稀土永磁体的最新进展

介绍了高性能烧结Ｎｄ－Ｆｅ－Ｂ系磁体、高性能辐向取向热挤在Ｎｄ－Ｆｅ－Ｂ磁体、注射成形ＮＤ－ＦＥ－Ｂ系各向同性粘结磁体、温压缩成形ＮＤ－ＦＥ０－Ｂ系各向同性粘结磁体,ＮＤ－ＦＥ－Ｂ系各向异性粘结磁体Ｓｍ－Ｆｅ－Ｎ＋α－Ｆｅ各向同性粘结磁体、Ｓｍ－Ｆｅ－Ｎ系各向异性地磁体、Ｓｍ－（Ｆｅ,Ｔｉ,Ｂ）系各向同性粘结磁体以及高温下使用的Ｓｍ－Ｃｏ系烧结磁体等的最新进展。     

SmTbFeCo磁光记录材料温度特性的平均场理论研究

基于平均场理论，提出重稀土－轻稀土－过渡族非晶薄膜温度特性的计算方法，详细讨论了薄膜成分对薄膜磁学和磁光性能的影响。研究表明，用适量的轻稀土元素替代重稀土元素，室温下饱和磁化强度增大，克尔角有所提高，薄膜的补偿点温度下降，恧大里点温度基本保持不变，并且饱和磁化强度和矫顽力随温变化趋向缓慢，从而可以拓宽磁光介质的使用温度范围。     

在宽温度范围应用的稀土磁体

在４．２－４２３的温度范围内，研究了Ｓｍ２Ｃｏ１７型烧结结磁和Ｎｄ－Ｆｅ－Ｂ模锻磁体。它们的磁性能与ＳｍＣｏ５和Ｎｄ－Ｆｅ－Ｂ烧结磁体不相上下。研究表明：这种Ｓｍ２Ｃｏ１７型磁体，在温度高达４２３Ｋ下应用，可认为是最好的。在４２３Ｋ下Ｓｍ２Ｃｏ１７磁体的磁性能为：Ｂｒ＝１０＼８ｋＧ，Ｈ＝１５．７ｋＯｅ和（ＢＨ）ｍａｘ＝２７．１ＭＧＯｅ。在５７３Ｋ下暴露半小时后，在磁导系数为２时，Ｓｍ２Ｃｏ１７磁体     

HDDR各向异性NdFeB粘结磁体研究

开发了用ＨＤＤＲ各向异性ＮｄＦｅＢ粉加环氧树脂做的高能积模压成型粘结磁体微波研究了Ｃｏ、Ｇａ含量地ＮｄＦｅＢ粘结磁体的磁性能的影响和工艺重复性,最后做出的各向异性粘结ＮｄＦｅＢＣｏＧａ磁体的磁性能为：Ｂｒ≥８００ｍＴ,ＨＣＪ≥８００ｋｍ,ＡＣＢ≥４４０ｋＡ／ｍ,（ＢＨ）ｍａｘ＝１２７±１６ｋＪ／ｍ＾３     

波导隔离器用Ce：YIG磁光薄膜的制备

波导隔离器用Ｃｅ：ＹＩＧ磁光薄膜可由溅射外延或溅射沉积后热处理结晶化两种方法制备。控计了制备过程中不同工艺条件对薄膜结晶性能及磁光特性的影响．     

永磁材料的磁稳定性

永磁材料的磁稳定性是永磁材料的重要指标,本文首先介绍了ＡｌＮｉＣｏ系、可加工Ｆｅ－Ｃｒ－Ｃｏ系、稀土钴系、Ｎｄ－Ｆｅ－Ｂ系和其它永磁系列的温度稳定性,然后介绍了永磁材料的时间稳定性及其他方面的稳定性,最后对如何提高磁稳定性问题进行了简单讨论。     

包钴包亚铁氧化铁磁粉表面的XPS研究

使用ＶＧ ＥＳＣＡＢ６电子能谱仪对不同产地的ＣｏＦｅ－ｒ－Ｆｅ２Ｏ３磁粉的表面进行了研究，对不同ＣｏＦｅ－ｒ－Ｆｅ２Ｏ３磁粉表面Ｃｏ，Ｆｅ元素可能的价态和组分进行了分析，探讨了包钴包亚铁磁粉可能采用的工艺。     

退火对低温射频磁控溅射Ba铁氧体薄膜结构及磁特性的影响

用ＲＦ磁控溅射法在纯Ａｒ气中，在硅基片不加热，制备了Ｂａ铁氧体薄膜，研究了退火温度对薄膜Ｃ轴垂直取向，结构及磁特性的影响，结果表明薄膜在７００℃氧气中退火可获得良好Ｃ轴垂直膜面择优取向，该薄膜的饱和磁化强度和矫顽力分别是Ｍｓ＝２９６ｋＡ／ｍ，Ｈｃ＝３１０．４ｋＡ／ｍ。退火温度过低或过高，都不利于形成Ｃ轴垂直膜面的择优取向。     

