共查询到16条相似文献,搜索用时 171 毫秒
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用溶胶-凝胶法制备BiFe1-x Cox O3样品,用X射线衍射仪、扫描电镜、能谱分析对样品的结构、微观形貌、元素组成进行了表征,用微波矢量网络分析仪测试了样品在2~18GHz微波频率范围的复介电常数、复磁导率,并计算了损耗角正切及微波反射率。结果表明,当掺杂量x=0、x=0.1、x=0.2,煅烧温度800℃时,产物的主相为钙钛矿型BiFeO3,同时还有杂相Bi25FeO40,颗粒形貌为尺寸约1.5μm的立方形;Co的掺入有利于提高体系的微波吸收性能。当样品厚度为1.8mm,x=0.2时,吸收峰值为-26.5dB,带宽为2.08GHz,在高频段有良好的微波吸收,材料兼具介电损耗和磁损耗但介电损耗相对较强。 相似文献
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采用脉冲激光沉积的方法, 在Pt/Ti/SiO2/Si衬底上生长Bi5Ti3FeO15 (BTFO15)多铁性薄膜, 并对其结构、磁性、铁电性、铁电畴等进行了研究。通过X射线衍射、扫描电镜以及高角环形暗场像-扫描透射电镜测试, 结果表明, 薄膜具有高结晶度和完美层状晶格结构, 两层Bi原子层紧密堆积, 两层Bi2O2之间有三层Bi层和三层Ti(Fe)O6八面体层, 构成三明治结构; 在室温下的磁滞回线和电滞回线证实了弱铁磁性和铁电性的共存; 采用压电响应力显微镜研究了薄膜的畴结构, 在面内和面外分别施加±3 V和±10 V的电压, 观测到了畴反转。这些研究结果对理解多铁性材料的微观结构和宏观特性的相互调制有重要意义。 相似文献
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利用原子集团多重散射方法分析了表面吸附系统CH_3O/Cu(100)的氧原子K壳层近边X射线吸收精细结构(NEXAFS)谱。理论分析直观地显示了NENAFS谱中各特征峰的可能组成,特别是确证了在X射线垂直入射下的谱线中的宽峰主要是由衬底的背散射所引起,也支持了CH_3O分子是垂直吸附在Cu(100)表面的观点,其可能倾角范围不超过10°。 相似文献
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Bi2O3-Li2O玻璃的结构研究 总被引:2,自引:0,他引:2
用X射线光电子能谱和拉曼光谱方法研究了Bi2O3-Li2O系玻璃的结构.X射线光电子能谱显示Bi2O3-Li2O玻璃的O1s电子结合能非常低,甚至低于碱硅酸盐玻璃中断桥氧的O1s电子结合能,并且O1s电子结合能随着氧化锂含量的增加而增加.拉曼光谱显示随着氧化锂含量的增加,位于高波数的拉曼振动带朝着更高的方向移动并且强度增加,而位于低波数的拉曼振动带朝着更低的方向移动并且强度下降;这反映了此系玻璃结构中的铋氧多面体的变形程度随Li2O含量的增加而增加. 相似文献
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系统地研究了新型稀土-半导体-磁性金属所组成的RSn3-xCox(R=Nd,Sm;x=0~0.3)系列的制备、晶体结构以及磁性。研究表明:RSn3-xCox具有AuCu3型立方结构,空间群Pm3m,稀土原子占据1a晶位,Sn占据3c晶位,Co部分替代Sn占据3c晶位。点阵常数与晶胞体积常数随Co掺杂量的增加而减小。其磁性变化与Co含量密切相关,随着Co含量的增加,稀土半导体化合物中产生铁磁性相,在Sm-Sn-Co体系中SmSn2.8Co0.2呈现混合磁性、SmSn2.7Co0.3呈现铁磁性,这有别于纯RSn3系列的磁性(低温反铁磁型和室温的顺磁性),为这类稀土半导体化合物作为新型磁电子材料的潜在应用提供了可能性。 相似文献
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以ZrO2、Pb304和TiO2为原料(Nb2O5为掺杂剂),采用柱面冲击波装置合成了Pb(Zr0.95 Ti0.05)O2(PZT95/5)粉体,并对粉体活性及其烧结性能进行了研究。XRD及SEM分析表明,利用冲击波的高温高压作用可以合成单一钙钛矿相PZT95/5粉体,并使得粉体发生了晶粒细化与晶格畸变,这有利于增强粉体活性,促进低温活化烧结。该粉体在1100℃的低温下即可烧结成瓷;在1200℃烧结3h,陶瓷体致密度达到最大,约7.79g/cm^3,且晶粒尺寸相近,分布均匀。 相似文献
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Wu J Wang J Xiao D Zhu J 《IEEE transactions on ultrasonics, ferroelectrics, and frequency control》2012,59(1):14-20
Bilayered thin films consisting of BiFe(0.95)Mn(0.05)O(3) (BFMO) and Bi(0.90)La(0.10)Fe(0.85)Zn(0.15O3) (BLFZO) layers were prepared on Pt-coated silicon substrates without any buffer layers by RF sputtering. The (110) orientation was induced with a high phase purity for all bilayers as a result of the introduction of the bottom (110)-oriented BLFZO layer. The low leakage current density of BFMO/BLFZO bilayers could be attributed to a combined effect of the BFMO and BLFZO layers. The dielectric constant increases, the remanent polarization decreases, and the coercive field slightly increases with increasing thickness of the BLFZO layer in BFMO/BLFZO bilayers. Magnetic properties in BFMO/BLFZO bilayers are improved by increasing the BFMO layer thicknesses. A large polarization value of 2Pr ~ 189.5 μC/cm2 is obtained for the BFMO/ BLFZO bilayer with a thickness ratio of 3:1, which is much larger than those reported for BFO-based single layers or multilayers, and a good fatigue behavior is demonstrated with an increase in measurement frequencies and driving electric fields. 相似文献
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《Materials Research Bulletin》2013,48(11):4628-4632
