于荣海2016高温磁性材料

1、 高温磁性材料高温磁性材料 于荣海于荣海 材料科学与工程学院材料科学与工程学院 北京航空航天大学北京航空航天大学 材料的性质材料的性质 1. 力学性质力学性质 2. 物理性质物理性质 2.1 电学性质电学性质 2.2 磁学性质磁学性质 2.3 光学性质光学性质 2.4 热学性质热学性质 2.5 超导电性超导电性 性质性质 使用性能使用性能 合成合成/制备制备 结构结构/成份成份 材料科学四要素材料科学四要素 Maglev吸引力和排斥力吸引力和排斥力 磁场的产生磁场的产生 电子绕核转动和自旋电子绕核转动和自旋 铁磁性铁磁性反铁磁性反铁磁性 亚铁磁性亚铁磁性 物质的磁性物质的磁性 磁畴磁畴-Mag

2、netic Domain 磁化过程和磁畴运动磁化过程和磁畴运动: i MM 磁畴和静磁能磁畴和静磁能 磁畴照片磁畴照片 磁滞回线磁滞回线 主要参数主要参数: Hc(矫顽力矫顽力); Bs(饱和磁化强度饱和磁化强度) i MM 软磁材料软磁材料永磁材料永磁材料 磁性材料的主要种类磁性材料的主要种类 Various soft magnetic materials Iron Fe-Si alloys Fe-Ni alloys Fe-Co alloys Soft ferrites MoFe2O3, M,ZnFe2O4 Amorphous alloys (Fe72Co8Si5B15) Nanocryst

3、alline alloys (Fe73.5Cu1Nb3Si13.5B9) Various hard magnetic materials Fe & Cot steel Ni and Co alloys (alnicos) Oxides (Hard ferrites) Rare earth inter-metallic compounds Examples of modern permanent magnets SmCo5 type (sintered) Sm2Co17 type (sintered) Bonded RE cobalt magnets(bonded SmCo5, Sm2Co17)

4、 Sintered Nd-Fe-B magnets Bonded Nd-Fe-B magnets ADVANCED MAGNETSADVANCED MAGNETSADVANCED MAGNETSADVANCED MAGNETS Maximum energy product (MGOe) 19601970198019902000 10 20 30 40 50 60 Hadjipanayis Sagawa Tawara Clark Ojima Yoneyama Strnat Velge Buschow Benz, Martin Nesbitt Hubbard Kaneko Sagawa Otsuk

5、i Kaneko Strnat Croat Koon 0 Years Coehoorn Wang Manaf Nagel Mishra Maximum energy product (MGOe) 19601970198019902000 10 20 30 40 50 60 Ray SmCo5 Sm2Co17 Nd2Fe14B Rodewald Strnat 0 Years Senno Nd2Fe14B/ -Fe 1st Generation REM 2nd generation REM3rd generation REM Nanocomposite REM Up to 100 MGOe 稀土永

6、磁材料进展稀土永磁材料进展 We are here ! Maximum energy product (MGOe) 19601970198019902000 10 20 30 40 50 60 Hadjipanayis Sagawa Tawara Clark Ojima Yoneyama Strnat Velge Buschow Benz, Martin Nesbitt Hubbard Kaneko Sagawa Otsuki Kaneko Strnat Croat Koon 0 Years Coehoorn Wang Manaf Nagel Mishra Maximum energy pro

7、duct (MGOe) 19601970198019902000 10 20 30 40 50 60 Ray SmCo5 Sm2Co17 Nd2Fe14B Rodewald Strnat 0 Years Senno Nd2Fe14B/ -Fe 1st Generation REM 2nd generation REM3rd generation REM Nanocomposite REM Up to 100 MGOe 稀土永磁材料进展稀土永磁材料进展 We are here ! 高温永磁材料高温永磁材料 15 yearsContract life 58 degrees WOrbital Slo

8、t Baikonur, KazakhstanSite ProtonVehicle Aug.28, 1997 (Aug. 27 in United States) Launch Date 1 Hughes 601HPSpacecraft PanAmSat Corporation Customer 15 yearsContract life 58 degrees WOrbital Slot Baikonur, KazakhstanSite ProtonVehicle Aug.28, 1997 (Aug. 27 in United States) Launch Date 1 Hughes 601HP

9、Spacecraft PanAmSat Corporation Customer PAS5 Satelite，1997 XIPS: The Latest Thrust in Propulsion Technology An ion propulsion engine incorporating high-temp SmCo magnets (red) powered the Deep Space 1 probe. 氙氙(Xe)离子空间推进器离子空间推进器 ADVANCED MAGNTSADVANCED MAGNTS 性能要求性能要求(极端条件极端条件) 1. 高温高温 700 oC，低温，低温

