钛酸锶钡（BST）薄膜的介电性能机理研究进展

钛酸锶钡(BST)薄膜是一种重要的铁电薄膜，应用广泛，是高新技术研究的前沿和热点之一。简要介绍BST薄膜的制备方法和应用，重点讨论BST薄膜的极化、电压非线性、漏电流的机理、表征及影响因素，并综述了铁电薄膜的疲劳机制和消除疲劳措施等方面的研究进展，提出了研究中需要解决的一些问题。     

钛酸锶钡(BST)薄膜的组成、结构与性能研究进展

钛酸锶钡 (BST)薄膜是一种重要的铁电薄膜 ,应用广泛 ,是高新技术研究的前沿和热点之一。简要介绍了BST薄膜的制备方法和应用 ,对此薄膜的基片、电极、晶界、界面、热处理、膜厚及组成、结构、性能等方面作了重点讨论 ,提出了研究中需要解决的一些问题     

钛酸锶钡（BST）薄膜的组成、结构与性能研究进展

钛酸锶钡(BST)薄膜是一种重要的铁电薄膜，应用广泛，是高新技术研究的前沿和热点之一。简要介绍了BST薄膜的制备方法和应用，对此薄膜的基片、电极、晶界、界面、热处理、膜厚及组成、结构、性能等方面作了重点讨论，提出了研究中需要解决的一些问题。     

铁电薄膜电疲劳研究进展

铁电薄膜在交变电场下发生电疲劳现象是影响其商业应用的主要障碍，也是目前国内外研究的热点。本文从铁电薄膜电疲劳的影响因素、疲劳机理和消除疲劳的措施出发综述了近年来国内外在铁电薄膜电疲劳研究方面取得的进展。     

钛酸锶钡薄膜掺杂改性研究进展

钛酸锶钡(BaxSr1-xTiO3,BST)薄膜具有优良的铁电、介电性能,在可调谐微波器件、动态随机存储器、红外探测器阵列等方面具有良好的应用前景.综述了近年来BST薄膜掺杂改性研究所取得的进展,特别是对晶格掺杂和晶界掺杂进行了较详细的评述,并对目前BST薄膜掺杂研究的几个前沿问题进行了详细的讨论.     

低损耗掺杂BST薄膜的射频磁控溅射沉积及其阻抗特性研究

利用射频磁控溅射法和快速热退火处理,在高电阻Si基片上制备了具有较低介电损耗的MgO掺杂Ba_(0.25)Sr_(0.75)TiO_3(BST)铁电薄膜。通过XRD和SEM,分别对BST铁电薄膜的微结构和表面形貌进行了分析。利用铁电分析仪和低频阻抗分析仪分别测试了BST薄膜样品的铁电特性和介电性能。研究表明,MgO掺杂的BST薄膜的介电损耗要低于纯的BST薄膜,并且在掺杂浓度为5%(摩尔分数)时,获得最佳的实验结果。在室温和250 Hz的条件下,测得700℃退火的BST铁电薄膜样品的矫顽电场强度(E_C)和剩余极化强(P_r)分别为1.15 V/cm和4.06μC/cm~2,介电常数和介电损耗因子分别为370和0.005。     

铁电薄膜及其在存储器件中的应用研究现状

概述了铁电薄膜在非易失存储器中的应用研究现状,将铁电存储器与其他类型存储器进行了比较,针对铁电薄膜在存储器中的应用,探讨了铁电薄膜制备工艺与半导体工艺兼容性、极化疲劳、尺寸效应等几方面的问题,指出了当前研究的重点.     

溅射工艺参数对Ba0.5Sr0.5TiO3薄膜沉积速率和介电性能的影响

铁电/介电BST(BaxSr1-xTiO3)薄膜在微电子学、集成光学和光电子学等新技术领域有广泛的应用前景.用射频磁控溅射方法制备了厚约700 nm的Ba0.5Sr0.5TiO3薄膜,采用Al/BST/ITO结构研究了溅射功率、溅射气压、O2/(Ar O2)比和基片温度对上述BST薄膜沉积速率和介电性能的影响,并根据这些结果分析了较优的工艺条件,同时用XRD、XPS和SEM研究了薄膜的晶相、组成和显微结构.     

