Volume 77, Issue 5, May 2006
Index of content:
- CONDENSED MATTER; MATERIALS
Noncontact surface tension and viscosity measurements of molten oxides with a pressurized hybrid electrostatic-aerodynamic levitator77(2006); http://dx.doi.org/10.1063/1.2198787View Description Hide Description
In order to measure the surface tension and the viscosity of molten oxides, the oscillation drop technique has been applied on a pressurized hybrid electrostatic-aerodynamic levitator. To suppress the electrical discharge between the top and bottom electrodes, the drop excitation method which has been used with high vacuum electrostatic levitators has been modified. As a demonstration, the surface tension and viscosity of liquid were measured using this new method. Over the interval, the surface tension was measured as , where is the melting temperature. Similarly, the viscosity was determined as over the same temperature interval.
77(2006); http://dx.doi.org/10.1063/1.2198833View Description Hide Description
A new experimental method describing the determination of the mechanical spectra (complex Young’s modulus versus temperature) of materials from the liquid to the glassy state, including the glass transition, is reported. The conventional vibration-reed method developed for solids is extended to composite systems consisting of a reed substrate and a deposited material. Mathematical expressions for the evaluation of the mechanical spectrum of the deposited material are obtained by solving either directly the vibrating equation of the nonuniform reed, or that of an equivalent uniform reed, with new length and stiffness, using a coordinate transformation. The mechanical spectra of glycerol and 1,2-propanediol carbonate covering the liquid and the glassy state are presented as examples in this work. The glass transitions of these two kinds of materials, as well as the recrystallization, melting and, evaporation processes of 1,2-propanediol carbonate, are identified in the respective spectra.
77(2006); http://dx.doi.org/10.1063/1.2200756View Description Hide Description
We describe a new high temperature environment based on aerodynamic levitation and laser heating designed for neutron scattering experiments up to . The sample is heated to the desired temperature with three lasers from different directions in order to obtain a homogeneous temperature distribution. The apparent temperature of the sample is measured with an optical pyrometer, and two video cameras are employed to monitor the sample behavior during heating. The levitation setup is enclosed in a vacuum-tight chamber, enabling a high degree of gas purity and a reproducible sample environment for structural investigations on both oxide and metallic melts. High-quality neutron diffraction data have been obtained on liquid and ZrNi alloy for relatively short counting times .
Facile, nanoresolution translation setup for the growth of organic crystal meta-nitroaniline by Bridgman technique77(2006); http://dx.doi.org/10.1063/1.2202930View Description Hide Description
A nanoresolution translation setup for Bridgman technique was designed and employed for the growth of organic crystalmeta-nitroaniline using stepper motor. Ultrasmooth and vibration-free translation was accomplished in microstepping mode. Linear translation of per microstep has been achieved. A potential molecular organic crystalmeta-nitroaniline of diameter and length has been successfully grown with good optical quality. Ultraviolet-visible-near-infrared spectra showed excellent transmission from . Etching studies reveal lower defect density.
77(2006); http://dx.doi.org/10.1063/1.2204907View Description Hide Description
We describe a new experimental technique to investigate coupling effects between different layers or modes in ferromagnetic resonance (FMR). Dual FMR frequencies are excited simultaneously and detected selectively in a broadband rf circuit using lock-in amplifier detection at separate modulation frequencies.