Single crystal

About: Single crystal is a research topic. Over the lifetime, 59617 publications have been published within this topic receiving 870828 citations.

Oxidation of Single‐Crystal Silicon Carbide Part I . Experimental Studies

Abstract: The oxidation of single crystal in dry oxygen (10−3–1 atm and 1200°–1500°C) followed parabolic kinetics. Two different apparent activation energies were calculated for oxidation of the (0001) C faces of , approximately 120 kJ/mol below 1350°C and 260 kJ/mol above 1350°C. Two regimes were not apparent for oxidation of the (0001) Si faces, and apparent activation energies lay between 223 and 298 kJ/mol. Double oxidation experiments using and indicated that the process is dominated by the transport of molecular oxygen at lower temperatures (<1300°C) with a substantial contribution from diffusion of ionic oxygen at higher temperatures. Epitaxially grown Si 13C films on alpha‐Si 12C substrates via CVD were used to study carbon transport behavior during oxidation of . Depth profiles for carbonaceous species using SIMS showed that carbon can transport quickly through the oxide layer, which eliminates the possibility that transport of carbonaceous species is rate controlling in the oxidation of . Oxidation mechanisms of are discussed on the basis of these results.

Large field induced strain in single crystalline Ni–Mn–Ga ferromagnetic shape memory alloy

Abstract: A room temperature free shear strain of 5.7% is reported in a single crystal of Ni–Mn–Ga having a composition close to the Heusler alloy Ni2MnGa. A twin boundary was created in a 2 mm×2 mm×25 mm single crystal using a permanent magnet with surface field strength of about 320 000 A/m. A sharp 6.5° bend occurs in the sample at the twin boundary. The surface magnetization changes abruptly across this boundary. By moving the sample relative to the edge of the magnet, we were able to sweep the boundary back and forth along the crystal length. Surface magnetization was measured using a Hall probe and the results confirm that the easy axis is the tetragonal c axis. Powder x-ray diffraction shows that the fcc to body-centered-tetragonal bct martensitic transition of this material involved a 6% reduction of the bct cell c/a ratio, from √ to about 1.33. The maximum achievable strain is thus estimated to be 6.2%. The twin planes in the system are the {112}bct and were observed to lie almost normal to the long axis of the sample tested.

Anisotropic Electron Transport Properties in Sumanene Crystal

Abstract: The high electron mobility with large anisotropy was attained in the needle-like single crystal of sumanene, which was indicated by time-resolved microwave conductivity (TRMC) measurement.

X-Ray Standing Waves at Crystal Surfaces

Abstract: With use of bromine atoms, deposited on the surface of a silicon single crystal, the presence of x-ray standing waves above the crystal surface has been detected under conditions of strong Bragg diffraction.