铁电存储器研究进展

铁电薄膜与半导体集成技术相结合而发展起来的铁电存储器,以其高密度、高速度、非易失性以及抗辐射性而大大优于目前任何一种半导体存储器。介绍了铁电存储器的存储原理、特点、基本存储单元、研究进展、应用及存在的问题等。     

铁电陶瓷材料性能退化机理

对铁电陶瓷材料老化、疲劳及电阻率退化的物理机制进行了综合评述。着重讨论了氧化空位与畴界、晶界以及陶瓷材料和电极的界面的相一作用对铁电陶瓷材料性能退化的影响。     

铁电薄膜材料的制备技术及应用

铁电薄膜材料、集成铁电器件以及与之相应的物理问题,引起物理学、材料科学与工程、微电子与光电子学等领域的科学技术人员和学者的关注。文章介绍了铁电薄膜新研究进展,对目前最常用的几种主要制备方法进行了评述,重点分析了铁电薄膜不同制备方法的优缺点。并对未来的可能进展作了简单的描述,指出了目前关于铁电薄膜研究中的一些问题,并提出一些解决问题的办法。     

科学家揭秘铁电材料的光电机制

美国能源部劳伦斯伯克利国家实验室及加州大学伯克利分校的研究人员揭开了铁电材料在光照条件下产生高压电的秘密。该研究发表在《物理评论快报》上。研究人员所采用的铁电材料是铋铁酸盐薄膜(BFO)。这种特别制作的薄膜有着不同寻常的特性,在数百微米的距离内整齐而有规律地排列着不同的电畴。电畴为条状,每个电畴宽为50纳米到300纳米,畴壁     

钛酸铅热力学及其铁电相变的研究

在不同边界条件下，考虑到钛酸铅的晶粒界面能和表面自由能，利用广义的Ｃｌａｕｓｉｕｓ－Ｃｌａｐｅｙｒｏｎ关系式以及Ｌａｎｄａｕ－Ｇｉｎｓｂｕｒｇ－Ｄｅｖｏｎｓｈｉｅ热力学方程，求得了在不同受力状态，薄膜厚度及超微粒子的晶粒尺寸与自发极化强度和铁电相变温度之间的关系，理论分析能够很好地解释实验现象，综合文献的报道，对钛酸铅的铁电物性给予了全面的总结。     

铁电薄膜材料的研究进展

近年来，随着铁电薄膜制备技术的发展，其应用领域不断扩大。本文综述近年来铁电薄膜材料研究进展情况，并指出存在的问题及其发展方向。     

铁电陶瓷薄膜的制备与结构表征

本文综述了近年来铁电陶瓷薄膜的化学制备方法,及薄膜材料在结构表征方面的最新研究进展。     

铁电液晶及其分子结构的特征

阐述了铁电液晶及其分子结构的特征,介绍了近十年来铁电液晶的发展情况,并较系统地讨论了液晶的分子结构对其铁电性能的影响。     

铁电阴极材料电子发射机理的实验研究

快极化反转在铁电阴极电子发射过程中具有决定性的作用,本工作采用ＸＲＤ,ＳＥＭ等方法铁电发射机理,ＸＲＤ图谱、胞参数测试结果以及扫描电镜观察到的电畴排列状况等从多个角度反映出不同铁电材料在前、后的晶体结构及电畴铁相应变化状况,对实验结果的分析有助于理解铁电阴极电子发射机理以及民组成、结构之间的关系。     

Fatigue Crack Growth in Ferroelectric Ceramics Driven by Alternating Electric Fields

Electric-field-induced fatigue crack growth in ferroelectric ceramic PZT-5 with precracks was investigated. The experimental results showed that there were two distinct characteristics in the crack growth under electric loading. Under low electric loads, microcracks located ahead of the main crack emerged and grew and, as a result, impeded the growth of the main crack. On the other hand, under high electric loads, microcracks were absent, and the main crack was the only mode of fatigue cracking. The main crack grew macroscopically along the original path perpendicular to the electric field. Microscopically, the crack grew along the grain boundaries and grain breakaway was observed. The crack growth rate was nonlinearly related to the cyclic electric load. Similar to mechanical fatigue, there existed a crack growth threshold in the applied electric-field amplitude below which the crack ceased to grow. A steady crack growth occurred when the applied electric field exceeded this threshold. An empirical model for crack growth was obtained. Domain-switching effect and fracture-mechanics concepts were used to explain the observed crack closure and crack growth under electric loads.     

