Improved optical and electrical properties of sol–gel-derived boron-doped zinc oxide thin films

Sol–gel spin-coating was used to grow zinc oxide (ZnO) thin films doped with 0–2.5 at.% B on quartz substrates. The structural, optical, and electrical properties of the thin films were investigated using field-emission scanning electron microscopy, X-ray diffraction (XRD), photoluminescence (PL), ultraviolet–visible spectroscopy, and van der Pauw Hall-effect measurements. All the thin films had deposited well onto the quartz substrates and exhibited granular morphology. The average crystallite size, lattice constants, residual stress, and lengths of the bonds in the crystal lattice of the thin films were calculated from the XRD data. The PL spectra showed near-band-edge (NBE) and deep-level emissions, and B doping varied the PL properties and increased the efficiency of the NBE emission. The optical transmittance spectra for the undoped ZnO and boron-doped zinc oxide (BZO) thin films show that the optical transmittance of the BZO thin films was significantly higher than that of the undoped ZnO thin films in the visible region of the spectra and that the absorption edge of the BZO thin films was blue-shifted. In addition, doping the ZnO thin films with B significantly varied the absorption coefficient, optical band gap, Urbach energy, refractive index, extinction coefficient, single-oscillator energy, dispersion energy, average oscillator strength, average oscillator wavelength, dielectric constant, and optical conductivity of the BZO thin films. The Hall-effect data suggested that B doping also improved the electrical properties such as the carrier concentration, mobility, and resistivity of the thin films.     

固体热载体热解淮南煤实验研究

自制处理量为1 kg煤的间歇式固体热载体热解装置,以淮南烟煤为原料,石英砂作热载体,对该煤进行热解特性评价实验。考察了热载体初始温度700 ℃～900 ℃、反应 4 min～16 min、煤粒径及热载体与煤的质量比5～9对热解产物产率和性质的影响。结果表明,提高热载体初始温度,气、液产率增加;延长反应时间和提高热载体比例,气体产率有所增加;热载体初始温度对热解气组成影响显著。提高热载体与煤的质量比和热载体初始温度,可以抑制半焦对热解反应器内壁的黏附。     

Determination and characterization of the pyrolysis products of isoprocarb by GC-MS

The pyrolysis behavior of isoprocarb (an insecticide with contact and stomach action) is investigated using pyrolysis-gas chromatography-mass spectrometry. The pyrolysis products are separated using an HP-5 column under temperature program with helium as the carrier gas. The total of 80 separated pyrolysis components at 600 degrees C, 750 degrees C, and 900 degrees C under helium atmosphere are identified using a probability-based matching search procedure, combined with the correlation of boiling point (BP) and Lee retention index (RI). Some of the BP values of the tentative components are estimated using the group contributions method because experimental values are not available. The levels of the identified components are estimated by the peak area normalization method from the chromatogram. It is found that isoprocarb decomposes more with the increase of temperature, and a large number of mono aromatics and polycyclic aromatic hydrocarbons and their derivatives are produced when the pyrolysis temperature is higher than 750 degrees C. The content of the decomposition products in the pyrolysate varies from 0.04% to 22.20%.     

Temperature variation of DC conductivity of poly(3-alkyl thiophenes) and their cocrystals

The dc conductivity of poly(3-alkyl thiophenes) (P3ATs) and their cocrystals are measured in the temperature range of -130 to 150 degrees C. Both solvent-cast films and the melt-cooled films are used. The former exhibit a sharp increase followed by a decrease in conductivity, whereas the latter show only a sigmoidal increase in conductivity with temperature. The sigmoidal increase of the melt-cooled samples is dependent on the regioregularity and alkyl chain length of the samples and is explained from the solid-state transformation of the interdigited type-II crystal to a noninterdigited type-I crystal. The type-I crystal itself has lower conductivity than type-II crystals, and the samples exhibit a blue shift in UV-vis absorption spectra with an increase in temperature. So the sigmoidal increase of conductivity is attributed to the increase in carrier mobility with temperature in the type-I crystals. The X-ray and DSC results suggest that during the transformation of type-II to type-I crystals with increasing temperature, localized crystallites of smaller dimensions separated by narrower amorphous portions are produced throughout the whole matrix. But in the type-II polymorph, the crystallites are large with a wider gap in between. The sigmoidal increase is attributed to the easier hopping of the charge carrier among the localized crystallites of the type-I crystal with increasing temperature. In the cocrystals, the smaller sigmoidal increase with increasing irregular sample concentration is valid for a lower concentration of such localized crystallites. The same is true for cocrystals with longer alkyl chain lengths. The interfibrillar contribution of conductivity through the network junctions together with the carrier hopping between the localized crystallites might be a possible reason for the metallic-type behavior of solvent-cast samples after a certain temperature. The melt-cooled films do not exhibit metallic-type behavior because of the absence of a fibrillar network morphology.     

