退火工艺对射频磁控溅射Bi:YIG薄膜磁性能的影响

对于用射频磁控溅射技术在Si基片上制备的Bi:YIG系薄膜,用快速循环退火方法对其进行晶化处理,研究了退火温度对Bi:YIG薄膜结晶状态和形貌的影响,以及退火气氛和循环周期对薄膜性能的影响.结果表明,用快速循环退火可以在si单晶基片上得到磁性能优良的薄膜(饱和磁化强度139 kA/m,矫顽力6.37 kA/m)并使薄膜形貌有较大改善,在石英基片上制备的薄膜法拉第角比常规退火的薄膜增大了约一倍.     

Application of high-temperature permanent magnets Sm（Co,Fe, Cu,Zr）z in PPM focusing system

Rare earth permanent magnets Sm（Co, Fe, Cu, Zr）z with outstanding performance and high-temperature thermal stability were fabricated. Optimized by Fe content and process, Sm（Co0.72Fe0.15Cu0.1Zr0.03）7.5 magnet with B1〉0.75 T and Hci〉1300 kA/m at 300 ℃ can be obtained. According to the performance data of Sm（Co0.72Fe0.15Cu0.1Zr0.03）7.5, the magnetic field along central axis Bz in periodic permanent magnet （PPM） focusing system was simulated using electromagnetic field analysis software Maxwell 2D/3D. The Bz exhibited typical cosine curve along central axis, and the peak value of Bz was high enough to meet the demand of PPM focusing system at room temperature even at 200±20 ℃. Additionally, a kind of simple cooling structure for PPM focusing system was designed by setting cooling pipe between polepieces. Simulated results showed that smooth cosine curve of Bz was successfully achieved with good control of the thickness of cooling pipe.     

线性自旋阀读磁头的材料性能及结构参数优化（二）

优化材料性能参数和自旋阀巨磁电阻磁头的结构参数是磁器件实用化的关键。基于建立的物理计算模型,首先将自旋阀巨磁电阻磁头传感单元作为有源磁电阻放入前端放大电路,对输出电压,二次谐波及线性区间进行态模拟发现在宽ｇ１＋ｇ２≤０．７μｍ,线性偏电流１０－５０ｍＡ范围内,自旋阀磁头相对记录介质有线性信号输出。     

烧结温度对镍锌功率铁氧体磁性能的影响

为得到Zn含量不同时NiZn铁氧体材料的最佳烧结温度,用氧化物法制备了NiZn铁氧体材料,研究了烧结温度对材料起始磁导率、功耗、饱和磁感应强度和微结构的影响.结果表明,适宜的烧结温度对制备功耗低、饱和磁感应强度高和较优起始磁导率的NiZn铁氧体材料至关重要,而Zn含量不同时对应材料的最佳烧结温度也各不相同.     

磁性微电子机械系统(MMEMS)中的关键问题

磁性微电子机械系统(MMEMS)是在传统的微电子机械系统(MEMS)基础上发展的,它在科学研究及应用领域中有着巨大的潜力.磁性材料和MEMS技术的兼容性问题此前已作为一个重要的问题论述过.本文就磁性MEMS技术中的线圈制作、软磁膜制备及硬磁膜制备等关键性问题加以概述.     

LTCC用低温烧结Mg-Cu-Zn铁氧体的研究

采用普通陶瓷工艺合成一系列低温烧结的Mg-Cu-Zn铁氧体(Mg0.5-xCuxZn0.5O)(Fe2O3)0.95(x=0.1、0.15、0.20、0.25、0.30),在900～1100℃研究了CuO加入量对磁性能和烧结特性的影响,在此基础上进一步研究了Bi2O3以及BaTiO3掺杂对900℃烧结Mg-Cu-Zn铁氧体的成相、致密化过程、显微结构和磁电性能的影响,结果显示,低温烧结的复合Mg-Cu-Zn铁氧体有望用作LTCC材料.     

Rare earth doped CaCu_3Ti_4O_(12) electronic ceramics for high frequency applications

Ca1-xRxCu3Ti4O12(R=La,Y,Gd;x=0,0.1,0.2,0.3) electronic ceramics were fabricated by conventional solid-state reaction method.The microstructure and dielectric properties as well as impedance behavior were carefully investigated.XRD results showed that the secondary phases with the general formula R2Ti2O7 existed at grain boundaries of rare earth doped ceramics,which inhibited abnormal grain growth.The dielectric constant decreased from 4×105 in pure CaCu3Ti4O12(CCTO) ceramics to 2×103 with rare earth doping.However,all samples showed high dielectric constant in broad frequency range(10 MHz).The cutoff frequency(f0) was remarkably shifted to higher frequency from 13 MHz(pure CCTO ceramics) to 80 MHz(Gd-doped CCTO ceramics).Meanwhile,the dielectric loss tangent rapidly decreased approximately 10 times.These improvements of dielectric properties by rare earth doping are very useful in wide frequency chip capacitor and LTCC devices.     

Cu对NiFe/Cu/NiFe层状薄膜的巨磁阻抗效应影响的研究

用直流磁控溅射方法制备了NiFe/Cu/NiFe层状薄膜 ,研究了Cu膜宽度对NiFe/Cu/NiFe层状薄膜的巨磁阻抗效应的影响 ,结果表明 ,层状薄膜的巨磁阻抗效应随Cu膜宽度发生振荡现象 ;并提出了一个等效电路模型直观地解释了层状薄膜增强巨磁阻抗效应的机理     

WCDMA中一种新的信道估计方法

本文介绍了第三代移动通信标准WCDMA(FDD)中基于时分复用的导引符号辅助瑞利衰落信道下的信道估计.提出了一种新的利用两个连续时隙的导引符号估计出的信道参数进行最小二乘意义下二次曲线内插的信道参数估计方法.仿真表明本方法能有效地估计出时隙中数据段的信道参数,尤其在高速及变速运动情况下,Rake接收机的性能得到了显著的改善.     

基于YIG单晶薄膜的陷波器设计

针对基于环球耦合谐振的钇铁石榴石(YIG)小球陷波器装配调试工艺复杂、不利于多通道集成的问题,提出了一种采用静磁波技术来实现YIG单晶薄膜陷波器结构与设计方法.该文通过对单晶薄膜陷波器工作原理的分析,静磁反向体波的角频率与波数(ω-k)色散特性与微带激励谐振换能器的静磁波激励特性的数值计算及器件仿真优化,设计了调谐工作...