摘要:

It has been found that adding Rh or Ru to MnBi is effective in stabilizing the high−temperature &bgr; phase (distorted NiAs structure) relative to the low−temperature &agr; phase (undistorted NiAs structure). This effect has been observed in both evaporated thin films and bulk samples. Addition of 1 at.% Rh to bulk MnBi increases the minimum time constant for the &bgr;→&agr; transformation by 5 orders of magnitude. Stabilization is important in the use of MnBi for thermomagnetic recording.

ISSN:0003-6951    

DOI:10.1063/1.88060

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A surface acoustic wave resonator is described which utilizes electrically shorted gratings to form a resonant acoustic cavity where energy is introduced and removed by means of a short interdigital transducer placed in the center. Experimental results are presented for a device with two 100−finger pair gratings and a 9.5−finger pair central interdigital transducer (IDT) and compared with theoretical calculations. The device exhibits a resonantQof 2300 at 47.55 MHz.

ISSN:0003-6951    

DOI:10.1063/1.88061

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A new type of acoustic waveguide analogous to the clad optical fiber waveguide is described and experimental results are given. Modes exist in this structure which confine the acoustic energy to approximately the core due to the lower acoustical velocity in this region. The waveguide is excited with specially electroded bulk shear transducers bonded to the end surfaces. In the ∼100−MHz region both radial and torsional type modes may be attractive for long−delay (near 1 msec) low−loss serial memory applications.

ISSN:0003-6951    

DOI:10.1063/1.88062

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A simple method is presented by which the voltage between electrodes on an interdigital surface acoustic wave (SAW) transducer is varied by means of capacitive voltage division. Using this technique, a capacitor is added in series with the capacitance of an electrode pair through the use of a single photolithographic mask. The capacitance values are determined by geometry alone. This method permits voltage weighting both transducers of a device, and it minimizes the effects of diffraction. Experimental results are presented in which the sidelobes in a SAW filter have been reduced to 45 dB below the passband level.

ISSN:0003-6951    

DOI:10.1063/1.88063

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

Experimental data are presented for shock propagation along the ⟨111⟩ crystallographic direction in single−crystal LiF. Within experimenal bounds, an elastic response to 30 kbar is observed. This is in marked contrast with identical ⟨100⟩ crystals and earlier studies on other single crystals. The elastic behavior along the ⟨111⟩ direction is in good agreement with low stress and strain rate studies but raises interesting questions regarding crystal strength and dislocation mechansim operative under shock loading.

ISSN:0003-6951    

DOI:10.1063/1.88064

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

The first measurements of multiphonon absorption in fluorites carried out by the technique of spectral emittance are reported. Also, the first detailed comparison of theory and experiment for multiphonon absorption in fluorites is carried out, utilizing the present as well as previous data. The results provide strong evidence of intrinsic behavior over a wide range of frequencies above the Rehstrahl in these crystals.

ISSN:0003-6951    

DOI:10.1063/1.88065

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

A high−angular−resolution retarding−grid minianalyzer has been constructed for studying the amplitudes of Auger electron signals as a function of emission angle. With a resolution of 2° in angle and 1% in energy, a correlation was established between the directions of maximum emission of the As 12−eV peak and the open crystallographic directions of the Kikuchi−like display from As (0001).

ISSN:0003-6951    

DOI:10.1063/1.88066

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

Heterostructure CdS1−xSex−CdS surface lasers which have a larger refractive index and a smaller band gap than CdS substrates were fabricated by vapor phase epitaxy and their laser characteristics at 80 K were studied by using a nitrogen gas laser excitation. The Se profiles which were deduced from the fluorescence wavelength were steplike but graded due to diffusion. The optical gain of the epitaxially grown surface layer was larger than that of CdS single crystal owing to optical confinement. By stripe geometry excitation, an intense axial single−mode output was observed up to the excitation intensity three times as high as the threshold 70 kW/cm2. Optical coupling between the active and passive layers was observed in the samples which have a double epitaxial layer.

ISSN:0003-6951    

DOI:10.1063/1.88067

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

Utilizing an electrically pumped single−heterostructure GaAs/GaAlAs distributed−feedback laser diode operating in fourth order we have obtained a highly collimated laser beam which is coupled out normal to the plane of thep−njunction rather than through the cleaved end mirrors. This beam is found to have an angular divergence of 0.35° in the dimension determined by the grating and is virtually 100% polarized with theEvector parallel to the grooves of the corrugated feedback structure.

ISSN:0003-6951    

DOI:10.1063/1.88068

出版商:AIP    

年代:1975

数据来源: AIP

摘要:

The deformation behavior of pulsed double−heterostructure diode lasers at both mirror and contact surfaces was investigated by means of an interferometric technique. The diodes, which were only supported by the pressure of a wire connection, showed at the end of a current pulse an elongation and deflection behavior. Longitudinal and flexural vibrations of the diodes were measured after the application of a single current pulse and for the flexural vibrations a resonance behavior was observed during a current pulse train.

ISSN:0003-6951    

DOI:10.1063/1.88051

出版商:AIP    

年代:1975

数据来源: AIP