Search

Anisotropic ceramics-bonded Nd-Fe-B-type magnet with high electrical resistivity was fabricated with the intention of suppressing induction of eddy current thus lowering operating temperature of the magnet used as rotor magnet in high-speed motor. The ceramics-bonded Nd-Fe-B-type magnet was fabricated by consolidating mixture of hydrogenation decomposition desorption recombination powder and oxide ceramics with the low melting point. Anisotropic ceramics-bonded (15 vol%) Nd-Fe-B-type magnet had remarkably enhanced electrical resistivity ($\sim 730~\mu \Omega \cdot \text {cm}$) with respect to the magnet without ceramics binder ($\sim 220~\mu \Omega \cdot \text {cm}$). Thanks to low-temperature consolidation of Nd-Fe-B-type particles using oxide ceramic binder with low melting point, the detrimental reaction between the magnetic particle surface and oxide was profoundly suppressed, thus retaining the high coercivity of initial magnetic particles even in the ceramics-bonded magnets. Ceramics-bonded (15 vol%) magnet, which had good room temperature magnetic performance ($_{\mathrm {i}}H_{\mathrm {c}}= 12.7$ kOe, $M_{\mathrm {r}}= 9.4$ kG, and (BH) $_{\mathrm {max}}= 17.0$ MGOe) still had reasonably good performance [ $_{\mathrm {i}}H_{\mathrm {c}}= 5.0$ kOe, $M_{\mathrm {r}}= 8.7$ kG, and (BH) $_{\mathrm {max}}= 10.2$ MGOe] at 150 °C. [ABSTRACT FROM AUTHOR]

Two types of re-substituted (FeCo)2B-type alloys with stoichiometric (Fe0.675Co0.3Re0.025)2B and 1.5 at% boron-excess compositions were prepared by suction casting and subsequent mechanical milling and annealing. Phase evolution in the (FeCo)2B-type alloys in the course of mechanical milling and annealing was investigated. Single-phase re-substituted (FeCo)2B-type material was prepared from stoichiometric (Fe0.675Co0.3Re0.025)2B by the combination of suction casting and mechanical milling. The two alloys had the same phase constitution of (Fe, Co)2B-type and amorphous phases in heavily milled state. However, the heavily milled alloys had different phase constitution after annealing; the stoichiometric alloy consisted of single (Fe, Co)2B-type phase, while the boron-excess alloy consisted of two-phase mixture of (Fe, Co)2B-type and (Fe, Co)B-type phases. The two heavily milled alloys had similar coercivity of around 1 kOe after full annealing. [ABSTRACT FROM AUTHOR]

This paper describes the features and performance of an analog and RF device technology development on a 14-nm logic FinFET platform. An optimized single-side gate contact RF device layout shows a Ft/F\text {max} of 314/180 GHz and 285/140 GHz for N and PFinFET device, respectively. The double-side gate contact structure with contact on either end of active gate enhances the peak F\text {max} performance to 227 and 195 GHz for both N and PFinFET devices, respectively. A significant boost in the PFinFET RF performance is observed compared to 28-nm planar PFET, which is attributed to the source/drain SiGe epitaxy stressor that results in higher hole carrier mobility. On the other hand, the thin channel body of FinFET structure facilitates a better electrostatic control of gate over the channel region and hence suppresses short channel effects including the drain-induced barrier lowering. Consequently, a significantly higher self-gain ( Gm/G\text {ds})~40 and 34 for both NFinFET and PFinFET is achieved. In addition, N/PFinFETs demonstrate superior 1/f noise of 17/35 fV ^2\mu \textm^2 /Hz at 1 kHz compared to 171/106 fV ^\mathrm \mathbf 2\mu \textm^2 /Hz of 28-nm planar N/PFETs. To extend the low-voltage operation and power saving of FinFET RF platform, ultralow Vt N/PFinFETs in the range of 50 mV Vt\text{s} are also developed. Furthermore, a deep n-well process is added to the platform to provide device and circuit isolation from substrate and supply noise, while realizing the creation of new devices such as vertical NPN, PCAP, and high breakdown voltage deep n-well junction diodes. Overall, a superior Ft/F\textsf {max} , high self-gain, low 1/f noise, and robust substrate isolation characteristics extend the capability of this new 14-nm FinFET technology to the analog and RF circuit applications. [ABSTRACT FROM AUTHOR]

