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Recently, study of physical properties of the liquid mixtures, their nature and behavior with change in frequency, temperature or concentration has gained interest. In the present work, ultrasonic velocity and attenuation measurements have been carried out in the binary mixture of nitrobenzene and ethanol using pulse echo technique in the temperature range of 274.15K-308.15K maintaining the temperature of the sample with an accuracy of ±0.1°C. It is observed that the mixture of nitrobenzene and ethanol shows maximum absorption at 277.15K at 0.27 moles of Nitrobenzene in the binary mixture. Critical nature of the mixture revealed by ultrasonic absorption indicates the molecular interaction between two liquids and attributes due to the fluctuation in the concentration.

The velocity and attenuation of longitudinal and transverse ultrasonic waves in (PbO)x–(V2O5)y–(P2O5)1−x−y glass systems of different compositions have been measured at temperatures between 80 and 300 K using the ultrasonic pulse echo overlap technique at 10 MHz. For each sample the velocity data have been used to find the elastic moduli and Debye temperature at different temperatures. The results indicate that for each sample, the velocities decrease slowly and steadily with increasing temperature. The temperature dependence of ultrasonic attenuation has been explained in terms of a thermally activated relaxation process. On the other hand, the combined effect of relaxation, anharmonicity, and the effect due to frozen-in fluctuation is taken into consideration to explain the variation of velocity with temperature.

The objective of this paper is to show that time-reversal invariance can be exploited in acoustics to accurately control wave propagation through complex media and create a variety of useful instruments. To illustrate the robustness of time reversal mirrors, several experiments conducted in multiply scattering media, in waveguides and in reverberant cavities are presented. They show that, contrary to long-held beliefs, multi pathing and multiple scattering enhances resolution in time reversal focusing, by making the effective size of the time reversal mirror much larger than its physical size. Applications of time-reversal mirrors in pulse echo detection and particularly in nondestructive testing will be discussed.

The acoustic velocities and their pressure dependence of various Zr- and Pd-based bulk metallic glasses (BMGs) have been measured by using a pulse echo overlap method. The elastic constants as well as their pressure dependence of the BMGs have been determined, and the equation of state of these BMGs was obtained and compared to that of other glasses and crystalline solids. The structural characteristic of the BMGs is discussed.

The acoustic velocities and their pressure dependence of bulk Zr41Ti14Cu12.5Ni9Be22.5C1 metallic glass (MG) have been measured up to 0.5 GPa by using a pulse echo overlap method. The elastic constants and thermodynamic parameters as well as their pressure dependence of the MG have been determined. The obtained elastic constants were compared to that of other kinds of glasses. More information about the microstructure, elastic properties, and glass forming ability of the MG was obtained.

We report an evolution of an all-digital ultrasonic pulse technique for measurements of elastic constants of solids. An unambiguous analytical procedure is described for determining the correct time delay of echoes without any need for actual echo overlap. We also provide a simple procedure for making corrections for transducer-bond-induced phase shifts. The precision of a measurement made with this system at ambient temperature exceeds one part in 107 without the use of mixers, gates, time delays, and other complications normally associated with such measurements.

Ultrasonic velocity measurements have been performed on a single crystal of cobalt disilicide by the pulse echo overlap method. The elastic constants have been calculated from the measurements of the propagation velocities of longitudinal and transverse waves in suitable crystallographic directions of the sample. The macroscopic elastic parameters of the cobalt disilicide were deduced from the elastic constants. They allow an estimation of the magnitude of the induced residual thermal stresses when this compound is present in a microelectronic device.

A new instrument is described which permits the travel time of ultrasonic waves to be measured accurately and conveniently by the pulse‐echo‐overlap method (PEO). The accuracy and versatility of the PEO method are reviewed, and optimal methods of preparing and interrogating samples are presented. Extensive data on a large blank of fused silica are presented. Longitudinal and shear wave velocities were calculated from the wave travel times through measured thicknesses, and the elastic moduli were subsequently calculated from the velocities and the measured density. Error analysis shows that the measurement of travel time contributed less than 20 ppm to the total error of about 400 ppm in the calculated moduli.

The five independent elastic constants of beryllium have been determined with the pulse echo technique at a frequency of 10 Mc/sec. The values extrapolated to 0°K are C11=29.94±0.06, C33=34.22±0.12, C44=16.62±0.05, C12=2.76±0.08, C13=1.1±0.5 in units of 1011 dyne/cm2. Voigt averaging and Reuss averaging of the single crystal elastic constants give excellent agreement because of the small magnitude of the nondiagonal elements, C12 and C13. The averaged values compare favorably with previous data from polycrystalline beryllium.

