电容位移测量仪的校准与薄膜的磁致伸缩测量

自制了一套电容位移测量仪的校准装置，并对DWS型电容位移测量仪进行了校准和标定，使位移测量仪在较宽的量程范围内获得的悬臂梁位移测量值的误差≤5％。通过采用经改进校准和标定的位移测量仪，利用悬臂梁-电容法测定了稀土超磁致伸缩薄膜样品的磁致伸缩系数λ，提高了测量精度。     

基于激光位移法的大磁致伸缩测量技术研究

基于激光位移法建立了一套大磁致伸缩材料测量装置,可以实现磁致伸缩系数的无接触、整体、准确测量。仪器测量磁致伸缩系数的复现性可达到2%。使用该装置测量不具有磁致伸缩性能的材料,结果显示仪器系统误差仅为3×10~(-6);装置测量纯镍样品饱和磁致伸缩系数的结果与理论值吻合良好。     

基片倾斜角度对TbFe薄膜磁致伸缩性能的影响

采用直流磁控溅射法制备了非晶态 TbFe磁致伸缩薄膜,通过基片的倾斜安装研究了基片倾斜角度对TbFe薄膜磁致伸缩性能的影响。结果表明:随着基片倾斜角度的增大 TbFe薄膜的磁致伸缩系数增大,在外加磁场110kA·m-1下基片倾斜角度为 60°时薄膜磁致伸缩系数达到最大值 1.02×10-4,并且随着基片倾斜角度的增大 TbFe薄膜的易磁化方向由垂直膜面方向逐渐转向平行膜面方向。这是由于倾斜基片溅射形成的倾斜的薄膜柱状微结构产生的形状各向异性引起的。     

计算磁致伸缩系数的优化算法

实验方法或有限元法可以获得磁致伸缩系数,但从避免试验操作不便和减少试验量考虑,提出一种计算磁致伸缩系数的优化算法,并研究了超磁致伸缩薄膜的变形问题.通过算例分析,结果发现,与有限元法相比,优化算法的计算结果与实验方法的结果吻合更好,具有较高的精确度.     

TbFe/Fe交换耦合磁致伸缩多层膜的制备

采用双靶磁控溅射法制备了 TbFe/Fe交换耦合磁致伸缩多层膜,考察了热处理时间、Fe层厚度、溅射功率以及Ar气分压对多层膜低场磁致伸缩性能的影响。研究结果表明:TbFe 磁致伸缩层与软磁 Fe层之间通过交换耦合作用以及热处理能明显提高薄膜的软磁性能和磁致伸缩性能;TbFe/Fe多层膜的磁致伸缩性能对热处理时间、Fe 层厚度、溅射功率、Ar 气分压等薄膜沉积参数十分敏感;与 TbFe 磁致伸缩薄膜相比TbFe/Fe交换耦合磁致伸缩多层膜水平方向的矫顽力从 16kA/m降低到 9.6 kA/m。在外加磁场为8000 A/m条件下,TbFe/Fe磁致伸缩多层膜最大磁致伸缩系数可达1.58×10-4。     

热处理温度对TbFe2/Fe交换耦合磁致伸缩多层膜的影响

采用直流磁控溅射在20mm×5mm×240μm抛光单晶硅片上制备了TbFe2/Fe磁致伸缩多层膜,主要研究了热处理温度对TbFe2/Fe磁致伸缩多层膜磁致伸缩系数的影响.采用量热分析法(DSC)、XPS以及光杠杆测试法对TbFe2/Fe磁致伸缩多层膜的晶化曲线、成分随深度的变化以及磁致伸缩系数进行了分析与测试.结果表明TbFe2薄膜的起始晶化温度为327℃,晶化温度为372℃;TbFe2/Fe磁致伸缩多层膜的最佳热处理温度为327℃,在此热处理温度下热处理60min,外加磁场1.6×104A/m时,TbFe2/Fe磁致伸缩多层膜磁致伸缩系数可达1.56×10-4.采用XPS分析了一个周期的TbFe2/Fe成分随薄膜深度的变化,未经热处理的薄膜Fe层和TbFe2层之间界面清晰,两层之间有少量的扩散.经327℃热处理60min的薄膜Fe层和TbFe2层界面发生了互扩散,原子数之比也发生了改变.     

超磁致伸缩薄膜难磁化轴方向动态特性研究

磁场驱动频率高是限制超磁致伸缩薄膜器件推广应用的关键因素之一,研究如何降低超磁致伸缩薄膜器件的磁场驱动频率对超磁致伸缩薄膜器件的推广应用将具有重要意义。在深入分析超磁致伸缩薄膜存在各向异性根本原因的基础上,结合薄膜磁致伸缩过程中磁畴的运动机理,提出只要能够克服超磁致伸缩薄膜中存在的退磁场,低磁场驱动频率下就可在难磁化轴方向获得更为优良动态特性的新思路。通过建立超磁致伸缩薄膜难磁化轴实验系统进行实验研究,结果表明通过施加合适的偏置磁场克服退磁场,可以使薄膜在难磁化轴方向产生响应优良的超谐共振,为低频驱动GMF器件的研制提供了一种新的思路。     

TbFe巨磁致伸缩薄膜材料的研究进展

对TbFe巨磁致伸缩薄膜材料的研究进展进行了综述.主要对TbFe巨磁致伸缩薄膜材料的应用前景和提高TbFe巨磁致伸缩薄膜材料的低场磁致伸缩性能的方法进行了总结,指出了TbFe磁致伸缩薄膜研究中存在的主要问题,并对未来的研究方向进行了展望.     