10、-180 oC. 2. 辐照和辐射辐照和辐射: gamma photon and particle radiation 3. 腐蚀环境腐蚀环境 4. 高真空高真空 NASAs Deep Space 1 Ion Engine 使用涂层的使用涂层的 SmCo基高温永磁材料。基高温永磁材料。 ADVANCED MAGNTS qIn the binary Sm-Co system the allowed d e v i a t i o n s f r o m t h e a l l o y s stoichiometries are limited. qThe eutectoid decomposit

11、ion of the 1:5 phase is extremely slow and not likely to occur in the practical alloys. qTypical magnets have the composition Sm(Co,Fe,Cu,Zr)z qZr allows greater deviations from the stoichiometry. At high temperatures, the continuous range of the 1:7 structure stretches from 1:5 to 2:17*. qAt lower

12、temperatures this solution phase will decompose into 2:17 and 1:5. _ * S. Derkaoui, N. Valignat and C.H. Allibert, J. Alloys and Compounds 232 (1996) 296. 1150 oC qThe hexagonal 1:5 structure consists of alternating Sm-Co and Co layers. qThe 2:17(R) structure is one of several 1:5 derivatives with o

13、rdered Co dumbbells. qIn the 2:17 magnets, the Cu and Fe atoms occupy the individual Co sites, while the Zr atoms occupy the dumbbell sites (i.e. the Sm sites of the parent 1:5 lattice). qIf extra Co atoms added, pairs of them replace the larger Sm atoms as t h e s o - c a l l e d dumbbells. Random

14、replacement does not change the lattice symmetry leading to the off-stoichiometric 1:5 stucture, sometimes c a l l e d t h e 1 : 7 structure. MicrostructureMicrostructure qThe Sm(Co0.692Fe0.1Cu0.168Zr0.04)8.5magnet shows a typical cellular and lamellar microstructures. qThe cell interiors have the r

15、hombohedral2:17 structure, while the cell boundaries have the hexagonal 1:5 structure. qThe 2:17(R) and 1:5 structures are perfectly coherent. qThe size of the cells depends on z 4 nm4 nm 0.433 nm 0.726 nm 0.726 nm 1:5H 2:17R 2:17R 4 nm4 nm4 nm4 nm 0.433 nm 0.726 nm 0.726 nm 1:5H 2:17R 2:17R Cellula

16、r structure Lamellar structure 830 C Quenched 0.7C/min 2h 400 C T 15 30 Time qqA typical evolution of cellular microstructure A typical evolution of cellular microstructure with heat treatment .with heat treatment . c-axis c-axis c-axis | c-axis Incomplete cells No lamella Cell size: 25 nm Few lamel

17、la Cell size: 72 nm, Lamella: 0.033/nm Cell size: 80 nm, Lamella: 0.054/nm Heat Treatment: Development of Cellular StructureHeat Treatment: Development of Cellular Structure No significant Hc qqAsAs- -developed cellular structure has developed cellular structure has a very low coercivity.a very low

18、coercivity. 1150 oC -60 -50 -40 -30 -20 -10 010 20 30 40 50 60 -10 0 10 20 30 40 50 60 70 80 Fe Zr Sm Co Cu Element Content (at%) Distance from Center of Cell Boundary (nm) 2:17 1:5 2:17 -60 -50 -40 -30 -20 -10 010 20 30 40 50 60 -10 0 10 20 30 40 50 60 70 80 Fe Zr Sm Co Cu Element Content (at%) Dis

19、tance from Center of Cell Boundary (nm) 2:17 1:5 2:17 qqIn the fully heat treated magnets the 1:5 cell boundaries are noIn the fully heat treated magnets the 1:5 cell boundaries are not only enriched in Sm and t only enriched in Sm and depleted in Co, but also enriched in Cu and depleted in Fe .depl

20、eted in Co, but also enriched in Cu and depleted in Fe . Heat Treatment: Cu DiffusionHeat Treatment: Cu Diffusion qqCoercivity of the 2:17 magnets increases as Cu concentrates at tCoercivity of the 2:17 magnets increases as Cu concentrates at the cell boundaries he cell boundaries during slow coolin

21、g.during slow cooling. 0 2 4 6 8 10 12 14 16 0.5 2 24 700 600 500 400 2 4 6 8 10 12 14 16 18 Coercivity (kOe) Co content at cell boundary (at. %) % Cu Hc AgingCooling Distance from center of cell boundary (nm) Sm(CoFeCuZr) Hci= 14.5 kOe Hci=36.0 kOe Cell Size=50nm Cell Size=110nm Tag=700C Tag=850C 时

22、效热处理温度的影响时效热处理温度的影响 Sm(CobalFe0.1Cu0.088Zr0.04)8.5 Cell size 35 nm 120 nm - Hc 5.6 kOe 32.0 kOe 0.4 kOe Aged at 850C 1h 9h 12h 时效热处理时间的影响时效热处理时间的影响 Effect of Z-ratio: Sm(CobalFe0.224Cu0.088Zr0.033)z bac z=7.0, Hci=15 kOe z=8.5, Hci=35 kOe z=9.0, Hci=8 kOe. Cell size: 88 nm 108 nm 237 nm 6.57.07.58.0

