We achieved the growth of extremely-high quality SiC crystal with two-step solution method with specially-designed seed crystals. The two-step growth consists of 1st step growth on Si-face for the reduction of threading dislocations and 2nd step growth on C-face for the reduction of basal plane dislocations and thickening. In this method, we can make the dislocation density extremely low, while the polytype easily changes during growth due to the absence of spiral hillocks originating from threading screw dislocation (TSD). In this study, we prepared specially designed seed crystals for both 1st and 2nd growth steps to provide steps continuously. In the seeds, a few TSDs exist at the upper-side of the step structure. Consequently, we demonstrated the suppression of the polytype transformation during the C-face growth with extremely low-dislocation-density crystal. Accordingly, we successfully obtained extremely low-dislocation density 4H-SiC with TSD, TED and BPD density of 11, 385 and 28 cm-2.

Amorphous MgNi+x%B(x=0,2,5,10) hydrogen storage alloys have been prepared by mechanical alloying (MA) and tested as hydrogen storage electrodes. The addition of boron can promote the MgNi alloy to form amorphous phase, increase the atom ratio of Ni/Mg at the alloy powders’ surface, and improve the thermal stability of MgNi alloy. The discharge capacity, the high rate dischargeability (HRD) and the exchange current density of the alloy electrodes all increased first, and then decreased with increasing the addition of boron. The maximum discharge capacity, the HRD400 and the exchange current density of the alloy with 5%B were 411.6mAh/g, 58.3% and 293.5mA/g respectively, which were 21.8%, 40.0% and 351.5% higher respectively, comparing with that of no boron addition. The electrochemical cycle stability of the alloy electrodes increased with increasing boron additions, and compared with no boron addition, the cycle capacity retention rate S20 of the alloy with 10%B increased 64.2%.