粘结Sm-Dy-Fe合金的磁致伸缩性能研究

采用粘结法制备了Sm_(1-x)Dy_xFe_2合金样品,测量了粘结合金样品的静态磁致伸缩、动态磁致伸缩系数、增量磁导率和磁-机械耦合系数,研究了磁致伸缩性能等随磁场H的变化规律。发现当x<0.12时合金的低场磁致伸缩随x的增加而增加,高场磁致伸缩随x的增加而降低。棒状Sm_(0.88)Dy_(0.12)Fe_2合金在H=200kA/m时的磁致伸缩达405×10~(-6),磁-机械耦合系数和动态磁致伸缩系数分别达到0.34和1.28nm/A,因而粘结Sm_(0.88)Dy_(0.12)Fe_2合金具有一定的实用价值。     

Mn-Zn铁氧体磁致伸缩系数的测量

磁致伸缩系数定义为磁性材料在外磁场作用下产生的长度或体积的相对变化量,是磁性材料基本特性参数之一。因此,准确地测量磁致伸缩系数对研究磁性材料有重要意义。由于Mn-Zn铁氧体的磁致伸缩系数在10~(-7)～10~(-3)范围内,故必须采用高灵敏度的测量方法。本文所介绍的自动测量系统,其灵敏度达到2×10~(-3),在12秒钟内自动描绘出λ-H曲线,而且测试操作方便。对于磁致伸缩系数λ≥20×10~(-3)的测量,误差小于±13%,测量数据重复性好。在室温至70℃范围内,可测量磁致伸缩系数λ随温度T的变化。     

Stress Induced Enhancement of Magnetization Reversal Process of DyFeCo Films With Perpendicular Magnetization

A method to control magnetization reversal in magnetic films with perpendicular magnetic anisotropy was demonstrated in this study. Alloys of rare earth-transition metals (RE-TM) with their extremely large anomalous Hall coefficient and relatively large magnetostriction constants were suitable to observe the stress induced anisotropy using anomalous Hall effect. Stress applied to the RE-TM thin films significantly reduced the perpendicular coercivity and nucleation field of the film in comparison with that of the film in stress-free condition. Dy_x(Fe₉₀Co₁₀)_1-x thin films revealed large Hall voltage and remarkable change in the coercivity under the mechanical tensile stress     

基于新型鼓包法测试NiFe2O4薄膜的力磁性能

为表征NiFe_2O_4(NFO)薄膜材料的力磁性能,利用自主研发的新型多场耦合鼓包测试系统和发展的铁磁材料鼓包力磁本构方程,采用溶胶-凝胶法和化学腐蚀法制备了NFO薄膜鼓包样品,并在不同力磁条件下研究了NFO薄膜力磁耦合性能。结果表明,在外加磁场为0Oe时,NFO薄膜弹性模量和残余应力分别为187.8GPa和500.8 MPa。随着外加磁场的增大,NFO薄膜弹性模量由0Oe时的187.8GPa逐渐增大到800Oe时的484.6GPa;磁致伸缩系数由200Oe时的-94.2×10~(-6)增大到800Oe时的-326.2×10~(-6)。当鼓包油压由0kPa增大到50kPa时,NFO薄膜剩余磁化强度降低75%,矫顽磁场降低44%。     

Coexistence of Low Damping and Strong Magnetoelastic Coupling in Epitaxial Spinel Ferrite Thin Films

Low‐loss magnetization dynamics and strong magnetoelastic coupling are generally mutually exclusive properties due to opposing dependencies on spin–orbit interactions. So far, the lack of low‐damping, magnetostrictive ferrite films has hindered the development of power‐efficient magnetoelectric and acoustic spintronic devices. Here, magnetically soft epitaxial spinel NiZnAl‐ferrite thin films with an unusually low Gilbert damping parameter (<3 × 10^?3), as well as strong magnetoelastic coupling evidenced by a giant strain‐induced anisotropy field (≈1 T) and a sizable magnetostriction coefficient (≈10 ppm), are reported. This exceptional combination of low intrinsic damping and substantial magnetostriction arises from the cation chemistry of NiZnAl‐ferrite. At the same time, the coherently strained film structure suppresses extrinsic damping, enables soft magnetic behavior, and generates large easy‐plane magnetoelastic anisotropy. These findings provide a foundation for a new class of low‐loss, magnetoelastic thin film materials that are promising for spin‐mechanical devices.     

