快淬Sm2（Fe,Al,Zr）17C1.5合金的磁性

利用Ｘ衍射线仪）、振动样品磁强计对含Ｚｒ快淬Ｓｍ２Ｆｅ（１．５－ｘ）ＺｒｘＡｌ１．５Ｃ１．５（ｘ＝０－０．８）合金的微结构和磁性进行了研究。结果表明，在合金中添加Ｚｒ以后，形成了一个高熔点的ＺｒＣ相。ＺｒＣ相对弥散分布在晶粒边界或晶粒交偶处，可有效地抑制快淬合金在晶化过程中的晶粒长大。样品在７５０℃经３０分钟时效后，获得了最佳剩 磁为５５Ａ·ｍ＾２／ｋｇ，矫顽力９２３ｋＡ／ｍ。其退磁曲线具有较好的     

Ferroelectric field effect in (La,Sr)CoO3/Pb(Zr,Ti)O3/(La,Sr)CoO3 heterostructures

Abstract

Epitaxial LaCoO₃/Pb(Zr,Ti)O₃/(La,Sr)CoO₃ (LSCO) heterostructures have been grown on LaAlO₃ by pulsed laser deposition for investigating ferroelectric field effect. In the heterostructure, semiconducting LaCoO₃ was used as a conducting channel layer, instead Si. The resistivity of the LaCoO₃ (LCO) channel layer was found to be dependent on an oxygen ambient, primarily the ambient oxygen pressure during deposition. The resistivity of the LCO layer varied in the range of 0.1 – 100 Ω cm. Ferroelectric field effect induced in LaCoO₃ layer was observed by measuring the resistance modulation of the LCO layer with respect to the polarized state of the PZT layer. The resistance modulation of 9% was obtained in the 680 Å thick LCO layer. Further the resistance modulation was improved up to 45% after applying dc bias. It is suggested that the LCO/PZT/LSCO heterostructure can be used as a ferroelectric field effect transistor.     

Chemical Processing and Properties of (Sr,Ca) 2 (Nb,Ta) 2 O 7 Thin Films

Ca-doped Sr 2 (Nb,Ta) 2 O 7 thin films have been synthesized by the chemical solution deposition. Homogeneous and stable (Sr,Ca) 2 (Nb,Ta) 2 O 7 precursor solutions were prepared by optimizing the reaction of starting metal alkoxides in ethanol with a key additive of 2-ethoxyethanol. The improvement of ferroelectric properties of the Sr 2 (Nb,Ta) 2 O 7 based films were achieved through the Ca substitution into Sr 2 (Nb 0.3 Ta 0.7 ) 2 O 7 as well as the optimization of heating conditions. The crystallization temperature of the layered perovskite (Sr 0.9 Ca 0.1 ) 2 (Nb 0.3 Ta 0.7 ) 2 O 7 thin films on Pt/Ir/Ti/SiO 2 /Si substrates was found to be above 750C. (Sr 0.9 Ca 0.1 ) 2 (Nb 0.3 Ta 0.7 ) 2 O 7 thin films crystallized at 750C exhibited P r of 0.51 w C/cm 2 and E c of 69 kV/cm.     

Effect of Nb Doping on (Sr,Ba)TiO3 (BST) Ceramic Samples

The effect of doping the Sr_0.3Ba_0.7Ti_(1–5y/4)Nb _y O₃ ceramic with different concentration of Nb is studied by scanning electron microscopy (SEM), X-ray diffraction and thermoelectric analysis. It is observed that the grain size decreases as the Nb concentration increases. The critical temperature T _c has a linear decrease at a rate of 19°C/mol% of Nb. The temperature dependence of the dielectric permittivity presents strongly broadened curves, which suggest a non Curie-Weiss behavior near the transition temperature. The diffuse phase transition coefficient () was also determined and its value leads to the conclusion that the degree of disorder in the system increases with the presence of the Nb cation.     

