摘要:

Stainless‐steel and Mo sheathed PbMo6S8wires have been fabricated by hot working from modified PbS, Mo, and MoS2mixed powders which were prepared by reacting Pb, Mo, and S at 530 °C. Critical current densities were investigated for different preparation conditions, and it is revealed that obtaining continuous current path between PbMo6S8grains is the most important factor to achieve high critical current density. TheJcvalue of 2.8×104A/cm2(8 T), 7.8×103A/cm2(15 T), and 1.3×103A/cm2(23 T) was observed for the PbMo6S7.0wire heat treated at 700 °C.

ISSN:0021-8979    

DOI:10.1063/1.341922

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

To advance new soft magnetic materials of an FeGaSi alloy into the commercial world, improvements on various properties were designed by introducing additive elements without sacrificing its high saturation magnetic induction. The detailed studies on the diversified properties, such as saturation magnetic induction, film internal stress, wear resistivity, and so on, were performed. High‐frequency permeability of the laminated structure film was also investigated. As a result, the Ru‐added FeRuGaSi alloy films, whose typical compositions are Fe72Ru4Ga7Si17and Fe68Ru8Ga7Si17(at. %), prove to be excellent soft magnetic materials especially appropriate for the magnetic recording/playback head core use.

ISSN:0021-8979    

DOI:10.1063/1.341923

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Strongly coercive films of &ggr;Fe2O3‐Fe3O4solid solution [xFe8/3O4‐(1−x)Fe3O4] have been deposited using a new pyrolysis technique. The magnetic and crystallographic properties of nonoxidized Fe3O4(x=0) and completely oxidized &ggr;Fe2O3(x=1) films are shown to be closely related to the planar stress present in the films. An x‐ray method is proposed for the study of the iron oxide film stress. The different results are applied to understand the origin of the strong coercive force of partially oxidized solid solution films.

ISSN:0021-8979    

DOI:10.1063/1.341924

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

We have measured coercive field and switching voltage versus thickness in PbZr0.54Ti0.46O3thin (0.15–0.50 &mgr;m) films, together with switching times and current transient shapes versus field and temperature. The results show activation fields of order 120 kV/cm at room temperature, threshold voltages below 1.3 V, and switching speeds faster than 100 ns, demonstrating that fast, nonvolatile memories can be constructed that are compatible with standard silicon or GaAs integrated circuit voltage levels, without the need for an internal voltage pump. The displacement current transient data yield 2.5 as the dimensionality of domain growth if one‐step intial nucleation rate is assumed, and are compatible with the theory of Ishibashi, yieldingimaxtmax/Ps=1.65±0.23, in comparison with the predicted 1.646. The switching time exhibits an activation field dependence upon both voltage and temperature through a single reduced parameter (TC−T)(VTC),−1in accord with the theory of Orihara and Ishibashi.

ISSN:0021-8979    

DOI:10.1063/1.341925

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

The photoluminescence and Raman scattering spectra of GaInP and AlInP grown by organometallic vapor‐phase epitaxy are measured to investigate the ordered and disordered crystalline states. It is found that ordered structure exists not only in the GaInP but also in the AlInP, and probably in the entire AlGaInP system, and that zinc doping over 1018cm−3makes it disordered. This disordering effect is attributed to the Zn diffusion in the GaInP epilayer during crystal growth which puts the once‐formed ordered atomic arrangement into a disordered state.

ISSN:0021-8979    

DOI:10.1063/1.341926

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Optical absorption and related characteristics in undoped, semi‐insulating GaAs crystals have been investigated, especially at the bleaching and thermal recovery stages. It has been shown that a broad absorption band at a longer wavelength grows as bleaching proceeds, in a reciprocal relation with the near‐infrared absorption band. It has been found that the bleached near‐infrared absorption shows rather abrupt recovery at a temperature around 130 K and that the recovery profile, i.e., the temperature derivative of the recovering absorption, is dependent upon the crystal composition and thermal prehistory. Hence, the present method, recovery characteristics of the bleached absorption method, may have applicability for elucidating defect properties as well as crystal characterization. Simultaneous measurements of extrinsic photoconductivity combined with related experimental results have lead to a conclusion that the extrinsic photoconductivity in the enhanced state is related to the metastable state of the deep lying defects. These experimental results are discussed systematically on the basis of the defect transition to and recovery from the metastable state.

