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In this paper, ultrasonic nozzle and its driving circuit were manufactured. And then, their electrical properties were investigated. Ultrasonic nozzle using multilayer ring-type piezoelectric ceramics was fabricated by Pb[(Mn1/3Nb2/3)0.02(Ni1/3Nb2/3)0.12(Zr0.50Ti0.50)0.86]O3 (abbreviated as PMN-PNN-PZT) composition which have excellent piezoelectric characteristics. The multilayer ring-type piezoelectric ceramics using pure Ag inner electrode was sintered at 900°C low temperatures. In order to drive ultrasonic nozzle, Pulse Width Modulation controller (abbreviated as PWM) of KA3525A was used. With increasing the input voltage of ultrasonic nozzle, average diameter of light oil droplet was increased up to 16V and then decreased. At the input voltage of 12 V, volume average diameter of light oil droplet showed the minimum value of 37.3 μm and also at the input voltage of 16V, volume average diameter of fuel oil droplet showed the maximum value of 51.3 μm.

In this study, in order to develop the composition ceramics for low temperature sintering multilayer piezoelectric actuator and ultrasonic vibrator, Pb(Mn 1/3 Nb 2/3 )O 3 –Pb(Ni 1/3 Nb 2/3 )O 3 –Pb(Zr 0.50 Ti 0.50 )O 3 (abbreviated as PMN–PNN–PZT) ceramics were fabricated using Li 2 CO 3 and Na 2 CO 3 as sintering aids, their structural, piezoelectric and dielectric characteristics were investigated according to the addition of CuO and Fe 2 O 3 , respectively. The addition of CuO and Fe 2 O 3 improved sinterability and density and suppressed secondary phase. In the CuO added PMN–PNN–PZT ceramics, mechanical quality factor ( Q m ) was improved due to the acceptor doping effect. However, in the Fe 2 O 3 added PMN–PNN–PZT ceramics, it seemed that Fe 2 O 3 reacted as softner because dielectric constant ( ɛ r ) and electromechanical coupling factor ( k p ) were significantly increased by the increase of grain size and sinterability. At 0.2 wt.% CuO added specimen sintered at 900 °C, density, electromechanical coupling factor ( k p ), mechanical quality factor ( Q m ), dielectric constant ( ɛ r ) and piezoelectric constant ( d 33 ) showed the optimum value of 7.856 g/cm 3 , 0.60, 1130, 1018 and 346 ( p C/N), respectively. At 0.2 wt.% Fe 2 O 3 added specimen sintered at 900 °C, density, electromechanical coupling factor ( k p ), mechanical quality factor ( Q m ), dielectric constant ( ɛ r ) and piezoelectric constant ( d 33 ) showed the optimum value of 7.850 g/cm 3 , 0.62, 975, 1275 and 377 ( p C/N), respectively. Taking into consideration above piezoelectric properties, it was concluded that PMN–PNN–PZT ceramics using 0.2 wt.% Fe 2 O 3 as additive showed the piezoelectric characteristics suitable for low loss and low temperature sintering multilayer piezoelectric actuator application.

In this study, piezoelectric and dielectric properties of lead-free Bi(Na, K)TiO 3 –SrTiO 3 (abbreviated as BNKT–ST) system piezoelectric ceramics were investigated for pressure sensor applications as a function of the amount of La 2 O 3 addition. With increasing the amount of La 2 O 3 addition, density and dielectric constant increased up to 0.9 wt.% La 2 O 3 and decreased above 0.9 wt.% La 2 O 3 . Electromechanical coupling factor ( k p ) showed the maximum value at 0.2 wt.% La 2 O 3 and decreased above 0.2 wt.% La 2 O 3 . Electromechanical coupling factor ( k p ), density, dielectric constant ( ɛ r ), piezoelectric constant ( d 33 ) and curie temperature ( T c ) were showed the optimum value of 0.40, 5.75 g/cm 3 , 768, 215 pC/N and 320 °C at 0.2 wt.% La 2 O 3 , respectively. The output voltage of the pressure sensor showed 0.48 V at 20 in H 2 O.

In this study, 0.96B ( )Ti + 0.04SrTi + 0.3 wt% N +0.2 wt% L + xwt % Mn were investigated as a function of the amount of Mn addition in order to improve dielectric and piezoelectric properties of Lead-free piezoelectric ceramics. With increasing the amount of Mn addition, the density, electromechanical coupling factor( ), piezoelectric constant( , ) and curie temperature (Tc) showed the maximum value of 5.7 g/㎤, 38 %, 219 pC/N, 26 mVㆍm/N and 32 at 0.1 wt% Mn addition, respectively, and mechanical quality factor( ) showed the maximum value of 158 at 0.3 wt% Mn addition.ddition.ion.n.