氟化物中Eu^2＋,Ce^3＋的浓度猝灭及其机理

本文详细地研究了ＢａＹＦ５和ＫＣａＦ３基质中Ｅｕ＾２＋、Ｃｅ＾３＋浓度对其发光的影响，发现两基质中Ｅｕ＾２＋、Ｃｅ＾３＋的猝灭浓度都较低；提出了Ｅｕ＾２＋、Ｃｅ＾３＋的浓度猝灭机理，计算了猝灭浓度和临界距离，并与实验结果进行了比较。     

某些氟化物的升华提纯

ＡｌＦ２在１１００℃升华时，因其蒸汽压和过滤金属氟化物杂质相近，升华分离比较困难，本工作采用较快速度升温和移动凝华区的办法，能满意地把带红棕色的ＦｅＦ３、ＣｕＦ２等杂质分离，得到含铁量〈１ｐｐｍ的无色ＡｌＦ３晶体。对ＢａＦ２、ＬａＦ３等高沸点氟化物原料，在１３５０℃升华时，能有效地除去过渡金属氟化物杂质。在氟化物玻璃中，存在Ｆｅ＾２＋Ｆｅ＾３＋的平衡，其中Ｆｅ＾３＋，其中Ｆｅ＾３＋从可见区到近红外     

高性能各向异性Sm2Fe17Nx磁粉的制备

本文研究了高性能各向异性Ｓｍ２Ｆｅ１７Ｎｘ磁粉的制备工艺路线与工艺参数。优化了制备与工艺参数。已制备出磁性能达到：Ｂｒ＝１．３９Ｔ，Ｈｃｉ＝８５０ＫＡ／ｍ和（ＢＨ）ｍ＝２３６ＫＪ／ｍ＾３的各向异性Ｓｍ２Ｆｅ１７Ｎ２．８８磁粉，该磁粉的各向异性场ＨＡ达到２０Ｔ。     

掺铋钇铁石榴石光吸收谱的理论计算

利用ＤＶ－Ｘα方法分别计算了Ｆｅ＾３＋Ｏ＾２－６和Ｆｅ＾３＋Ｏ＾２－４原子族的能态密度和能级，在能级图的基础上，给出了０．５－０．９μｍ（１．６ｅｒ－２．３ｅｖ）范围内Ｂｉ－ＹＩＧ与吸收有关的跃迁能级，振子强度和跃迁线宽，并计算了相应的吸收谱，理论计算与实验结果符合较好。     

毫米波用六角铁氧体多晶材料

用普通陶瓷工艺制备了ＢａＡｌｘＦｅ１２－ｘＯ１９六角铁氧体多晶材料,随着Ｘ的增加,饱和磁化强度减小,居里温度下降,磁晶各向异性场增加。其结果可以通过假设Ａｌ＾３＋取代了２ａ位和１２Ｋ点阵位上的Ｆｅ＾３＋来解释。     

ZnxFe3—xO4的制备及性能

采用合适加剂在碱性溶液中制备了ＦｅＺｎ铁氧体，研究了其形成机理及磁性能，提出ＦｅＺｎ铁氧体的形成机理为：Ａｎ＾２＋＋２Ｆｅ＾３＋＋８０Ｈ＾－→ＺｎＦｅ２Ｏ４＋４Ｈ２Ｏ Ｆｅ＾２＋＋２Ｆｅ＾２＋＋８０Ｈ＾－→Ｆｅ３Ｏ４＋４Ｈ２Ｏ。     

Zn-Ti取代的BaFe12O19铁氧体

采用标准陶瓷工艺,并进行湿压磁场成型和氧气氛烧结制备了高取向度、低介电损耗的各向异性Ｂａ（ＺｎＴｉ）ｘＦｅ１２－２ｘＯ１９多晶六角铁氧体,随着ｘ值增大,磁化强度减小,居里温度下降,磁晶各向异性常数减小。结果可以通过假设Ｚｎ＾２＋取代了四面体４ｆ１次点阵位和六面体２ｂ次点阵位上的ＦｅＴ＾３＋;Ｔｉ＾４＋取代了自旋向上的八面体１２ｋ,２ａ次点阵位上的Ｆｅ６３＋来解释。     

