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A crack extending downward along the seed of a beta-gallium oxide (β-Ga2O3) crystal grown using the edge-defined film-fed growth (EFG) method severely affects the efficiency of crystal slicing. In this study, the influence of the crack on the structural, electronic, and optical properties, as well as the defects in the β-Ga2O3 crystal, was investigated. The causes of the crack were also discussed in this study. Compared with the low crystalline crystal on the right side of the crack, the single crystal on the left side exhibits superior crystalline quality, according to the high-resolution X-ray diffraction and Raman scattering spectra. The Hall data and optical transmission spectra reveal that the crack has a negligible effect on the carrier concentration and optical bandgap. The PL results indicate that the right crystal has more defects caused by oxygen vacancies than the left crystal. Rugby-ball-shaped dislocation etch pits were discovered using a chemical etching approach. The average dislocation densities on the left and right sides of the crack were 9 × 103 cm−2 and 3 × 104 cm−2, respectively.

The pyramid–prism interface in “point-seed” rapidly grown DKDP (KDxH2–xPO4) crystals affects the quality of tripler-cut samples used in inertial confinement fusion devices. In this study, a cuboid DKDP crystal without a pyramidal sector was rapidly grown. The quality of the cuboid DKDP crystal was evaluated by measuring the deuterium homogeneity, crystalline quality, transmission spectrum, and laser-induced damage performance. The total number N of tripler-cut samples that can be obtained from the cuboid DKDP crystal is easily calculated. The size of the tripler-cut sample is approximately equal to the cross-section of this cuboid DKDP crystal. Moreover, as this cuboid DKDP crystal has a regular shape, calculating the mass of the crystal and accurately controlling the supersaturation of the solution during growth is easy. The successful crystal growth using this proposed approach establishes the possibility of growing large-aperture cuboid DKDP crystals. Currently, research on the rapid growth of a cuboid...

To investigate the pyramid–prism (PY–PR) boundary of a rapidly grown KDP crystal, the exact position of the PY–PR boundary of an X-cut rapidly grown KDP sample is determined by measuring the refractive-index non-uniformity. The peak-valley value of Δ(ne–no) near the PY–PR boundary is approximately 3 × 10−6, and the width of the distortion area near the PY–PR boundary is approximately 0.6 mm. The FWHM values of the high-resolution X-ray diffraction peaks in the pyramidal sector, the prismatic sector, and the region containing the PY–PR boundary are all 0.008°, indicating the fine crystalline quality of the crystal. Moreover, the existence of the PY–PR boundary does not affect the fine crystalline quality. From the pyramidal sector to the prismatic sector, the transmittance in the ultraviolet region decreases gradually when crossing the PY–PR boundary. The fluences corresponding to 50% laser-induced damage (LID) probability are 11.9, 12.8, and 17.0 J cm−2 (3 ns, 355 nm) for the PY–PR boundary, the pyramidal sector, and the prismatic sector, respectively. By identifying different types of defects in each sector, it is found that the PY–PR boundary exhibited the worst LID performance. This is because there are more bulk microdefects in the PY–PR boundary. These defects are more likely to be inclusions induced by the instability of the steps near the PY–PR boundary.

To reduce the seed length while maintaining the advantages of the cuboid KDP-type crystal, a long-seed KDP crystal with size $471~\text{mm}\times 480~\text{mm}\times 400~\text{mm}$ is rapidly grown. With almost the same high cutting efficiency to obtain third harmonic generation oriented samples, this long-seed KDP-type crystal can be grown with a shorter seed than that of the cuboid KDP-type crystal. The full width at half maximum of the high-resolution X-ray diffraction of the (200) crystalline face is 28.8 arc seconds, indicating that the long-seed KDP crystal has good crystalline quality. In the wavelength range of 377–1022 nm, the transmittance of the long-seed KDP crystal is higher than 90%. The fluence for the 50% probability of laser-induced damage (LID) is $18.5~\text{J}/\text{cm}^{2}$ (3 ns, 355 nm). Several test points survive when the laser fluence exceeds $30~\text{J}/\text{cm}^{2}$ (3 ns, 355 nm), indicating the good LID performance of the long-seed KDP crystal. At present, the growth of a long-seed DKDP crystal is under way.