铁电薄膜及铁电存储器的研究进展

铁电薄膜是具有铁电性且厚度尺寸为数纳米到数微米的薄膜材料,因其在非挥发性铁电随机存储器方面的潜在应用而受到广泛关注.综述了新型无铅、无疲劳Bi4Ti3O12(BIT)基铁电薄膜材料的制备和改性及性能表征方法,阐述了铁电薄膜的3种失效机制及铁电薄膜存储器的研究现状,最后提出了铁电薄膜及存储器今后可能的研究方向.     

有机铁电薄膜的研究进展

有机铁电薄膜材料因具有光电效应、压电效应、铁电等性能,可广泛应用于电子器件而备受关注.综述了聚偏氟乙烯[Poly(vinylidene fluoride)]及其共聚物铁电材料的结构和性能,从有机铁电薄膜的3种疲劳机理和降低疲劳的措施出发,综述了近年来国内外在铁电薄膜电疲劳研究方面所取得的进展,总结了有机铁电薄膜的应用,提出了今后可能开展的工作.     

LaNiO_3导电氧化物薄膜的制备及应用研究

综述了退火温度、气氛和衬底对LNO薄膜结构和电性能的影响,详细介绍了LNO薄膜作底电极或过渡层在钙钛矿结构的PLT、PZT、BST铁电和BFO铁磁电薄膜生长过程中对其铁电性能和疲劳性能的影响。     

Low loss and highly tunable (Ba,Sr)(Ti,Mn)O<Subscript>3</Subscript>/(Ba,Sr)TiO<Subscript>3</Subscript> bilayered films for electrically tunable microwave device applications

Ba_0.05Sr_0.95TiO₃ (BST), 5 mol% Mn-doped BST (Mn-BST) and bilayered Mn-BST/BST films with a thickness of about 100 nm were fabricated by using pulsed laser deposition technique on MgO single crystal substrates, and their microwave dielectric properties were comparatively investigated. It was confirmed that all the BST-based films were crystallized in pure single-oriented perovskite phase. There appeared nanosized pores in the BST film; after addition of Mn, however, the film surface morphology became denser while exhibiting an increased roughness, and ultimately, a smooth and dense morphology was achieved by the design of bilayered Mn-BST/BST film. Coherently, the microwave dielectric properties of BST films were enhanced by Mn doping and more significantly enhanced in the bilayered Mn-BST/BST film. As a result, for the bilayered film, a very low loss tangent of 0.017–0.007 and a high dielectric tunability of 70.9% under E?=?36 V/μm were simultaneously obtained at 79 K and L-band frequency (1–2 GHz), thereby resulting in an extremely high commutation quality factor of 14492. The excellent microwave dielectric properties obtained in the Mn-BST/BST bilayered film originate not only from the Mn-doping effect, but are also ascribed to the pre-deposition of BST layer, which serves as a good template for the growth of Mn-BST film.     

Ba0.6Sr0.4TiO3薄膜的微结构及铁电性能研究

采用射频磁控溅射法制备了Ba0.6Sr0.4TiO3(简称BST)薄膜材料,研究了BST薄膜的组成、晶体结构、表面形貌及介电性能.介电偏压特性曲线和电滞回线都表明其具有铁电性,厚度为500 nm、晶粒尺寸为30 nm的BST薄膜,介电系数电压变化率(介电调谐率)为29.4%,矫顽场强(EC)约为12.1 kV/cm,并讨论了介电偏压特性曲线和电滞回线之间的联系,解释了电滞回线不对称的原因.     

On the fatigue crack growth behaviour of selective laser melting fabricated Inconel 625: Effects of build orientation and stress ratio

The building of Inconel 625 material was carried out using the selective laser melting method, and its fatigue crack growth property at ambient temperature was experimentally investigated. Compact‐tension specimens with different building orientations were utilized to determine the stress intensity factor threshold and fatigue crack growth rate curves at different stress ratios (R). The results indicated that the fatigue crack growth properties in the near threshold stress intensity factor and Paris regions were greatly affected by the loading factor, as well as the orientation of the alloy. The mechanism of fatigue crack growth at different stages was observed and discussed using scanning electron microscopy. Finally, based on the framework of the linear elastic fracture, a new and applicable effective driving force factor range was introduced to replace the traditional stress intensity factor range (ΔK) with good accuracy for all of the fatigue crack growth test data, considering both the stress ratio and orientation.     