固体热载体热解霍林河褐煤实验研究

在处理量为10kg/h的粉煤-固体热载体移动床实验装置上,以循环灰为热载体对其进行了热解特性评价实验.考察了热解温度(460℃~610℃)、反应时间(6min~8min)及煤粒粒径对热解产物产率和组成的影响.结果表明,随着热解温度的升高,气体产率增大;焦油产率在520℃时达到最大值4.94%.热解煤气的热值为19.80...     

扎赉特旗油砂在氮气气氛下的热解制油研究

油砂是一种含有沥青或其他重质石油的沉积岩,主要用于提取油砂沥青,以生产合成原油。中国拥有相当数量的油砂资源,目前还未开采,仅处于初步研究阶段。加拿大在20世纪初期就展开了油砂的开采及制油研究工作,并于20世纪70年代由加拿大合成油公司实现了工业化生产。油砂生产的沥青和合成油已占其石油总产量的1／4以上。     

熔盐热裂解大豆油的特性研究

以大豆油为原料,在ZnCl₂-KCl熔融盐体系中考察了进料速量、载气流量、反应温度及进料量对其热裂解的影响。采用气相色谱-质谱联用仪(GC-MS)表征生物油组成。结果表明,进料速量和载气流量主要通过改变大豆油的反应停留时间影响裂解效果。当进料速率为1.2 g/min及不通载气时,大豆油停留时间较长,裂解较充分;随着温度升高,生物油得率增大,含氧化合物含量及酸值上升;随着进料量增大,生物油得率稳定在70%左右,但脱羧效果有所下降。经过催化加氢,生物油性质得到了明显的改善,组分分布与0^#柴油分布大体相似。     

裂解气相色谱-质谱联用技术研究黑香豆酊的热裂解行为

采用裂解气相色谱-质谱联用法研究了香精黑香豆酊在不同温度下的裂解行为,分析了黑香豆酊在不同温度下的热裂解产物,并用归一化法进行了定量。结果发现黑香豆酊在不同温度下表现出不同的转移行为,其热解产物和机理也各不相同。检索到苯并呋喃、香豆素和肉桂醛等16种致香物质。随着温度的升高,裂解产物中逐渐产生出有害物质。初步探讨了香豆素可能的裂解机理,为香味物质在卷烟燃烧过程的转化行为提供了例证。     

UV assisted pyrolysis of solution deposited BiFeO<Subscript>3</Subscript> multiferroic thin films. Effects on microstructure and functional properties

BiFeO₃ thin films were processed on platinized silicon substrate via chemical solution deposition. Short wave UV assisted pyrolysis was conducted in oxygen atmosphere in order to obtain a fine and homogeneous grain structure. Phase pure thin films with a pronounced (100) texture were obtained at a fairly low annealing temperature of 600°C. For comparison specimens processed without UV assisted pyrolysis were also investigated. It is shown that UV assisted pyrolysis leads to a substantial improvement of leakage resistance properties. Polarization switching could also be obtained using capacitance-voltage (C-V) curves. The leakage current was investigated as a function of temperature. Interpretation in terms of Frenkel-Poole mechanism leads to a high trap depth in the range of 2.4 eV which is attributed to the creation of Fe²⁺ centres. For both microstructures investigated well saturated magnetization loops were obtained with a remnant magnetization of 2Mr = 5.4 emu/cm³ and a coercive fields in the range of 2Hc = 200 Oe. Slightly higher saturation magnetization 2Ms of 55.4 emu/cm³ was obtained for UV assisted pyrolysis in comparison to 45.8 emu/cm³ for the thin films processed without UV.     

Investigation of the Evolution Behavior of Light Tar During Bituminous Coal Pyrolysis in a Fluidized Bed Reactor

The evolution behavior of the light tar fraction of tar during large bituminous coal particle pyrolysis in a fluidized bed reactor at 500-900℃ was investigated to optimize the industrial process. The coal residence time was varied from 30 s to 150 s. The crude tar obtained was distilled and separated into the light fraction and the heavy fraction through an evaporator under conditions of 280℃ and 10⁴ Pa. The light tar was subjected to GC-MS analysis, and the 300 main species in each spectrum were determined and analyzed. The experimental results showed that the evolution behavior of the light tar fraction and the heavy tar fraction presented spectacularly different variation trends with pyrolysis temperature and coal residence time. The molecular weight and number of rings per aromatic compound molecule contained in the light tar fraction increased with increasing pyrolysis temperature because of polymerization. It was also observed that the amount of methyl substituents decreased with an increasing number of rings per molecule of poly-aromatic ring compounds. The chain aliphatic compound evolution was suppressed and underwent heterocyclization with increasing temperature.     

