Fundamental and progress of Bi_2Te_3-based thermoelectric materials

Thermoelectric materials,enabling the directing conversion between heat and electricity,are one of the promising candidates for overcoming environmental pollution and the upcoming energy shortage caused by the over-consumption of fossil fuels.Bi2Te3-based alloys are the classical thermoelectric materials working near room temperature.Due to the intensive theoretical investigations and experimental demonstrations,significant progress has been achieved to enhance the thermoelectric performance of Bi2Te3-based thermoelectric materials.In this review,we first explored the fundamentals of thermoelectric effect and derived the equations for thermoelectric properties.On this basis,we studied the effect of material parameters on thermoelectric properties.Then,we analyzed the features of Bi2Te3-based thermoelectric materials,including the lattice defects,anisotropic behavior and the strong bipolar conduction at relatively high temperature.Then we accordingly summarized the strategies for enhancing the thermoelectric performance,including point defect engineering,texture alignment,and band gap enlargement.Moreover,we highlighted the progress in decreasing thermal conductivity using nanostructures fabricated by solution grown method,ball milling,and melt spinning.Lastly,we employed modeling analysis to uncover the principles of anisotropy behavior and the achieved enhancement in Bi2Te3,which will enlighten the enhancement of thermoelectric performance in broader materials

Synergistically Toughening Effect of SiC Whiskers and Nanoparticles in Al_2O_3-based Composite Ceramic Cutting Tool Material

In recent decades, many additives with different characteristics have been applied to strengthen and toughen Al2O3-based ceramic cutting tool materials. Among them, SiC whiskers and SiC nanoparticles showed excellent performance in improving the material properties. While no attempts have been made to add SiC whiskers and SiC nanoparticles together into the ceramic matrix and the synergistically toughening effects of them have not been studied. An Al2O3-SiCw-SiC np advanced ceramic cutting tool material is fabricated by adding both one-dimensional SiC whiskers and zero-dimensional SiC nanoparticles into the Al2O3 matrix with an effective dispersing and mixing process. The composites with 25 vol% SiC whiskers and 25 vol% SiC nanoparticles alone are also investegated for comparison purposes. Results show that the Al2O3-SiCw-SiCnp composite with both 20 vo1% SiC whiskers and 5 vol% SiC nanoparticles additives have much improved mechanical properties. The flexural strength of Al2O3-SiCw-SiCnp is 730＋ 95 MPa and fracture toughness is 5.6 ± 0.6 MPa.m1/2. The toughening and strengthening mechanisms of SiC whiskers and nanoparticles are studied when they are added either individually or in combination. It is indicated that when SiC whiskers and nanoparticles are added together, the grains are further refined and homogenized, so that the microstructure and fracture mode ratio is modified. The SiC nanoparticles are found helpful to enhance the toughening effects of the SiC whiskers. The proposed research helps to enrich the types of ceramic cutting tool and is benefit to expand the application range of ceramic cutting tool.

DPGL:The Direct3D9-based Parallel Graphics Library for Multi-display Environment

The emergence of high performance 3D graphics cards has opened the way to PC clusters for high performance multi- display environment. In order to exploit the rendering ability of PC clusters, we should design appropriate parallel rendering algorithms and parallel graphics library interfaces. Due to the rapid development of Direct3D, we bring forward DPGL, the Direct3D9-based parallel graphics library in D3DPR parallel rendering system, which implements Direct3D9 interfaces to support existing Direct3D9 application parallelization with no modification. Based on the parallelism analysis of Direct3D9 rendering pipeline, we briefly introduce D3DPR parallel rendering system. DPGL is the fundamental component of D3DPR. After presenting DPGL three layers architecture, we discuss the rendering resource interception and management. Finally, we describe the design and implementation of DPGL in detail, including rendering command interception layer, rendering command interpretation layer and rendering resource parallelization layer.

