The electrochemical property, chemical composition and crystal structure of electroless Co-Ni-B-Ce alloy plated in general state as well as in magnetic field were studied using potentiometer, plasma emission spectrome...The electrochemical property, chemical composition and crystal structure of electroless Co-Ni-B-Ce alloy plated in general state as well as in magnetic field were studied using potentiometer, plasma emission spectrometer, X-ray diffractometer, transmission electron microscope. The results show that the static potential and polarizability of electroless Co-Ni-B alloy are remarkably improved as the plating is carried out in magnetic field in the presence of a little amount of cerium in plating bath. Because of the action of magnetic field and rare earth element cerium, the boron content in alloy decreases, while cobalt and nickel contents increase. As a result, the amorphous Co-Ni-B alloy transforms to the microcrystalline Co-Ni-B-Ce alloy when the plating is in general state, and the Co-Ni-B alloy makes a crystalline transformation because of the action of magnetic field and rare earth element cerium.展开更多
Single-grain models with different cerium contents or structural parameters have been introduced to investigate the reversal magnetization behaviors in cerium-containing magnets. All the micromagnetic simulations are ...Single-grain models with different cerium contents or structural parameters have been introduced to investigate the reversal magnetization behaviors in cerium-containing magnets. All the micromagnetic simulations are carried out via the object oriented micromagnetic framework(OOMMF). As for single(Nd,Ce)_2 Fe_(14)B type grain, the coercivity decreases monotonously with the increase of the cerium content. Four types of grain structure have been compared: single(Nd,Ce)_2 Fe_(14)B type, core((Nd,Ce)_2 Fe_(14)B)-shell(Nd_2 Fe_(14)B) type with 2 nm thick shell, core(Ce_2 Fe_(14)B)-shell(Nd_2 Fe_(14)B) type, and core(Nd_2 Fe_(14)B)-shell(Ce_2 Fe_(14)B) type. It is found that core((Nd,Ce)_2 Fe_(14)B)-shell(Nd_2 Fe_(14)B)type grain with 2 nm thick shell always presents the largest coercivity under the same total cerium content. Furthermore,the relationship between the coercivity and the shell thickness t in core((Nd,Ce)_2 Fe_(14)B)-shell(Nd_2 Fe_(14)B) type grain has been studied. When the total cerium content is kept at 20.51 at.%, the analyzed results show that as t varies from 1 nm to 7 nm, the coercivity gradually ascends at the beginning, then quickly descends after reaching the maximum value when t = 5 nm. From the perspective of the positions of nucleation points, the reasons why t affects the coercivity are discussed in detail.展开更多
Zn and Co multi-doped CeO2 thin films have been prepared using an anodic electrochemical method. The structures and magnetic behaviors are characterized by several techniques, in which the oxygen states in the lattice...Zn and Co multi-doped CeO2 thin films have been prepared using an anodic electrochemical method. The structures and magnetic behaviors are characterized by several techniques, in which the oxygen states in the lattice and the absorptive oxygen bonds at the surface are carefully examined. The absorptive oxygen bond is about 50% of the total oxygen bond by using a semi-quantitative method. The value of actual stoichiometry δ′ is close to 2. The experimental results indicate that the thin films are of a cerium oxide-based solid solution with few oxygen vacancies in the lattice and many absorptive oxygen bonds at the surface. Week ferromagnetic behaviors were evidenced by observed M-H hysteresis loops at room temperature. Furthermore, an evidence of relative ferromagnetic contributions was revealed by the temperature dependence of magnetization. It is believed that the ferromagnetic contributions exhibited in the M-H loops originate from the absorptive oxygen on the surface rather than the oxygen vacancies in the lattice.展开更多
