CPC H03H 9/02574 (2013.01) [H03H 3/08 (2013.01); H03H 9/02559 (2013.01); H03H 9/02897 (2013.01); H03H 9/25 (2013.01); H10N 30/06 (2023.02); H10N 30/072 (2023.02); H10N 30/086 (2023.02)] | 9 Claims |
1. A layered body comprising:
a ceramic substrate formed of polycrystalline ceramic and having a supporting main surface, and
a piezoelectric substrate formed of a piezoelectric material and having a bonding main surface in contact with the supporting main surface,
wherein at the supporting main surface, a mean of grain sizes of the polycrystalline ceramic is 0.5 μm or more and less than 15 μm,
a standard deviation of the grain sizes is less than 1.5 times the mean,
the polycrystalline ceramic is not formed of the piezoelectric material, and
a residual stress at the supporting main surface of the ceramic substrate formed of the polycrystalline ceramic is −300 MPa or more and 300 MPa or less.
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