Thermoelectric properties of polycrystalline (SnSe)1-x(AgSnSe2)x/2 alloys

SnSe is considered as a thermoelectric material with great potential and advantages due to the record of high thermoelectric figure of merit (ZT) of 2.6 ?at 923 ?K in single crystals. However, it is difficult to use single crystal SnSe in practice due to its poor mechanical properties and high manufacturing costs. Meanwhile, the polycrystalline SnSe also is also not suitable for applications due to its much lower thermoelectric performance compared with single crystal SnSe. Therefore, improving the thermoelectric properties of polycrystalline SnSe has become a hot research topic. In this paper, AgSnSe₂ doped into SnSe to increase the carrier density of the system and thus improve its thermoelectric properties. It is found that the addition of AgSnSe₂ can effectively improve the thermoelectric performance of polycrystalline SnSe. A peak ZT of 0.81 was obtained at 713 ?K for (SnSe)_0.95(AgSnSe₂)_0.025, which is 305% higher than that of the undoped one. This reveals that AgSnSe₂-doped SnSe alloy may become a thermoelectric material system with great application potential and significance.     

Mg掺杂Ba（Zr0．25Ti0．75）O3薄膜的介电调谐性能

采用溶胶凝胶工艺,在Pt／Ti／SiO2／Si衬底制备了Mg掺杂Ba（Zr0．25Ti0．75）O3（BZT）薄膜．利用X射线衍射（XRD）和原子力显微镜（AFM）分析测定了物相微结构和薄膜表面形貌,研究了Mg掺杂含量对BZT微结构和介电调谐性能的影响．结果表明Mg掺杂BZT使薄膜表面粗糙度、晶粒尺寸、介电常量、介电损耗和调谐量都降低;5mol％Mg掺杂BZT薄膜有最大的优值因子为16．3,其介电常数、介电损耗和调谐量分别为289．5、0．016和26．8％．     

0.94(Bi0.5Na0.5)TiO3-0.06Ba(Zr0.25Ti0.75)O3陶瓷的制备、表征与热释电性能

以BaCO3、Na2CO3、TiO2、ZrO2和Bi2O3为原料,通过固相反应法合成了铁电粉末材料0.96(Bi0.5Na0.5)TiO3-0.04Ba(Zr,Ti)O3(BNT-BZT),采用常压烧结法制备了BNT-BZT陶瓷片.考察压力和烧结温度对陶瓷致密性的影响,并对BNT-BZT粉末和陶瓷片的结构、形貌和成分进...     

Ml0.75Mg0.25Ni3.5-x Alx合金储氢性能及电化学性能研究

在Ar气保护下,采用悬浮熔炼方法制备Ml0.75 Mg0.25 Ni3.5 -xAlx(x=0.05 ～0.25)合金,系统研究Al部分取代Ni对合金的相结构、吸放氢性能和电化学性能的影响.结果表明,合金的相结构主要由具有六方CaCu5结构的(La,Pr) Ni5相、(La,Pr) Mg2Ni9相和(La,Nd)2 N...     

Thermoelectric properties of Al substituted misfit cobaltite Ca3（Co1-xAlx）4O9 at low temperature

Thermoelectric properties of Al substituted compounds Ca3（Co1-xAlx）4O9 （x=0, 0.03, 0.05）, prepared by a sol-gel process, have been investigated in the temperature range 305-20 K. The results indicate that after Al substitution for Co in Ca3（Co1-xAlx）4O9, the direct current electrical resistivity and thermopower increase due to the reduction of carrier concentration. Experiments show that Al substitution results in decreased lattice thermal conductivity. The figure of merit of temperature behavior suggests that Ca3（Co0.97Al0.03）4O9 would be a promising candidate thermoelectric material for high-temperature thermoelectric application.     