Enhancement of magnetic performance of the Nd–Fe–B-type die-upset magnet by using RF3 (R = Dy, Pr, Nd, Ce, La)-doping as a source of rare-earth substituent was investigated. Commercial melt-spun flakes of Nd13.6Fe73.6Co6.6Ga0.6B5.6 were mixed with 1.6 wt.% RF3 (R = Dy, Pr, Nd, Ce, La) powder. The mixture was hot pressed and then die upset. Coercivity of the die-upset magnet was enhanced by RF3 (R = Dy, Pr, Nd)-doping without severely sacrificing magnetic performance. In the RF3-doped magnet, active substitution between the R atoms from the added RF3 and the Nd atoms in the neighboring flakes occurred to form thin R-diffused shells near the surface of the flakes. Coercivity enhancement for the RF3 (R = Dy, Pr)-doped magnet was largely attributed to the enhancement of the anisotropy field of (Nd,Dy)2Fe14 B- or (Nd,Pr)2 Fe14 B-type grains in the R-diffused shell on the flake surface. Coercivity enhancement in the NdF3-doped magnet was attributed to grain boundary restructuring in the R-diffused shell region. [ABSTRACT FROM PUBLISHER]

An RF3 (R = La, Ce, Pr, Nd, and Dy)-doped Nd13.6Fe73.6Co6.6Ga0.6B5.6 hot-pressed magnet was prepared using melt-spun flakes. The substitution of Nd in Nd–Fe–B flakes by rare-earth dopant in the hot-pressed magnets doped with various RF3 and its effect on coercivity were investigated. In the RF3-doped Nd13.6Fe73.6Co6.6Ga0.6B5.6 magnet hot pressed at the modest temperature (735 °C), the dopants Ce, Pr, Nd, and Dy actively substituted Nd in the region near the flake surface to form the thin shell in the flake. RF3 (R = Dy, Nd, and Pr) doping achieved significant coercivity enhancement in the hot-pressed magnet, and it was attributed to the enhanced anisotropy field of the Nd2Fe14B-type grains (for Dy and Pr doping) and grain boundary restructuring (for Nd doping) in the shell. The most profound coercivity enhancement as high as 5 kOe was achieved in the DyF3-doped magnet. Doping with the light rare-earth elements using RF3 (R = La and Ce) led to poor coercivity enhancement with respect to the RF3 (R = Dy, Nd, and Pr) doping. [ABSTRACT FROM AUTHOR]

For bonded micro-magnet application, fine particles with high permanent magnetic performance are required. As the HDDR-treated Nd-Fe-B-type material consists of very fine grains (\sim 0.3~\mu\m), the fine particles prepared from the HDDR-treated material are expected to have high magnetic performance even in the form of fine particles. Fine Nd-Fe-B-type particles were prepared by mechanical milling of the HDDR-treated \Nd12.5{\Fe}80.6{\B}6.4{\Ga}0.3{\Nb}0.2 material, and coercivity of the fine particle was investigated. Coercivity of the HDDR-treated Nd-Fe-B-type material was radically reduced by mechanical milling. Surface oxidation was the major contributory factor for the radical coercivity reduction. Chemical etching of the oxidized surface led to significant recovery of the coercivity. Unlike the mechanically milled fine particles of sintered Nd-Fe-B-type magnet, which lose coercivity almost completely, the moderately milled and etched fine particles (20 - 80~\mu\m) of HDDR-treated Nd-Fe-B-type material exhibited high coercivity over 12 kOe. [ABSTRACT FROM PUBLISHER]