共查询到19条相似文献,搜索用时 109 毫秒
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采用溶胶凝胶法制备了Ti1-xCrxO2±δ体系系列样品.利用扫描电子显微镜(SEM),X射线光电子能谱(XPS),粉末X射线衍射分析(XRD)方法研究了Ti1-xCrxO2±δ系列样品的颗粒尺寸、形貌、组分化学态、相关系和固溶区范围;并利用超导量子干涉磁强计对样品的磁性能进行了研究.采用Rietveld结构精修的方法研究了Cr的不同掺杂量对TiO2晶体结构的影响,研究表明,1000℃烧结的样品的固溶区范围是x=0—0.03,为金红石单相;随着Cr掺杂量的增加,金红石相晶胞参数规律性地减小;当x>0.03,为金红石相和CrO2相两相共存.综合XRD和磁性测量结果,500℃烧结的样品的固溶区范围是x=0—0.02,为锐钛矿单相;随着Cr掺杂量的增加,锐钛矿相晶胞参数规律性地减小;当x≥0.04,为锐钛矿相和绿铬矿相(Cr2O3)两相共存.XPS实验结果表明,500℃和1000℃退火的样品中Cr都是以Cr+3和Cr+6两种化学态存在,1000℃烧结的样品中可能有更多的Cr3+转化为Cr6+.根据M-H和M-T曲线的测试结果发现,本文500℃烧结的Ti1-xCrxO2±δ体系样品当x=0—0.02时,为室温铁磁性.当x≥0.04时,由铁磁相和顺磁相所组成,在低温下有较强的铁磁性;室温下主要是顺磁相,铁磁相只占据很小的体积分数.
关键词:
1-xCrxO2±δ体系')" href="#">Ti1-xCrxO2±δ体系
相关系
固溶区
磁性能 相似文献
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利用固相反应烧结技术制备La0.1Bi0.9-xEuxFeO3系列化合物. 利用X射线粉末衍射进行物相鉴定和结构分析,确定了材料的相关系:x≤0.05,材料为R3c结构相;0.08≤x≤0.12,材料为赝R3c结构相;x≥0.15是Pbnm相,其中0.15≤x≤0.20区域Pbnm相存在畸变. 磁测量结果表明,材料具有弱铁磁性,对于x≤0.20材料,磁矩在x=0.12成分存在极值. 利用阻抗分析仪测量了室温介电常数随成分的变化关系.讨论了材料的结构与弱铁磁性和室温介电常数间的关系.
关键词:
0.1Bi0.9-xEuxFeO3')" href="#">La0.1Bi0.9-xEuxFeO3
X射线衍射
磁性
介电常数 相似文献
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针对NiS2-xSex系统在x=1.00附近发生的反铁磁量子相变,制备了一系列NiS2-xSex(x=0.96, 0.98, 1.00, 1.05, 1.10和1.20)多晶样品,对其结构、磁性质和电阻率进行了系统的观测.结果发现:样品磁化率-温度关系呈现典型的强关联电子系统特征;与铜氧化物超导体相类似,它们的电阻率-温度关系在很宽的温
关键词:
量子相变
反铁磁自旋涨落
2-xSex体系')" href="#">NiS2-xSex体系 相似文献
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采用了传统的固相烧结工艺,制备了不同Zr和Hf掺杂量的SrBi4Ti4-xZrxO15(x=000,003, 006,010,020)和SrBi4Ti4-xHfxO15(x=000,0005, 0015,0030,0060)的陶瓷
关键词:
4Ti4-xZrxO15')" href="#">SrBi4Ti4-xZrxO15
4Ti4-xHfxO15')" href="#">SrBi4Ti4-xHfxO15
铁电性能
介电性能 相似文献
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采用基于密度泛函理论和平面波赝势技术的CASTEP程序对Zn1-xBexO合金电子结构和光学性质进行了计算.当0≤x≤1,其带隙从0.963 eV变化到7.293 eV.分析了晶格畸变和能带间排斥效应对带隙的影响.当Be含量x=0.125,0.25,0.375,0.5,0.625,0.75时,a/b轴压应变控制着带隙变化;当x=0.875,1时,c轴压应变控制着带隙变化.能带间的p-d排斥影响价带顶变动,Γ1v与Γ1c之间排斥影响导带底变动.这些能带间的排斥效应被用来分析Zn1-xBexO带隙变动.另外,也分析了Zn1-xBexO介电函数虚部ε2.
关键词:
带结构
光学性质
应变
排斥 相似文献
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Solid state mechanical activation method was applied for surface modification of LiMn2O4 by Li-M-O (M = Co, Co+Ni) and for preparation of composite mixed LiMn2O4/LiCoO2 cathode materials. Pristine LiMn2O4 was ground with correspondent precursors (for coating) or with LiCoO2 (for composites) in high-energy planetary mills and then heat treated at different temperatures. As prepared materials were studied by XRD, 7Li MAS NMR spectroscopy, XPS, SEM and electrochemical cycling. It has been shown that both ‘core-shell’ and composite materials prepared by mechanochemical process are characterized by superior electrochemical performance due to smaller particles and chemical modification of LiMn2O4. 相似文献
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用乙二醇为溶剂,用三氯化铁、二氯化钴和醋酸铵为起始反应试剂,通过溶剂热反应首次合成了纳米结构CoxFe3-xO4多孔微球.用X射线衍射仪(XRD)、透射电子显微镜(TEM)和扫描电子显微镜(SEM)表征样品的结构和形貌,结果表明,所制备的单分散CoxFe3-xO4多孔微球为立方多晶结构,其直径约300 nm,是由约30
关键词:
xFe3-xO4')" href="#">CoxFe3-xO4
多孔微球
磁性
交换偏置效应 相似文献
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Fluorine substituted Li1.27Cr0.2Mn0.53O2 electrode, prepared by sol–gel method, was investigated in the present work. Thermal analysis was done on this cathode material
and found to be thermally stable with a loss of weight near 300 °C. Influence of fluorine substitution on the structural and
electrochemical properties of the Li1.27Cr0.2Mn0.53O2 electrode was studied by X-ray diffraction (XRD) and field emission scanning electron microscope. XRD pattern of the fluorine-doped
Li1.27Cr0.2Mn0.53O2 cathode material quenched at 900 °C indicates a phase pure material. The charge–discharge profile of the prepared cathode
material showed that the fluorine substitution for oxygen in the cathode material resulted in improved capacity retention.