The fire retardant behavior of various chlorides on cellulose

TG, DTA, and TMA data on the pyrolysis of α-cellulase powder in air is reported together with the modified pyrolysis behavior of the cellulose impregnated with between 2–3% (w/w) of calcium, potassium, sodium and zinc chlorides. The lower temperature of onset of the pyrolysis (as shown by TG and TMA), the increased peak areas of the DTA exotherms, and the elimination of an initial endotherm present in the pure cellulose, all suggest an increased flammability for the impregnated samples. Other properties of the impregnated celluloses however favor a fire retardancy effect; these are an increase in the temperature of the first exothermic peak on the DTA, a reduction in the maximum rate of mass loss, a reduction in the% mass loss occurring in the first mass loss period, and an increase in the% ash remaining at 800°C. The relative effect of the various chlorides is examined and shown to correlate with other data already published.     

气相色谱-质谱法研究香叶基-β-D-吡喃葡萄糖苷的热裂解行为

为了研究香叶醇的糖苷类香料前体香叶基-β-D-吡喃葡萄糖苷的热裂解行为,在200,300,400 ℃条件下,分别采用 在线模式的裂解仪无氧裂解和离线模式的高温熔盐加热裂解,热解产生的物质均经毛细管气相色谱-质谱仪进行定性和定 量检测。根据实验结果,对香叶基-β-D-吡喃葡萄糖苷的裂解机理进行了初步探讨。实验发现,香叶基-β-D-吡喃葡萄糖 苷在200 ℃条件下裂解量很少;300 ℃条件下裂解产生大量香叶醇,而其他杂质较少;随着温度的升高,400 ℃条件下裂解 产生的副产物明显增加。实验结果表明以300 ℃条件下裂解效果最好。同时,香叶基-β-D-吡喃葡萄糖苷热裂解产生了特 征香味成分香叶醇,其裂解的基本反应是O-糖苷键的断裂。在试验的两种方法中,在线裂解模式实验方法先进,定性直接, 结果准确;离线裂解模式实验方法操作方便,简单易行,而且在定性基础上可以实现定量分析。     

Pyrolysis behavior of phosphorus polyesters

The pyrolysis behavior of aromatic–aliphatic polyesters containing either a pendant 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) group or a phosphine oxide group incorporated into the polymer backbone was studied using a combination of thermogravimetry and pyrolysis-GC/MS. The behavior of the phosphorus polyesters was compared to that of non-phosphorus-containing reference polymers. It could be shown that the DOPO group mainly does not interfere with the polyester decomposition. It produces two main pyrolysis products, o-hydroxybiphenyl and dibenzofuran, with the latter one requiring a higher pyrolysis temperature. Minor products containing the DOPO ring result from secondary decomposition reactions. In contrast, the phosphine oxide group strongly modifies the polyester pyrolysis behavior by decreasing the degradation temperature and changing the composition of pyrolysis products. Among of those, phosphinites and a phosphinate could be identified indicating rearrangement processes of the phosphine oxide group taking place upon pyrolysis. Mass spectra of organophosphorus products and pyrolysis schemes of polyesters are discussed.     

Influence of pyrolysis temperature on the properties of sol–gel derived zinc oxide films

The influence of pyrolysis temperature on the properties of sol–gel derived zinc oxide films has been investigated. As-deposited films were pyrolyzed at 300 °C for 30 min and at 500 °C for 10 min. Final annealing was done at 600 °C for 30 min in air. The as-grown films deposited on soda-lime-silica glass substrates were highly c-axis oriented. Distinct grain structure was present in the film pyrolyzed at 500 °C, while the surface of the film pyrolyzed at 300 °C was smooth and no observed texture. The surface of ZnO pyrolyzed at 300 °C was covered with needle-like grain growth. With increasing pyrolysis temperature at 500 °C, a three-dimensional island formation was appeared.     

