This study examines paraelectric Bi1.5Zn1.0Nb1.5O7 (BZN), which has no hysteresis and high dielectric strength, for energy density capacitor applications. To increase the breakdown dielectric strength of the BZN film further, poly(vinylidene fluoride) BZN-PVDF composite film is fabricated by aerosol deposition. The volume ratio of each composition is calculated using dielectric constant of each composition, and we find that it was 12:88 vol% (BZN:PVDF). To modulate the structure and dielectric properties of the ferroelectric polymer PVDF, the composite film is heat-treated at 200 oC for 5 and 30 minutes following quenching. The amount of α-phase in the PVDF increases with an increasing annealing time, which in turn decreases the dielectric constant and dielectric loss. The breakdown dielectric strength of the BZN film increases by mixing PVDF. However, the breakdown field decreases with an increasing annealing time. The BZN-PVDF composite film has the energy density of 4.9 J/cm3, which is larger than that of the pure BZN film of 3.6 J/cm3.

Lead free (Ba0.7Ca0.3) TiO3 thick films with nano-sized grains are prepared using an aerosol deposition (AD) method at room temperature. The crystallinity of the AD thick films is enhanced by a post annealing process. Contrary to the sharp phase transition of bulk ceramics that has been reported, AD films show broad phase transition behaviors due to the nanosized grains. The polarization-electric hysteresis loop of annealed AD film shows ferroelectric behaviors. With an increase in annealing temperature, the saturation polarization increases because of an increase in crystallinity. However, the remnant polarization and cohesive field are not affected by the annealing temperature. BCT AD thick films annealed at 700 ℃/2h have an energy density of 1.84 J/cm3 and a charge-discharge efficiency of 69.9%, which is much higher than those of bulk ceramic with the same composition. The higher energy storage properties are likely due to the increase in the breakdown field from a large number of grain boundaries of nano-sized grains.

Studies on lead-free piezoelectrics have been attractive as means of meeting environmental requirements. We synthesized lead-free piezoelectric (Bi1/2Na1/2)TiO3-Ba(Cu1/3Nb2/3)O3 (BNT-BCN) ceramics, and their dielectric, piezoelectric, and strain behavior were characterized. As BCN with a tetragonal phase was incorporated into the rhombohedral BNT lattice, the lattice constant increased. A small amount of BCN increased the density and dielectric constant forming the complete solid solution with BNT. However, BCN above 10 mol% was precipitated into a separate phase, and which was detected with XRD. In addition, EDX measurement revealed that Cu in BCN was not distributed homogeneously but was accumulated in a certain area. A lower density with a large amount of BCN was attributed to the nonsinterable property of BCN with large tetragonaliy. The dielectric constant vs the temperature change and the strain vs the electric field indicated that the ferroelectric property of BNT was diminished and paraelectric behavior was enhanced with the BCN addition. BNT-7.5BCN showed a 0.11% unimorph strain with a 9.0 kV/mm electric field with little hysteresis.

Negative temperature coefficient (NTC) materials have been widely studied for industrial applications, such assensors and temperature compensation devices. NTC thermistor thick films of Ni1+xMn2-xO4+δ (x=0.05, 0, −0.05) werefabricated on a glass substrate using the aerosol deposition method at room temperature. Resistance verse temperature (R-T)characteristics of the as-deposited films showed that the B constant ranged from 3900 to 4200 K between 25oC and 85oCwithout heat treatment. When the film was annealed at 600oC 1h, the resistivity of the film gradually decreased due tocrystallization and grain growth. The resistivity and the activation energy of films annealed at 600oC for 1 h were 5.203, 5.95,and 4.772KΩ·cm and 351, 326, and 299meV for Ni0.95Mn2.05O4+δ, NiMn2O4, and Ni1.05Mn1.95O4+δ, respectively. The annealingprocess induced insulating Mn2O3 in the Ni deficient Ni0.95Mn2.05O4+δ composition resulting in large resistivity and activationenergy. Meanwhile, excess Ni in Ni1.05Mn1.95O4+δ suppressed the abnormal grain growth and changed Mn3+ to Mn4+, givinglower resistivity and activation energy.

Nitrous oxide (N2O) is an important trace gas in the atmosphere not only because of its large global warming potential (GWP) but also because of the role in the ozone depletion in the stratosphere. It has been known that soil is the largest natural source of N2O in global emission. However, anthropogenic sources contributing from industrial section is likely to increase with rising the energy consumption, and transportation as well. In this study, a total of 32 gasoline-powered passenger vehicles (ranging from small to large engine's displacement and also ranging from aged catalyst to new catalyst) were tested on the chassis dynamometer system in order to elucidate the characteristics of N2O emission from automobiles under different driving modes. Ten different driving modes developed by NIER were adapted for the test. The results show that the N2O emission decreases logarithmically with increase of vehicle speed over the all test vehicles (N2O emission = -0.062 Ln (vehicle speed) + 0.289, r2=0.97). It revealed that the larger engine's displacement, the more N2O emission were recorded. The correlation between N2O emission and catalyst aging was examined. It found that the vehicles with aged catalyst (odometer record more than 8,0000km) emit more N2O than those with new catalyst. Average N2O emission was 0.086±0.095 N2O-g/km (number of samples=210) for the all test vehicles over the test driving modes.