Paper presented at the Third International Conference on Ionic Devices (ICID 2006), Chennai, Tamilnadu, India, December 7–9,
2006. 相似文献
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W. Sukkabot 《哲学杂志》2020,100(7):917-926
ABSTRACTUsing spin-polarised generalised gradient approximation (GGA?+?U), I successfully investigate the electronic properties of the monoclinic NaMnO2 doped with Cr, Fe and V atom to enhance the electrochemical performance. The expansion of volumes is induced by the dopants. The lowest conduction band and highest valence band are mostly from d orbital of Mn atom and transition-metal dopants which are responsible for the electronic conductivity. Na(Mn, Fe)O2 is a semiconductor with the reduced band gap. Cr and V doping in NaMnO2 compound reveal the half-metallic performance. The enhancement of the insertion potentials is induced by transition-metal dopants. The electronic conductivity of NaMnO2 cathode material is improved by Cr-doping scheme. Finally, this research presents the new horizons for the expenditure of transition-metal doping for designing and improving the NaMnO2 cathode materials in Na-ion rechargeable batteries. 相似文献
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采用机械合金化制备了n型(Bi1-xAgx)2(Te1-ySey)3合金粉体,对其进行XRD分析表明Bi,Te,Ag,Se单质粉末,经2h球磨后实现了合金化;SEM分析表明随着机械合金化时间延长粉体颗粒变得均匀、细小,颗粒尺寸在微米至亚微米数量级.采用放电等离子烧结制备了块体样品,研究了合金成分和球磨时间对热电性能的影响.结果表明材料的热电性能与掺杂元素有密切关系,Ag有利于提高功率因子和降低晶格热导率,球磨10h的(Bi0.99Ag0.01)2(Te0.96Se0.04)3合金粉末的烧结块体具有最大的功率因子和最低的晶格热导率,并在323K取得最高ZT值0.52.
关键词:
1-xAgx)2(Te1-ySey)3合金')" href="#">(Bi1-xAgx)2(Te1-ySey)3合金
机械合金化
放电等离子烧结
热电性能 相似文献
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采用熔体旋甩结合放电等离子烧结(MS-SPS)技术制备了单相n型四元(Bi0.85Sb0.15)2(Te1-xSex)3(x=0.15,0.17,0.19,0.21)化合物,并对所得样品的微结构和热电传输性能进行了系统研究.样品自由断裂面的场发射扫描电子显微镜及抛光面的背散射电子成分分析表明:块体材料晶粒细小,晶粒排列紧密,成分分布均匀且相结构单一,样品中存在大量10—100nm的层状结构.随着Se含量x的增加,样品的电导率和热导率逐渐增加,而Seebeck系数逐渐降低.相比商业应用的区熔材料,MS-SPS方法合成的高Se组成的样品均在425K后表现出更高的ZT值,其中(Bi0.85Sb0.15)2(Te0.83Se0.17)3样品具有最高的ZT值,在360K可达到0.96,并在320—500K均保持较高的ZT值,500K时其ZT值相比区熔材料提高了48%.此外,通过调节Se的含量,可以有效地调控材料的ZT峰值出现的温度段,这对多级或梯度热电器件的制备具有重要意义. 相似文献
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通过溶胶-凝胶旋涂方法结合后退火工艺在Si(100)上制备了不同厚度的La0.9Sr0.1MnO3(LSMO)薄膜,利用X射线衍射(XRD)和共焦显微拉曼散射(Raman)研究了LSMO/Si(100)薄膜的微结构.研究结果表明90 nm厚的LSMO薄膜具有正交相结构,当厚度大于150 nm时,薄膜具有菱方相结构. 150 nm厚的薄膜的Raman图谱中,490 cm-1和602 cm-1正交结构
关键词:
薄膜
1-xSrxMnO3')" href="#">La1-xSrxMnO3
共焦显微拉曼
微结构 相似文献
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Ch.V. Subba Reddy Edwin H. Walker Jr. S.A. Wicker Sr. Quinton L. Williams Rajamohan R. Kalluru 《Current Applied Physics》2009,9(6):1195-1198
Vanadium dioxide nanorods were synthesized through a hydrothermal reaction from V2O5 xerogel, poly(vinyl pyrrolidone) (PVP) and lithium perchlorate (LiClO4). The prepared samples were characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy (SEM), transmission electron microscopy (TEM) and electrochemical discharge–charge cycling in lithium battery. SEM images reveal the nanorods to have dimensions on the order of 1–3 μm in length and 10–50 nm in diameter. The measured initial discharge capacity of the lithium battery with a cathode made of VO2 (B) nanorods was 152 mA h/g. 相似文献