Ferroelectric K0.5Na0.5NbO3 catalysts for dye wastewater degradation

K_0.5Na_0.5NbO₃ (KNN) particles were prepared by a solid–state method. X–ray diffraction, scanning electron microscopy, UV–visible spectrophotometry, and electrochemical impedance spectroscopy were used to study the structure, morphology, and properties of the samples. The obtained KNN is a ferroelectric material with orthorhombic perovskite structure at room temperature. The KNN particles can be used as piezo/photo–bicatalysts for degrading organic pollutants by utilizing vibrational and solar energy; the catalytic activity of the particles can be significantly improved owing to their polarization under an applied electric field. Poled KNN particles show a bicatalytic degradation ratio of rhodamine B (RhB) dye reaching 92% after 60 min. The results indicate that the KNN particles can be applied as attractive ferroelectric catalysts for organic pollutant degradation.     

混凝土疲劳机理研究进展

混凝土材料在循环荷载作用下的损伤和破坏,即在应力和应变的反复作用下所发生的性能变化称为混凝土疲劳.本文就混凝土疲劳损伤研究、疲劳断裂研究、疲劳概率分析、疲劳预测模型分析、疲劳数值模拟、疲劳分析软件概况以及疲劳荷载谱处理等方面,分析探究了混凝土疲劳机理研究取得的进展及其发展趋势.     

磁记忆用于柱塞泵腔体检测的研究

将磁记忆检测技术应用于柱塞泵腔体检测,提出了柱塞泵腔体的磁记忆检测方法,并对发现的缺陷磁记忆信号进行分类分析。分析结果表明:磁记忆检测技术是检测柱塞泵腔体的有效方法,对腔体不同类型缺陷有较好的识别效果。     

Ferroelectric BaTiO3@ZnO heterostructure nanofibers with enhanced pyroelectrically-driven-catalysis

In this work, an obvious enhancement of pyroelectrically-driven catalytic activity is found in BaTiO₃@ZnO heterostructures synthesized hydrothermally and then calcined. The pure BaTiO₃ is able to decompose up to 45% of the RhB dye in aqueous solution (5?mg/L) under 30–54?°C cold-hot cycle. As the ZnO content coating on the surface of the BaTiO₃ nanofibers is increased from 0 to 5?wt%, the decomposition ratio of the BaTiO₃@ZnO heterostructures for RhB dye in aqueous solution first increases and then decreases, giving a maximum value of 97% at 2.5?wt%. The kinetic rate constant (K?=?0.06384 cycle^?1) of the catalytic reaction for BaTiO₃ @2.5%ZnO is 4 times higher than that of pure BaTiO₃. The enhancement of catalytic activity of BaTiO₃@ZnO may be due to the formation of a semiconductor junction in which the electric field effectively separating the pyro-induced electron-hole pairs and further accelerates carrier migration. The ferroelectric heterostructures of BaTiO₃@ZnO show pyroelectrically-driven-catalysis and may hold potential for use in decomposing dye wastewater through harvesting cold-hot alternation thermal-energy.     

迅速发展的计算机存储铁电薄膜记忆材料

综述了迅速发展的计算机用新型氧化铋系层状铁电薄膜记忆材料的晶体结构、极化特点、应用原理以及它与传统PZT类材料相比的优越性。概述了此类薄膜的制备方法,分析了该类薄膜目前尚存在的问题并展望了未来发展的趋势。     

金属材料的腐蚀疲劳研究现状

金属材料在服役工况下常常受到腐蚀介质与交变载荷的共同作用,发生发生腐蚀疲劳破坏。简要概述了腐蚀疲劳机理(裂纹萌生与裂纹扩展机理)及其影响因素(力学因素、材料特性、环境因素)。讲述了腐蚀疲劳试验技术,并对存在的问题及发展方向进行了展望。     

Ferroelectric ZrO2 ultrathin films on silicon for metal-ferroelectric-semiconductor capacitors and transistors

Enhanced ferroelectric properties of nanoscale ZrO₂ thin films by an HfO₂ seed layer are demonstrated in metal-ferroelectric-semiconductor (Si) capacitors and transistors prepared with a low thermal budget of 400 °C. The seeding effect of the HfO₂ layer leads to the enhancement of crystallization into the orthorhombic phase and the increase of remnant polarization of the sub-10 nm ZrO₂/HfO₂ bilayer structure. The ferroelectric field-effect transistor with the ZrO₂/HfO₂ bilayer gate stack reveals a large memory window of ~1.2 V and a steep subthreshold swing below 60 mV/decade. As compared with the Hf_0.5Zr_0.5O₂ thin film, superior ferroelectric properties of the ZrO₂/HfO₂ bilayer structure show great potential for ferroelectric memory devices fabricated on Si substrates.     

Ferroelectric lithography

The fact that domain polarization affects the surface properties suggests a method to direct chemical reactions on ferroelectric substrates. In combination with domain manipulation at small scales, a new lithography process is developed to assemble several classes of nanostructures. Three domain patterning techniques, which employ contact electrodes, SPM and e-beam are introduced, with focus on the physical interactions between electrons and ferroelectrics. The effects of electron beam parameters on polarization reorientation are quantified and it is shown that both positive and negative polarization can be achieved depending on conditions. Potential applications of ferroelectric lithography on fabrication of complex structures are illustrated.