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Feb 2011

Volume 82, Issue 2, Articles (02xxxx)

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back to top Condensed Matter; Materials

A novel method for on-orbit measurement of space materials degradation

Ronen Verker, Eitan Grossman, and Irina Gouzman

Rev. Sci. Instrum. 82, 023901 (2011); http://dx.doi.org/10.1063/1.3529878 (7 pages) | Cited 1 time

Online Publication Date: 1 February 2011

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The low Earth orbit (LEO) environment is considered hazardous to spacecraft, resulting in materials degradation. Currently, in order to evaluate the degradation of materials in LEO, a retrieval of space exposed samples is required. In this study, a novel approach is proposed to evaluate degradation of materials in LEO without the need of retrieval. The method is utilizing photovoltaic cells (PVCs), an existing component onboard of any satellite. The PVCs are coated by various materials which are sensitive to different LEO constituents, such as atomic oxygen (AO) or ultra-violet (UV) radiation. The method's acronym is ORMADD (on-ORbit MAterials Degradation Detector). The ORMADD's principle of operation is based on measuring the PVC output power which depends on the cell coating material's optical transmission. Erosion of the coating by AO or coloring due to UV radiation affects its optical transmission and, accordingly, the PVC output. The ORMADD performance was tested using different coatings, such as polyimide and amorphous carbon (sensitive to AO), and siloxane based coating which is sensitive to UV radiation. The proposed ORMADD reveals sensitivity to different LEO components and can be used either as material degradation detector or as an AO monitor.
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89.40.Dd Air transporation
85.60.Gz Photodetectors (including infrared and CCD detectors)
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)

Pressure cell for investigations of solid–liquid interfaces by neutron reflectivity

Martin Kreuzer, Thomas Kaltofen, Roland Steitz, Beat H. Zehnder, and Reiner Dahint

Rev. Sci. Instrum. 82, 023902 (2011); http://dx.doi.org/10.1063/1.3505797 (7 pages) | Cited 4 times

Online Publication Date: 9 February 2011

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We describe an apparatus for measuring scattering length density and structure of molecular layers at planar solid–liquid interfaces under high hydrostatic pressure conditions. The device is designed for in situ characterizations utilizing neutron reflectometry in the pressure range 0.1–100 MPa at temperatures between 5 and 60 °C. The pressure cell is constructed such that stratified molecular layers on crystalline substrates of silicon, quartz, or sapphire with a surface area of 28 cm2 can be investigated against noncorrosive liquid phases. The large substrate surface area enables reflectivity to be measured down to 10−5 (without background correction) and thus facilitates determination of the scattering length density profile across the interface as a function of applied load. Our current interest is on the stability of oligolamellar lipid coatings on silicon surfaces against aqueous phases as a function of applied hydrostatic pressure and temperature but the device can also be employed to probe the structure of any other solid–liquid interface.
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68.08.De Liquid-solid interface structure: measurements and simulations
87.16.D- Membranes, bilayers, and vesicles

Photopyroelectric response of PTCa/PEEK composite

Giuliano Pierre Estevam, Washington Luiz Barros de Melo, and Walter Katsumi Sakamoto

Rev. Sci. Instrum. 82, 023903 (2011); http://dx.doi.org/10.1063/1.3552193 (6 pages) | Cited 1 time

Online Publication Date: 17 February 2011

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A pyroelectric composite made of calcium modified lead titanate ceramic and polyether–ether–ketone high performance polymer was obtained in the film form by hot pressing the ceramic/polymer mixture into the desired composition. After polarization with a suitable electric field, a ceramic composite film (60% vol.) exhibited a pyroelectric figure of merit three times higher than that of a lead zirconate titanate ceramic. The material was used as infrared radiation sensor. The voltage responsivity decreases with the inverse of the frequency showing the same behavior of the thermally thick sensor. The reproducibility of the sensor responses was observed.
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85.60.Gz Photodetectors (including infrared and CCD detectors)
78.20.nc Photopyroelectric effects

High efficiency multichannel collimator for structural studies of liquids and low-Z materials at high pressures and temperatures

