SrB4O7 (SBO) shows superior transparency in the vacuum ultraviolet (UV) region, a high radiation damage threshold, and high nonlinearity, and SBO crystals have therefore attracted great interest as materials for low-cost, high-power UV light sources. To use SBO crystals as laser sources, it is essential to grow transparent SBO crystals. Here we show the effects of temperature gradient G on the growth of SBO crystals by the micro-pulling-down method. At low G, SBO crystal fibers were obtained. The density of striations and the size of voids also decreased with decreasing G. These results demonstrate that a low G is essential for growing completely transparent SBO crystal fibers. In addition, we considered the effects of G on the oscillatory growth of SBO crystals in relation to latent heat removal.
We studied the effects of alloy composition and heat-treatment conditions of the Fe-Co magnetostrictive alloys on the output voltage of a cantilever-type vibration energy harvester with the alloys. Fe-Co binary alloys that were annealed and subsequently water-quenched produced higher output voltages than those produced by alloys that were cold-rolled or annealed but not quenched. Annealed and quenched Fe-Co alloys possessed higher saturation magnetization, permeability, and magnetostriction susceptibility but lower residual magnetization, coercive force, and magnetostriction. Thus, we found that it was necessary to control not only the alloy composition and magnetostriction but also other magnetic parameters in order to increase the output voltage of power generator using magnetostrictive materials.
Boron nitride nanosheets (BNNSs) are attractive 2-dimensional nanomaterials with excellent thermal conductivity, mechanical properties, and thermal stability. It is therefore significant to develop new simple methods to produce BNNSs. In this study, BNNSs with nanometer thicknesses and diameters of several hundreds of nanometers were produced by alcoholysis-assisted exfoliation from hexagonal boron nitride (h-BN) through sonication of h-BN in primary alcohols such as butanol and hexanol. Atomic force microscopy images of the BNNSs revealed that the morphologies were dependent on alcohol species and preparation methods. Infrared absorption spectra of the BNNSs suggested that alcoholysis of B–N bonds in primary alcohols during sonication processes was essential for BNNS production.
The metal organic decomposition (MOD) method enables the coating of any oxide material via atmospheric baking of a solution applied to a substrate and enables the fabrication of thin films via simple processes such as using spin coaters. We used titanium oxide, zinc oxide (ZnO), ytterbium oxide, and erbium oxide as MOD solutions. We mixed Ti, Zn, Yb, and Er at arbitrary mixing ratios, applied them on substrates, and then heated them at 1000°C for 4 h under atmosphere. We found that the maximum value for luminance of the upconversion (UC) scintillator can be obtained with mixture ratios of the base material Ti : Zn = 1 : 1 and Yb : Er additives = 0.06 : 0.02. When Yb : Er ratios were from 1:3 to 3:1, a 550 nm green light and 650 nm red light were observed. Moreover, by varying the mixture ratio of RE elements, the UC emission intensity can be controlled. As a result, the UC scintillators produced via the MOD method show the potential for use as multi-functional materials in displays and solid-state illumination.