This work reports the study concerning the structure and magnetic properties of undoped CeO_2 and Fe-doped CeO_2(Ce_(1-x) Fe_xO_2, 0.01 ≤ x ≤ 0.07) nanospheres with diameters of 100~200 nm prepared by hydrothermal m...This work reports the study concerning the structure and magnetic properties of undoped CeO_2 and Fe-doped CeO_2(Ce_(1-x) Fe_xO_2, 0.01 ≤ x ≤ 0.07) nanospheres with diameters of 100~200 nm prepared by hydrothermal method using polyvinylpyrrolidone(PVP) as surfactant. The prepared samples were studied by using X-ray diffraction(XRD), Raman spectroscopy, transmission electron microscopy(TEM), high-resolution transmission electron microscopy(HRTEM), X-ray absorption near-edge structure(XANES), and vibrating sample magnetometry(VSM). The XRD results showed that Fe-doped CeO_2 was single-phased with a cubic structure, and with Fe^(3+)successfully substituting in Ce^(4+) sites. Raman spectra showed a redshift of F_(2g) mode that caused by the Fe doping. The samples of both undoped CeO_2 and Fe-doped CeO_2 exhibited room temperature ferromagnetism, and the saturated magnetization(Ms) increased with increasing Fe content until x = 0.05, and then the samples displayed ferromagnetic loops as well as paramagnetic behavior. The roles of Ce^(3+) and Fe^(3+)spin electrons are discussed for the ferromagnetism in the Fe-doped CeO_2.展开更多
利用恒电位仪、等离子发射光谱仪、电子能谱仪、X射线衍射仪、透射电子显微镜等研究了在常态和磁场条件下化学镀Co Ni B Ce合金的电化学性质、化学组成和组织结构。结果表明 ,微量稀土和磁场的介入改善了化学镀Co Ni B合金的静止电位和...利用恒电位仪、等离子发射光谱仪、电子能谱仪、X射线衍射仪、透射电子显微镜等研究了在常态和磁场条件下化学镀Co Ni B Ce合金的电化学性质、化学组成和组织结构。结果表明 ,微量稀土和磁场的介入改善了化学镀Co Ni B合金的静止电位和极化度 ;随镀液里稀土金属Ce量的增加 ,化学镀Co Ni B Ce合金镀层中的Ce含量是先增加后下降 ,均在Ce的质量浓度为 0 8g/L时达到最大值。在磁场和稀土铈的作用下 ,化学镀Co Ni B Ce合金镀层中B的含量减少 ,Co和Ni的含量增加 ,因而在常态下非晶态的Co Ni B镀层转变成了微晶结构的Co Ni B Ce镀层 ,在磁场条件下含稀土Ce的镀层则发生了晶化转变。展开更多
研究了磁场条件下化学镀Co- Ni- B -Ce合金镀层的微观表面形貌、显微硬度和磨损体积。结果表明,化学镀Co- Ni -B合金镀层表面由“圆锥峰”构成,表面较为平整,添加稀土Ce后,镀层变得凹凸不平;在外加磁场下施镀,镀层表面起伏更大。镀液... 研究了磁场条件下化学镀Co- Ni- B -Ce合金镀层的微观表面形貌、显微硬度和磨损体积。结果表明,化学镀Co- Ni -B合金镀层表面由“圆锥峰”构成,表面较为平整,添加稀土Ce后,镀层变得凹凸不平;在外加磁场下施镀,镀层表面起伏更大。镀液里添加Ce以及在磁场条件下,明显地提高了Co -Ni -B合金镀层的显微硬度和耐磨性,随镀液中Ce添加量增加,合金镀层的硬度和耐磨性都是先增加后降低,当镀液里Ce的添加量为0. 8g/L时,硬度和耐磨性均达到了峰值。展开更多
基金Project(50371023) supported by the National Natural Science Foundation of China
文摘The electrochemical property, chemical composition and crystal structure of electroless Co-Ni-B-Ce alloy plated in general state as well as in magnetic field were studied using potentiometer, plasma emission spectrometer, X-ray diffractometer, transmission electron microscope. The results show that the static potential and polarizability of electroless Co-Ni-B alloy are remarkably improved as the plating is carried out in magnetic field in the presence of a little amount of cerium in plating bath. Because of the action of magnetic field and rare earth element cerium, the boron content in alloy decreases, while cobalt and nickel contents increase. As a result, the amorphous Co-Ni-B alloy transforms to the microcrystalline Co-Ni-B-Ce alloy when the plating is in general state, and the Co-Ni-B alloy makes a crystalline transformation because of the action of magnetic field and rare earth element cerium.
基金supported by the National Natural Science Foundation of China(Grant Nos.51590882 and 51871063)
文摘Single-grain models with different cerium contents or structural parameters have been introduced to investigate the reversal magnetization behaviors in cerium-containing magnets. All the micromagnetic simulations are carried out via the object oriented micromagnetic framework(OOMMF). As for single(Nd,Ce)_2 Fe_(14)B type grain, the coercivity decreases monotonously with the increase of the cerium content. Four types of grain structure have been compared: single(Nd,Ce)_2 Fe_(14)B type, core((Nd,Ce)_2 Fe_(14)B)-shell(Nd_2 Fe_(14)B) type with 2 nm thick shell, core(Ce_2 Fe_(14)B)-shell(Nd_2 Fe_(14)B) type, and core(Nd_2 Fe_(14)B)-shell(Ce_2 Fe_(14)B) type. It is found that core((Nd,Ce)_2 Fe_(14)B)-shell(Nd_2 Fe_(14)B)type grain with 2 nm thick shell always presents the largest coercivity under the same total cerium content. Furthermore,the relationship between the coercivity and the shell thickness t in core((Nd,Ce)_2 Fe_(14)B)-shell(Nd_2 Fe_(14)B) type grain has been studied. When the total cerium content is kept at 20.51 at.%, the analyzed results show that as t varies from 1 nm to 7 nm, the coercivity gradually ascends at the beginning, then quickly descends after reaching the maximum value when t = 5 nm. From the perspective of the positions of nucleation points, the reasons why t affects the coercivity are discussed in detail.