Effects of Thickness and Temperature on Thermoelectric Properties of Bi2Te3-Based Thin Films

Bi_2Te_3 thin films and GeTe/B_2Te_3 superlattices of different thicknesses are prepared on the silicon dioxide substrates by magnetron sputtering technique and thermally annealed at 573 K for 30 min. Thermoelectric（TE）measurements indicate that optimal thickness and thickness ratio improve the TE performance of Bi_2Te_3 thin films and GeTe/B_2Te_3 superlattices, respectively. High TE performances with figure-of-merit（ZT） values as high as 1.32 and 1.56 are achieved at 443 K for 30 nm and 50 nm Bi_2Te_3 thin films, respectively. These ZT values are higher than those of p-type Bi_2Te_3 alloys as reported. Relatively high ZT of the GeTe/B_2Te_3 superlattices at 300-380 K were 0.62-0.76. The achieved high ZT value may be attributed to the unique nano-and microstructures of the films,which increase phonon scattering and reduce thermal conductivity. The results indicate that Bi_2Te_3-based thin films can serve as high-performance materials for applications in TE devices.

Total Ionization Dose Effects on Charge Storage Capability of Al2O3/HfO2/Al2O3-Based Charge Trapping Memory Cell

Because of the discrete charge storage mechanism, charge trapping memory（CTM） technique is a good candidate for aerospace and military missions. The total ionization dose（TID） effects on CTM cells with Al2O3/HfO2/Al2O3（AHA） high-k gate stack structure under in-situ 10 keV x-rays are studied. The C-V characteristics at different radiation doses demonstrate that charge stored in the device continues to be leaked away during the irradiation,thereby inducing the shift of flat band voltage（V（fb））. The dc memory window shows insignificant changes, suggesting the existence of good P/E ability. Furthermore, the physical mechanisms of TID induced radiation damages in AHA-based CTM are analyzed.

Removal of Basic and Non-Basic Nitrogen Compounds from Model Oil by FeCl_(3)-Based Ionic Liquids

The low-viscosity FeCl_(3)-based ionic liquids(ILs)prepared from the interaction of anhydrous FeCl_(3) and alkyl imidazolium bromide([1-alkyl-3-methyl-imidazolium]Br,alkyl=ethyl,butyl,hexyl,octyl)are highly effective for the denitrogenation of model oil containing quinoline or indole.The results indicate that the chain length of the alkyl group on the imidazolium cation has little influence on the N-extraction efficiency.With the selected IL[Bmim]Br/FeCl_(3),up to 99.1%of N-extraction efficiency from model oil containing quinoline can be attained at an extraction temperature of 30°C with an IL/oil mass ratio of 1/7 and an extraction time of 30 min.The indole extraction efficiency reaches 98.9%at an IL/oil mass ratio of 1:1.Moreover,the quinoline extraction efficiency remains as high as 92.3%after the IL has been recycled four times.

Study of Bi_2O_3-based Rare Earth Solid Electrolyte Used in Fuel Cell

Solid ceramic electrolyte materials (Bi_2O_3)_(0.75)(Y_2O_3)_(0.25) and(Bi_2O_3)_(0.65)(Gd_2O_3 )_(0.35)were synthesized.Their crystal structure, XPS spectra and the change of ionic conductivity versus temperature were measured.A Bi_2O_3-based rare earth solid electrolyte fuel cell with ZrO_2-Y_2O_3 protection film was made.

New flexible CsPbBr_(3)-based scintillator for X-ray tomography

The evolution of lead halide perovskites used for X-ray imaging scintillators has been facilitated by the development of solution-processable semiconductors characterized by large-area,flexible,fast photoresponse.The stability and durability of these new perovskites are insufficient to achieve extended computed tomography scanning times with hard X-rays.In this study,we fabricated a self-assembled CsPbBr_(3)-based scintillator film with a flexible large-area uniform thickness using a new roomtemperature solution-processable method.The sensitivity and responsivity of X-ray photon conversion were quantitatively measured and showed a good linear response relationship suitable for X-ray imaging.We also demonstrated,for the first time,that the self-assembled CsPbBr_(3)-based scintillator has good stability for hard X-ray microtomography.Therefore,such an inexpensive solution-processed semiconductor easily prepared at room temperature can be used as a hard X-ray scintillator and equipped with flexible CsPbBr3-based X-ray detectors.It has great potential in three-dimensional high-resolution phase-contrast X-ray-imaging applications in biomedicine and material science because of its heavy Pb and Br atoms.

