排序方式: 共有16条查询结果,搜索用时 15 毫秒
1.
Reduced-temperature ordering of FePt nanoparticle assembled films by Fe30Pt70/Fe3O4 core/shell structure
下载免费PDF全文
![点击此处可从《中国物理》网站下载免费的PDF全文](/ch/ext_images/free.gif)
In this paper, Fe30Pt70/Fe3O4 core/shell nanoparticles were synthesized by chemical routine and the layered polyethylenimine (PEI)-Fe30Pt70/Fe3O4 structure was constructed by molecule-mediated self-assembly technique. The dimension of core/shell structured nanoparticles was that of 4nm core and 2 nm shell. After annealing under a flow of forming gas (50%Ar2+30%H2) for 1 h at or above 400℃, the iron oxide shell was reduced to Fe and diffused to Pt-rieh core, which leaded to the formation of L1. phase FePt at low temperature. The x-ray diffraction results and magnetic properties measurement showed that the chemical ordering temperature of Fe30Pt70/Fe3O4 core/shell nanoparticles assembly can be reduced to as low as 400℃. The sample annealed at 400℃ showed the eoereivity of 4KOe with the applied field of 1.5T. The core/shell structure was suggested to be an effective way to reduce the ordering temperature obviously.[第一段] 相似文献
2.
用熔体快淬法制备了纳米复合永磁样品Pr9Fe74Co12B5 与Pr9Fe74Co12B5Sn0.5,分析了样品的起始磁化、反磁化过程,测得样品的总磁化率、可逆磁化率以及样品的磁黏滞性.结果表明,两样品在室温下均表现为单一硬磁相磁化行为,在低温下表现为双相行为,且由于添加Sn后使晶粒均匀化从而导致样品低温下的双相行为更加明显.添加Sn后引起样品中软磁相含量和软磁相晶粒尺寸的增加,使磁化反转中可逆磁化部分增多,且使反磁化形核场降低.磁黏滞性研究表明,热激活体积与软磁相晶粒的大小有关.
关键词:
纳米复合永磁
磁化反转
磁粘滞 相似文献
3.
用熔体快淬法制备了纳米复合永磁样品Pr9Fe74Co12B5与Pr9Fe74Co12B5Sn0.5,分析了样品的起始磁化、反磁化过程,测得样品的总磁化率、可逆磁化率以及样品的磁黏滞性.结果表明,两样品在室温下均表现为单一硬磁相磁化行为,在低温下表现为双相行为,且由于添加Sn后使晶粒均匀化从而导致样品低温下的双相行为更加明显.添加Sn后引起样品中软磁相含量和软磁相晶粒尺寸的增加,使磁化反转中可逆磁化部分增多,且使反磁化形核场降低.磁黏滞性研究表明,热激活体积与软磁相晶粒的大小有关. 相似文献
4.
通过微磁学有限元方法研究了微结构对各向异性的Sm(Co,Cu,Fe,Zr)z磁性能的影响, 并 对不同温度下的退磁曲线进行了计算.计算结果表明,矫顽力随着2∶17相晶粒尺寸的增大 而增大,随1∶5晶界相厚度的增大而减小;通过减小晶界相厚度或增大晶粒尺寸可以有效提 高 磁能积.反磁化的物理机制主要为形核机制,主要表现为首先在晶界相形成反磁化核,随 着 磁场的增大反磁化核不断长大,最后导致整个磁体的磁化反转;而当温度升高时,晶界相逐 渐变成非磁性相,使得反磁化核难以形成,因此出现了反常的矫顽力温度依赖关系.
关键词:
微磁学
有限元
微结构
磁性能 相似文献
5.
6.
Enhanced hyperthermia performance in hard-soft magnetic mixed Zn0.5CoxFe2.5−xO4/SiO2 composite magnetic nanoparticles
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
High quality Zn0.5CoxFe2.5?xO4(x=0,0.05,0.1,0.15)serial magnetic nanoparticles with single cubic structures were prepared by the modified thermal decomposition method,and Zn0.5CoxFe2.5?xO4/SiO2 composite magnetic nanoparticles were prepared by surface modification of SiO2.The magnetic anisotropy of the sample increases with the increase of the doping amount of Co2+.When the doping amount is 0.1,the sample shows the transition from superparamagnetism to ferrimagnetism at room temperature.In the Zn0.5CoxFe2.5?xO4/SiO2 serial samples,the maximum value of specific loss power(SLP)with 1974 W/gmetal can also be found at doping amount of x=0.1.The composite nanoparticles are expected to be an excellent candidate for clinical magnetic hyperthermia. 相似文献
7.
Effects of dipolar interactions on the magnetic hyperthermia of Zn_(0.3)Fe_(2.7)O_4 nanoparticles with different sizes
下载免费PDF全文
![点击此处可从《中国物理 B》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Tumor-targeted magnetic hyperthermia has recently attracted much attention.Magnetic nanoparticles(NPs) are heat mediator nanoprobes in magnetic hyperthermia for cancer treatment.In this paper,single cubic spinel structural Zn0.3Fe2.7O4 magnetic NPs with sizes of 14 nm-20 nm were synthesized,followed by coating with SiO2 shell.The SLP value of Zn0.3Fe2.7O4/SiO2 NPs below 20 nm changes non-monotonically with the concentration of solution under the alternating current(AC) magnetic field of 430 kHz and 27 kA/m.SLP values of all Zn0.3Fe2.7O4/SiO2 NPs appear a peak value with change of solution concentration.The solution concentrations with optimal SLP value decrease with increasing magnetic core size.This work can give guidance to the better prediction and control of the magnetic hyperthermia performance of materials in clinical applications. 相似文献
8.
Effect of composition on texture and magnetic the crystallographic properties of the Sm(Co,Fe,Cu,Zr)z ribbons prepared by simple processing
下载免费PDF全文
![点击此处可从《中国物理》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Sm(Co_balFe_yCu_xZr_w)_z ribbons have been prepared by melt spinning at a low wheel velocity followed by short-time aging and slow cooling the as-spun ribbons from 850 to 400℃. It is found that the composition can significantly influence the degree of crystallographic texture of the ribbons. The 1:7 phase of the as-spun ribbons is segregated into 1:5 and 2:17 phases by the simple processing procedure. However, the crystallographic texture is still preserved in the ribbons after precipitation hardening. (BH)_{\rm max} about 86kJ/m^{3} can be obtained in the Sm(Co, Fe, Cu, Zr)_{z} ribbons by the adjustment of composition. 相似文献
9.
10.
Effect of Magnetic Anisotropy on Magnetic Thermal Induction of Mn_(0.3)Zn_(0.3)Co_xFe_(2.4-x)O_4 Nanoparticles
下载免费PDF全文
![点击此处可从《中国物理快报》网站下载免费的PDF全文](/ch/ext_images/free.gif)
Mn_(0.3)Zn_(0.3)Co_xFe_(2.4-x)O_4 series magnetic nanoparticles are prepared by the high-temperature organic solvent method, and Mn_(0.3)Zn_(0.3)Co_xFe_(2.4-x)O_4@SiO_2 composite nanoparticles are prepared by the reverse microemulsion method. The as-prepared samples are characterized, and the results show that the magnetic anisotropy constant of nanoparticles increases with the cobalt content, and the magnetic thermal induction shows a trend of increasing first and then decreasing. The optimal magnetic thermal induction is obtained at x = 0.12 with a specific loss power of 2086 w/gmetal, which is a bright prospect in clinical magnetic hyperthermia. 相似文献