Ultrasonic Transducer Materials

ISBN-13: 9781475704709 / Angielski / Miękka / 2012 / 185 str.

O. E. Mattiat

Opis

In recent years remarkable progress has been made in the development of materials for ultrasonic transducers. There is a continuing trend towards increasingly higher frequency ranges for the application of ultrasonic trans- ducers in modern technology. The progress in this area has been especially rapid and articles and papers on the subject are scattered over numerous technical and scientific journals in this country and abroad. Although good books have appeared on ultrasonics in general and ultrasonic transducers in particular in which, for obvious reasons, materials play an important part, no comprehensive treatise is available that represents the state-of-the-art on modern ultrasonic transducer materials. This book intends to fill a need for a thorough review of the subject. Not all materials are covered of which, theoretically, ultrasonic trans- ducers could be made but those that are or may be of technical impor- tance and which have inherent electro acoustic transducer properties, i.e., materials that are either magnetostrictive, electrostrictive, or piezoelectric. The book has been devided into three parts which somewhat reflect the historic development of ultrasonic transducer materials for important tech- nical application. Chapter 1 deals with magnetostrictive materials, magnetostrictive met- als and their alloys, and magnetostrictive ferrites (polycrystalline ceramics). The metals are useful especially in cases where ruggednes of the transducers are of overriding importance and in the lower ultrasonic frequency range.

Spis treści

1 Magnetostrictive Metals and Piezomagnetic Ceramics as Transducer Materials.- 1 Introduction.- 1.1. Ultrasonic Generators and Detectors.- 1.2. Magnetostriction Filters.- 2. Fundamentals of Magnetostriction.- 2.1. Static Magnetostriction Phenomena.- 2.2. Magnetostrictive Forces.- 2.3. Magnetrostriction Constants.- 2.4. Material Criteria.- 2.5. Effect of Hydrostatic Pressure on Magnetostriction.- 2.6. Effect of Mechanical Stress on Magnetostriction.- 3. Eddy Current Effects on Material Constants.- 4. Relation between Static and Dynamic Magnetostriction Phenomena.- 5. Methods of Material Measurement.- 5.1. Motional Impedance Methods.- 5.2. Measurement under Hydrostatic Pressure.- 5.3. Measurement under Static Compressive Stress.- 6. Magnetostrictive Properties of Materials.- 6.1. Nickel.- 6.2. Ni-Fe Alloy.- 6.3. Al-Fe Alloy.- 6.4. Other metals.- 6.5. Cobalt Rondel.- 6.6. Ferrites.- 6.7. Theoretical Models for the Characteristics of Magnetostriction in Polycrystalline Metals.- 7. Consideration of Large Signal Operation.- 7.1. Theoretical Approach.- 7.2. Experimental Approach.- References.- 2 Piezoelectric Crystals and Ceramics.- 1. Introduction.- 2. Fundamentals of Piezoelectricity.- 2.1. Basic Action and Linear Static Equations.- 2.2. Effect of Crystal Symmetry.- 2.3. The Piezoelectric Coupling Factor.- 3. Modes of Vibration of Piezoelectric Elements.- 3.1. Low-Frequency Modes.- 3.2. High-Frequency or Thickness Modes.- 3.3. The Effective Coupling Factor—The Piezoelectric Resonator.- 4. Ferroelectricity.- 4.1. General Description.- 4.2. Piezoelectricity in Ferroelectrics—The Piezoelectric Ceramics.- 4.3. Nonlinearities—Domain Effects.- 4.4. Phase Transitions.- 5. Dissipation in Piezoelectric Materials.- 5.1. General.- 5.2. Effects on Transducer Efficiency and Power Capacity.- 6. Parameters of Important Piezoelectric Crystals.- 6.1. Older Piezoelectric Crystals.- 6.2. Newer Piezoelectric Crystals.- 7. Parameters of Piezoelectric Ceramics.- 7.1. General.- 7.2. Aging in Piezoelectric Ceramics and Effects of High Static Stress.- Notation.- References.- 3 Piezoelectric Transducer Materials and Techniques for Ultrasonic Devices Operating Above 100 MHz.- 1. Introduction.- 1.1. Scope of Chapter.- 1.2. Results from the Equivalent Circuit Analysis of High-Frequency Ultrasonic Devices Using Piezoelectric Transducers.- 1.3. Properties of Transducer Materials and Acoustic Materials of Interest for High-Frequency Applications.- 2. Materials and Techniques for Bonded Plate Transducers.- 2.1. Single-Crystal Materials.- 2.2. Ceramic Transducer Materials.- 2.3. Bonding and Lapping Techniques for High-Frequency Transducers.- 3. Evaporated and Sputtered Film Transducers.- 3.1. Electroelastic Properties of Cadmium Sulfide and Zinc Oxide in the Form of Thin Films.- 3.2. Evaporation Techniques for Forming CdS Transducers.- 3.3. Sputtering Techniques for Forming ZnO Transducers.- 3.4. Other Compounds of Potential Interest for Film Transducers.- 4. Concluding Remarks.- References.