Byung-Guk Ahn

Bender Typed Piezoelectric Multilayer Actuator

A Bender typed Multilayer Actuator(BMA) for decreasing the depolarization effect was designed and fabricated. Unlike bimorph and multimorph actuators in which depolarization occurred, the BMA did not generate depolarization because the polarization and the electric field directions are the same. The simulated results indicate that higher displacement of the BMA can be achieved by increasing input voltage. Compared with the multimorph actuator, the proposed actuator is expected to extend a life time as well as acceptable voltage range.

Microstructure and Microwave Dielectric Properties of (1-x)Ba(Co 1/3 Nb 2/3 )O₃ -xBa(Zn 1/3 Nb 2/3 )O₃ Ceramics

Ba(Co 1/3 Nb 2/3 )O₃ (BCN) has a 1 : 2 ordered hexagonal structure. Q-value of BCN increased with increasing sintering temperature however, it significantly decreased when the sintering temperature exceeded 1400℃. Ba(Zn 1/3 Nb 2/3 )O₃ (BZN) has the 1:2 ordered hexagonal structure and the degree of the 1 : 2 ordering decreased with the increase of the sintering temperature. The Q-value of the BZN increased with increasing the sintering temperature and BZN sintered at 1400 ℃ for 6 h has a maximum Q-value. For (1-x)Ba(Co 1/3 Nb 2/3 )O₃ -xBa(Zn 1/3 Nb 2/3 )O₃ [(1-x)BCN-xBZN] ceramics, the 1 : 2 ordered hexagonal structure was observed in the specimens with x≤0.3 and the BaNb 6 O 16 second phase was found in the specimens with x≥0.6. Grain growth, which is related to the BaNb 6 O 16 second phase occurred in the specimens with x 0.5. In this work, the excellent microwave dielectric properties of τ f =0.0 ppm/℃, e r =34.5 and Q×f=97,000 GHz were obtained for the 0.7BCN-0.3BZN ceramics sintered at 1400℃ for 20 h.