用HDDR工艺研制高矫顽力Sm2Fe17Nx粉

本文论述了在制备高矫顽力Ｓｍ２Ｆｅ１７Ｎｘ磁粉过程中ＨＤＤＲ（氢化歧化）工艺的应用；研究了Ｓｍ２Ｆｅ１７Ｎｘ的氢化歧化行为。在６００℃￣１１００℃氢化处理时，Ｓｍ２Ｆｅ１７相分离为α－Ｆｅ和氢钐化合物，随后热处理真空脱氢，蜂窝状Ｓｍ２Ｆｅ１７相直径大约是５０￣５００ｎｍ，在７７５℃经ＨＤＤＲ工序处理的氮化Ｓｍ２Ｆｅ１７粉矫顽力为８．７ＫＯｅ。     

几种稀土铁石榴石晶体的磁光性能

采用助熔剂法生长稀土铁石榴石单晶Ｙ３Ｆｅ５Ｏ１２，（ＢｉＣａ）３（ＦｅＶ）５Ｏ１２和（ＧｄＢｉ）３Ｆｅ５Ｏ１２，在近红外波段以磁光调制倍频法测量晶体的法拉第磁光旋转谱，同其它几种材料相比，（ＧｄＢｉ）３Ｆｅ５Ｏ１２晶体磁光优值大，是制作非互易光学器件较为理想的法拉第旋转晶体．     

Excess Bismuth-Dependent Characteristics of Chemical Solution Deposited Bi3.15La0.85Ti3O12 Thin Films

The phase formation and electrical properties of (Bi_3.15La_0.85)Ti₃O₁₂ (BLT) thin films prepared by the chemical solution deposition method on Pt/Ti/SiO₂/Si substrates have been investigated. It was observed that the microstructure and electrical properties of BLT thin films dramatically varied with the excess Bi content. The crystallographic orientation of BLT films was varied with excess Bi content and the intermediate rapid thermal annealing (RTA) process. While BLT thin films prepared without intermediate RTA process have ?117? orientation irrespective of excess Bi content, BLT thin films with RTA process at 450°C have an orientation change with excess Bi content. The leakage current of BLT thin films slightly increased with increasing excess Bi content up to 6.5% and then considerably decreased in BLT film with 10% Bi, where was revealed to be almost stoichiometric composition.     

EFFECTS OF PZT BUFFER LAYERS ON PZFNT FERROELECTRIC THIN FILMS

ABSTRACT

PZFNT thin films were fabricated on 5-inch Pt/Ti/SiO₂/Si and PZT/Pt/Ti/SiO₂/Si substrates by RF magnetron sputtering method and rapid thermal annealing process. By investigating the two thin films at various annealing temperatures, the results show that the annealing temperature of PZFNT thin films without PZT buffer layers is about 730°C, which is higher than that of PZFNT films with PZT buffer layers. By use of PZT buffer layers, the annealing temperature of PZFNT films is decreased greatly, and the dielectric and ferroelectric properties are improved. In the optimum process, the thin films with PZT buffer layers have a dielectric constant of 1199 and dielectric loss of 3.0% at 1 KHz. The remanent polarization and coercive field of the thin films are 21.1 μC/cm² and 53.5 KV/cm respectively. The films have the significant potential for FRAM and pyroelectric infrared detectors.     

Fe:SmCo(Cr)薄膜的结构、磁性能与磁光克尔效应

利用脉冲激光沉积工艺,分别在单晶Si(100)衬底和玻璃(Si O2)衬底上制备Fe:Sm Co/Cu(Cr)薄膜,研究了Fe掺杂对Sm Co薄膜结构、磁性能与磁光效应的影响。实验发现,衬底对Fe掺杂Sm Co薄膜性能有很大影响,Si衬底薄膜的矫顽力和饱和磁化强度均优于玻璃衬底样品;同时退火温度也会影响Fe掺杂Sm Co薄膜形貌及磁性能,高温退火后,Sm Co衍射峰得到了增强,尤其是Sm Co5的(001)、(002)和(003)衍射峰最为明显,这是由于高温退火后Cu(111)衍射峰增强的缘故。同时发现,退火后的Si O2衬底与Si衬底样品的磁性和磁光效应均得到增强,但Si O2衬底的矫顽力Hc变化更明显,这是因为较高的表面应力会导致样品的矫顽力增强。因此可以通过调节Fe含量来控制样品的磁光性能,这就为优化Sm Co薄膜作为磁光存储介质的性能指出了一个研究方向。     

Structure and dielectric properties of Ba(Sn0.2Ti0.8)O3 thin films grown on different substrates by a sol-gel process

Ba(Sn_0.2Ti_0.8)O₃ (BTS) thin films were deposited on Pt/Ti/SiO₂/Si and LaNiO₃/Pt/Ti/SiO₂/Si substrates by a sol-gel processing technique, respectively. The influences of substrates on the phase and microstructure of the thin films were examined. Dielectric properties of the thin films were investigated as a function of frequency and direct current electric field. The results showed that the substrates strongly influenced the microstructure and the dielectric properties of the films. The properties of BTS thin films on LaNiO₃/Pt/Ti/SiO₂/Si substrates were superior to that of the films grown on Pt/Ti/SiO₂/Si substrates.     