The frequency of the ``reference'' oscillator in a coherent pulse echo apparatus is phase‐locked to the spacing in time of the acoustic echoes. A change in echo spacing is thereby converted to the same fractional change of oscillator frequency, which is measured continuously. Echo spacing changes of 2 to 3 parts in 108 have been resolved at 12 Mc. The gated AFC circuit which controls the reference oscillator derives its error voltage from a phase‐detected echo. The error voltage is zero when the echo is in quadrature with the reference. When the echo spacing changes, the AFC shifts the reference frequency to preserve the quadrature condition. The system is largely insensitive to changes of echo amplitude because such changes do not affect the quadrature condition. The attainable accuracy is set mainly by the temperature stability of the sample. There is a detailed discussion of circuitry, performance, and suggested refinements.

The velocity of sound in liquid metals can be determined to ±0.01% using an ultrasonic pulse echo comparison technique. Several corrections must be taken into account due to thermal expansion effects in the apparatus and an apparent phase shifting to be described. The velocity of sound in liquid indium is presented as determined from this apparatus. Finally, a liquid metal cell of fused quartz is suggested which eliminates the thermal expansion effects and other operational problems of the described liquid metal cell.

The six adiabatic elastic stiffness constants of bismuth have been determined at 301°K by an ultrasonic pulse echo technique. The results are: c11 = 63.5, c33 = 38.1, c44 = 11.30, c66 = 19.4, c14 = +7.23, and c13 = 24.5, all in units of 1010 d/cm2. These values were redundantly determined by the measurement of 14 different velocities in four different single crystals of zone‐purified bismuth. The velocities are believed accurate to better than 1%, the principal error arising from the uncertainty of the transducer transit time correction. The moduli are in poor agreement with the previously determined static elastic compliance constants reported by Bridgman. Some data on the velocity of sound in bismuth at 98° and at 4.2°K are also presented.

The adiabatic elastic moduli of lead have been measured from 4.2° to 300°K using the ultrasonic pulse echo method. The Debye θn obtained from the 4.2° K modulus values is 105.3° K and is to be compared with the θn of 108° K obtained from specified heat measurements.

A superposed pulse echo overlap method is described as a method to determine ultrasonic sound velocity. This method has the advantages both of the pulse echo superposition and the pulse echo overlap methods; round‐trip time of echoes through the specimen was determined by overlapping the superposed echoes on the oscilloscope. Accurate and quick measurements of sound velocity in solids and liquids become possible by this method.

Circuitry for a simple and accurate ultrasonic attenuation recording system, for use with the pulse echo technique is described. Direct processing of low level signals and the use of generally available laboratory equipment reduce cost. Sensitivity is enhanced by the use of sufficient zero offset.

A technique is described for measuring ultrasonic attenuation by determining the inflectional points of ultrasonic standing wave resonance lines. Results obtained by this technique are compared to those obtained by the pulse echo technique. A suggestion is given for automating the system to make simultaneous measurements of velocity and attenuation

The velocities of the ultrasonic waves in sodium chlorate crystal, viz., V12 and V13, with propagation direction (100) and vibration direction (010) and (001), respectively, are found to be equal to within 0.1%. This shows that the classical theory of elasticity is adequate to describe the elastic behavior. The elastic constants of this crystal, obtained by the author using the pulse‐echo method, are also reported. The effect of piezoelectricity on the elastic constants of sodium chlorate crystal is shown to be too small, well within the present experimental accuracy.

Using an ultrasonic pulse echo technique operating at frequencies ∼10 Mc/sec, we have obtained the following elastic constants for cubic PbF2: C11=8.88×1011 dyn/cm2, C12=4.72×1011 dyn/cm2, C44=2.454×1011 dyn/cm2 at 27°C. From these data a Debye θ of 221.2°K was calculated.

A simple and inexpensive device is described which in conjunction with conventional pulse echo equipment allows the direct measurement of the time interval between the zeros of selected individual cycles in different echoes with an accuracy better than 0.2 ns.

A modified liquid buffer technique has been devised and used for the measurement of ultrasonic attenuation in polystyrene samples. The use of a small area probe makes the requirements on sample parallelism less stringent than with the usual single transducer pulse echo method. For this immersion technique rather large samples have to be used; while sample preparation is greatly facilitated.

Modification of the pulse‐echo‐overlap equipment to make it compatible with any ordinary scope, which does not have an intensity modulation facility, is described.

Ultrasonic paramagnetic resonance (UPR) techniques are given for recording the derivative of UPR absorption with respect to magnetic field and for measurement of spin relaxation rates. The X‐band pulse echo, spin relaxation spectrometer utilizes high power pulses from one magnetron to saturate the spin system. Low power pulses from another magnetron are then used to monitor the recovery from saturation by varying the delay between the saturating and monitoring pulses.