高温高压合成的硅酸锶有铕铋的发光特性

用高温高压方法合成了Ｓｒ２ＳｉＯ４Ｅ＾３＋ｕ，Ｂｉ＾３＋和ＳｒＳｉＯ３Ｅｕ＾３＋＿，Ｂｉ＾３＋，研究了合成压力对其发光性能的影响，与用溶胶－凝胶共沉淀法和常压高温法合成的产品作比较，常压制备的ＳｒＳｉＯ３Ｅｕ＾３＋，Ｂｉ＾３＋为六角结构，而在２．３４－４．１０ＧＰａ的合成压力范围内，它转变为赝正交结构；常压下Ｓｒ２ＳｉＯ４；Ｅｕ＾３＋，Ｂｉ＾３＋，为单斜结构，在４．２ＧＰａ的合成压力下，未发现其结     

一种用于宽带温度稳定光隔离器的新型磁光材料

以Ｂｉ２Ｏ３／Ｂ２Ｏ３为主要助熔剂,用改进的高温助熔剂法生长出一种新型掺铋 事稀土铁石榴石（ＨｏＹｂＢｉ）３Ｆｅ５Ｏ１２单晶,研究了磁光性能,法拉第旋转温度和波长特性在１０－１１０℃,单昌的法拉第旋转温度系数Ｓ＝θＦ＾－１（ｄθＦ／ｄＴ）在λ＝１．５５μｍ时为４．６×１０＾－４Ｋ＾－１,比ＹＩＧ单晶的法拉第旋转温度系数小,在λ＝１．５５μｍ时,（ＨｏＹｂＢｉ）３Ｆｅ５Ｏ１２单晶的法拉第旋转波长系数     

300KeV氩离子辐照非晶态合金两代表面发泡形成

室温下，用３００ＫｅＶ氩离子辐照了非晶态合金Ｆｅ４０Ｎｉ４０Ｐ１２Ｂ８、Ｆｅ４０Ｎｉ４０Ｓｉ１２Ｂ８、Ｆｅ３９Ｎｉ３９Ｖ２Ｓｉ１２Ｂ８和Ｆｅ３９Ｎｉ３９Ｍｏ２Ｓｉ１２Ｂ３，研究了表面形貌随剂量的演变。在所研究的１．０×１０＾１７到５．０×１０＾１７离子／ｃｍ＾２的剂量范围，表面形貌以发泡形貌为主，并观测到了两代表面发泡的形成，第二代表面发泡的直径与第一代发泡相比，明显减小。油射自始至终影响着表面形     

硅基板上Fe掺杂TiO2氧敏薄膜的制备、结构与性能研究

采用溶胶-凝胶法,以Ti(OC₄H₉)₄为前驱体,用提拉法在硅基板上制备了掺Fe的TiO₂氧敏薄膜,对薄膜物相结构进行了X射线衍射(XRD)测定,利用扫描电镜(SEM)对薄膜微结构进行了观察.结果表明:在硅基板上生长的TiO₂薄膜中锐钛矿相为均匀小晶粒分布结构,金红石相以大尺度团聚结构形貌出现.Fe离子的掺杂对硅基板上制备的TiO₂薄膜中金红石相的形成有很大的影响.Fe的掺入降低了金红石相的形成温度约100℃,Fe掺量在6mol% 时,形成金红石相的量达到最大,即析晶能力最强.薄膜中形成晶相的晶格常数在<6mol%的低Fe范围内,随较小的Fe离子取代较大的Ti离子,锐钛矿相和金红石相的晶格常数都随之减小;在>6mol%的高Fe掺量范围内,随Fe掺量的增加,体系缺陷过量增加,晶格结构畸变严重,伴随着畸变能的释放,金红石相的晶格常数c轴逐渐增长,n轴略有下降(或基本不变). TiO₂氧敏薄膜的氧敏性能受金红石相含量和氧空位浓度控制.当Fe离子掺杂浓度为6mol% 时,金红石相及相应氧空位达到最大值,TiO₂氧敏薄膜的氧敏性能也达到最大值,比刚形成金红石相的薄膜的氧敏性能增加近19倍.     