(Ni0.75Fe0.25)73Nb5Si10B12非晶合金的等温晶化与结构转变

采用旋铸急冷工艺在大气环境中制各出了（Ni0.75Fe0.25）73Nb5Si10B12非晶合金带材．X射线衍射分析表明，样品为完全非晶．采用DiamondTG／DTA差热分析仪测量了非晶薄带的热稳定性及其相关参数Tg、Tx、Tm等．在720、750、800K分别对试样进行等温退火处理，在通商纯氢气保护下保温60min利用X射线衍射分析了非晶合金等温晶化时相转变及组织转变．在720K退火，组织仅发生少量晶化，先析出γ-（Fe，Ni）固溶体相；750K时发生部分晶化，组织为γ-（Fe，Ni）固溶体、（Fe，Ni）23nB6、Ni31Si12和Nb2Ni0.16；800K时合金完全晶化，组织与750K时相同．     

Cu_(60)Zr_(29)Ti_(11)大块非晶合金的黏度特征和强液体行为

采用铜模铸造法制备了Cu60Zr29Ti11大块非晶合金,用X射线衍射仪、三点压弯式黏度仪对该非晶合金的动力学性质进行了研究.测定了大块非晶合金Cu60Zr29Ti11在过冷液相区的黏度,得到了它的动力学脆性系数m=31,以及流变激活能E=63.4kJ/mol.表明大块非晶合金Cu60Zr29Ti11是一种强液体,有较强的非晶形成能力,形成非晶比较稳定.分析了合金在过冷态的流变激活能变化规律,发现流变激活能的变化并不符合Kivelson的Super-Arrhenius公式.     

Stable structure of Zr_(49)Cu_(44)Al_7 metallic glass matrix composite with CuZr phase under high pressure up to 40.8 GPa

Ternary Zr49Cu44Al7 metallic glass matrix composite rods with CuZr nano-phase,exhibiting an elastic strain of 1.6% and a high strength of 1.78 GPa,have been manufactured. The structural evaluation of the ternary metallic glass matrix composite under high pressure has been investigated using angle dispersive X-ray diffraction with a synchrotron radiation source. The investigation shows that the amorphous matrix structure is stable under pressures up to 40.8 GPa at room temperature. No pressure induced CuZr n...     

杂环聚芳醚砜、聚芳醚酮及其共聚物合成与性能研究

以自制的新型类双酚化合物4-（2-甲基-4-羟基苯基）-2,3-二氮杂萘-1-酮（mM-HPPZ)为单体,与4,4′-二氟二苯酮,4,4′-二氯二苯砜进行溶液缩聚反应,合成了一类新型间甲基取代聚芳醚砜（PPES）、聚芳醚酮（PPEK）及其共聚物聚芳醚砜酮（PPESK,n(S)/n(K)=1/1)材料,并对其聚合条件作了初步探讨;利用核磁共振、红外光谱分析研究了双酚单体及其聚合物的结构,利用DSC、TGA对聚合物的耐热性能进行了分析。实验结果表明,该类双酚单体具有与双酚类似的活性,可以进行聚合反应,新型间甲基取代聚芳醚玻璃化转变温度高（Tg=520-558K);耐热稳定性好,其在氮气氛下5%热失重温度为693K左右,合成的间甲基取代聚芳醚砜、聚芳醚酮及其共聚物聚芳醚砜酮在氯仿、四氯乙烷、四氢呋喃和酰胺类溶剂中可溶解成膜。     

(Bi0.95Na0.75K0.2-xLix)0.5Ba0.05TiO3无铅压电陶瓷性质研究

采用溶胶-凝胶法制备了(Bi0.95Na0.75K0.2-xLix)0.5Ba0.05TiO3(NBT-KBT-BT xLi)微粉,并利用此微粉烧结出高密度无铅压电陶瓷.研究了陶瓷表面的显微结构,发现陶瓷主要组成为钙钛矿相结构,Li 的引入使陶瓷中产生呈针状的第二相.介电温谱表明该系列陶瓷是典型的弛豫型铁电体,居里温度在330℃附近.测量NBT-KBT-BT xLi陶瓷的压电常数,发现当x=0.05时,样品的压电常数d33高达197 pC/N,机电耦合系数kt为0.33,损耗tanδ为0.05,相对电容率rε为789.     

