and glancing angle X-ray diffraction.     

Influence of substrate temperature on the structural and optical properties of crystalline ZnO films obtained by pulsed spray pyrolysis

In this work, we report on the structural and optical properties of ZnO films deposited by pulsed spray pyrolysis at relatively low temperatures, compatible with a large variety of substrates and processing technologies. Crystalline ZnO films were deposited onto glass substrates using zinc acetate dihydrate dissolved in distilled water with concentration of 0.2 M. The temperature of the substrate was varied in the range T_s = 473–673 K with ΔТ = 50 K. Effect of T_s were investigated by scanning electron microscopy, x‐ray diffraction and energy dispersive x‐ray, and optical spectroscopies. Also, the influence of T_s on the grain size, phase composition, texture quality, coherent scattering domain size, crystal lattice parameters, chemical composition, transmission coefficient, and the bang gap of the ZnO films were studied. X‐ray diffraction analysis revealed that films were polycrystalline with hexagonal phase and showed as preferential orientation (101) at T_s < 573 K and (100) and (002) at T_s > 573 K. Scanning electron microscopy (SEM) measurements showed that the substrate temperature has a strong effect on morphology of the films. Energy dispersive analysis revealed that ZnO films consisted of the non‐stoichiometric compounds. Optical measurements showed ZnO films to be highly transparent in the visible region, and optical band gap is shifting from 3.18 eV to 3.30 eV. Copyright © 2015 John Wiley & Sons, Ltd.     

Thermal behaviour of precursors for CuInS2 thin films deposited by spray pyrolysis

The thermal decomposition of precursors for copper indium disulphide (CuInS₂) thin films obtained by drying aqueous solutions of copper chloride (CuCl₂), indium chloride (InCl₃) and thiourea (SC(NH₂)₂) at the Cu:In:S molar ratios of 1:1:3 (1) and 1:1:6 (2) was monitored by simultaneous thermogravimetry /differential thermal analysis/ evolved gas analysis-mass spectrometry (TG/DTA/EGA-MS) measurements in a dynamic 80 %Ar + 20 %O₂ atmosphere. X-ray diffraction (XRD) and Fourier transform infrared (FTIR) spectroscopy were used to characterise the dried precursors and products of the thermal decomposition. The precursors 1 and 2 are mixtures of copper and indium chloride thiourea complex compounds, whilst 1 can also contain unreacted InCl₃. The thermal degradation of 1 and 2 in the temperature range of 30–800 °C consists of six steps with a total mass loss of 71.5 and 89.8 %, respectively. According to XRD, CuInS₂ is formed below 300 °C. Decomposition of 1 and 2 is completed at 620 and 600 °C, respectively. The final decomposition product of 1 at 800 °C consists of a mixture of In₂O₃ and CuO phases, whilst 2 consists of In₂O₃, CuO and Cu₂In₂O₅ phases. EGA by MS revealed the release of CS₂, NH₃, H₂NCN and HNCS, which upon their oxidation also yield COS, SO₂, HCN and CO₂.     

The effect of polyvinyl alcohol (PVA) on the optical,electrical and solid state properties of copper zinc tin sulfide (CZTS) deposited by sensitive spray pyrolysis (SSP)

Recently, the use of CZTS as the basis for other generation of low cost thin films solar cells has stimulated further researches. Its excellent p-type absorber nature, relatively high absorption coefficient and ideal energy band-gap of 1.5eV motivated these efforts. Additionally, CZTS consist of earth-abundant, cheap and non-toxic elements with very low manufacturing cost. Initially, copper indium gallium selenide (CIGS) solar cell device emerged but suffered limitations in further development because of rare indium and gallium in the device structure therefore, CZTS is recently preferred as an alternative to CIGS commercial solar cell absorber layer. In this work, solution mixture of CZTS and PVA was deposited on a substrate at temperature of 150 °C. Sensitive spray pyrolysis was used to grow the thin films where calculated amount of the precursor mixture was allowed to fall and be deposited on a heated substrate to form CZTS/PVA thin films. Subsequently, the thin film samples were annealed at a temperature of 200^oCfor 1 h to achieving pure crystalline thin film formation. SEM, XRD analysis, Optical, Solid State properties and Raman analysis were studied. The XRD analysis showed that the thin films fell into the pure kesterite structure of CZTS. Results show that produced thin films exhibited higher absorption coefficient and optical conductivity than pure CZTS, 10⁶ m^?1 and 10¹⁴(S^?1) against 10⁴cm^?1 and 10¹²(S^?1) respectively. The band-gap is between 1.53eV and 1.73eV. Using a PVA concentration of 0.05 M yielded highest absorbance and optical conductivity with lowest real dielectric constant and transmittance. These improved optical, electrical and solid state properties suitably qualify these thin films as absorber layer material for solar cell applications.     

