Metal halide perovskites (MHPs) have attracted attention as new display materials due to their excellent optical properties, but their application is limited by the complexity of conventional synthesis methods and the film formation processes. As an alternative, color conversion film fabricated via the aerosol deposition (AD) process using CsPbBr₃/Al₂O₃ powder, a ceramic matrix-based MHP composite, has expanded the practical utility of MHPs by simplifying both the synthesis and film formation steps. Nevertheless, the hammering effect that occurs during the AD process can damage the MHP crystal structure, leading to degradation of its optical properties. Therefore, in this study, to overcome the problem of optical degradation, we compared the structural and photoluminescence (PL) properties of films fabricated by adding polytetrafluoroethylene (PTFE), a material with a buffering effect, to the CsPbBr₃/Al₂O₃ starting powder at mass ratios of 0, 0.1, 0.5, 1, and 2 wt% to mitigate the hammering effect. The film containing 1 wt% PTFE exhibited the highest PL performance, achieving a luminous efficiency of 52.1 lm/W. This improvement is attributed to PTFE providing an optimal buffering effect without forming aggregates on the film surface. These results further enhance the applicability of AD-based color conversion films and are expected to contribute to the development of high-resolution display technologies.

With the recent active development of laser-based weapons/monitoring/communication systems, there is a significant increase in the demand for improved performance of piezoelectric actuators, a key component of both deformable mirror (DM) and fast steering mirror (FSM) in the systems. The conventional polycrystalline piezoelectric ceramic actuators have limitations in improving their characteristics, so the ultrahigh strain PMN-PZT piezoelectric single crystal multilayer actuators have been developed. In this study, the basic experimental methods were developed to evaluate their stability as well as reliability. The limitations of deformation and applied voltage were confirmed through the breakdown voltage test, and the degree of stability was confirmed through the hammering test. In this study, the breakdown voltage test and the hammering test were confirmed to be effective methods to evaluate their stability as well as reliability. Through these studies, the next-generation PMN-PZT piezoelectric single-crystal multilayer actuator is expected to be applied to various piezoelectric application fields by securing reliability as well as excellent piezoelectric properties.

Al₂O₃ powders with particle sizes of 0.35 μm, 0.5 μm, 1.5 μm, and 2.5 μm are deposited onto glass and Cu substrates using the aerosol deposition (AD) process. The deposition characteristics of Al₂O₃ films using those four types of Al₂O₃ powders are investigated to determine the influence of the particle size on the films. To observe detailed micro-structures of the films, the cross-section and surface morphology are observed. Then, the crystalline size and internal strain are calculated from X-ray diffraction peaks in order to confirm the hammering effect as well as the micro-strain during the AD deposition. From the above results, deposition mechanisms related to the particle size are studied. The results of this study indicate the optimal particle size and formation mechanisms for dense Al₂O₃ film with a smooth surface roughness as well as for a porous Al₂O₃ film with a rough surface roughness.