合金成分对Pr2Fe14B/α-Fe纳米复合永磁材料组织与磁性的影响

用XRD、TEM、Mossbauer谱和VSM等实验方法,研究了不同Pr含量、B含量和Cu含量的Pr2Fe14B/α Fe型纳米复合快淬带的显微结构与磁性。结果表明:PrxFe94-xB6合金在x=8(α Fe体积分数约30%)时磁性能最佳,Br=1.29T,Hci=461.7kA/m,(BH)max=165.6kJ/m3;Pr8.5(Fe0.8Co0.2)86.5-xCuxB5合金在x=0.5时获得最佳的磁性能;随B含量增加,富B相在晶界分布,Pr8Fe92-xBx交换耦合减弱,磁性能单调下降。     

Nd_x(Fe_(0.933)B_(0.067))100-x纳米合金的磁性

台湾清华大学研究了Ndx(Fe0.933B0.067)100-x合金的磁性．将合金成分Fe／B比率固定在14，变化Nd含量、试验合金Ndx(Fe0.933B0.067)100-x（x=3，4，5，6，8和11）用单辊快淬法制备，辊速40fn／s，M气保护．热处理采用加热速度大于600℃／min的快速退火工艺．实验结果表明，热处理后Ndx(Fe0.933B0.067)100-x内禀矫顽力从X=3的27.2hA／m升到X=11的725．6bA/m，剩磁风从x=3的1．44gT降到x=11的1．04Th，科磁比在0．71～0．78及最大磁能积(BH)max为150.4kJ/m3．平均形核场从：x=3时80kA／m，x—4.5时200hA／m,x—6时320hA／m，x—8时40…     

(Fe1-xCox)84Zr3.5Nb3.5B8Cu1非晶合金的高温和低温磁性

用磁天平（MB）及提拉样品磁强计（ESM）研究了（Fe1-xCox）84Zr3.5Nb3.5B8Cu1（x＝0－0．8）非晶合金高温与低温磁性的变化，结果表明，该非晶态合金加热到800－900℃后，除x＝0．8的合金外，，合金的室温饱和磁化强度均比淬态有所提高；X射线衍射的结果表明，x＝0，0．2，0．4，0．6的合金中析出单一的a-Fe（Co）相，x＝0．8的合金中析出Co3B，FeB相，当x＝1．0时合金中析出单一的fccCo相。该非晶合金在1．5K时的饱和磁化强度σs随Co含量的增加先增大，当x＝0．2时达到最大值，然后随着x的增大，合金的σs逐渐下降。     

PrFeBZr纳米复合永磁材料的研究

用振动样品磁强计(VSM)研究了PrxFe94.3-xB5.7Zr1(x=9．4，9．8，10．2，10．6，11，11．4)系列快淬带在淬速V=22m／s的淬态和真空退火态(670℃)样品的磁性能和磁滞回线的变化情况，发现该系列合金在淬速V=20m／s下样品S2(Pr11Fe83.3B5.7Zr1)取得了最好的磁性能为：Jc=0．76T，Hc=977．3kA／m，(BH)max=98．8kJ／m^3；最佳快淬和晶化热处理都可以使软磁相与硬磁相耦合。     

各向异性Sm2Fe17Nx磁粉的结构与磁性能

研究了Sm2Fe12Nx磁粉的制备、结构与磁性能，发现Sm—Fe合金的铸态组织主要由Sm2Fe17、α—Fe和SmFe2三种物相组成，而经过1000℃均匀化退火48h处理后富Sm的SmFe2相基本消失，α—Fe相的品粒变小，数量减少。随着氯化时间延长到10h，Sm2Fe17相始终未改变其Th2Zn17型结构，而氯原子浓度增加，所有的X射线衍射峰均向小角度方向移动；但在氮化时间超过10h后，物相要发生变化，导致磁性能降低。在500℃下流动的氮气氛中对Sm2Fe17合金氮化2、4、6、10h未加磁场取向的磁粉中，以氮化6h的磁性能值最高：σr＝35．44Am^2/kg(emu／g)，Hc＝58kA／m(729．03Oe)。磁性能值偏低的原因与测量磁场较低，粒径分布不均匀及粒径较大有关。     

添加Y对快淬Pr2Fe14B薄带磁性能的影响

利用溶体快淬法研究了Y的添加对Pr2Fe14B合金磁性能的影响。结果表明：薄带Pr2Fe14B的最佳铜辊转速为30 m/s。Pr12-xYxFe84B6 (x=0~12)快淬薄带主要由各向异性、纳米结构的R2Fe14B相组成,其矫顽力、剩磁,剩磁比和饱和磁化强度均随着Y含量的增加而减少。Pr12-xYxFe84B6快淬薄带的磁晶各向异性随着Y替代量的增加而降低,导致矫顽力逐渐减少,这是由于Y2Fe14B的磁晶各向异性低于Pr2Fe14B。然而,只要Y元素含量不超过4at%,Pr12-xYxFe84B6快淬薄带的退磁化曲线的方形度较好,晶粒间交换耦合作用也比较强。     