Integrated ferroelectric stacked mim capacitors with 100 nF/mm2and 90 V breakdown as replacement for discretes

This paper shows for the first time integrated thin film ferroelectric metal-insulator-metal capacitors on silicon with a record high capacitance density above 100 nF/mm² combined with a breakdown voltage of 90 V and a lifetime exceeding 10 years at 85degC and 5 V. The high capacitance density was obtained by a combination of material optimizations resulting in a dielectric constant of 1600, and stacking of capacitors. The reliability of these ferroelectric capacitors was studied in detail with accelerated lifetime testing. The high performance of the integrated capacitors in this paper shows great potential for applications demanding high capacitance densities combined with electrostatic discharge protection.     

Drying temperature effects on microstructure, electrical properties and electro-optic coefficients of sol-gel derived PZT thin films

Transparent lead zirconium titanate (PZT) thin film is suitable for a variety of electro-optic application, and the increasing of the electro-optic coefficient of PZT film is one of the important factors for this application. In this study, the main processing variable for improving an electro-optic coefficient was the drying temperature: 300, 350, 450 and 500°C in sol-gel derived PZT thin films. The highest linear electro-optic coefficient (1.65×10⁻¹⁰ (m/V)) was observed in PZT film dried at 450°C. The PZT film showed the highest perovskite content, polarization (P_max=49.58 μC/cm², P_r=24.8 μC/cm²) and dielectric constant (532). A new two-beam polarization (TBP) interferometer with a reflection configuration was used for electro-optic testing of PZT thin films which allows measurement of the linear electro-optic coefficient of thin film with strong Fabry–Perot (FP) effect usually present in PZT thin film.     

Influencing factors on the pyroelectric properties of Pb(Zr,Ti)O3 thin film for uncooled infrared detector

Zr-rich PZT thin films were synthesized by metallorganic decomposition and their dielectric and pyroelectric properties were investigated with different ratios of zirconium/titanium and poling condition. All the films became effectively (1 1 1) textured and well crystallized at the annealing temperature of 700 °C. With increasing Zr content, coercive field increased and voltage dependent capacitance curve appeared asymmetrical, indicating the presence of antiferroelectric phase, PbZrO₃, in film composition. The pyroelectric coefficient in the practically applicable temperature ranges of 20–60 °C was found to be maximum for the thin film with 0.85 mol of zirconium in PZT. Further increase in zirconium content led to severe deterioration in pyroelectric properties. The values of pyroelectric coefficient and figures of merit were greatly influenced by poling direction and temperature. The result was explained in terms of electric phase and state of polarization in film.     

Determination of properties of wedged, nonuniformly thick, and absorbing thin films by using a new numerical method

Nonuniformity in the thickness of thin films can severely distort their transmission spectra as compared with those of flat, smooth films. Methods that extract properties such as refractive index, thickness, and extinction coefficient of such films can suffer inaccuracies when they are applied to wedged or nonuniformly thick films. To accurately extract optical properties of nonuniform films, we have developed a novel numerical method and efficient constitutive relations that can determine film properties from just the transmission spectrum for films that are locally smooth with negligible scattering loss. This optimum parameter extraction (OPE) method can accommodate films with two-dimensional thickness variation that would result in significant errors in the values of refractive index and film thickness if not considered. We show that for carefully chosen test cases and for actual pulsed-laser-deposition AlN thin films, properties such as refractive index, extinction coefficient, and film thickness were very accurately determined by using our OPE method. These results are compared with previous techniques to determine the properties of thin films, and the accuracy of and applicable conditions for all these methods are discussed.     

水基金属有机物分解法制备Ba0.5Sr0.5TiO3薄膜的研究

制备了水基Ｂａ＾２＋、Ｓｒ＾２＋、Ｔｉ＾４＋三元有机物溶液。根据红外光 谱测定及对比实验分析了溶液配制过程中化学反应机理。采用金属有机物分解法（ＭＯＤ）制备Ｂａ０．５Ｓｒ０．５ＴｉＯ３（ＢＳＴ）薄膜。通过ＸＲＤ、ＳＥ趱 阻抗分析仪等分析测试手段,薄膜的相结构、微观形态及电性能。结果表明,所制备ＢＳＴ薄 数矿晶相结构,结晶完整晶粒小（１０－５０ｎｍ）,显微结构均匀致密,并具有良好的电性能（电容密度为     

在聚酰亚胺衬底上低温制备超薄热敏铂膜的研究

通过在聚合物衬底上制备热敏薄膜可以实现非平、屈曲物体表面温度的实时监控和测量。利用脉冲激光沉积技术在聚酰亚胺衬底上低温（250℃左右）制备了超薄铂热敏薄膜,其室温下的电阻温度系数为1．01×10^-3／K。通过增加ZnO过渡层,可使铂薄膜的电阻温度系数增大为1．55×10^-3／K。