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1.
用磁控溅射方法制备了系列 (Fe0 .86 Zr0 .0 33Nb0 .0 33B0 .0 6 8Cu0 .0 1 ) x(Al2 O3) 1 -x颗粒膜样品 ,体积百分比x从 0 .3 3~ 0 .63 ,样品厚度约为10 0nm。室温下在Fe0 .86 Zr0 .0 33Nb0 .0 33B0 .0 6 8Cu0 .0 1 体积百分比x =0 .43时得到 17.5 μΩ·cm的最大饱和霍耳电阻率 ,比纯铁磁金属提高了 3~ 4个量级。对其磁性和微结构进行了研究 ,样品霍耳电阻率随外场的变化曲线 ρxy~H与磁场平行于膜面时的磁化曲线M~H有相似性 ,说明霍尔电阻率 ρxy与磁化强度M相关。样品电阻率 ρxx随金属体积百分比x的减小而增加 ,在x =0 .43附近发生突变 ,从金属导电变为绝缘体。根据微结构和输运性质对可能的机制进行了探讨  相似文献   

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The room temperature creep behaviors of Mg61Cu28Gd11 and(Mg61Cu28Gd11)99.5Sb0.5 bulk metallic glasses(BMGs) were revealed by means of nanoindentation technique.The creep mechanism was explored by characterization of creep rate sensitivity,creep compliance and retardation spectra.The results showed that the experimental creep curves could be well described by a generalized Kelvin model.The low creep rate sensitivity of both Mg-based BMGs indicated that their room temperature creep was dominated by localized shear flow.In addition,the(Mg61Cu28Gd11)99.5Sb0.5 glassy alloy exhibited lower creep rate sensitivity,creep compliance and milder retardation peak,indicating its higher creep-resistance and less relaxed state.Furthermore,the creep retardation spectrum consisted of two relatively separated peaks with the well defined characteristic relaxation times.  相似文献   

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In contrast to the conclusion of W. D. Hitt's (see record 1969-16600-001) analysis, a hermeneutic view of behaviorism and phenomenology suggests that man is neither of these models but is the relation between them. Work toward such a comprehensive model has been done by M. Merleau-Ponty (1963). (PsycINFO Database Record (c) 2010 APA, all rights reserved)  相似文献   

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为了提高La-Mg-Ni基贮氢合金的荷电保持率,本文研究了La/Nd比的变化对La-Mg-Ni基贮氢合金自放电性能的影响。随着Nd替代La量的增加,(LaxNdy)0.9Mg0.10Ni3.09Mn0.12Co0.60Al0.13(x/y=5,4,3,2,1)合金的荷电保持率先增大后减小,当x/y=4时,其荷电保持率达到最大值80.8%(318 K)。合金电极贮存后,FESEM-EDS和XRD分析表明,合金颗粒表面形成了Mg(OH)2和Nd(OH)3。P-C-T曲线和Tafel极化测试表明,随着Nd含量的增加,金属氢化物的稳定性呈现先增加后降低和腐蚀电流先减小后增大的规律。  相似文献   

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Magnetocaloric effect and magnetic properties of La0.9Ce0.1(Fe0.99Mn0.01)11.6Si1.4 and its hydride La0.9Ce0.1(Fe0.99Mn0.01)11.6Si1.4H1.6 were investigated. The Curie temperature of La0.9Ce0.1(Fe0.99Mn0.01)11.6Si1.4 was increased by hydrogen absorption. XRD patterns showed that the structure of La0.9Ce0.1(Fe0.99Mn0.01)11.6Si1.4H1.6 remained NaZn13-type. The Curie temperature (TC) of the sample was increased from 174 K to 331 K. The homogeneity of the hydrogen absorption for La0.9Ce0.1(Fe0.99Mn0.01)11.6Si1.4H1.6 was proven very well by the random measurement of DSC. The magnetic entropy △SM of La0.9Ce0.1(Fe0.99Mn0.01)11.6Si1.4H1.6 had peak at 326 K. The peak value of-△SM-was 12.3 and 7.8 J/(kg.K) under magnetic field change of 0-2 T and 0-1 T,respectively,which was comparable with Gd5Si2Ge2. The negative slope and inflection point of the Arrott curve indicated that the first-order magnetic transition of La0.9Ce0.1(Fe0.99Mn0.01)11.6Si1.4 was reserved after hydrogen absorption.  相似文献   

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分别采用电热法(conventional synthesis,CS)和微波法(microwave synthesis,MS)合成Pb(Zr<,0.52>Ti<,0.48>)O<,3>(简称PZT)粉体,利用X射线衍射(XRD),扫描电镜(SEM)和激光粒度分析仪分别对粉体的相组成、形貌和粒度分布进行表征,并根据实验结果...  相似文献   