23、8.59.09.5 5 10 15 20 25 30 35 40 Hic (kOe) Z-Ratio Brief Summary of Element EffectBrief Summary of Element Effect in 2:17 Magnetsin 2:17 Magnets Effect of Cu : leads to the formation of 1:5 cells Effect of Zr : leads to the formation of lamella Effect of Fe : leads to higher magnetization Cu element

24、 plays key role in increased coercivity 计算机硬盘以及计算机硬盘以及 微电子机械系统微电子机械系统 (MEMS)的的小型小型 化及高性能化化及高性能化 关键技术之一关键技术之一: : 磁性材料的磁性材料的 小型化小型化、高性能化高性能化和集成化和集成化 磁记录材料磁记录材料 磁记录装置原理图磁记录装置原理图 MAGNETIC RECORDING Particulate Recording Media Thin Film Recording Media MAGNETIC RECORDING Particulate Recording Media Thin

25、Film Recording Media Si T. Ox., SiO2 AlN BaM Si T. Ox., SiO2 amorphous-BaM BaM Si T. Ox., SiO2 AlN BaM Si T. Ox., SiO2 AlN BaM Si T. Ox., SiO2 amorphous-BaM BaM Si T. Ox., SiO2 amorphous-BaM BaM 磁介质材料磁介质材料 磁记录的三种方式的发展磁记录的三种方式的发展磁记录的三种方式的发展磁记录的三种方式的发展 水平磁记录水平磁记录 比特的晶粒组成（比特的晶粒组成（100个以上的晶粒）个以上的晶粒） 热稳定性

26、与密度上限热稳定性与密度上限 垂直磁记录垂直磁记录 退磁场退磁场 膜厚与热稳定性膜厚与热稳定性 分立垂直磁记录分立垂直磁记录 减小相互作用减小相互作用 热稳定性热稳定性 三种磁记录方式示意图三种磁记录方式示意图 CoCrPtB-based granular thin film: low thermal stability Co-Pd or Co-Pt multilayered ( 20 layers) film: large grainsize CoCrPt-oxide thin film: FePt or CoPt Trend in Perpendicular Recording FilmT

27、rend in Perpendicular Recording Film Nanofabrication Nanofabrication methods can be divided into two categories: Top-down methods Example: lithography Bottom-up methods Example: quantum dots and self-assemble Photol i thographyPhotol i thography UV substratephotoresist etchant mask Spin coating Mask

28、 and exposeDevelop Etching Resist removal Final Product Can make complex 3-D shapes using gray-scale techniques Electron Beam Electron Beam Lithography and Nanofabrication High MMPMMA Low MMPMMA Indium Tin Oxide Glass Exposure DevelopmentMetal depositionLiftoff Bilayer e-beam resist structure. A hig

29、h molecular weight PMMA is spun on top of a slightly more sensitive bottom layer of low melecular weight PMMA. The resist is developed in MIBK:IPA giving an undercut. The resist is removed in a liquid solvent leaving the pattern. 液滴沉积过程示意图液滴沉积过程示意图液滴沉积过程示意图液滴沉积过程示意图 全固态，全固态，550微米微米 半固态，半固态，50150微米微米

30、 全液态，全液态，150微米微米 半固态薄层半固态薄层 TEM Characterization of Particles TEM Characterization of Particles Made by the Cluster GunMade by the Cluster Gun 24681012 0 100 200 300 400 Dav=5.75 nm Stan. dev.=1.5 nm Number of particles Particle diameter, nm 24681012 0 100 200 300 400 Dav=6.1 nm Stan. dev.=1.1 nm Nu

31、mber of particles Particle Diameter, nm 24681012 0 100 200 300 400 Dav=5.75 nm Stan. dev.=1.5 nm Number of particles Particle diameter, nm 24681012 0 100 200 300 400 Dav=6.1 nm Stan. dev.=1.1 nm Number of particles Particle Diameter, nm Heating stage transforms the FePt particles from the fcc to fct

32、 phase without much increase in average particle size. Nanoparticles by Chemical SynthesisNanoparticles by Chemical Synthesis Fe(CO)5 Pt(acac)2 A schematic diagram of preparing FePt nanoparticles by chemical A schematic diagram of preparing FePt nanoparticles by chemical synthesissynthesis Solvent E

33、vaporation 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 3.9114.1684.4264.6844.942 Population % Size (nm) 4.48 0.15 nm (3.3%) 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 3.9114.1684.4264.6844.942 Population % Size (nm) 4.48 0.15 nm (3.3%) 20 nm 4.480.15 nm(3.3%) 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 3.9114.1684.4264.6844.942 Population % Size (nm) 4.48 0.15 nm (3.3%) 0 0.02 0.04 0.06 0.08 0.1 0.12 0.14 3.9114.1684.4264.6844.942 Population % Size (nm) 4.48 0.15 nm (3.3%) 20