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.

Mn-doped Pb(In_1/2Nb_1/2)O₃-Pb(Mg_2/3Nb_1/3)O₃-PbTiO₃ (Mn:PIN-PMN-PT) single crystals, which exhibit improved phase transition temperatures and coercive field properties compared to Pb(In_1/2 Nb_1/2)O₃-Pb(Mg_2/3Nb_1/3)O₃-PbTiO₃ (PIN-PMNPT) single crystals, are expected to be utilized in high-power acoustic transducers. Bridgeman method, growing single crystals along the axial direction from melt, is most widely used method for single crystal growth with large size and high quality. However, single crystal boules grown by the Bridgeman method demonstrate a PT compositional variation, giving rise a distribution of crystal structure and material properties along the growing axis. To employ piezoelectric single crystals grown by the Bridgeman method for acoustic transducers, it is essential to investigate their overall property distribution. In this study, the compositional distribution and property variation of Mn:PIN-PMN-PT single crystals grown by the Bridgeman method was investigated. Measured compositional distribution of PT was from 29% to 32.5% in the Rhombohedral crystal region of the boule. Two types of specimen, [011]-poled Mn:PIN-PMN-29PT and Mn:PIN-PMN-32PT single crystals, were fabricated and tested to obtain full property variation at both ends of the Rhombohedral crystal region. The properties related to the 32 directional vibration mode and the properties related to high-power driving were measured to confirm the overall distribution of properties by composition.

A 100 mm × 50 mm-sized (100) gallium oxide (Ga₂O₃) single crystal ingot was successfully grown by edge-defined film-fed growth (EFG). The preferred orientation and the quality of grown Ga₂O₃ ingot were compatible with a commercial Ga₂O₃ substrate by showing strong (100) orientation behaviors and 246 arcsec in X-ray rocking curve. Raman characterization was also performed for both samples; thereby providing various Raman-active characteristics of Ga₂O₃ crystals. In particular, we observed A_g(5) and A_g(10) peaks of Raman active mode, directly related to the impurity of the grown Ga₂O₃ crystal. Hence, the comparison of the crystal quality and Raman analysis might be useful for further enhancement of Ga₂O₃ single crystal quality in the future.

As the demand for new and renewable energy increases due to the depletion of fossil fuels, solar power generation, a core energy source for new and renewable energy, requires research on solar modules for high output power generation. In this paper, the electrical characteristics of solar cell strip at the edge and in the center of single-crystal silicon having a semi-square shape were analyzed. The cell strip located in the center showed the efficiency increase by 0.26% compared to the cell strip at the edge of the solar cell. A shingled photovoltaic module was manufactured for each cell strip. As a result, the output power of the module using the cell strip located in the center was higher by 0.992%.

[011] poled ternary Pb(In_1/2Nb_1/2)O₃-Pb(Mg_1/3Nb_2/3)O₃-PbTiO₃ (PIN-PMN-PT) single crystals have been investigated for active materials for acoustic transducers because of their high piezoelectric properties in both shear and transverse modes. In order to use [011] poled PIN-PMN-PT single crystals for acoustic transducers, the characterization of full-matrix material properties is required. In this study, full sets of compliance, dielectric, and piezoelectric constants of [011] poled rhombohedral PIN-PMN-PT were measured by a resonance method. Dimensions and geometries of 12 samples were proposed for measuring 17 independent material constants of [011] poled rhombohedral PIN-PMN-PT single crystals. Two sets of samples with different PT concentrations, 0.24PIN-0.49PMN-0.27PT and 0.24PIN-0.46PMN-0.30PT, were fabricated and their material properties were measured. Measured impedance spectra and simulated impedance spectra of the samples were compared to check the accuracy of the measurements.

For the last decades, a research hotspot for the halide perovskites (HPs) is now showing great progress in terms of improving efficiency for numerous photovoltaic devices (PVDs). However, it still faces challenges in the case of long-term stability in the air atmosphere. Defect-free high-quality HP single crystals show their promising properties for the remarkable development of highly efficient and stable PVDs. Here, we summarize the growth processing routes for the stable HP single crystals as well as briefly discuss the pros and cons of those well-established synthesis routes. Furthermore, we briefly include the comparison note between the HP single crystals and polycrystalline perovskite films regarding their device applications. Based on the future progress, the review concludes subjective perspectives and current challenges for the development of HPs high-quality PVDs.

Electrical poling is a crucial step to convert ferroelectrics to piezoelectrics. Nevertheless, no systematic investigation on the effect of poling has been reported. Given that the poling involves an alignment of spontaneous polarization, the condition for poling should be different when a material has an internal bias field that influences the domain stability. Here, we present the effect of poling profile on the dielectric and piezoelectric properties in Mn-doped Pb(Mg_1/3Nb_2/3)O₃-29 mol%PbTiO₃ single crystal with an internal bias field. We showed that both the dielectric permittivity and the piezoelectric coefficient were further enhanced when the poling procedure ends with a field application along the opposite direction to the internal bias field. We expect that the current finding would give a clue to understanding the true mechanism for the electrical poling.

This aim of this study was to develop a process for creating bulk single-crystal YBaCuO superconductors in a high magnetic field. To support the bulk unidirectional growth of YBa₂Cu₃O_7-y, SmBa₂Cu₃O_7-y seeds were planted inside YBaCuO composites and samples were produced by melting, enabling the growth of two YBaCuO superconductors. Due to the magnetism generated inside the superconductor of the upper sample, the magnetization inside the superconducting single crystals was evenly distributed, the sharpness of the induced magnetic force was improved, and the superconducting magnetization were significantly improved. This approach is widely applicable for the production of superconducting wires and current leads used for DC power breakers.

In this paper, a underwater acoustic Tonpilz transducer with the piezoelectric single crystal(72PMN-28PT) is developed. The thickness and the number of piezoelectric elements are theoretically designed with the equivalent circuit analysis to have the desired resonance frequency. In order to compare the performances, a piezoelectric ceramic transducer is also manufactured and their electrical impedance, TVR (transmitting voltage response), RVS (receiving voltage response) and beam pattern are compared.

In this paper, the growing orientation of PMN-PT single crystal is analyzed using the Laue-Back Reflection Method. Two kinds of PMN-PT single crystals are grown using the Bridgman growing method in the [001] and [111] directions and their the Laue photographs are simulated assuming cubic crystal systems. From the comparison between simulation and test results, it can be concluded that the single crystals are grown in the desired crystal orientations.

For the practical application of a YBCO superconductor bulk, the superconductor bulk magnet with high magnetic field on a large area surface should be fabricated. To make this, YBCO single crystal bulks with fine Y2BaCuO5(Y211) particles have been prepared by the top-seed melt growth(TSMG) method with YBa2Cu3Ox, Y2O3, and CeO2 mixing precursor. By using Y2O3 instead of Y2BaCuO5 as precursor, the manufacturing process became simpler and more economical. The microstructures, trapped field and critical current density of the various conditioned YBCO bulks have been observed, analyzed and measured. The different characteristic values of the several samples have been analyzed from the viewpoint of their microstructures. We have developed a 8x12 cm size superconductor bulk magnet, up to 3 T class, by using the 4 T class-high field superconducting magnetizer and confirmed the applicability of the transmission level circuit breakers by measuring the strength and speed of the superconductor bulk magnet actuator.