STUDY ON THE INFRARED TRANSMITTING As_2Te_3-BASED CHALCOHALIDE GLASSES

This paper reports the formation and some properties of a new class of chalcohalide glasses in the As2Tef iodide systems. The As2Te3-Pb12, As2Te3-HgI2, As2Te3-CitI and As2Te3-AgI systems can form stable bulk glasses in wide composition regions ?and no bulk glass formation was found in the As2Te3-TH sys-tem. As2Te3-based glasses have glass transition tempera-

Thermoelectric Transport by Surface States in Bi2Se3-Based Topological Insulator Thin Films

We develop a tractable theoretical model to investigate the thermoelectric （TE） transport properties of surface states in topological insulator thin films （TITFs） of Bi2Sea at room temperature. The hybridization between top and bottom surface states in the TITF plays a significant role. With the increasing hybridization-induced surface gap, the electrical conductivity and electron thermal conductivity decrease while the Seebeck coefficient increases. This is due to the metal-semiconductor transition induced by the surface-state hybridization. Based on these TE transport coefficients, the TE figure-of-merit ZT is evaluated. It is shown that ZT can be greatly improved by the surface-state hybridization. Our theoretical results are pertinent to the exploration of the TE transport properties of surface states in TITFs and to the potential application of Bi2Sea-based TITFs as high-performance TE materials and devices.

Synthesis, Electrochemistry, and Fluorescence of Two Ru(phen)_3^(2+)-based Surfactants

Two new Ru(phen) -based surfactants. Ru(phen)2(phenNHCO-C(11))(PF6)2 and Ru(phen)2(phenNHCO-C(17))(PF6)2. have been designed and synthesized, whose chemical structures were characterized by means of IR. 1H NMR and MS. Also. electrochemistry and fluorescence of them are reperted.

微波溶剂热法快速合成CoSb_(3)纳米粉体的工艺研究

以CoCl_(2)和SbCl_(3)为前驱物、NaBH_(4)为还原剂、无水乙醇和聚乙二醇(200)为溶剂,采用微波溶剂热法合成了CoSb_(3)纳米粉体,并考察了反应温度、前驱物的摩尔比以及保温时间对CoSb_(3)纳米粉体的影响。通过XRD、SEM、TEM、激光粒度仪分别对样品的物相、形貌、晶粒尺寸进行表征。结果表明,当反应温度分别为210、230℃和250℃时,样品的主相分别为CoSb、CoSb_(2)和CoSb_(3)。在250℃保温10 min时,产物同时存在CoSb_(3)、CoSb_(2)、Sb三相;保温时间延长至20 min,CoSb_(2)和Sb相含量减少,产物中主相为CoSb_(3)相;保温时间延长至30 min可得到高纯CoSb_(3)相。通过Rietveld精修法对CoSb_(3)产物进行定量分析,CoSb_(3)相质量分数在90.9%以上。CoSb_(3)样品的晶体形貌为小颗粒球状,晶粒分布均匀,平均晶粒尺寸为33 nm。

Effect of MgO-Cr_(2)O_(3) and Mg0-MgAl_(2)0_(4)-based refractories on refractory-steel interface reaction and cleanliness of pipeline steel

