BAW temperature sensitivity and coupling in langanite

    Authors

    M. P. da Cunha; E. L. Adler;D. C. Malocha

    Comments

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    Abbreviated Journal Title

    IEEE Trans. Ultrason. Ferroelectr. Freq. Control

    Keywords

    Acoustics; Engineering, Electrical & Electronic

    Abstract

    One of the now materials belonging to the trigonal class 32, to which quartz belongs, is langanite (LGN, La(3)Ga(5.5)Nb(0.5)O(14)). High-quality LGN single crystals are now available, and, although similar in composition and structure to langasite (LGS, La(3)Ga(5)SiO(14)), LGN has smaller thermal expansion coefficients and comparable piezoelectric constants to LGS. These are desirable material properties for both SAW and BAW applications that require low frequency dependence on temperature. This paper examines in detail the LGN characteristics: phase velocity, temperature coefficient of frequency (TCF), electromechanical coupling coefficient, and power flow angle for both singly and doubly rotated plate cuts. Contour plots of these characteristics are constructed, revealing orientation regions where zero TCF and high coupling exist and suggesting potentially interesting cuts for practical BAW device design. Temperature compensated cut regions with coupling coefficients as high as 0.16 are predicted, which is twice the value for AT-cut quartz. along with a temperature compensated cut with cubic behavior around room temperature for one of the sets of material constants used. With such desirable properties. LGN is a promising candidate material for BAW applications requiring low temperature sensitivity with superior bandwidth characteristics due to its values of coupling coefficient larger than quartz. Several other orientations with low TCF and high coupling are also identified.

    Journal Title

    Ieee Transactions on Ultrasonics Ferroelectrics and Frequency Control

    Volume

    49

    Issue/Number

    5

    Publication Date

    1-1-2002

    Document Type

    Article

    Language

    English

    First Page

    656

    Last Page

    663

    WOS Identifier

    WOS:000175662600014

    ISSN

    0885-3010

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