Bi4Ti3O12铁电薄膜的制备及研究进展

铁电薄膜具有良好的铁电、介电性能,在非挥发存储器件方面有很好的应用前景.本文介绍了钛酸铋(Bi4Ti3O12)铁电薄膜的研究现状,对目前Bi4Ti3O12铁电薄膜最常用的几种主要制备方法及其掺杂改性进行了评述,指出了Bi4Ti3O12铁电薄膜研究中亟待解决的几个问题.     

Characteristics of Bi4Ti3O12 thin films on ITO/glass and Pt/Si substrates prepared by R.F. sputtering and rapid thermal annealing

Bi₄Ti₃O₁₂ thin films are deposited on ITO/glass and Pt/Ti/Si(100) substrates by R.F. magnetron sputtering at room temperature. The films are then heated by a rapid thermal annealing (RTA) process conducted in oxygen atmosphere at temperatures ranging from 550–700^∘C. X-ray diffraction examination reveals that the crystalinity of the films grown on Pt/Ti/Si is better than that of the films grown on ITO/glass under the same fabrication conditions. SEM observation shows that the films grown on Pt/Ti/Si are denser than those grown on ITO/glass substrates. Interactive diffusion between the Bi₄Ti₃O₁₂ film and the ITO film increases with the increase of annealing temperature. The optical transmittance of the thin film annealed at 650^∘C is found to be almost 100% when the effect of the ITO film is excluded. The relative dielectric constants, leakage currents and polarization characteristics of the two films are compared and discussed.     

THE STUDY OF THE MICROSTRUCTURE AND TUNABILITY OF Ba(SnxTi1-x)O3 THIN FILMS

ABSTRACT

Barium tin titanate Ba(Sn_xTi_1?x)O₃ (BTS, x = 0.05,0.1,0.15,0.2,0.25) thin films have been prepared by sol-gel technique on Pt/Ti/SiO₂/Si substrates. The influences of Sn content on the evolution of the phase and microstructure of the thin films were examined. Dielectric properties of the thin films were investigated as a function of frequency and direct current electric field. The result shows that the Sn content strongly influences the microstructure and the dielectric properties of the films. This work clearly reveals the highly promising potential of BTS films for application in tunable microwave devices.     

Development of ferroelectric PZT thin films by the sol-gel technique for non-volatile memory applications

Abstract

PZT thin films have been prepared via a sol-gel route using standard butoxide and acetate precursors. The solution compositions were modified by the addition of acetylacetone in 2 methoxyethanol, which has the effect of changing the solution complex and therefore its deposition and drying characteristics. Varying amounts of excess lead were included in some cases. The films were prepared by spin coating onto Pt/Ti electroded silicon with an intermediate barrier layer of either boron phosphate silica glass (BPSG) or thermal silicon oxide and the resulting samples subjected to a range of thermal annealing conditions in an oxidising atmosphere. Several methods have been investigated including two regimes using rapid furnace annealing (RFA) up to 700°C and slow annealing at 450°C in air. The latter method yielded highly (111) oriented and crack-free perovskite films with no evidence of other orientations, whereas the former route showed the presence of (100) and (110) orientations. The correlation between the thermal anneal method and orientation will be discussed. Surface electrode dots have been evaporated onto the film to allow electrical measurements. The ferroelectric and fatigue properties of these films have been assessed with respect to non-volatile memory applications. The implications of film quality and thermal processing on the overall ferroelectric performance will be discussed.     

Piezo- and pyroelectric properties of lead scandium tantalate thin films

Abstract

This paper discusses the piezo- and pyroelectric properties of lead scandium tantalate thin films prepared by modified sol-gel technology. Films were deposited on Pt/Ti/SiO₂/Si-sub-strates at 530–630 °C. The quality of the thin films was optimized by design of both the deposition conditions and the solution chemistry. These approaches include spin coating speed, drying plus crystallization temperature and time, drying atmosphere, the use of rapid thermal annealing, PST sol composition, Pb-excess concentration and mixing method. The finished thin films were characterized by optical microscopy, X-ray diffraction, atomic force microscopy, and pyroelectric measurements at 30°C under a DC-bias. Piezo-response AFM was conducted on PST to monitor various piezoelectric responses, which depend on the micro-structure of the film. The maximum pyroelectric figure-of-merit F_D was 3.85×10^?5 Pa^?1/2 at 30°C and 1 kHz under a 35 V DC-bias.     

Effect of a Second Annealing Process on the Properties of BaTiO3 Thin Films on Polycrystalline Nickel Substrates Grown by Polymer-Assisted Deposition

Ferroelectric BaTiO₃ thin films were successfully deposited on nickel foils by a chemical solution technique named polymer-assisted deposition. It is found that a second annealing in oxygen using a rapid thermal annealing furnace would strongly affect the electric properties of the as-prepared thin films. Dielectric and ferroelectric properties have been systematically studied. The correlation between the second annealing conditions and dielectric properties was established and discussed. Optimized second annealing condition was found.