ISSN:0021-8979    

DOI:10.1063/1.341927

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Electronic Raman scattering (ERS) has been used to study residual shallow acceptors in undoped semi‐insulating (SI) GaAs grown by the liquid‐encapsulated Czochralski technique. The dispersion of the cross section for ERS of shallow acceptors, as well as its absolute value, has been measured. It is shown that ERS allows a quantitative analysis of residual shallow acceptors in SI GaAs. Calibration factors for C and Zn acceptors are given. The detection limit of ERS is determined to ∼5×1014cm−3for 500‐&mgr;m‐thick standard wafers. Spatially resolved measurements show a systematic variation of the residual acceptor concentration across 2‐in. GaAs wafers.

ISSN:0021-8979    

DOI:10.1063/1.341928

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

The effect of Si+implantation on the allowed and forbidden first‐order and on the resonantly excited second‐order Raman spectrum of GaAs has been studied. The implantation dose was varied between 5×1011and 1×1016ions/cm2. For doses exceeding 1015cm−2, the Raman spectrum of a completely amorphized surface layer was observed. In samples implanted with doses ≤1015cm−2, which show a partly crystalline/amorphous mixed state, the relative intensities of amorphous and crystalline features in the Raman spectrum vary significantly for different exciting photon energies. This is explained by differences in the dispersion of the Raman susceptibility in amorphous and crystalline GaAs. Dipole‐forbidden but defect‐induced first‐order scattering by longitudinal optical zone center [LO(&Ggr;)] phonons shows an initial increase with implantation dose, which is, for excitation resonant with theE1gap, followed by a saturation and even a decrease in intensity. This is understood in terms of an implantation‐induced broadening and lowering of theE1gap resonance in the Raman susceptibility which counteracts the increase in radiation defects. The intensity of resonantly excited 2LO(&Ggr;) phonon scattering shows a monotonic decrease with increasing dose, which also indicates a broadening of theE1gap resonance in the corresponding Raman susceptibility. These results demonstrate the sensitivity of resonant Raman scattering to radiation damage induced changes in the dielectric function and open the possibility for a sensitive assessment of implantation damage in GaAs.

ISSN:0021-8979    

DOI:10.1063/1.341929

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Mean electronic resonant wavelength of some single substance liquid crystals obtained by ultraviolet transmission spectrum and by wavelength dependent birefringence agrees very well. Both ground and higher state &pgr;→&pgr;* electronic transitions are found to make a major contribution to the observed birefringence of those liquid crystals containing delocalized &pgr; electrons. The role of the &sgr;→&sgr;* electronic transitions may or may not be significant, depending on the liquid crystal composition.

ISSN:0021-8979    

DOI:10.1063/1.341930

出版商:AIP    

年代:1988

数据来源: AIP

摘要:

Optical and electro‐optic properties of some highly conjugated nematic liquid crystals (LCs): 4‐cyano‐4’‐n‐alkyltolanes (n‐CDP) and 4‐cyano‐4’‐n‐alkylstilbene (n‐CS) were studied at elevated temperature. Results are compared with 4‐cyano‐4’‐n‐pentylbiphenyl (5CB). These LCs exhibit large birefringence, small viscoelastic coefficient, and low threshold voltage. Their potential application for modulating visible and infrared radiation is addressed.

ISSN:0021-8979    

DOI:10.1063/1.341931

出版商:AIP    

年代:1988

数据来源: AIP