CIGS薄膜太阳电池研究进展

Cu(In,Ga)Se2(CIGS)薄膜太阳电池以其具有的诸多优势成为最具发展潜力的太阳电池之一。随着CIGS薄膜太阳电池光电转换效率世界纪录的不断被刷新,继续提高电池性能、研究无Cd缓冲层材料,发展柔性衬底CIGS薄膜电池及组件,优化现有的工艺流程,开发低成本的吸收层沉积工艺,尽快将实验室技术转移为CIGS电池组件的商业化生产成为今后的研究热点。主要介绍了CIGS薄膜太阳电池近年来在这些方面的研究进展。     

Pb(Zr,Ti)O3 thin film growth on yttrium-treated Si(100)

Abstract

Pulsed laser ablation has been used to deposit ferroelectric Pb(Zr, Ti)O₃ (PZT) thin films on Si(100) and on yttrium-treated Si(100) substrates. The yttrium (Y) treatment of a Si surface followed by oxidation resulted in formation of a very thin, Y-enhanced SiO₂ antidiffusion barrier layer, thereby suppressing the undesirable PZT/Si interdiffusion. The best PZT film grown on Y-treated Si(100) had a breakdown voltage of 0.6 MV/cm, a coercive field of 71 KV/cm, and a remanent polarization of 18 μC/cm².     

Fast-switching-speed,low-forward-voltage-drop static induction (SI) thyristor

A static induction (SI) thyristor using a normally-off planar-gate structure in a low power class has been developed to be used as a power switching device in a three-phase inverter circuit. A 600 V-15 A class SI thyristor with very fast switching time (tgt, tgq) and low forward voltage drop (V_TM) was designed and created. This design was performed with a reasonable wafer structure (n^?/n/p⁺), an n^? base carrier concentration and thickness, and a gate structure (gate diffusion length and gate-gate pitch). Microscopic processing was used to obtain this SI thyristor. The performance trade-off between turn-off time and forward voltage drop is controlled by a lifetime control process using proton irradiation that results in a very fast switching time with tgt of 500 ns and tgq of 500 ns with V_TM of 1.5 V (at I_T= 18 A). At a current level of I_T = 18 A, the current density in the active area becomes 200 A/cm², which indicates that the performance of the SI thyristor is superior to that of conventional IGBTs and MOSFETs.     

2,4,6-三(2-烯丙基苯氧基)-1,3,5-三嗪与双马来酰亚胺共聚物的研究

以三聚氯氰为原料，合成三嗪烯丙基衍生物，并与双马来酰亚胺发生共聚反应。研究了2，4，6-三(2-烯丙基苯氧基)1，3，5-三嗪(TAPT)与二苯基甲烷双马来酰亚胺(BMDPM)不同组成比例对共聚物的力学性能的影响。用TGA分析研究了共聚物的热稳定性。结果表明TAPT／BMDPM组成比在45％～60％时，共聚物的力学性能有明显改善，但热稳定性能却比BMDPM均聚物稍有降低。     

Piezoelectric and elastic properties of layered materials of Cu(In,Cr)P2(S,Se)6 system

In this contribution, we present new results of ultrasonic and piezoelectric investigation in layered materials of Cu(In,Cr)P₂(S,Se)₆ system including the phase transitions points. It was shown, that in low temperature phase the electromechanical coupling parameters substantially increased after polarization of the material. The large anisotropy of linear and nonlinear elastic properties was observed. The largest critical ultrasonic attenuation anomalies appeared for ultrasonic wave propagating normal to layers: i.e. along polarization direction. From measurements of the amplitude of second longitudinal ultrasonic harmonic we showed that these layered crystals have extremely high elastic nonlinearity in the direction normal to layers. DC bias electric field induced piezoelectricity due to electrostiction was observed in the paraelectric phase of pure materials and their solid solutions. The piezoelectric memory was observed after samples were kept for long time in DC electric field along polar axis at fixed temperature in the paraelectric phase.     

Slow Dielectric Relaxation in Pb(Zr,Ti)O3 and (Ba,Sr)TiO3 Ferroelectric Thin Films

An impedance analysis of Ni/Pb(Zr,Ti)O₃/Pt thin-film structures based on measurements at the frequencies from 100 Hz to 100 MHz, along with the data of Grazing Angles XRD, TEM and photo-electric study, is used to obtain electronic structure of the PZT thin films deposited by sol-gel method on silicone substrates. Both slow capacitance relaxation and charging/discharging currents versus time under step-voltage excitation have been studied in (Ba,Sr)TiO₃ thin films between SrRuO₃ electrodes.     

