Piezoelectric single crystal-polycrystalline ceramic composite, preparation method therefor, and piezoelectric and dielectric application components using same

A method of manufacturing a piezoelectric single crystal-polycrystalline ceramic composite, the method comprising:

• preparing single crystal grains a by crushing a piezoelectric single crystal having a perovskite type structure ([A][B]O3) in 50 μm or more;
• preparing polycrystal powder grains b having an average grain size distribution of 0.1 to 5 μm, thereby carrying out mixing and heat treatment so that a ratio between the grain size distributions a/b reaches 20 or more;
• and
• growing the piezoelectric single crystal through the heat treatment so that a grain size of the piezoelectric single crystal reaches 100 μm or more,
• wherein the ratio between the grain size distributions a/b after the heat treatment reaches 20 to 100, and
• wherein the piezoelectric single crystal is contained in a range of 30 to 80 vol % after the heat treatment.

A piezoelectric single crystal-polycrystalline ceramic composite comprising:

• a mixture of a piezoelectric single crystal having a perovskite type structure ([A][B]O3), and polycrystalline ceramic grains,
• wherein the composite satisfies the following:
• an average grain size distribution a of the piezoelectric single crystal is 100 to 1,000 μm;
• an average grain size distribution b of the polycrystalline ceramic grains is 2 to 20 μm;
• and
• a ratio a/b between the grain size distributions is 20 to 100,
• wherein under a condition of the room temperature, the piezoelectric single crystal-polycrystalline ceramic composite has
• (1) a dielectric constant K3T of 3,000 or more,
• (2) a piezoelectric charge constant d33 of 1,200 pC/N or more, and
• (3) a phase transition temperature of 80° C. or more.