Synthesis and characterization of alumina- and zirconia-based powders obtained by the ultrasonic spray pyrolysis

The ultrasonic spray pyrolysis (USP) technique was used for synthesis of alumina- and zirconia-based powders. The starting agents were aqueous solutions, atomized by the ultrasonic spray generator and pyrolized in the furnace under the open-air conditions. The powders prepared by USP were in the form of solid and hollow aggregates (spheres) consisted of nanosize amorphous grains as determined by the microscopy and the X-ray diffraction techniques. The alumina-based powders were consolidated by the pulse plasma sintering resulting in single-phase materials. Different behavior of solid and hollow particles during the isostatic sintering is found; a higher degree of deformation of spheres is observed in the second case.     

Thin films of Ln1−xSrxCoO3 (Ln=La, Nd and Gd) and SrRuO3 by nebulized spray pyrolysis

Thin films of La_1−xSr_xCoO₃, Nd_0.5Sr_0.5CoO₃, Gd_0.5Sr_0.5CoO₃ and SrRuO₃ have been deposited on Si(100), LaAlO₃(100) and SrTiO₃(100) single crystal substrates by nebulized spray pyrolysis. The films deposited on Si are generally polycrystalline, but they are highly oriented on the oxide substrates. The cobaltate films are generally not metallic, but exhibit low resistivity specially when x=0.3 and 0.5, the latter also exhibiting ferromagnetic characteristics. Films of La_0.7Sr_0.3CoO₃ show negative magnetoresistance of 35% around 180 K. Films of SrRuO₃ are metallic on Si and LaAlO₃ substrates but show an insulator–metal transition on SrTiO₃ around 130 K, around which temperature negative magnetoresistance is observed.     

Battery performance of nanostructured lithium manganese oxide synthesized by ultrasonic spray pyrolysis at elevated temperature

Nanostructured lithium manganese oxide with spherical particles was synthesized via ultrasonic spray pyrolysis technique. The material shows a pronounced stability upon prolonged cycling at room temperature at high charge–discharge rates up to 10C. The electrochemical performance of the cell at elevated temperature was remarkably improved by addition of AlPO₄ to the electrolyte. The AC impedance spectroscopy study showed the interface stabilization by the AlPO₄ additives and the suppression of the interface impedance development upon prolonged cycling.     

基于热重红外联用分析的PE、PS、PVC热解机理研究

利用TGA-FTIR联用技术考察了PE、PS、PVC三种典型塑料的热解特性。结果表明,热稳定性从弱到强依次为PVC、PS、PE。PE热解反应过程为典型的一段式反应,红外光谱分析结果表明,PE热解过程为无规则断链形式,生成产物成分复杂,且随热解过程而改变,开始以饱和烃基团为主,中后期以烯烃基团为主,同时有少量炔烃;PS热解过程同样为一段式反应,红外光谱显示主要热解产物为苯乙烯单体,说明热解过程主要是苯乙烯的解聚过程;PVC热解过程较为复杂,主要分为脱氯阶段和共轭多烯重构阶段,红外光谱结果表明,产物中有芳香族化合物。脱氯过程和共轭多烯重构、环化过程在时间和空间上有重合,给二噁英类污染物的生成制造了可能。     

Thermal decomposition of silver cyano complex and characterization its decomposition products by ETA,DSC, DTA and TG

It was found by DTA and TG that [Phenyl₂I][Ag(CN)₂] in the solid state is chemically stable on heating in argon up to 160°C. During heating to higher temperatures it decomposes, forming volatile products such as [Phenyl]I, [Phenyl]NC and (CN)₂ [1]. After heating the sample to 500°C metallic silver resulted. The volatile and intermediate solid products were analysed by IR-spectroscopy.It was found by means of DTA and ETA that an isophase reversible transition takes place when the sample is heated and cooled, not higher than 100°C. At heating higher than 100°C the sample melts (melting pointT _m=135°C). The enthalpy melting was determined by means of DSC (H=–28 kJ·mol^–1).By means of ETA the disorder degree of the final decomposition product was estimated. The value of the activation energy of radon diffusion in the temperature range 720°–500°C equals 32.6 kJ·mol^–1.Dedicated to Prof. I. N. Bekman Moscow State University at the occasion of his 50th birthday     

Preparation of copper-indium sulfide thin films by single-source OMCVD: Mass-spectral investigation of decomposition path of the organometallic sources

In order to prepare high-quality CuInS₂ thin films vapor phase decomposition patterns of three copper-indium binuclear complexes, and as candidates for source materials were investigated using EI MS. The complex 1c showed series of intensive peaks due to the fragmentation of M⁺. For 1a, only a fragmentation pattern starting from BuIn(S₂CNBu₂)₂ was detectable. This should suggest that 1a decomposed into BuIn(S₂CNBu₂)₂ and copper sulfide before vaporization. In addition an ambiguous feature could be observed for 1b, viz. two fragmentation paths. Consequently, we judge that 1c is a suitable source complex to prepare CuInS₂ thin films via a single-source OMCVD process. Thus chalcopyrite CuIns₂ thin films were successfully prepared via single-source OMCVD using 1c as a source complex, with T_substrate400°C, T_source80°C, base pressure 0.7 Torr and carrier (nitrogen) flow rate 0.8 L min^?1. Fragmentation of two copper dithiocarbmates, Cu(S₂CNBu₂)₂ and Cu[S₂CN(i-Pr)₂]₂, and two butylindium thiolates, Bu₂InS(i-Pr) and BuIn[S(i-Pr)]₂, as components of 1 is additionally discussed.     