Numerical simulations are performed to understand the variation of KDP crystal surface height by a rapid growth technique. The theoretical models used in numerical simulations couple the macroscopic transport of solute and impurities with the microscopic interfacial kinetics processes. Studies are specifically made to growth rate fluctuation at each growth interface subject to variations in crystal size, bulk supersaturation, rotation rate of the stirring paddle, and impurities. It is found that predicted interface moving speeds, equivalent to the growth rate, are uniformly distributed normal to each pyramidal and prismatic faces at macroscale by taking into account the interfacial kinetics process; however, they fluctuate wavily at microscale. The amplitude of growth rate fluctuation is on the order of micrometer. The fluctuation in growth rate will cause KDP crystal surface height variation and lead to the formation of micron-sized and nanosized inclusions in the crystals. Increasing crystal size and bu...

A deuterated potassium dihydrogen phosphate (DKDP) crystal with about 70% deuterium level was grown by a rapid horizontal growth method with independent design equipment, which includes a continuous filtration system. The cooling program during crystal growth was designed according to a self-developed software to catch the size of growing crystal in real time. The crystal structure, optical performance and laser induced damage threshold (LIDT) of this DKDP crystal were investigated in this paper. The deuterium concentration of the crystal was confirmed by the neutron diffraction technique, which was effective and available in determining a complete range of deuteration level. The dielectric property was measured to evaluate the perfection of the lattice. The transmittance and LIDT were carried out further to evaluate the optical and functional properties of this DKDP crystal grown in the rapid horizontal growth technique. All of the detailed characterization for DKDP figured out that the 70% deuterated KDP crystal grown in this way had relatively good qualities.

In order to develop a new kind of dissolvable alloy used for hydraulic fracturing tools, a series of Al Mg Ga In Sn alloys with different Mg contents were prepared by smelting and casting methods to investigate the effect of Mg on the reactivity of alloys with water. Their microstructures were investigated by means of XRD and SEM. The Volta potential difference (ΔVPD) of the interfacial phases with Al was measured using AFM/SKPFM. Mg forms different intermetallic compounds with low melting point metals, depending on Mg additions in alloys. Different from the formation of In3Sn phase in Al Ga In Sn alloys, the In3Sn phase disappears in Mg-bearing alloys. The experiments found that the reactivities of Mg-bearing alloys with water are closely related to Mg content of alloys and water temperature. The alloys react with water slowly at the beginning of reaction, following with a fast reaction. From the corrosive morphologies of alloys, the precipitation of low melting point metals from interfacial phases was observed at Al grain boundaries. The lower electric potential of interfacial phases than Al was accounted for the precipitation of low melting point metals, because the interfacial phases form micro-galvanic cells with Al when alloys contact with water. A reaction mechanism of Mg-bearing alloys with water was proposed to explain the reactivties of alloys with water.

Al Ga In Sn alloys were prepared by using traditional casting metallurgy method with different additions of Al 5Ti 1B grain refiner. Their microstructures were investigated by means of X-ray diffraction (XRD) and scanning electron microscope (SEM) with energy dispersed X-ray (EDX). The Al grains of alloys are refined significantly from 129 μm to 57 μm with increasing Ti content from 0.03 wt% to 0.24 wt%. Many thin dendrites that are a few micrometers thick are observed within Al grains. Al-water reactivities were performed under different water temperatures. The alloy with Ti content of 0.12 wt% shows the maximum H2 generation rate under different water temperatures, which is above 5 times of Ti-free alloy. The H2 yields of alloys drop from 87% to 30% with rising Ti content from 0.03 wt% to 0.24 wt% at the water temperature of 30 °C, but they rise to about 90% when the water temperature is above 50 °C. The growth mechanism of alloys and the effect of grain refinement on Al-water reactivities are discussed.

