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  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 1569-1571 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: GaN:Mg/AlGaN single-heterojunction light-emitting diodes were grown on Si(111) substrates by plasma-assisted molecular-beam epitaxy. High-quality Mg-doped GaN layers with hole concentrations up to 1.2×1017 holes/cm3 and intense low-temperature photoluminescence, which increases in annealed samples, were obtained. Smooth AlGaN layers, with surface roughness below 5 nm, were used as buffer layers. Continuous-wave room-temperature ultraviolet electroluminescence was observed at 365 nm with a full width at half maximum of 8 nm. An estimated optical power output of 1.5 μW was achieved under 15 V/35 mA operation. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 8174-8180 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Amorphous carbon films with an sp3 content up to 25% and a negligible amount of hydrogen have been grown by evaporation of graphite with concurrent Ar+ ion bombardment. The sp3 content is maximized for Ar+ energies between 200 and 300 eV following a subplantation mechanism. Higher ion energies deteriorate the film due to sputtering and heating processes. The hardness of the films increases in the optimal assisting range from 8 to 18 GPa, and is explained by crosslinking of graphitic planes through sp3 connecting sites. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 87 (2000), S. 74-77 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: The use of a new Brillouin spectroscopic technique evidences the existence of internal stresses in white plasma assisted chemical vapor deposited diamond and allows a first assessment concerning their magnitude. The evaluation of the internal stresses is based on the pressure coefficients related to the longitudinal and transverse elastic constants. © 2000 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 85 (1999), S. 7349-7354 
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: A direct evaluation of elastic properties and refractive indices of sol–gel derived calcium modified lead titanate films has been made by means of Brillouin spectroscopy using a new experimental configuration. Amorphous films deposited on platinized substrates were treated at temperatures between 350 and 650 °C, using rapid thermal annealing. A variation of the sound velocity in the films with the annealing temperature was measured. A clear decrease at 375 °C and a continuous softening of the sound velocity up to 475 °C were observed. The latter is followed by a jump toward higher values of the sound velocity when the samples are treated at higher temperatures. Grazing incidence x-ray diffraction and profilemetry have been used to monitor structural changes and variation of film thickness with temperature, inferring relations among these parameters and properties obtained from the Brillouin measurements. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 71 (2000), S. 2563-2571 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A new electronic design for continuous monitoring of the motional series resonant frequency of a quartz crystal microbalance either in vacuum or in single-face contact with a fluid medium is presented. The motional resistance is directly measured and a simple method for measuring L and C parameters of the Butterworth–Van Dyke equivalent circuit is described. The results are in agreement with impedance analyzer measurements. © 2000 American Institute of Physics.
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  • 6
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 2738-2739 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A straight-through high vacuum gate valve with Conflat(R) type flanges, well within the manufacturing capabilities of small workshops is described. The valve is based on the translational displacement of only one part provided with a grove for a standard Viton O ring. Other sealings are performed with Viton and Teflon gaskets. The valve requires relatively small space in the pipeline direction, and is bakeable to 150 °C, open. © 1995 American Institute of Physics.
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  • 7
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 66 (1995), S. 5288-5291 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: A conduction calorimeter where the sample is pressed between two identical heat fluxmeters, each having 50 chromel–constantan thermocouples, is described. The fluxmeters were built to obtain linear heat conduction and with enough rigidity to apply a controlled uniaxial stress on the sample. The method of measurement, together with the fact that the sensors themselves apply the stress to the sample, allow us to obtain absolute values of the specific heat. The specific heat of strontium titanate ferroelastic crystal is measured without stress and under an applied uniaxial stress on the face (110). The measurements were carried out while cooling the sample at a constant rate of 0.06 K/h. The data obtained at intervals of 0.02 K are compared with those obtained with an unannealed and an annealed sample, respectively. © 1995 American Institute of Physics.
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  • 8
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 65 (1994), S. 229-241 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: An innovative, Couette-type viscometer/rheometer was developed, designed, and fabricated with the main objective being to measure viscosity and elastic properties of low-viscous, non-Newtonian, and visco-elastic fluids, like dilute polymer solutions. The goal was to simplify and improve some existing drawbacks of commercial instruments employing several novel design solutions, particularly with regard to instrument precision and sensitivity. With a single pair of cylinders and a torsion bar stiffness of 0.116 Nm/rad, viscosities from 0.5 to 50 000 cP (centi-Poise) in a shear-rate range from 1 to 200 s−1, and oscillatory tests from 0.1 to 10 Hz, could be measured. The transducers' electronic signals are handled by a software, developed in C language, and an IBM-PC compatible computer with a data acquisition board. The innovative design solutions (use of a cruciform torsion bar, optoelectronics sensors, and a novel alignment procedure) have improved the critical instrument performance and reduced the number and cost of components, customarily used in commercial viscometers/rheometers. The overall steady shear-rate calibration was performed using the standard-viscosity fluids of 51 and 445 cP. Initial results show high precision (around 4%), particularly at higher velocities. The oscillatory testing was performed by measuring the phase shift between the stress and strain for viscoelastic fluids and for the limiting case of a standard Newtonian fluid. The novel design has proved efficient and with potential for further improvements.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 57 (1986), S. 499-499 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: It is suggested how an ordinary differential Bourdon gauge can easily be transformed into an absolute manometer.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 56 (1985), S. 1262-1264 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: Two devices which can be used in switching experiments on bulk samples, capable of eliminating the instability in electrical contacts, as well as providing a means of regulating the contact pressure of the electrodes, are described. To clarify the utility of these devices, the results of a study on the dependence between the parameters electrical resistance and contact pressure are shown, as well as some results obtained from experiments based on the phenomenon of electrical switching.
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