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Dec 1999

Volume 70, Issue 12, pp. 4457-4738

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back to top CONDENSED MATTER; MATERIALS

Improved laser-heated pedestal growth system for crystal growth in medium and high isostatic pressure environment

D. Reyes Ardila, J. P. Andreeta, C. T. M. Ribeiro, and M. Siu Li

Rev. Sci. Instrum. 70, 4606 (1999); http://dx.doi.org/10.1063/1.1150120 (3 pages) | Cited 6 times

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A modified apparatus for single-crystal-fiber growth in an isostatic gaseous environment and for a large range of pressure (100 mbar up to 100 bar) using a floating-zone-type method known as laser-heated pedestal growth is described. The difficulties and advantages of its design are discussed through examples of crystal growth of some oxide materials. © 1999 American Institute of Physics.
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81.10.Fq Growth from melts; zone melting and refining
42.62.-b Laser applications

The double-diamond anvil cell, the poor-man’s megabar pressure cell

Isaac F. Silvera

Rev. Sci. Instrum. 70, 4609 (1999); http://dx.doi.org/10.1063/1.1150121 (3 pages) | Cited 4 times

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We present a new configuration for diamond anvils used in high pressure research. We show how to make a gasketed diamond indentor cell (DIC) in a conventional diamond anvil cell (DAC). Moreover, diamond anvils an order of magnitude smaller than those currently used can easily be mounted, with minor modification. These configurations are called DIC-DACs and double DACs (D-DACs). D-DACs have been tested to a megabar and appear to have the same range as a conventional DAC. D-DACs can lower the cost of diamonds for high pressure research by more than an order of magnitude. © 1999 American Institute of Physics.  
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07.35.+k High-pressure apparatus; shock tubes; diamond anvil cells

Microindentation device for in situ study of pressure-induced phase transformations

Yury Gogotsi, Thomas Miletich, Michael Gardner, and Michael Rosenberg

Rev. Sci. Instrum. 70, 4612 (1999); http://dx.doi.org/10.1063/1.1150122 (6 pages) | Cited 13 times

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In situ microscopic and spectroscopic studies of samples allow us to understand the mechanisms and measure kinetics of phase transformations in materials. We use a light microscope and a Raman microspectrometer to study phase transformations induced by contact loading. Many interesting phenomena occur in materials during indentation that can only be analyzed during indentation, in situ. By analyzing what occurs to ceramics and semiconductors in situ we can gain valuable insight into the mechanisms and kinetics of phase transformation. A microindentation device has been designed and fabricated to achieve these objectives. The microindentation device can provide the means to study pressure-induced phase transformations in real time. The basic design of the device is adaptable to several configurations, so that the device may be used in a wide variety of applications. The device consists of a piezoelectric actuator (piezoelectric translator), load cell, linear microscrew stage, translation stage containing the specimen mount and specimen holder, and diamond-tip indenter. For the first time, an indentation tester has been coupled with a Raman microspectrometer to conduct in situ studies of pressure-induced phase transformations. This article describes the design, operation, and experimentation of a microindentation device for the in situ analysis of pressure-induced phase transformations in materials. © 1999 American Institute of Physics.
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07.35.+k High-pressure apparatus; shock tubes; diamond anvil cells
62.50.-p High-pressure effects in solids and liquids
64.70.K- Solid-solid transitions

High temperature ultrasonic sensor for the simultaneous measurement of viscosity and temperature of melts

Krishnan Balasubramaniam, Vimal V. Shah, R. Daniel Costley, Gary Boudreaux, and Jagdish P. Singh

Rev. Sci. Instrum. 70, 4618 (1999); http://dx.doi.org/10.1063/1.1150123 (6 pages) | Cited 9 times

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An ultrasonic sensor that simultaneously measures temperature and viscosity of molten materials at very high temperature is described. This sensor has applications as a process monitor in melters. The sensor is based on ultrasonic shear reflectance at the solid–melt interface. A delay line probe is constructed using refractory materials. A change in the time of flight within the delay line is used to measure the temperature. The results obtained from this sensor on various calibration glass samples demonstrate a measurement range of 100–20 000 P for the viscosity and 25–1500 °C for the temperature. © 1999 American Institute of Physics.
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43.35.Yb Ultrasonic instrumentation and measurement techniques
47.80.-v Instrumentation and measurement methods in fluid dynamics
07.20.Dt Thermometers
07.20.Ka High-temperature instrumentation; pyrometers
43.38.Fx Piezoelectric and ferroelectric transducers

A novel quartz dendritic growth chamber for low temperature microgravity experimentation

Dean S. Schrage and Diane C. Malarik

Rev. Sci. Instrum. 70, 4624 (1999); http://dx.doi.org/10.1063/1.1150124 (10 pages) | Cited 1 time