基金supported by the Natural Science Foundation of Zhejiang Province,China(Grant No.LY12A01002)the National Natural Science Foundation of China(Grant Nos.11204058 and 21073162)the Hangzhou Dianzi University,China(Grant No.KYF09150603)
文摘Zn and Co multi-doped CeO2 thin films have been prepared using an anodic electrochemical method. The structures and magnetic behaviors are characterized by several techniques, in which the oxygen states in the lattice and the absorptive oxygen bonds at the surface are carefully examined. The absorptive oxygen bond is about 50% of the total oxygen bond by using a semi-quantitative method. The value of actual stoichiometry δ′ is close to 2. The experimental results indicate that the thin films are of a cerium oxide-based solid solution with few oxygen vacancies in the lattice and many absorptive oxygen bonds at the surface. Week ferromagnetic behaviors were evidenced by observed M-H hysteresis loops at room temperature. Furthermore, an evidence of relative ferromagnetic contributions was revealed by the temperature dependence of magnetization. It is believed that the ferromagnetic contributions exhibited in the M-H loops originate from the absorptive oxygen on the surface rather than the oxygen vacancies in the lattice.
基金the Thailand Research Fund through the Royal Golden Jubilee Ph.D.program (Grant No. PHD/0275/2550)supported by Suranaree University of Technology (SUT)the Office of the Higher Education Commission under NRU project of Thailand
文摘This work reports the study concerning the structure and magnetic properties of undoped CeO_2 and Fe-doped CeO_2(Ce_(1-x) Fe_xO_2, 0.01 ≤ x ≤ 0.07) nanospheres with diameters of 100~200 nm prepared by hydrothermal method using polyvinylpyrrolidone(PVP) as surfactant. The prepared samples were studied by using X-ray diffraction(XRD), Raman spectroscopy, transmission electron microscopy(TEM), high-resolution transmission electron microscopy(HRTEM), X-ray absorption near-edge structure(XANES), and vibrating sample magnetometry(VSM). The XRD results showed that Fe-doped CeO_2 was single-phased with a cubic structure, and with Fe^(3+)successfully substituting in Ce^(4+) sites. Raman spectra showed a redshift of F_(2g) mode that caused by the Fe doping. The samples of both undoped CeO_2 and Fe-doped CeO_2 exhibited room temperature ferromagnetism, and the saturated magnetization(Ms) increased with increasing Fe content until x = 0.05, and then the samples displayed ferromagnetic loops as well as paramagnetic behavior. The roles of Ce^(3+) and Fe^(3+)spin electrons are discussed for the ferromagnetism in the Fe-doped CeO_2.
基金Project(52174303)supported by the National Natural Science Foundation of ChinaProject(2125026)supported by the Fundamental Research Funds for the Central Universities,China。
文摘利用恒电位仪、等离子发射光谱仪、电子能谱仪、X射线衍射仪、透射电子显微镜等研究了在常态和磁场条件下化学镀Co Ni B Ce合金的电化学性质、化学组成和组织结构。结果表明 ,微量稀土和磁场的介入改善了化学镀Co Ni B合金的静止电位和极化度 ;随镀液里稀土金属Ce量的增加 ,化学镀Co Ni B Ce合金镀层中的Ce含量是先增加后下降 ,均在Ce的质量浓度为 0 8g/L时达到最大值。在磁场和稀土铈的作用下 ,化学镀Co Ni B Ce合金镀层中B的含量减少 ,Co和Ni的含量增加 ,因而在常态下非晶态的Co Ni B镀层转变成了微晶结构的Co Ni B Ce镀层 ,在磁场条件下含稀土Ce的镀层则发生了晶化转变。
文摘 研究了磁场条件下化学镀Co- Ni- B -Ce合金镀层的微观表面形貌、显微硬度和磨损体积。结果表明,化学镀Co- Ni -B合金镀层表面由“圆锥峰”构成,表面较为平整,添加稀土Ce后,镀层变得凹凸不平;在外加磁场下施镀,镀层表面起伏更大。镀液里添加Ce以及在磁场条件下,明显地提高了Co -Ni -B合金镀层的显微硬度和耐磨性,随镀液中Ce添加量增加,合金镀层的硬度和耐磨性都是先增加后降低,当镀液里Ce的添加量为0. 8g/L时,硬度和耐磨性均达到了峰值。