Ti(C,N)基金属陶瓷刀具切削性能及磨损机理

文章介绍用常规粉末冶金方法制备添加纳米 Ti N的 Ti C-10 Ti N-16 Mo-5 Co-5 N i-1C系金属陶瓷刀具 ,通过较系统的切削试验 ,研究了此种金属陶瓷刀具在切削正火态 45 #钢时的切削性能及磨损机理。结果表明 ,金属陶瓷刀具适用于较高速度下的切削 ,其切削速度 vc、进刀量 f对刀具后刀面磨损量的影响较大 ,而切削深度 ap对刀具的磨损影响较小 ,刀具的失效形式主要是磨损。     

First-principles calculations to study the optical/electronic properties of 2D VS2 with Z doping (Z = N,P, As,F, Cl and Br)

Monolayer VS₂ is expected to be an encouraging candidate for optoelectronic devices owing to its excellent optical/electrical performance. In this paper, first-principles calculations were conducted to figure out the optical/electrical performance of 2D VS₂ doped with Z doping (Z ?= ?N, P, As, F, Cl and Br). The results show that there was a downward trend in formation energies when the doping element ranged from left to right and from bottom to top in the periodictable of elements. VS₂ became more conductive with N, P and As doping, and transited from the semiconducting to metallic state with F, Cl and Br doping. For the optical properties, N, P, As and Br doping reduced the reflectivity of pristine VS₂ in the near-infrared region (0.6 eV–1.6 ?eV). Moreover, P, F, Cl and Br-doping reduced the migration energy barrier of Li atoms in VS₂, which may help to design the rechargeable Li ion batteries with high rate capability.     

多元Ti(CN)膜的制备和性能研究

为研究多元Ti（CN）膜层，用空心阴极离子镀方法，通入不同比例C2H2和N2反应气体，以研究反应气体流量变化对膜层性能的影响，筛选出C2H2与N2的最佳比例，确定镀膜的最佳工艺参数，并对最佳工艺条件下的膜层进行了硬度和膜基结合力等的测试，用X－衍射仪，电镜，金相显微镜等对膜层的微观组织结构进行了分析，结果表明，镀膜工艺可行，慕支性能优异，膜基结合好，为以后多元膜层的推广使用提供了实验和理论依据。ii     

Properties of PbLa（Zr,Sn, Ti）O3 ceramics near ferroelectric-antiferroelectric phase boundary

Shirane found in the middle of the 20th century that the solid solution PZT had a lot of fine characteristics and carried out detailed researches[1]. The critical phase transition field of antiferroelectric decreased by adding titanate. Titanate expands t…     

PbO对Pb(Zr0.52Ti0.48)O3陶瓷相成分的影响

采用固相反应法制备了一系列Pb(Zr0.52Ti0.48)O3压电陶瓷,研究了过量PbO对PZT陶瓷相成分的影响.用X射线衍射对陶瓷的相结构进行了分析,采用场发射扫描电镜对断面形貌进行表征,并用能谱仪对微观区域的陶瓷成分进行测试.实验结果表明:当PbO缺乏时,陶瓷上表面易出现由PbZrO3分解产生的ZrO2,下表面易出现PbTi3O7和焦绿石相.当PbO过量时,陶瓷微观区域的成分会发生波动,成分的一致性也将受到破坏.此外,过量PbO还将使PZT相结构发生向富钛方向的移动.采用先进的陶瓷制备工艺有助于克服成分波动和相结构变化现象.     

Spectroscopic study on the photophysical properties of chlorine substituted tetraphenylporphyrin-histidine and its zinc(Ⅱ)complexes

The photophysical properties of ortho-CI,meta-CI and para-CI substituted tetraphenylporphy-rin-histidine and their zinc (II) complexes have been studied by means of steady-state absorption and fluo-rescence spectroscopies, as well as time-resolved fluo-rescence spectroscopy. For the cases of both free-base and zinc complexes, it was found that the ortho-chlorine substitution onto the phenyl rings significantly altered the fluorescence quantum yield, thefluorescence lifetime and the ratio between radiative and nonradiative deactivation rates of the porphyrin chromophore, i.e. the photophysical parameters were quite different from those of meta- and para-substituted compounds. On the other hand, however, the introduction of covalently-linked histidine did not exert much effects on the photophysical behavior of the porphyrin chromophore. The results are interpreted interms of the steric effect and the heavy-atom effect from the chlorine atoms substituted onto the phenyl rings.     