Combined cycle plants: Yesterday,today, and tomorrow (review)

Gas turbine plants (GTP) for a long time have been developed by means of increasing the initial gas temperature and improvement of the turbo-machines aerodynamics and the efficiency of the critical components air cooling within the framework of a simple thermodynamic cycle. The application of watercooling systems that were used in experimental turbines and studied approximately 50 years ago revealed the fundamental difficulties that prevented the practical implementation of such systems in the industrial GTPs. The steam cooling researches have developed more substantially. The 300 MW power GTPs with a closedloop steam cooling, connected in parallel with the intermediate steam heating line in the steam cycle of the combined cycle plant (CCP) have been built, tested, and put into operation. The designs and cycle arrangements of such GTPs and entire combined cycle steam plants have become substantially more complicated without significant economic benefits. As a result, the steam cooling of gas turbines has not become widespread. The cycles—complicated by the intermediate air cooling under compression and reheat of the combustion products under expansion and their heat recovery to raise the combustion chamber entry temperature of the air—were used, in particular, in the domestic power GTPs with a moderate (700–800°C) initial gas turbine entry temperature. At the temperatures being reached to date (1300–1450°C), only one company, Alstom, applies in their 240–300 MW GTPs the recycled fuel cycle under expansion of gases in the turbine. Although these GTPs are reliable, there are no significant advantages in terms of their economy. To make a forecast of the further improvement of power GTPs, a brief review and assessment of the water cooling and steam cooling of hot components and complication of the GTP cycle by the recycling of fuel under expansion of gases in the turbine has been made. It is quite likely in the long term to reach the efficiency for the traditional GTPs of approximately 43% and 63% for PGUs at the initial gas temperature of 1600°C and less likely to increase the efficiency of these plants up to 45% and 65% by increasing the gas temperature up to 1700°C or by application of the steam cooling in the recycled fuel cycle.     

覆铜板用低分子量双端羟基聚苯醚树脂

低分子量α,ω-双(2,6-二甲基羟苯基)聚苯醚(PPO-2OH)具有优异的电性能和耐热性能,改性后的热固性聚苯醚树脂是高性能覆铜板的理想基材之一。介绍了低分子量PPO-2OH的合成方法和热固化改性研究过程,概述了近几年低分子量PPO-2OH针对覆铜板应用的研究进展。     

覆Co(Ⅱ)-Ni/Al(OH)x的制备、结构与电化学性能

采用化学沉淀法制备了覆Co(Ⅱ)-Ni/Al(OH)x电极材料,并用XRD、SEM和粒度分布仪研究了材料的晶体结构、表观形貌和粒度分布,以恒流充放电实验测试了以其为正极活性物质组装的MH/Ni试验电池的充放电性能.结果表明:覆Co(Ⅱ)-Ni/Al(OH)x样品具有α-Ni(OH)2型晶体结构,采用覆Co(Ⅱ)-Ni/Al(OH)x电极材料制备的MH/Ni试验电池的最高放电比容量为424.53 mAh/g,600次循环后的放电比容量(395.24 mAh/g)仍为其最高放电比容量的93.1%.     

General Catalogue of Vol.29, (2005)

~~General Catalogue of Vol.29,(2005)~~     

Polarization Switching in (100)/(001) Oriented Epitaxial Pb(Zr, Ti)O3 Thin Films

Thin films made of (100)/(001)-oriented Pb(Zr, Ti)O₃ (PZT) were deposited by liquid-delivery metal-organic chemical vapor deposition on Ir/MgAl₂O₄/SiO₂/Si(100) substrates. For comparison, PZT thin films were also deposited on Ir/MgO(100) substrates. The X-ray scan spectra for the (202) reflections revealed that the PZT films have four-fold symmetry. It indicates that the PZT films were epitaxially grown as a cube-on-cube structure on both substrates. The switchable polarization (Q_sw) of the PZT capacitors on the silicon substrate was only 23 C/cm² at 1.8 V; however, Q_sw of PZT capacitors on MgO was 99 C/cm². In the case of PZT films deposited on silicon, the volume fraction of (001)-oriented domains (which contribute to polarization switching) was 15.1% (calculated from an XRD pattern). This result is due to the lower Q_sw of PZT capacitors on silicon. By piezoresponse-force microscopy, switchable and unswitchable domains could be identified by imaging color contrast, namely, (001) and (100) domains, respectively. Consequently, domain distribution of the PZT film on a silicon substrate indicates that the (001) domain exists in the (100) domain matrix.