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使用电弧熔炼法制备了La1.1Fe11.4Si1.55Ge0.05合金。研究了用少量的Ge替代Si后,La1.1Fe11.4Si1.55Ge0.05合金的磁性和磁热效应。粉末X射线衍射结果表明:在1273K真空退火处理10d后,合金La1.1Fe11.4Si1.55Ge0.05主相为NaZn13型立方结构,存在微量的α-Fe相。热磁曲线M-T与Arrott曲线表明:在居里温度Tc=205K处发生由铁磁性(TTc)转变为顺磁性(TTc)的二级磁相变。在磁场变化0~1.5T下,根据等温磁化曲线通过Maxwell关系式计算得出最大磁熵变-ΔSmmax=9J.kg-.1K-1。Ge替代Si后该合金在其居里温度Tc处-ΔSm-T曲线半高宽增大,使合金的相对制冷能力RCP(S)有所提高。  相似文献   

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Lanthanide(     
《稀土》2000,21(2):12-15
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Nanoscaled SrAl12O19:Er3+ and SrAl12O19:Yb3+,Er3+ phosphors were synthesized by a combustion method.The emission intensities of every sample were compared by a new method with the emission of codoped Gd3+ ions as a reference.Compared with their bulk material prepared by the solid-state reaction method,a higher Er3+ quenching concentration,as high as 20%,was observed in the nanoscaled phosphors for both visible(VIS) and near infrared(NIR) emissions.The higher quenching concentration in both VIS and NIR regio...  相似文献   

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A series of Eu~(2+)doped and Eu~(2+)/Mn~(2+) co-doped Mg_(0.695)Si_(0.695)Al_(1.39)O_(3.65)N_(0.35)(MSAON) phosphors were synthesized by solid-state reaction at a lower temperature of 1500℃.The crystal morphology and structure of MSAON host were characterized by SEM,TEM and XRD.The quantum yield(QY) for Eu~(2+)doped MSAON phosphors was measured as high as 62%,indicating the excellent luminous efficiency.For the Eu~(2+)/Mn~(2+)co-doped MSAON phosphor,the photoluminescence spectrum and delay curves reveal the efficient energy transfer(ET) process from Eu2+to Mn~(2+)ions.Meanwhile,the corresponding energy transfer efficiency,critical distance and mechanism are discussed in detail.Temperature-dependent emission spectrum shows the thermal and color stabilities.The emission color of MSAON:Eu~(2+),Mn~(2+)phosphors could be tuned from blue through white to red via varying the concentration of Mn~(2+) ions.White-light-emitting diodes(WLEDs) were successfully fabricated by encapsulating the phosphors in nUV LED(365 nm) devices obtaining white light with color rendering index(CRI) as high as 87.7.The results reveal that the MSAON:Eu~(2+),Mn~(2+)phosphors could have potential application in the field of n-UV WLEDs.  相似文献   

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张安运 《稀土》2001,22(1):1-4
研究了1,2-双(1′-苯基-3′-甲基-5′-氧代吡唑-4′-基)乙二酮-[1,2](H  相似文献   

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二溴对甲基偶氮甲磺光度法同时测定钙和钡   总被引:1,自引:0,他引:1       下载免费PDF全文
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The structure and magnetic hysteresis properties of the cast Sm_(1-x)Zr_x(Fe_(0.92)Ti_(0.08))_(10)(x = 0-0.3)alloys and melt-spun ribbons prepared from them were studied.In the cast alloy with x0.2, a considerable amount of the eutectic phase is found in the SEM micrographs.Analysis of the temperature dependences of the magnetic susceptibility and XRD patterns allows amorphous state in the as-spun ribbons with x0.2 to be determined.The specific magnetization measured in a field of 17 kOe and remanence decrease with increasing annealing temperature from 800 to 900 ℃ and weakly depend on Zr concentration.The maximal value of coercivity Hc = 4.7 kOe is obtained on the ribbons with x = 0.2 after annealing at 850℃ for 10 min.After additional hydrogenation of the ribbons,both the coercivity and remanence increase by 54% and 7%,respectively.  相似文献   

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We have designed a synthetic cornea that has a transparent hydrogel optic and a porous skirt. The device has been implanted in rabbit corneas. We have shown that keratocytes migrate into the device and deposit a complex extracellular matrix. The immediate response is detected in the surrounding stroma, and the secondary response is seen after cells have deposited a matrix in the disc. After implantation, a decrease in keratan sulfate accompanied by an increase in dermatan sulfate was detected in the surrounding tissue compared to the unwounded corneal stroma. The glycosaminoglycans in the disc resemble that of an injured stroma. The appearance of heparan sulfate and growth factors, bFGF and TGFbeta, was not detected until 6 weeks after implantation. The growth factors were detected at the interface between the device and the tissue and become more diffuse over time. Methods of controlled release in vivo were used to enhance the rate of fibroplasia and wound repair. While these were successful in the cornea itself, when combined with the synthetic cornea the response was magnified and the initial attempts yielded neovascularization and edema. Currently, efforts are being directed at controlling the release within the porous haptic so that fibroplasia is enhanced while minimizing an inflammatory response.  相似文献   

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