Al alloys containing 3 wt.% of Ga, In and Sn were prepared using arc melting technique. Their microstructures were investigated by means of X-ray diffraction and scanning electron microscope with energy dispersed X-ray, and interface reactions were detected using differential scanning calorimeter. The alloys consist of different low melting point phases at Al grain boundaries, which melting points depend on the compositions of alloys. Al-water reactivities were investigated under different water temperatures. The reaction temperatures above 40 °C are much higher than the melting point of ternary Ga–In–Sn (GIS) eutectic of 10.4 °C, indicating that GIS eutectic is already not the mechanism of Al-water reaction. The reaction temperature and the reaction rate of alloys vary with the mass ratio of In/Sn. Reasons concerning the microstructure changes and Al-water reactivities are discussed.

To further improve the quality of the cuboid DKDP crystal, the effect of thermal annealing at 160 °C were evaluated. After thermal annealing, the symmetry of the HRXRD of the X-cut sample is much better, indicating that the uniformity of the cuboid crystal is improved. The transmittance of annealed THG-oriented sample is obviously higher than the as-grown THG-oriented sample from 400 to 300 nm. At 355 nm, the transmittance of the THG-oriented sample increases from 80.4% to 87.9% after thermal annealing. Besides, thermal annealing is also beneficial to the weak absorption properties at 355 nm of the X-cut cuboid DKDP crystal. The average weak absorption of the X-cut sample is decreased from 26.6 ppm to 12.3 ppm, and the standard deviation of the X-cut sample is decreased from 17.0 ppm to 4.8 ppm after thermal annealing. The LID performance of the THG-oriented sample is improved through thermal annealing, and the fluences corresponding to 50% probability of LID is increased from 13.4 to 14.8 J/cm2 (@3ns, 355 nm). Also, the density of the defect with low LID threshold decreases by two-thirds. The above results indicate that thermal annealing is an effective means to further improve the quality of the cuboid DKDP crystal.

The microstructural characteristics of microphase Y-Ti2SC in Ni-based superalloys have been studied by means of analytical transmission electron microscopy (TEM). In the standard heat treated samples, the Y phase always exhibits slab morphology forming either the sandwiched plate in MC or the side-by-side structure with MC. Moreover, the Y phase also maintains an definite crystallographic orientation relationship of [ 1 2 ‾ 1 0 ] Y / / [ 1 1 ‾ 0 ] MC and (0 0 0 1)Y//(1 1 1)MC with the MC-type carbide. Stacking fault which results from the insertion of two Ti–C layers has been identified in the Y-Ti2SC phase. Combined with high resolution TEM (HRTEM) and first-principles calculations, we also determine the most stable interfacial structure between Y phase and MC carbide. Additionally, we find that Y-Ti2SC phase can solutionize amounts of beneficial elements Hf and Zr from the matrix during long-term annealing process, which leads to its lattice expansion. This solution phenomenon is detrimental for superalloys due to the consumption of the beneficial elements.

A volumetric experimental set-up used for measuring hydrogen absorption–desorption characteristics of hydrogen storage material will be presented. Although the experimental set-up is mainly employed to do hydrogen absorption–desorption cycling (including pressure cycling and thermal cycling) measurement automatically, it also can incidentally provide general measurements such as pressure-composition-temperature (P–C–T) curves and kinetics measurements in manual way in the ranges of 0.004–12 MPa and 213–773 K. The experimental set-up can be used to investigate the influence of hydrogen absorption–desorption cycles to hydrogen storage properties of material. The leakage rate of the whole experimental set-up was evaluated systemically. The usability and reliability of the experimental set-up were checked with LaNi 5 and Pd/K (kieselguhr).