Growth, structure, and properties of BiFeO3/-BiCrO3 films obtained by dual cross beam PLD

The properties of epitaxial Bi(2)FeCrO(6) thin films, recently synthesized by pulsed laser deposition, have partially confirmed the theoretical predictions (i.e., a magnetic moment of 2 micro(B) per formula unit and a polarization of approximately 80 microC/cm(2) at 0 K). The existence of magnetic ordering at room temperature for this material is an unexpected, but very promising, result that needs to be further investigated. Because magnetism is assumed to arise from the exchange interaction between the Fe and Cr cations, the magnetic behavior is strongly dependent on both their ordering and the distance between them. We present here the successful synthesis of epitaxial Bi(2)Fe(x)CryO(6) (BFCO x/y) films grown on SrTiO3 substrates using dual crossed-beam, pulsed-laser deposition. The crystal structure of the films has different types of (111)-oriented superstructures, depending on the deposition conditions. The multiferroic character of BFCO (x/y) films is proven by the presence of both ferroelectric and magnetic hysteresis at room temperature. The oxidation state of Fe and Cr ions in the films is shown to be 3+ only, and the difference in macroscopic magnetization with Fe/Cr ratio composition could only be due to ordering of the Cr(3+) and Fe(3+) cations to the modification of the exchange interaction between them.     

Structure and magnetic properties of Fe films with pyramid-like nanostructures deposited by oblique target direct current magnetron sputtering

Fe thin films were deposited by oblique target direct current magnetron sputtering on Si (100) and (111) substrates. The structure, surface morphology and magnetic properties of the thin films were characterized using X-ray diffraction, field emission scanning electron microscopy, and superconducting quantum interference device magnetometer, respectively. The results reveal that the structure of the as-deposited Fe thin films is body-centered cubic with the preferential [110] crystalline orientation. A pyramid-like nanostructure with sharp tip was formed on the surfaces of Fe thin films under appropriate sputtering power. Formation of the pyramid-like nanostructure is mainly owed to the enhancement of atomic mobility and the bombardment effect with increasing of sputtering power. Meanwhile, the crystalline orientation of Si substrate and the intrinsic stress in the films are expected to have little contribution to the formation of the pyramid-like nanostructure. The magnetic anisotropy was found in the as-deposited Fe thin films, and varies with the thickness of the Fe thin films. As the film thickness increases from 604 to 1,786 nm, the magnetic anisotropy field and the uniaxial anisotropy constant increase from 3.8 to 5.6 kOe, and from 0.4 × 10⁶ to 1.1 × 10⁶ erg/cm³, respectively, which indicates that besides magnetocrystalline anisotropy, stress induced anisotropy and shape anisotropy also exist in the as-deposited Fe thin films.     

单相Bi0.95Eu0.05Fe0.95Co0.05O3纳米颗粒的结构及其铁磁特性

采用溶胶-凝胶法制备了单相Bi0.95 Eu0.05Fe0.95 Co0.05 O3纳米粉末。用X射线衍射仪(XRD)和扫描电子显微镜(SEM)测量分析了其结构和形貌,结果表明样品仍为钙钛矿菱方结构。样品Fe2p的X射线吸收谱(XAS)表明样品中Fe的价态处于Fe2+和Fe3+的混合态。利用振动样品磁强计(VSM)测量样品的磁性特征,结果表明样品具有完整闭合的磁滞回线,表现出室温的铁磁性,相比BiFeO3样品磁性得到明显增强。     

Ferromagnetic Resonance Study of Fe/Cu Multilayer Thin Film

Fe/Cu/Fe multilayer thin film was grown on Si (100) substrate by using magnetron sputtering technique at room temperature. Dynamic and static magnetisations of the film have been investigated using ferromagnetic resonance (FMR) and vibrating sample magnetometer (VSM) techniques in the temperature range of 10–300 K. From the room-temperature in-plane FMR measurements, a growth-induced uniaxial magnetic anisotropy was observed. Out-of-plane FMR measurements exhibited a large magnetic anisotropy due to a large saturation magnetisation of Fe. A computer code was written to simulate the experimental FMR data and to obtain the magnetic parameters of the Fe/Cu/Fe multilayer thin film. g value, effective magnetisation, uniaxial anisotropy field and perpendicular anisotropy constant from the fitting of the angular dependence of the resonance field at both the in-plane and out-of plane geometries were determined. The exchange bias effect was observed from the low-temperature VSM measurements. The saturation magnetisation and coercive field decrease with increasing temperature due to the increase of the thermal fluctuations.     