The interaction of MgO-MgAl_(2)O_(4)-based and MgO-Cr_(2)O_(3)-based refractories with X70 molten steel was studied by immersion experiments at 1560℃.The effects of immersion time(30 and 60 min)on the contents of total oxygen(TO),Al,Nb,Si,Mn,and Cr as well as the composition,number density,and size distribution of inclusions in the molten steel were investigated.The influence of the penetration and erosion degree of the molten steel to the refractory on the steel-refractory interface layer was analyzed.The results show that,at 1560℃,the MgO-MgAl_(2)O_(4)-based refractory can better control the contents of TO and the composition of molten steel compared with the MgO-Cr_(2)O_(3)-based refractory.The TO content is only 16×10^(-4) wt.%in the molten steel after reacted with the Mg0-MgAl_(2)O_(4)-based refractory at the end point of refining,4 accounting for 11.5%of that reacted with the MgO-Cr_(2)O_(3)-based refractory(139×10^(-4) wt.%).The number density of inclusions is only 14 mm^(-2),and the average size ofinclusions is only 1.31μm,with thelargest proportion of inclusions in 1-2μm(70%).The Al_(2)O_(3)-MnS-CaO complex inclusions in the original steel changed to complex inclusions dominated by Cr-Nb-Mn-S-O and MgO.Al_(2)O_(3),corresponding to the MgO-Cr_(2)O_(3)-based and MgO-MgAl_(2)O_(4)-based refractories,respectively.The MgO.Al_(2)O_(3) layer was formed at the reaction interface between MgO-MgAl_(2)O_(4)-based refractory and molten steel,which is helpful to restrict the erosion of refractories and the pollution of molten steel.The damage mechanism of the MgO-Cr_(2)O_(3)-based refractory is mainly permeation and chemical reaction,while the damage of the MgO-MgAl_(2)O_(4)-based refractory is mainlyscouring erosion.

Substitution of Pb with (Li_(1/2)Bi_(1/2)) in PbZrO_(3)-based antiferroelectric ceramics

PbZrO_(3)-based antiferroelectric(AFE)ceramics are promising dielectrics for high-energy-density capacitors due to their reversible phase transitions during charge-discharge cycles.In this work,a new composition series,[Pb_(0.93-x)La_(0.02)(Li_(1/2)Bi_(1/2))_(x)Sr_(0.04)][Zr_(0.57)Sn_(0.34)Ti_(0.09)]O_(3),with Li^(+)and Bi^(3+)substitution of Pb^(2+)at x=0,0.04,0.08,0.12,0.16 is investigated for the microstructure evolution,ferroelectric(FE)and dielectric properties.It is found that Li^(+) and Bi^(3+) substitution can significantly reduce the sintering temperature and simultaneously enhance the dielectric breakdown strength.An ultrahigh energy efficiency(94.0%)and a large energy density(3.22 J/cm^(3))are achieved in the composition of x=0.12 with a low sintering temperature(1075℃).

Prediction and interpretation of photocatalytic NO removal on g-C_(3)N_(4)-based catalysts using machine learning

Predictive modeling of photocatalytic NO removal is highly desirable for efficient air pollution abatement.However,great challenges remain in precisely predicting photocatalytic performance and understanding interactions of diverse features in the catalytic systems.Herein,a dataset of g-C_(3) N_(4)-based catalysts with 255 data points was collected from peer-reviewed publications and machine learning(ML)model was proposed to predict the NO removal rate.The result shows that the Gradient Boosting Decision Tree(GBDT)demonstrated the greatest prediction accuracy with R 2 of 0.999 and 0.907 on the training and test data,respectively.The SHAP value and feature importance analysis revealed that the empirical categories for NO removal rate,in the order of importance,were catalyst characteristics>reaction process>preparation conditions.Moreover,the partial dependence plots broke the ML black box to further quantify the marginal contributions of the input features(e.g.,doping ratio,flow rate,and pore volume)to the model output outcomes.This ML approach presents a pure data-driven,interpretable framework,which provides new insights into the influence of catalyst characteristics,reaction process,and preparation conditions on NO removal.