无Cu的Fe-Nb-B纳米软磁合金中B和Nb的作用

研究了B和Nb对Fe－Nb－B合金中纳米品和剩余非品基体的显微结构和内禀磁性的影响，并讨论了B和Nb的作用．用单辊熔体旅淬法制备Fe86－xNbxB14（X=0～8）合金．晶化行为和显微结构用差示扫描量热法和透射电镜研究，居里温度（Tc）和超精细场用热重力分析仪和57Fe穆斯堡尔诺测量．Fe86-xB14。（x=0～8）最初品化样品的品位尺寸，从x＝0～4的＞50nm减小到x＝5～8的＜20nm．x＝4～6时激活能明显增加而晶粒尺寸明显减小．由于成核的激活能通常高于核生长的激活能．激活能的增加对成核机制到完全结晶过程有重大贡献．当x—4～6时晶粒尺寸减…     

Nb元素对纳米晶（Nd，Pr）FeB／α-Fe复合永磁合金显微结构与磁性能的影响

添加Nb元素会使(Nd,Pr)FeB/α-Fe纳米晶复合永磁合金的平均晶粒尺寸显著减小.用AFM观察快淬(Nd,Pr)10.5Fe81.5-xNbxCo2B6(x(at%,下同)=0.0,0.5,1.0,1.5,2.0,2.5,3.0)合金条带自由表面的显微结构,晶粒平均直径从不含Nb的(Nd,Pr)10.5Fe81.5Co2B6合金的175 nm减小到含2 at%Nb的(Nd,Pr)10.5Fe79.5Nb2Co2B6合金的68 nm,晶粒平均直径细化了61%;当Nb超过2 at%后,Nb含量的增加对晶粒的细化作用明显减弱,含3 at%Nb的合金平均晶粒直径为63 nm,比含2 at%Nb仅细化了7.3%.含2 at%Nb的(Nd,Pr)10.5Fe79.5Nb2Co2B6合金,粘结磁体磁性能达到最佳值,Bτ=0.665 T,Hci=748 kA·m-1,(BH)m=73 kJ·m-3.Nb元素含量在2 at%Nb以下时,合金晶粒粗大,磁性能较低;超过2 at%后,富集在晶界处的富Nb晶间相加厚,晶粒间的交换作用和剩磁增强效应减弱,合金的内禀矫顽力虽然增加,但剩磁Bτ和最大磁能积(BH)m降低.     

Nb和Zr对（Nd，Pr）2Fe14B／α-Fe磁体晶化行为和磁性能的影响

采用熔体快淬及晶化退火工艺制备了纳米双相（Nd，Pr）2Fe14B／α-Fe型磁体，研究了Nb和Zr的添加对磁体磁性能、微观结构和晶化行为的影响。结果表明：添加Nb和Zr可提高α—Fe相的晶化温度，抑制α—Fe的析出和长大，避免亚稳相的形成，从而提高硬磁相的体积百分比。Nb和Zr复合添加能细化晶粒，增强硬磁相和软磁相问的交换耦合作用，显著提高纳米晶双相永磁合金的磁性能。合金（Nd，Pr）2Fe14B／α-Fe经过最佳热处理后，磁性能达到Br=1．10T，iHc=534．2kA／m，（BH）max=143．6kJ／m^3。     

Fe64-xCoxNd7B25Nb4（x=0～40）块体合金的晶化过程和磁性能研究

采用铜模吸铸法制备了Fe64-xCoxNd7B25Nb4(x=0～40)块体合金,利用X射线衍射仪(XRD)、差示扫描量热仪(DSC)和振动样品磁强计(VSM)研究了该体系合金的非晶形成能力、晶化过程和磁性能。结果表明:Fe64-xCoxNd7B25Nb4(x=0～40)块体合金具有良好的非晶形成能力。在Co含量为0at%～40at%范围内,合金基本为非晶态。该系合金铸态时为软磁性,晶化处理后则表现为硬磁性。随着Co含量的不同,合金的晶化行为和晶化后的产物及对应的磁性能均有明显的变化。不含Co元素时,合金发生两级晶化反应;晶化过程中出现了亚稳相Fe23B6,随着退火温度的升高,Fe23B6分解为Fe3B和α-Fe相。添加Co元素后,合金只发生一级晶化反应。Co含量为20at%的合金在1 003 K退火后,内禀矫顽力高达1 164 kA/m。     

X-ray diffraction study of Ba0.985Na0.015Ti0.985Nb0.015O3, Ba0.6Na0.4Ti0.6Nb0.4O3 and Ba0.3Na0.7Ti0.3Nb0.7O3 compositions