Evolved gas analysis of dichlorobis(thiourea)zinc(II) by coupled TG-FTIR and TG/DTA-MS techniques

Identification and monitoring of gaseous species released during thermal decomposition of the title compound 1, Zn(tu)₂Cl₂, (tu=thiourea, (NH₂)₂C=S) have been carried out in flowing air atmosphere up to 800°C by both online coupled TG-EGA-FTIR and simultaneous TG/DTA-EGA-MS. The first gaseous products of 1, between 200 and 240°C, are carbon disulfide (CS2) and ammonia (NH₃). At 240°C, an exothermic oxidation of CS₂ vapors occurs resulting in a sudden release of sulphur dioxide (SO₂) and carbonyl sulphide (COS). An intense evolution of hydrogen cyanide (HCN) and beginning of the evolution of cyanamide (H₂NCN) and isothiocyanic acid (HNCS) are also observed just above 240°C. Probably because of condensation and/or polymerization of cyanamide vapors on the windows and mirrors of the FTIR gas cell optics, some strange baseline shape changes are also occurring above 330°C. Above 500°C the oxidation process of organic residues appears to accelerate which is indicated by the increasing concentration of CO₂, while above 600°C zinc sulfide starts to oxidize resulting in the evolution of SO₂. All species identified by FTIR gas cell were also confirmed by mass spectrometry, except for HNCS. This revised version was published online in July 2006 with corrections to the Cover Date.     

Solar photocatalytic activities of porous Nb-doped TiO2 microspheres prepared by ultrasonic spray pyrolysis

Ultrasonic spray pyrolysis method was used to prepare Nb-doped TiO₂ porous microspheres with an average diameter of 500 nm for solar photocatalytic applications. The effect of Nb-doping on morphology, structure, surface area, as well as spectral absorption properties of TiO₂ microspheres was investigated with SEM, TEM, XRD, Raman spectra, BET, and UV-Vis absorption spectra. The Nb-doping decreased the grain size of TiO₂ porous microsphere, and influenced its surface area and pore size distribution dependent on the doping concentration, but changed negligibly the morphology and size of TiO₂ microspheres. Moreover, the Nb-doping was observed to extend the spectral absorption of TiO₂ into visible spectrum, and the absorption onset was red-shifted for about 88 nm at a doping level of 5% compared to pristine TiO₂ microspheres. Under solar or visible irradiation, Nb-doped TiO₂ microspheres showed higher photocatalytic activity for methylene blue degradation compared with TiO₂ microspheres, which could be ascribed to the extended light absorption range and the suppression of electron-hole pair recombination.     

Preparation and properties of solution-processed zinc tin oxide films from a new organic precursor

Transparent,smooth and dense zinc tin oxide (ZTO) thin films have been successfully produced by using a new precursor solution,zinc acetate and tin(II) 2-ethylhexanoate mixed with 2-ethanolamine in methoxyethanol.The ZTO films have been prepared by spin-coating,followed by thermal treatment in oxygen atmosphere.The morphology,composition,crystallinity and band gap energy (Eg) of the ZTO thin films have been characterized by Atomic Force Microscopy (AFM),Atomic Emission Spectrometry (AES),X-ray Diffraction (...     

Study of a Brazilian spent catalyst as cement aggregate by thermal and mechanical analysis

Fluidized catalytic cracking units of refineries normally use zeolite catalysts to treat heavy oil fractions. This catalyst is regenerated continuously, but due to the reduction of its activity during the process, it is partially substituted by a new catalyst make-up. The spent residue has a high content of silicon and aluminum oxides and usually presents pozzolanic properties. This paper presents the study of a Brazilian spent catalyst, which is being tested as a pozzolanic aggregate in partial substitution to cement. Pastes were prepared with 15, 20 and 25% in substitution to cement mass and analyzed after 28 days of hydration. Hydrated paste samples were analyzed by simultaneous thermogravimetry and differential thermal analysis, to quantify the calcium hydroxide consumption, as well as the content of other main hydrated cement phases. Compressive strength analysis was also performed after 28 days of hydration. Although, as spent catalyst content is increased, the pozzolanic activity is confirmed by the increase of calcium hydroxide consumption on cement mass basis, unlikely to other studied spent FCC catalysts, tested for the same purpose, the compressive strength of respective paste specimens decreases, due to the increase of other hydrated phases formation.