Effect of bromization on the properties of a series of sub-stituted 1,8,15,22-tetra(2,4-ditertbutylphenoxy) phthalocyanines

As a novel kind of functional dyes, phthalocyanines and metallophthalocyanines have been attracting the at-tention of many scientists for many years. Recently, the chemistry of Pcs has been undergoing a renaissance because Pcs and many of their derivatives exhibit theirproperties for potential application in materials science[1,2 One of the main questions in the field of phthalocya-nines research is to modify the molecular structure re-placing the benzene-spherical hydrogen atoms by various s…     

Microstructure and mechanical properties of （Ti,AI,Zr）N/（Ti,AI,Zr,Cr）N films on cemented carbide substrates

（Ti,Al,Zr）N/（Ti,Al,Zr,Cr）N bilayer films were deposited on cemented carbide （WC-8%Co） substrates by multi-arc ion plating （MAIP） using two Ti-AI-Zr alloy targets and one pure Cr target. To investigate the composition, morphology, and crystalline structure of the bilayer films, a number of complementary methods of elemental and structural analysis were used, namely, scanning electron microscopy （SEM）, energy disperse X-ray spectroscopy （EDS）, and X-ray diffraction （XRD）. Adhesive strength and mechanical properties of the films were evaluated by scratch testing and Vickers microindentation, respectively. It is shown that the resulting films have a TiN-type face-centered cubic （FCC） structure. The films exhibit fully dense, uniform, and columnar morphology. Furthermore, as the bias voltages vary from -50 to -200 V, the microhardness （max. Hv001 4100） and adhesive strength （max. 〉 200 N） of the bilayer films are superior to those of the （Ti,Al,Zr）N and （Ti,Al,Zr, Cr）N monolayer films.     

Hydrogen absorption-desorption characteristic of (Ti0.85Zr0.15)1.1Cr1-xMoxMn based alloys with C14 Laves phase

The microstructure and hydrogen absorption-desorption characteristic of (Ti_0.85Zr_0.15)_1.1Cr_1-xMo_xMn (x ?= ?0.05, 0.1, 0.15, 0.2 ?at.%) alloys were investigated. The results showed that the corresponding alloys were determined as a single phase of C14-type Laves structure. With the increase of Mo content, the maximum and reversible hydrogen absorption capacity decreased, the slope factor H_f increased. Among the studied alloys, (Ti_0.85Zr_0.15)_1.1Cr_0.95Mo_0.05Mn had the best overall properties for practical application of hydrogen storage materials. The maximum and reversible hydrogen storage capacity were 1.76 ?wt% and 1.09 ?wt%, the slope factor H_f was 0.51, and its dissociation enthalpy (ΔH_d) and entropy change (ΔS_d) were 23.1 ?kJ ?mol^?1H₂, 93.8J ?K^?1mol^?1H₂ at 303K, respectively. By studying the dissociation pressures of the synthesized metal hydrides, it was found that Mo had a special effect on the dissociation pressure of Ti–Zr–Cr–Mo–Mn alloys. Among the four alloys, (Ti_0.85Zr_0.15)_1.1Cr_0.95Mo_0.05Mn alloy had the largest hydrogen absorption capacity and the fastest hydrogen desorption rate, which can meet the commercialization demand of hydrogen fuel cell hydrogen supply system.     

Effects of temperature on hydrostatic pressure-induced FE-AFE phase transition in PbLa(Zr, Sn, Ti)O3 ceramics

Hydrostatic pressure-induced ferroelectricantiferroelectric (FE-AFE) phase transition and the pressure dependence of dielectric properties in La-doped Pb(Zr,Sn, Ti)O₃ ceramics were researched; the effects of temperature on hydrostatic pressure-induced FE-AFE phase transition and dielectric properties of the samples were studied. It was found that the temperature made the FE-AFE phase transition pressure decrease, and there existed the behavior of dielectric frequency dispersion and phase transition diffusion in the dielectric-pressure spectrum. These phenomena were very useful to enrich and develop the knowledge on the diffused phase transition behavior of polycomponent relaxor ferroelectric.