The Ba_0.985Na_0.015Ti_0.985Nb_0.015O₃, Ba_0.6Na_0.4Ti_0.6Nb_0.4O₃ and Ba_0.3Na_0.7Ti_0.3Nb_0.7O₃ compositions of the (1 − x) BaTiO₃–xNaNbO₃ (BTNNx) system have been studied by X-ray diffraction and by measurements of dielectric properties. The specimens with composition BTNN (x = 0.015, 0.40 and 0.70) have been refined by the JANA program from X-ray powder diffraction data. Ceramic samples with composition (1 − x) BaTiO₃ + xNaNbO₃ (where x = 0.015, 0.40 and 0.70) were prepared by calcinations from appropriate mixture of BaCO₃, TiO₂, Na₂CO₃ and Nb₂O₅. The calcined powder was sintered at temperature range 1200–1400 °C. As the composition x increased from 0.015 (and 0.70), the ferroelectric ceramics (x = 0.015, FE) with tetragonal phase changed to the ferroelectric relaxors (RFE, x = 0.40). RFE ceramics showed a peculiar diffuse phase transition and dielectric relaxation at the low temperature (down to 180 K) due to a frustration between RFE and FE state. These ceramics present the classical ferroelectric character when 0 ≤ x < 0.075 and 0.55 < x ≤ 1 and relaxor character when 0.075 ≤ x ≤ 0.55.     

Magnetic, electrical and plastic properties of Fe76Nb2Si13B9, Fe75Ag1Nb2Si13B9 and Fe75Cu1Nb2Si13B9 amorphous alloys

Influence of 1 h annealing in vacuum on magnetic, electrical and plastic properties of Fe₇₆Nb₂Si₁₃B₉, Fe₇₅Ag₁Nb₂Si₁₃B₉ and Fe₇₅Cu₁Nb₂Si₁₃B₉ melt spun ribbons were carefully investigated. It was shown that in all cases soft magnetic properties can be significantly enhanced by applying 1-h annealing at characteristic temperatures T_op. This optimization annealing causes that permeability increases more than 15-times and magnetic losses (tangent of loss angle) achieves a minimum in relation to the as quenched state. Using structural examinations (X-ray and HRTEM) it was shown that for the Fe₇₅Cu₁Nb₂Si₁₃B₉ alloy the optimized microstructure corresponds to a nanocrystalline αFe(Si) phase whereas in other alloys to a relaxed amorphous phase free of iron nanograins. As a consequence of this fact the Fe₇₆Nb₂Si₁₃B₉ and Fe₇₅Ag₁Nb₂Si₁₃B₉ alloys show higher plasticity in comparison to the nanocrystalline Fe₇₅Cu₁Nb₂Si₁₃B₉ alloy. Temperatures of the first stage of crystallization, and related diffusion parameters were determined using measurements of resistivity versus temperature with different heating rates.     

Fe2+-Ni2+-NH3-NH4+-C2O42-H2O体系的沉淀配合平衡热力学

针对草酸盐配位共沉淀热分解还原法制备超细铁镍合金粉过程中Fe2+-Ni2+-NH3-NH4+-C2O42--H2O体系的溶液平衡建立热力学分析模型,并根据模型进行相关计算,揭示反应体系中各物质随pH值、氨及草酸浓度的变化关系。结果表明:溶液中的Fe主要以[Fe(C2O4)n]2 2n络合物形式存在,而铁氨络合物含量很低。当氨含量较低时,溶液中的Ni主要以[Ni(C2O4)n]2 2n存在;氨含量较高时,在酸性条件下,溶液中的Ni主要以[Ni(C2O4)n]2 2n存在,在碱性条件下,则主要以[Ni(NH3)n]2+存在。低pH值下,Ni的沉淀率较Fe的高,而高pH值下,Ni的沉淀率则较Fe的低。     

Al2O3-Sm2O3-CeO2电解质的性能（英文）

采用溶胶-凝胶法和低温燃烧技术制备Ce1-xSmxO2（x=0,0.1,0.2,0.3）和掺杂Sm和（2%-8%）Al2O3的二氧化铈;研究其合成、结构、致密化、导电性和热膨胀等性能,并利用XRD研究其结构和相组成。结果表明,于1300°C烧结球团,获得致密的陶瓷,于1250°C在Ce0.8Sm0.2O0.2中加入2%和4%的Al2O3以促进烧结。利用扫描电子显微镜观察烧结后球团的表面形貌,使用双探针交流阻抗谱研究总离子电导率。     