Effects of Magnetization on Thermoelectric Transport Properties of CoSb_(3)Material

The effects of magnetization on the phase composition,microstructure and thermoelectric transport properties of CoSb_(3)were studied systematically.The magnetic properties of CoSb_(3)material were also measured at room temperature in order to confirm its magnetic category.The results of XRD and FESEM analysis indicated that the phase composition and microstructure of the CoSb_(3)were not affected by magnetization.The results of thermoelectric transport measurement showed that the electrical and thermal transport properties of materials were also not affected by magnetization.These results were mainly attributed to the diamagnetism of the CoSb_(3)material,which were consistent with the results of the magnetic properties measurement.This study is expected to provide a special research perspective for studying the effects of the external conditions on the structure and properties of thermoelectric materials.

CoSb_3-graphite composite anode material for lithium ion batteries

The CoSb_3-graphite composite was prepared by ball-milling. Theelectrochemical performance of the composite material was evaluated using the lithium ion model cellLi / LiPF_6 (EC + DMC) / CoSb_3C_4. It was found that the CoSb_3C_4 composite shows higherreversible capacity than the pure CoSb_3 alloy, and its first reversible (Li-ions removal) capacityreaches 721 mA centre dot h centre dot g^(-1), which exceeds the theoretical capacity (550 mA centredot h centre dot g^(-1)) of CoSb_3C_4.

不同压力下CoSb_(3)电子结构和光学性质的第一性原理研究

基于密度泛函理论(DFT)的第一性原理,采用广义梯度近似(GGA)研究了不同压力下CoSb_(3)的能带结构、态密度、声子色散曲线、拉曼光谱和红外光谱的变化规律。在0~20 GPa范围内,随着施加压力强度的增加,能带带隙增加,但仍为间接带隙半导体;对CoSb_(3)的声子色散曲线分析发现,在施加0~20 GPa压力时声子色散曲线仍然没有虚频出现,这表明在此压力范围内CoSb_(3)结构稳定;在施加压力过程中拉曼光谱和红外光谱都发生了移动,拉曼光谱发生蓝移。

IN situ Confocal Microprobe Raman Spectroscopic Studies on Defective La-based Complex Oxides

The adsorption of O2 over defective La2O3-based OCM catalysts with anionic vacancies , and the reaction of surface oxygen species with CH4 were studied by means of in situ confocal microprobe Raman spectra. The partially reduced oxygen species O2, O , O (O<&<1 ) and even the lattice oxygen ion O2-can be detected on the surface of O2-pretreated La2O3-based catalysts. At lower temperatures (< 573 K) it is peroxide species O- or O- that is more essential for the coupling of methane,while at higher temperature. the superoxide O2 and lattice oxygen species O2-are rather important. It is easier for fluoride-containing La2O3-based catalysts to induce the oxygen species with fewer negative charges and the basicity of the cat- alyst surface is weakened , so that the C2 selectivity for OCM reaction is improved.

高压下CoSb_(3)的结构相变及其电子性质

基于第一性原理计算研究了CoSb_(3)在0~100 GPa范围内的相变行为.研究表明:当压强为25.3 GPa时,CoSb_(3)的结构由Im-3相(常压下)转变到P-1相;当压强为32.8 GPa时,CoSb_(3)的结构由P-1相转变为I-42m相.计算CoSb_(3)晶体结构的声子显示,Im-3相、P-1相和I-42m相在各自的压强范围内其动力学均具有稳定性.计算CoSb_(3)的能带结构结果显示,Im-3相在Γ对称点的带隙为0.224 eV,P-1相、I-42m相在费米表面附近其导带和价带重叠,且均为金属相.计算CoSb_(3)晶体结构的电子局域函数显示,在3个相的结构中Co原子和Sb原子之间均存在极性共价键.计算CoSb_(3)晶体结构的Bader电荷转移显示,Co原子是受主,Sb原子是施主,即电荷从Sb原子向Co原子转移.