典型城市固体废弃物热解动力学机理研究

利用热重（TGA）技术研究了城市固体废弃物中塑料橡胶类、木质纤维素类、织物类和厨余类四大类可燃组分中七种典型固体废弃物热解反应过程。实验结果表明,塑料类和织物类最难热解,厨余类组分最易热解;采用Freeman-Carroll法对七种典型固体废弃物热解进行数据处理,从20种常用的固相反应机制函数中遴选出最优解,利用优化的数学函数和动力学参数建立动力学模型,结果表明,PE和羊毛线热解主要反应阶段的最优固相反应模型是球形相界面反应模型;橡胶粉、杨树枝热解反应模型遵循化学反应规律;米饭和本白棉布热解曲线遵循幂函数法则;白菜的最优模型是三维扩散模型。     

Crystallization Behavior of SiO2-TiO2 Ceramics Derived from Titanosiloxanes on Pyrolysis

The crystallization behavior of SiO2-TiO2 ceramics derived from titanosiloxanes was investigated in relation to the structure of the precursor and the pyrolysis temperature. The titanosiloxanes, [Si(OBut)2OTi(acac) 2O]2, [(ButO)3SiO] 2Ti (OPri)2, and [(ButO)3SiO] 3Ti(OPri), were pyrolyzed in an air atmosphere to form SiO2-TiO2 ceramics which crystallized to anatase at 600–650°C, 700–750°C, and 800–850°C, respectively. The crystallization temperature decreased with increased titanium content of the precursor. The average crystallite size of anatase increased with increased pyrolysis temperature and the titanium content. The crystallization temperature and the crystallite size for SiO2-TiO2 ceramics is controlled by the precursor structure, which may enable control of the physical properties of the ceramic materials.     

高硫石油焦高温热解过程及硫析出特性研究

为深入了解高硫石油焦在工业应用高温工况下的热解过程以及硫的析出特性,本研究采用高温固定床对青岛高硫石油焦进行了高温(900-1500℃)热解实验,考察了高温热解下热解气体释放规律,热解过程中焦的物理孔隙结构以及化学特性的演变,并对热解过程中硫的析出与演变特性进行了研究。结果表明,随着热解温度的升高,石油焦热解气中的H_2含量逐渐增加,CO含量变化不大,CH_4与CO_2含量则逐渐下降;热解焦的比表面积与平均孔隙均随热解温度的升高有所增加,颗粒的表面形态则受温度影响较小;热解温度的升高会降低石油焦中含有的非定型碳比例,提高其微晶结构的有序性以及石墨化程度;热解焦的气化活性随热解温度的升高先降低后升高,在1100℃附近有最小值; 1500℃高硫石油焦硫元素析出率达81.34%,仅少量硫醇类有机硫和噻吩环内的硫元素得以残存。     

The effect of acid treatment on the pyrolysis behavior of sewage sludges

One sewage sludge (SLA) from Ávila region (Spain) was selected and used as raw material in order to study the influence of acid treatment on the pyrolysis behavior of sewage sludges. SLA was heat treated with acid solutions at pH 1 and pH 2 leading to SLA-1 and SLA-2, respectively. Characterization of samples has showed that acid treatment leads to metals removal and modifications in the organic matter composition of sewage sludge. Pyrolysis of three samples showed that SLA and SLA-1 have a similar pyrolysis behavior whereas SLA-2 shows a slightly extended temperature interval for pyrolysis, beginning at lower temperature and finishing at higher temperatures.     

The effect of acid treatment on the pyrolysis behavior of sewage sludges

One sewage sludge (SLA) from Ávila region (Spain) was selected and used as raw material in order to study the influence of acid treatment on the pyrolysis behavior of sewage sludges. SLA was heat treated with acid solutions at pH 1 and pH 2 leading to SLA-1 and SLA-2, respectively. Characterization of samples has showed that acid treatment leads to metals removal and modifications in the organic matter composition of sewage sludge. Pyrolysis of three samples showed that SLA and SLA-1 have a similar pyrolysis behavior whereas SLA-2 shows a slightly extended temperature interval for pyrolysis, beginning at lower temperature and finishing at higher temperatures.     

聚酰亚胺LB膜热解制备SiC薄膜的XPS研究

用XPS对沉积在硅基片上的聚酰亚胺LB膜以及由它真空热解制备的SiC薄膜进行了研究 ,并对其形成过程进行了跟踪分析 .XPS结果显示聚酰亚胺LB膜结构均匀 ,质量良好 ;真空热解时 ,约在 6 70℃时LB膜中的C与衬底Si反应形成SiC ;Ar离子溅射深度俄歇谱表明所制备的SiC膜中Si和C浓度成梯度分布 ,说明SiC是由Si和C相互扩散反应形成的