Synthesis and electrochemical properties of LiNi0.4Mn1.5Cr0.1O4 and Li4Ti5O12

Spinel compound LiNi_0.4Mn_1.5Cr_0.1O₄ (LNMCO) and Li₄Ti₅O₁₂ (LTO) were synthesized by the sol-gel method and the solid-state method, respectively. The particle sizes of the products LiNi_0.4Mn_1.5Cr_0.1O₄ and Li₄Ti₅O₁₂ were 0.5 to 2 um and 0.5 to 0.8 um, respectively. All samples exhibited excellent electrochemical properties. A LiNi_0.4Mn_1.5Cr_0.1O₄/Li₄Ti₅O₁₂ (LNMCO/LTO) cell was fabricated and was demonstrated to exhibit good electrochemical properties at the high current rate of 1 C. When the specific capacity was determined based on the mass of the LNMCO cathode, the LNMCO/LTO cell delivered 125 mAh g⁻¹ at 1 C and 77 mAh g⁻¹ at 5 C. The capacity retentions after 30 cycles were 94.4 % and 83.1 %, respectively.     

Sinterability and dielectric properties of Ba0.55Sr0.4Ca0.05TiO3-CaTiSiO5-Mg2TiO4 composite ceramics

The composite ceramics of Ba_0.55Sr_0.4Ca_0.05TiO₃-CaTiSiO₅-Mg₂TiO₄ (BSCT-CTS-MT) were prepared by the conventional solid-state route. The sintering performance, phase structures, morphologies, and dielectric properties of the composite ceramics were investigated. The BSCT-CTS-MT ceramics were sintered at 1100 °C and possessed dense microstructure. The dielectric constant was tailored from 1196 to 141 as the amount of Mg₂TiO₄ increased from 0 to 50 wt%. The dielectric constant and dielectric loss of 40 wt% Ba_0.55Sr_0.4Ca_0.05TiO₃-10 wt% CaTiSiO₅-50 wt% Mg₂TiO₄ was 141 and 0.0020, respectively, and the tunability was 8.64% under a DC electric field of 8.0 kV/cm. The Curie peaks were broadened and depressed after the addition of CaTiSiO₅. The optimistic dielectric properties made it a promising candidate for the application of tunable capacitors and phase shifters.     

Thermodynamics and phase diagrams in the binary systems Na2O-SiO2, Na2O-GeO2, Na2O-B2O3, Li2O-B2O3, CaO-B2O3, SrO-B2O3, and BaO-B2O3

We applied our model to the enthalpy of mixing data of the binary systems Na₂O-SiO₂, Na₂O-GeO₂, Na₂O-B₂O₃, Li₂O-B₂O₃, CaO-B₂O₃, SrO-B₂O₃, and BaO-B₂O₃. The most stable composition in the liquid, that is where the enthalpy of mixing is most negative, is with a metal-oxygen ratio of 4 to 3, for monovalent metals (Na and Li) and 3 to 4 for divalent metals (Ba and Ca) in liquid silicates or borates. The same applies to the CaO-SiO₂, CaO-Al₂O₃, PbO-B₂O₃, PbO-SiO₂, ZnO-B₂O₃, and ZnO-SiO₂ systems. The oxygen to metal ratio, its constant value in various types of systems, reflects and describes the structure of the liquid. Using the analyzed enthalpies of mixing data and the available phase diagrams, we calculated the enthalpies of formation of the various binary compounds. The results are in excellent agreement with data in the literature that were obtained from direct solid-solid calorimetry.     

Phase transition and piezoelectric properties of K0.48Na0.52NbO3-LiTa0.5Nb0.5O3-NaNbO3 lead-free ceramics

Plate-like NaNbO₃ (NN) particles were used as the raw material to fabricate (1 − x)[0.93 K_0.48Na_0.52Nb O₃-0.07Li(Ta_0.5Nb_0.5)O₃]-xNaNbO₃ lead-free piezoelectric ceramics using a conventional ceramic process. The effects of NN on the crystal structure and piezoelectric properties of the ceramics were investigated. The results of X-ray diffraction suggest that the perovskite phase coexists with the K₃Li₂Nb₅O₁₅ phase, and the tilting of the oxygen octahedron is probably responsible for the evolution of the tungsten-bronze-typed K₃Li₂Nb₅O₁₅ phase. The Curie temperature (T_C) is shifted to lower temperature with increasing NN content. (1 − x)[0.93 K_0.48Na_0.52NbO₃-0.07Li(Ta_0.5Nb_0.5)O₃]-xNaNbO₃ ceramics show obvious dielectric relaxor characteristics for x > 0.03, and the relaxor behavior of ceramics is strengthened by increasing NN content. Both the electromechanical coupling factor (k_p) and the piezoelectric constant (d₃₃) decrease with increasing amounts of NN. 0.01-0.03 mol of plate-like NaNbO₃ in 0.93 K_0.48Na_0.52NbO₃-0.07Li(Ta_0.5Nb_0.5)O₃ gives the optimum content for preparing textured ceramics by the RTGG method.