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The material science community has demonstrated keen interest in performing a range of thermodiffusional dendritic growth studies in microgravity. While each of these experiments differ in the thermal-physical properties of the test fluid, the initial dendrite seeding configuration, and the resultant dendrite morphology, they are similar as each must be conducted within a growth chamber. Clearly, the growth chamber is the single most crucial experimental component because the ambience delivered by the chamber intrinsically effects the resultant dendritic growth. A unique sample chamber, comprised nearly entirely of precision machined quartz components, was developed for use in the microgravity experiment Isothermal Dendritic Growth Experiment (IDGE), which was conducted in the cargo bay of the Space Shuttle Columbia, as part of the Fourth United States Microgravity Payload (USMP-4), in November 1997. The growth chamber discussed is conventional in the selection of the construction materials, but is unique and unconventional from the standpoint of the quartz fabrication and microgravity operation. First, the selection of a fused quartz material was design enabling because the test fluid, pivalic acid, an organic material which melts at 35.975 °C, could be maintained ultrapure over the three-year duration of the complete experiment (assembling, ground test, shuttle integration, flight). Second, the quartz chamber has demonstrated large-scale fabrication of complicated fused quartz pieces, into a final monolithic structure. Third, the quartz chamber was successfully interfaced with ancillary hardware and was not damaged or operationally compromised through ground testing, shuttle launch, microgravity experimentation and shuttle return. Fourth and finally, the chamber has demonstrated a novel means to control, in a microgravity environment, a vapor bubble, which was included in the chamber to provide a volume dedicated to the expansion of the sample fluid during heating. The bubble was controlled by applying a Couette flow device to generate a transient, controlled cavitation of the test fluid. Overall, the critical technologies derived in the present study should lend themselves directly to the development of future microgravity dendritic growth experiments, thereby minimizing program risk and cost. © 1999 American Institute of Physics.
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81.10.Mx Growth in microgravity environments
68.70.+w Whiskers and dendrites (growth, structure, and nonelectronic properties)
81.10.Fq Growth from melts; zone melting and refining
06.60.Ei Sample preparation (including design of sample holders)

Thermal diffusivity measurement of silicon samples by a combined piezoelectric and pyroelectric method

M. Aravind and P. C. W. Fung

Rev. Sci. Instrum. 70, 4634 (1999); http://dx.doi.org/10.1063/1.1150125 (6 pages) | Cited 4 times

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In the past, when thermal diffusivity measurement of materials were carried out by photoacoustic signal detection using transducers, only the piezoelectric or the pyroelectric property of the transducers was considered. In case the transducer exhibits both piezoelectric and pyroelectric properties, one of these properties had been suppressed during the experimentation, obviously more errors are introduced this way. We use polyvinylidene difluoride (PVDF) as the detector for thermal waves. Since PVDF has both piezoelectric and pyroelectric properties, we show in this article that the signal detected by the transducer is a sum of both the piezoelectric and pyroelectric effects. Silicon semiconductor samples are considered in this article to compare the theory with experimental results. Although both the piezoelectric and pyroelectric properties are found in the resultant signal at all the frequency ranges considered, we find that when the samples are thermally thick, the piezoelectric contribution to the detected signal is slightly more than the pyroelectric contribution and vice versa when the sample is thermally thin. This behavior of the combined signal can be explained by the fact that in an optically opaque solid heat is generated very close to the surface, following absorption. This heat is communicated to the PVDF as long as the thermal diffusion length is larger than the thickness (i.e., the sample is thermally thin). At high frequencies the solid becomes thermally thick and the pyroelectric nature decreases as both the optical and thermal contact of the sample with the detector diminishes. Since both the properties are considered in our theory, we can measure the thermal diffusivity of a general sample without “artificial suppression.” Moreover, from our analysis we can deduce the physical thickness of the sample from the critical frequency, which is the frequency at which the sample changes from thermally thin to thermally thick. This transition is clearly evident in the amplitude curve as a change in slope is detected at the critical frequency. © 1999 American Institute of Physics.
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07.20.-n Thermal instruments and apparatus
66.70.-f Nonelectronic thermal conduction and heat-pulse propagation in solids; thermal waves
85.50.-n Dielectric, ferroelectric, and piezoelectric devices

A superconducting quantum interference device magnetometer system for quantitative analysis and imaging of hidden corrosion activity in aircraft aluminum structures

A. Abedi, J. J. Fellenstein, A. J. Lucas, and J. P. Wikswo

Rev. Sci. Instrum. 70, 4640 (1999); http://dx.doi.org/10.1063/1.1150126 (12 pages) | Cited 18 times

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We have designed and built a magnetic imaging system for quantitative analysis of the rate of ongoing hidden corrosion of aircraft aluminum alloys in planar structures such as intact aircraft lap joints. The system utilizes a superconducting quantum interference device (SQUID) magnetometer that measures the magnetic field associated with corrosion currents. It consists of a three-axis (vector) SQUID differential magnetometer, magnetic, and rf shielding, a computer controlled x-y stage, sample registration, and positioning mechanisms, and data acquisition and analysis software. The system is capable of scanning planar samples with dimensions of up to 28 cm square, with a spatial resolution of 2 mm, and a sensitivity of 0.3 pT/Hz1/2 (at 10 Hz). In this article we report the design and technical issues related to this system, outline important data acquisition techniques and criteria for accurate measurements of the rate of corrosion, especially for weakly corroding samples, and present preliminary measurements. © 1999 American Institute of Physics.
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81.70.Ex Nondestructive testing: electromagnetic testing, eddy-current testing
85.25.Dq Superconducting quantum interference devices (SQUIDs)
07.55.Ge Magnetometers for magnetic field measurements
07.05.Hd Data acquisition: hardware and software

Laser-induced rotation of a levitated sample in vacuum

Won-Kyu Rhim and Paul-François Paradis

Rev. Sci. Instrum. 70, 4652 (1999); http://dx.doi.org/10.1063/1.1150127 (4 pages) | Cited 18 times

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A method of systematically controlling the rotational state of a sample levitated in a high vacuum using the photon pressure is described. A zirconium sphere was levitated in the high-temperature electrostatic levitator and it was rotated by irradiating it with a narrow beam of a high-power laser on a spot off the center of mass. While the laser beam heated the sample, it also rotated the sample with a torque that was proportional both to the laser power and the length of the torque arm. A simple theoretical basis was given and its validity was demonstrated using a solid zirconium sphere at ∼2000 K. This method will be useful to systematically control the rotational state of a levitated sample for the containerless materials processing at high temperature. © 1999 American Institute of Physics.
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37.10.Vz Mechanical effects of light on atoms, molecules, and ions
07.20.Ka High-temperature instrumentation; pyrometers
42.62.Cf Industrial applications
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