(Bi0.95La0.05)(Fe0.97Mn0.03)O3/NiFe2O4 double layered thin film was prepared on a Pt(111)/Ti/SiO2/Si(100) substrate by a chemical solution deposition method. X-ray diffraction and Raman scattering spectroscopy studies confirmed the formation of the distorted rhombohedral perovskite and the inverse spinel cubic structures for the (Bi0.95La0.05)(Fe0.97Mn0.03)O3/NiFe2O4 double layered thin film. The (Bi0.95La0.05)(Fe0.97Mn0.03)O3/NiFe2O4 double layered thin film exhibited well saturated ferromagnetic (2 Mr of 18.1 emu/cm3 and 2Hc of 0.32 kOe at 20 kOe) and ferroelectric (2Pr of 60 μC/cm2 and 2Ec of 813 kV/cm at 866 kV/cm) hysteresis loops with low order of leakage current density (4.5 × 10−6 A/cm2 at an applied electric field of 100 kV/cm), which suggest the ferroelectric and ferromagnetic multi-layers applications in real devices. 相似文献
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以金属盐及柠檬酸为原料, 采用溶胶-凝胶法制备了尖晶石氧化物Co2-xMn1+xO4和Co2-xFexMnO4系列, 通过XRD、FT-IR及PPMS等手段研究了Co2MnO4及系列掺杂样品的成相、结构、磁性等特征。结果表明, Co2-xMn1+xO4系列在x<0.6时, 呈单相立方结构, 晶格常数和磁性随着Mn掺杂量的增加而增大, x≥0.6时逐渐向四方结构转化, 磁性下降, 并呈现磁化强度不易饱和的特征; Co2-xFexMnO4系列样品在x<1.75成分范围内均可保持立方结构, 且晶格常数和磁性都随着x增大而提高。这些变化主要是由于掺杂原子尺度及磁矩均大于原有元素, 掺杂后样品内部的磁性相互作用有所增强。 相似文献
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Yongtao Li Hongguang Zhang Xueguang Dong Qi Li Wei Chen Hao Liu Xiaopeng Ge Xing’ao Li Chenglin Dong Shanling Ren 《Journal of Superconductivity and Novel Magnetism》2014,27(2):575-579
The Mn-doped and the (Pb, Mn)-codoped BiFeO3 polycrystalline samples are prepared by a sol–gel method. The X-ray diffraction patterns manifest that all samples are in single phase and a lattice structural transformation appears during doping process. Compared with Mn-doped BiFeO3, the magnetic property of (Pb, Mn)-codoped BiFeO3 is enhanced and ferroelectric polarization decreases. The results of XAFS indicate that the bond length of Fe–O shortens due to doping Mn ions into BiFeO3, which results in the increase of magnetic property. Pb ion doping makes the valence state of Mn ion change, rather than Fe ion, and induces the occurrence of Mn4+–O–Fe3+ antiferromagnetic coupling, which decreases the magnetic property of the Bi0.95Pb0.05Fe0.95Mn0.05O3 sample. 相似文献
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We report here the structural and electrical properties of Zn0.95M0.05O ceramic varistors, M = Zn, Ni and Fe. The samples were tested for phase purity and structural morphology by using X-Ray diffraction XRD and scanning electron microscope SEM techniques. The current-voltage characteristics J-E were obtained by dc electrical measurements in the temperature range of 300–500 K. Addition of doping did not influence the hexagonal wurtzite structure of ZnO ceramics. Furthermore, the lattice parameters ratio c/a for hexagonal distortion and the length of the bond parallel to the c axis, u were nearly unaffected. The average grain size was decreased from 1.57 μm for ZnO to 1.19 μm for Ni sample and to 1.22 μm for Fe sample. The breakdown field EB was decreased as the temperature increased, in the following order: Fe > Zn > Ni. The nonlinear region was clearly observed for all samples as the temperature increased up to 400 K and completely disappeared with further increase of temperature up to 500 K. The values of nonlinear coefficient, a were between 1.16 and 42 for all samples, in the following order: Fe > Zn > Ni. Moreover, the electrical conductivity s was gradually increased as the temperature increased up to 500 K, in the following order: Ni > Zn > Fe. On the other hand, the activation energies were 0.194 eV, 0.136 and 0.223 eV for all samples, in the following order: Fe, Zn and Ni. These results have been discussed in terms of valence states, magnetic moment and thermo-ionic emission, which were produced by the doping, and controlling the potential barrier of ZnO. 相似文献