The utility model discloses piezoelectric ceramic. A body comprises an arc-shaped coupling surface which can be coupled with an arc-shaped or spherical structure. The beneficial effects of the utilitymodel are that: the utility model discloses a beneficial effect is: the arc-shaped coupling surface can be matched with the curvature of an arc-shaped or circular structure, and a gap between the twostructures can be effectively reduced during connection, so that the thickness of a coupling agent in the bonding process between the coupling agent and the arc-shaped or spherical structure can be reduced, attenuation in the ultrasonic propagation process is reduced, and a good coupling effect is achieved.