Dielectric properties of La/Zr codoped Ba0.67Sr0.33TiO3 ceramics prepared from citrate–nitrate combustion derived powders

La/Zr codoped Ba_0.67Sr_0.33TiO₃ (BST) ceramics were fabricated via citrate–nitrate combustion derived powders, and the microstructure and dielectric properties of BST ceramics were investigated. All ceramic samples show a pure perovskite structure. The dielectric constant and loss decrease with increasing Zr content. The additions effectively suppress the grain growth of BST ceramics. It is found that the temperature-permittivity characteristics for codoped BST ceramics could be controlled using various doping content.     

交替中间热处理BST薄膜介电性能研究

用溶胶凝胶(Sol-Gel)法制备了三种钛酸锶钡(Ba_0.6Sr_0.4TiO₃, BST)薄膜：常规的四层薄膜, 在逐层制备过程中,对首层薄膜进行中间热处理(Preheat-treatment, PT)的四层薄膜及间隔或交替地对奇数层薄膜进行中间热处理（称为交替中间热处理(Alternate-preheat-treatment, APT)）的八层薄膜. 用XPS研究薄膜表面成分化学态, 用SEM和AFM观察表面形貌及晶化, 并进行了介电性能测试. 结果表明, 常规薄膜介电性能差; 经PT, 薄膜裂纹和缩孔显著减少,形貌明显改善,表面非钙钛矿结构显著减少, 介电性能明显提高; 经APT, 薄膜形貌进一步改善,平均晶粒大小约30nm,非钙钛矿结构进一步减少, 介电损耗明显降低,介电稳定性和介电强度大幅度提高. APT为制备退火温度低及结构均匀致密的纳米晶BST薄膜提供了新方法, 可满足低频实用要求. 退火温度对薄膜厚度的影响也进行了讨论.     

The effect of Bi1.5Zn0.5Nb0.5Ti1.5O7 cover layer on the dielectric and tunable properties of Ba0.6Sr0.4TiO3/Bi1.5Zn0.5Nb0.5Ti1.5O7 bilayered thin films

Bi_1.5Zn_0.5Nb_0.5Ti_1.5O₇ (BZNT) thin films with different thicknesses as cover layers were deposited on the Ba_0.6Sr_0.4TiO₃ (BST) thin films on the Pt/Ti/SiO₂/Si substrates by radio frequency magnetron sputtering method. The microstructure, surface morphology, dielectric and tunable properties of BST/BZNT heterogeneous bilayered films were investigated as a function of the thickness of BZNT films and the effect of BZNT films on the asymmetric electrical properties of BST/BZNT bilayered films was discussed. It was found that BZNT cover layer significantly improved the leakage current and the dielectric loss, and the dielectric constant and tunability of BST/BZNT bilayered thin films simultaneously decreased with the increasing thickness of BZNT films. The BST/BZNT bilayered thin film with a 50 nm BZNT cover layer gave the largest figure of merit (FOM) of 33.48 with the upper tunability of 55.38%. The asymmetric electrical behavior of BST/BZNT bilayered films is probably related to an internal electric field caused by built-in voltages at Pt/BST and BZNT/Au interfaces.     

Structural and dielectric properties of Ba0.7Sr0.3TiO3 thin films grown on thin Bi layer-coated Pt(111)/Ti/SiO2/Si substrates

In this work, the growth and study of dielectric properties of Ba_0.7Sr_0.3TiO₃ (BST) thin films grown on thin Bi layer coated Pt(111)/Ti/SiO₂/Si substrates, depending on thin Bi layer thickness is reported. The BST thin film (thickness 180 nm) grown on 10-nm-thick Bi layer exhibited more improved structural and dielectric properties than that grown on bare Pt(111)/Ti/SiO₂/Si substrate. The 10-nm-thick Bi layer in optimum configuration was effective for the grain growth of BST phase and suppressed the formation of the oxygen-deficient layer at the interface between the BST thin film and bottom electrode, which resulted in an increase in dielectric constant and a decrease in leakage current density of the Pt/BST thin film/Pt capacitor.     

载荷频率对金属及其合金高周疲劳特性的影响

采用超声高频加载方法进行高周疲劳试验时,应考察载荷频率对材料疲劳特性的影响。本文从微观组织结构和外部环境两方面论述了疲劳特性的频率效应,从裂纹扩展率、断口分析等方面回顾和介绍了频率对合金钢、钛合金、铝合金三类常用金属疲劳特性的影响,比较了三者异同。最后展望了高周和超高周疲劳研究的方向和方法及其在工程中的应用。