An Ultrasonic Sensor for Process Modeling and Proces Control of Ceramic Superconductors
This research demonstrates the feasibility of utilizing nondestructive ultrasonic sensors to monitor the effects of oxygen content, processing time and temperature on the resultant mechanical, structural, and electrical properties of high temperature ceramic superconductors. Ultrasonic velocity changes, as a function of processing time and temperature, have clearly been shown to indicate the transformation between orthorhombic and tetragonal phases in Y-Ba-Cu-O.
A Teflon pressure-transducer-specimen bond for ultrasonic measurements over a wide temperature range
Abstract A major limitation for the application of megahertz ultrasonic techniques to the study of the properties of solids is the problem of finding transducer-specimen bonds useful over a wide temperature range. A Teflon pressure bond has been developed and tested. It appears to overcome most of the problems, and promises to allow for many studies previously more difficult or impracticable.
Ferroelectric lithium niobate. 1. Growth, domain structure, dislocations and etching
Abstract Lithium niobate (LiNbO 3 ) is a material of considerable interest in view of its unusual ferroelectric, optical, acoustic and piezoelectric properties. The growth of large single crystals by the Czochralski and Bridgman-Stockbarger techniques is described. Angles between crystallographic planes and a stereographic projection are given. The crystals show the presence of ferroelectric domains, the polar axis being the c -axis (hexagonal setting). Polishing, etching, microscopic, X-ray topographic and other techniques were used to examine the domains, dislocations and other imperfections in some detail. The preparation of single domain material and poling experiments will be discussed in paper 2 of this series.