Enhancement of Faraday rotation in 3D/Bi:YIG/1D photonic heterostructures

We suggest a new design of magnetophotonic crystals. Microcavity-type magnetic photonic heterostructures exhibiting enhanced magneto-optical Faraday rotation have been fabricated. Such a heterostructure comprises an opal film (3D photonic crystals), a bismuth substituted iron garnet (Bi:YIG) spacer film acting as the defect layer, and a dielectric multilayer (1D photonic crystal). Localized mode was shown to exist in the photonic band gap as a result of resonant interference in heterostructures. The observed enhancement of Faraday rotation was more than three times as compared with that of the Bi:YIG constituent. We have also found that the heterostructures exhibit an unusual polarization-dependent response.     

Lead substitution in yttrium iron garnet

Polycrystalline and single crystal thin films of lead substituted Y₃Fe₅O₁₂ (Pb-YIG) have been prepared. The lattice parameter (a_o) has been measured as a function of composition and the relationship $\text{Δ}\text{a}{}_{\mathrm{o}}\text{= 0.040}\text{x}\text{A}\text{?}$ and 0.060x Å for polycrystalline and epitaxially grown films, respectively has been deduced (x is the number of lead atoms per formula unit). From the behaviour of polycrystalline Pb-YIG upon annealing we conclude that the thin films have a non-equilibrium composition. The hyperfine fields at the 57Fe nuclei measured by the Mössbauer effect are essentially the same as those of YIG. The Mössbauer spectra of the epitaxially grown films demonstrate that a growth-induced uniaxial magnetic anisotropy is present.     

Quantum Theory of Spin Wave Gap in Ultrathin Magnetic Films

A simple quantum model is presented for the spin wave energy gap in single-layer and thin magnetic films that include both the magnetic out-of-plane and in-plane anisotropies. The films are assumed to be under the influence of the out-of-plane direction of the applied magnetic field at zero temperature. The calculated equations present a nonzero spin wave gap at zero magnetic field which is strongly affected by anisotropies. The effects of the film thickness and the role of the applied field are also examined. We discuss the results in connection with experimental data reported for nanocrystalline amorphous CoFeB films with growth-induced anisotropy.     

Fatigue-less relaxor ferroelectric thin films with high energy storage density via defect engineer

Thin film capacitors with excellent energy storage performances,thermal stability and fatigue endurance are strongly desired in modern electrical and electronic industry.Herein,we design and prepare lead-free 0.7Sr0.7Bi0.2TiO3-0.3BiFeO3-x％Mn(x=0,0.5,1.5,2,3)thin films via sol-gel method.Mn ions of divalent valence combine with oxygen vacancies,forming defect complex,which results in marked decline in leakage current and obvious enhancement in breakdown strength.A high energy storage density～47.6 J cm-3 and good efficiency～65.68％are simultaneously achieved in 2％Mn doped 0.7Sr0.7Bi0.2TiO3-0.3BiFeO3 thin film capacitor.Moreover,the 2％Mn-doped thin film exhibits excellent thermal stability in wide operating temperature range(35-115℃)and strong fatigue endurance behaviors after 108 cycles.The above results demonstrate that 2％Mn-doped 0.7Sr0.7Bi0.2TiO3-0.3BiFeO3 thin film capacitor with superior energy storage performances is a potential candidate for electrostatic energy storage.     

钇铁石榴石薄膜材料的光吸收谱及Bi,Al掺入对谱的影响研究

采用单离子晶场跃迁模型，拟合出钇铁石榴石（ＹＩＧ）薄膜材料的光吸收谱，与实验谱吻合得较好。从实验和理论上分析了（ＢＩＡＩ）ＹＩＧ 薄膜材料的光吸收谱，结果表明，Ａｌ３＋离子的作用如同稀释剂一样，减小了光吸收，Ｂｉ３＋离子由于其强的自旋轨道耦合作用，增大了跃迁振子强度和跃迁线宽，从而增大了光吸收损耗，在此基础上所作的（ＢｉＡｌ）ＹＩＧ的理论谱与实验谱符合得较好。