G. Morard, M. Mezouar, S. Bauchau, M. Álvarez-Murga, J.-L. Hodeau, and G. Garbarino

Rev. Sci. Instrum. 82, 023904 (2011); http://dx.doi.org/10.1063/1.3551988 (6 pages) | Cited 1 time

Online Publication Date: 18 February 2011

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A high efficiency multichannel collimator (MCC) device has been developed at the high pressure beamline ID27 of the European Synchrotron Radiation Facility to drastically reduce the x-ray background from the sample environment in the Paris-Edinburgh press. The main technical difficulty, which resides in the minimum slits size achievable using the classical mono-bloc design, has been resolved using an original concept based on a set of independent slits. Then, a very small slit size of 50 μm was manufactured resulting in a great improvement of the signal to background ratio. In addition, the transfer function of the MCC has been measured using the x-ray diffusion signal of a metal doped glass and efficiently applied to correct the raw data. The potential of this new device is illustrated in two challenging examples: iron–sulfur liquid structures and C60 polymerization process at high pressure and high temperature.
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07.85.-m X- and γ-ray instruments

A broadband and high throughput single-monochromator Raman spectrometer: Application for single-wall carbon nanotubes

Gábor Fábián, Christian Kramberger, Alexander Friedrich, Ferenc Simon, and Thomas Pichler

Rev. Sci. Instrum. 82, 023905 (2011); http://dx.doi.org/10.1063/1.3544023 (5 pages) | Cited 3 times

Online Publication Date: 18 February 2011

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See Also: Publisher's Note

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We present a high sensitivity single-monochromator Raman spectrometer which allows operation with a tunable laser source. The instrument is based on the modification of a commercial Raman spectrometer; such instruments operate with interference Rayleigh filters which also act as laser mirrors and are usually considered as inherently narrow band. In our design, the two tasks are separated and the filter can be freely rotated without much effect on the light alignment. Since rotation shifts the filter passband, this modification allows tunable operation with efficient stray light filtering down to 150 cm−1. The design is optimized for single-wall carbon nanotubes, for which the performance is demonstrated using a tunable dye laser source. The spectrometer thus combines the high sensitivity with the broadband characteristics of usual triple monochromator systems.
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81.07.De Nanotubes
78.67.Ch Nanotubes
78.30.Na Fullerenes and related materials
78.20.Ek Optical activity
42.79.Ci Filters, zone plates, and polarizers
42.79.Bh Lenses, prisms and mirrors

Combined ultrasonic elastic wave velocity and microtomography measurements at high pressures

Yoshio Kono, Akihiro Yamada, Yanbin Wang, Tony Yu, and Toru Inoue

Rev. Sci. Instrum. 82, 023906 (2011); http://dx.doi.org/10.1063/1.3552185 (7 pages) | Cited 2 times

Online Publication Date: 23 February 2011

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Combined ultrasonic and microtomographic measurements were conducted for simultaneous determination of elastic property and density of noncrystalline materials at high pressures. A Paris–Edinburgh anvil cell was placed in a rotation apparatus, which enabled us to take a series of x-ray radiography images under pressure over a 180° angle range and construct accurately the three-dimensional sample volume using microtomography. In addition, ultrasonic elastic wave velocity measurements were carried out simultaneously using the pulse reflection method with a 10° Y-cut LiNbO3 transducer attached to the end of the lower anvil. Combined ultrasonic and microtomographic measurements were carried out for SiO2 glass up to 2.6 GPa and room temperature. A decrease in elastic wave velocities of the SiO2 glass was observed with increasing pressure, in agreement with previous studies. The simultaneous measurements on elastic wave velocities and density allowed us to derive bulk (Ks) and shear (G) moduli as a function of pressure. Ks and G of the SiO2 glass also decreased with increasing pressure. The negative pressure dependence of Ks is stronger than that of G, and as a result the value of Ks became similar to G at 2.0–2.6 GPa. There is no reason why we cannot apply this new technique to high temperatures as well. Hence the results demonstrate that the combined ultrasonic and microtomography technique is a powerful tool to derive advanced (accurate) P–V–Ks–G–(T) equations of state for noncrystalline materials.
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43.35.Yb Ultrasonic instrumentation and measurement techniques
07.85.-m X- and γ-ray instruments

