J. de Klerk

Elastic Constants of Single‐Crystal Mo and W between 77° and 500°K

Using a high frequency cw mechanical resonance technique, the adiabatic elastic constants of single crystals of molybdenum and tungsten were measured between 77° and 500°K.

Thermal and elastic properties of silicate oxyapatite crystals

The elastic constants, thermal expansion, thermal conductivity, and heat capacity are reported for a new class of laser hosts‐the silicate oxyapatites. For Ca2La8(SiO4)6O2 the five independent elastic constants obtained from sound velocity measurements are C11=1.71, C12=0.62, C33=1.71, C44=0.52, and C13=0.39×1012 dyn/cm2, the thermal expansion coefficients at 300 K are 8.9×10−6 and 6.6×10−6 K−1 for the [1010] and [0001] directions, respectively, and the room‐temperature conductivity is about 0.019 W cm−1 K−1. Sound velocity and thermal expansion data suggest a Debye temperature between 400 and 500 K.

Thin‐Film Piezoelectric Transducers used as Generators and Detectors of Microwave Phonons, with some Attenuation Measurements in SiO2

The manner in which thin‐film piezoelectric transducers are used is determined by their intended application. Attenuation measurement transducers should be capable of independent generation of each of the three pure acoustic modes and should exhibit low electromechanical conversion efficiency, whereas device transducers should exhibit maximum possible electromechanical conversion efficiency. Multilayer transducers offer increased power handling capabilities and higher electrical impedances than single‐layer transducers at high frequencies. An anomalous behavior of quartz in the presence of CdS is discussed. Attenuation measurements of the L, T1, and T2 modes along the X1 axis of synthetic quartz are presented.

Thin film zinc oxide transducers for use in microwave devices

Abstract Acoustic generation using class 6mm crystals is discussed before describing a method of depositing thin single crystal piezo-electric transducers of ZnO for converting microwave electromagnetic energy to phonon energy. The effects of varying substrate temperature and vapour pressure on the crystal structure, physical characteristics and electromechanical coupling factor are discussed.

Elastic Constants and Debye Temperature of TiC Using a New Ultrasonic Coherent Pulse/cw Technique

A new simple but sensitive ultrasonic velocity measurement technique, using a coherent pulse/cw system, is described. The technique can readily be used for velocity measurements in either small or large samples, and does not require elaborate instrumentation. This technique has been used to measure the velocities of all three pure acoustic modes along a (110) direction of a single crystal of TiC. These velocities were then used to calculate the elastic constants and the Debye temperature for this sample. The measured velocities are vL = 9.230×105 cm sec−1, vT1 = 6.425×105 cm sec−1, and vT2 = 5.927×105 cm sec−1. The calculated elastic constants are c11 = 3.891×1012 dyn cm−2, c12 = 0.433×1012 dyn cm−2, c44 = 2.032×1012 dyn cm−2, and the room temperature Debye temperature is 935°K.

Recent advances in microwave phonon generation and detection and their application to the study of phonon-phonon interactions in quartz

Abstract This paper discusses the design of a tunable resonant coaxial microwave cavity and gives the design of a practical cavity for use between 1 Gc/s and 8 Gc/s. It then describes a technique for producing exponentially decaying echo envelopes and a method of accurately measuring small changes in low attenuation rates. Measurements made in quartz at low temperatures and 1000 Mc/s are quoted

Elastic constants of α-ZnS

Abstract The elastic constants of hexagonal zinc sulfide were measured at room temperature. Velocity measurements used for computing the elastic constants were made at 10 solmc sec using a coherent pulse/cw technique. The derived values of the elastic constants, in units of 10 13 soldyn cm 2 are: c11 = 1.312, c12 = 0.663, c13 = 0.509, c33 = 1.408 and c44 = 0.286. Curves of intersection of the velocity surfaces with the XZ plane are given and compared with similar curves for hexagonal cadmium sulfide.

Ultrasonic transducers: 3. Surface wave transducers

Abstract The many examples cited indicate the potential use of elastic surface waves in modern radar and communications signal processing. The use of surface waves reduces the physical size of most devices by factors as large as 10 5 over their electromagnetic counterparts. An added attractive feature of elastic surface wave devices is that the fabrication techniques involved are compatible with integrated microcircuit techniques so widespread in general microwave technology.

MEASURED ELECTRICAL CHARACTERISTICS OF INTERDIGITAL SURFACE WAVE TRANSDUCERS ON LITHIUM NIOBATE

The radiation resistance and reactance as a function of frequency has been measured for interdigital comb structures used for generating z propagating surface waves on a yz surface of LiNbO3. The quantities reveal a basic asymmetry about the center frequency of surface wave generation due to the simultaneous launching of bulk waves.

Ultrasonic cw Spectrometer for the Investigation of Electron Spin‐Phonon Interactions in Solids

A cw acoustic spectrometer operating in the frequency range of 10 to 1000 Mc is described. The acoustic probe, applicable to low temperature measurements, is characterized by its mechanical resonance properties. Several of the novel features of the spectrometer are described in some detail. The apparatus, essentially the acoustic analog of an electron paramagnetic resonance microwave transmission spectrometer, has been applied to the study of electron spin‐phonon interactions in solids.