Piezoelectric materials for acoustic wave applications

摘要

Piezoelectric materials for acoustic wave applications havenchanged markedly over the past 20 years in terms of both the types ofnmaterials available and the quality of individual samples. The totalnfamily of acoustic wave materials now includes piezoelectricnglass-ceramics having crystallographic and polar orientation andncrystals having symmetry classes mm2, 32, 3m, 4mm, 6mm, and 4¯3m.nThe symmetry classes 6mm and 4¯3m also occur frequently innpiezoelectric semiconductor materials that are now available in bothnbulk and thin-film configurations. In this paper, we bring together andnextract the various reported values of the material constants mainly ofninterest for surface acoustic wave (SAW) device applications. Wenidentify for the user community those sets of constants from which SAWndesign calculations can reliably be made, and discuss the constants andntheir reliability for langasite, lithium niobate/lithium tantalate, andndilithium tetraborate. The relevant material constants include: massndensity Ρ, elastic stiffness cij, piezoelectric stress enij, dielectric permittivity εii, and thenthermal expansion coefficients Αii. Except for thensemiconductor materials, only data published after 1978 are included,nsince the reference literature (Landolt-Bornstein) amply covers thosenyears prior to 1978