Effect of window reflections on photonic Doppler velocimetry measurements

T. Ao and D. H. Dolan

Rev. Sci. Instrum. 82, 023907 (2011); http://dx.doi.org/10.1063/1.3551954 (8 pages) | Cited 3 times

Online Publication Date: 24 February 2011

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Photonic Doppler velocimetry (PDV) has rapidly become a standard diagnostic for measuring velocities in dynamic compression research. While free surface velocity measurements are fairly straightforward, complications occur when PDV is used to measure a dynamically loaded sample through a window. Fresnel reflections can severely affect the velocity and time resolution of PDV measurements, especially for low-velocity transients. Shock experiments of quartz compressed between two sapphire plates demonstrate how optical window reflections cause ringing in the extracted PDV velocity profile. Velocity ringing is significantly reduced by using either a wedge window or an antireflective coating.
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06.30.Gv Velocity, acceleration, and rotation

Calorimetry of epitaxial thin films

David W. Cooke, F. Hellman, J. R. Groves, B. M. Clemens, S. Moyerman, and E. E. Fullerton

Rev. Sci. Instrum. 82, 023908 (2011); http://dx.doi.org/10.1063/1.3554440 (4 pages) | Cited 4 times

Online Publication Date: 24 February 2011

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Thin film growth allows for the manipulation of material on the nanoscale, making possible the creation of metastable phases not seen in the bulk. Heat capacity provides a direct way of measuring thermodynamic properties of these new materials, but traditional bulk calorimetric techniques are inappropriate for such a small amount of material. Microcalorimetry and nanocalorimetry techniques exist for the measurements of thin films but rely on an amorphous membrane platform, limiting the types of films which can be measured. In the current work, ion-beam-assisted deposition is used to provide a biaxially oriented MgO template on a suspended membrane microcalorimeter in order to measure the specific heat of epitaxial thin films. Synchrotron x-ray diffraction showed the biaxial order of the MgO template. X-ray diffraction was also used to prove the high quality of epitaxy of a film grown onto this MgO template. The contribution of the MgO layer to the total heat capacity was measured to be just 6.5% of the total addenda contribution. The heat capacity of a Fe.49Rh.51 film grown epitaxially onto the device was measured, comparing favorably to literature data on bulk crystals. This shows the viability of the MgO/SiNx-membrane-based microcalorimeter as a way of measuring the thermodynamic properties of epitaxial thin films.
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07.20.Fw Calorimeters
81.15.Jj Ion and electron beam-assisted deposition; ion plating
68.55.aj Insulators
65.40.Ba Heat capacity

Viscometer using drag force measurements

M. H. Noël, B. Semin, J. P. Hulin, and H. Auradou

Rev. Sci. Instrum. 82, 023909 (2011); http://dx.doi.org/10.1063/1.3556445 (7 pages) | Cited 2 times

Online Publication Date: 28 February 2011

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A robust and precise viscometer using the forces exerted by a laminar flow inside a small duct is presented: the force is measured on a long cylindrical sensor dipped into the flow. Two devices of respective volumes 1.4 and 0.031 ml have been realized, demonstrating that the technique is usable with small fluid volumes. Several Newtonian and non-Newtonian fluids have been tested at shear rates ranging from 0.3 to 10 s−1 for the first device and from 85 to 2550 s−1 for the second one. For Newtonian fluids, of viscosities ranging from 10−3 to 0.1 Pa s, the linear response of the device has been verified and a 90% agreement with the values provided by commercial rheometers is obtained. For non-Newtonian polymer solutions, the variation of the force with the flow velocity allows one to determine the dependence of the viscosity on the shear rate. Two shear thinning polymer solutions with a power law behavior at intermediate shear rates have been investigated and their rheological parameters have been determined.
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47.80.-v Instrumentation and measurement methods in fluid dynamics
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