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C is rhombohedral graphite-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is two-dimensional and consists of two C sheets oriented in the (0, 0, 1) direction. C is bonded in a trigonal planar geometry to three equivalent C atoms. All C–C bond lengths are 1.42 Å.
C is rhombohedral graphite-like structured and crystallizes in the orthorhombic Fmmm space group. The structure is two-dimensional and consists of two C sheets oriented in the (0, 0, 1) direction. C is bonded in a trigonal planar geometry to three equivalent C atoms. All C–C bond lengths are 1.42 Å.
C is Graphite-like structured and crystallizes in the orthorhombic Cmme space group. The structure is two-dimensional and consists of two C sheets oriented in the (0, 0, 1) direction. C is bonded in a trigonal planar geometry to three equivalent C atoms. All C–C bond lengths are 1.42 Å.
C is rhombohedral graphite-like structured and crystallizes in the hexagonal P6/mmm space group. The structure is two-dimensional and consists of one C sheet oriented in the (0, 0, 1) direction. C is bonded in a trigonal planar geometry to three equivalent C atoms. All C–C bond lengths are 1.42 Å.
C crystallizes in the trigonal R-3m space group. The structure is two-dimensional and consists of twelve C sheets oriented in the (0, 0, 1) direction. C is bonded in a trigonal planar geometry to three equivalent C atoms. All C–C bond lengths are 1.43 Å.
C is Graphite-like structured and crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of one C sheet oriented in the (0, 0, 1) direction. C is bonded in a trigonal planar geometry to three equivalent C atoms. There is one shorter (1.42 Å) and two longer (1.43 Å) C–C bond length.
C is rhombohedral graphite-like structured and crystallizes in the hexagonal P6/mmm space group. The structure is two-dimensional and consists of one C sheet oriented in the (0, 0, 1) direction. C is bonded in a trigonal planar geometry to three equivalent C atoms. All C–C bond lengths are 1.43 Å.
C is rhombohedral graphite-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is two-dimensional and consists of two C sheets oriented in the (0, 0, 1) direction. C is bonded in a trigonal planar geometry to three equivalent C atoms. All C–C bond lengths are 1.42 Å.
C is rhombohedral graphite-like structured and crystallizes in the hexagonal P6/mmm space group. The structure is two-dimensional and consists of one C sheet oriented in the (0, 0, 1) direction. C is bonded in a trigonal planar geometry to three equivalent C atoms. All C–C bond lengths are 1.42 Å.
C is Graphite structured and crystallizes in the orthorhombic Cmme space group. The structure is two-dimensional and consists of two C sheets oriented in the (0, 0, 1) direction. C is bonded in a trigonal planar geometry to three equivalent C atoms. There is two shorter (1.42 Å) and one longer (1.43 Å) C–C bond length.
C crystallizes in the tetragonal I4/mmm space group. The structure is two-dimensional and consists of two C sheets oriented in the (0, 0, 1) direction. C is bonded in a square co-planar geometry to four equivalent C atoms. All C–C bond lengths are 1.62 Å.
C crystallizes in the orthorhombic Cmcm space group. The structure is two-dimensional and consists of two C sheets oriented in the (0, 0, 1) direction. C is bonded in a square co-planar geometry to four equivalent C atoms. All C–C bond lengths are 1.63 Å.
C crystallizes in the orthorhombic Cmcm space group. The structure is two-dimensional and consists of two C sheets oriented in the (0, 0, 1) direction. C is bonded in a square co-planar geometry to four equivalent C atoms. All C–C bond lengths are 1.61 Å.
C crystallizes in the monoclinic P2/m space group. The structure is one-dimensional and consists of one C ribbon oriented in the (1, 0, 0) direction. C is bonded in a linear geometry to two equivalent C atoms. Both C–C bond lengths are 1.28 Å.
Aluminum doping can improve the phase stability of metastable compound Sm 2 Fe 17 C x with a high carbon content (x > 1.5). We investigated the preferential site substitution of Al, chemical bonding, and structural stability in Sm 2 (Fe,Al) 17 C 3 using first-principle calculations. Our results reveal a strong correlation between the preferential substitution of Fe by Al and the atomic site chemical environment, which affects the overall phase stability. Specifically, Al preferentially occupies the 9d site in Sm 2 (Fe,Al) 17 C 3 . At the same time, Al prefers the site 6c in its parent phase Sm 2 (Fe,Al) 17 . Partial replacement of Fe with Al leads to a more negative formation energy, indicating enhanced thermodynamic stability. Crystal Orbital Hamilton Population (COHP) and Crystal Orbital Bond Index (COBI) analysis suggest that insertion of carbon weakens the bonding strength of Sm-Fe (18f) and Sm-Fe (18h), resulting in metastability of Sm 2 Fe 17 C x . Doping Al strengthens Al-Fe, Al-Sm, Sm-Fe (18f, 18h) and Fe–C bonding in Sm 2 (Fe,Al) 17 C 3 , as revealed by calculated COHP and COBI. These effects contribute to improved phase stability in the Al-doped 2:17 interstitial compound.
Results are presented of simultaneous measurements of H-alpha (MSDP at Meudon) and C IV (UVSP onboard SMM) of Active Region 2701 made on October 2, 1980. Isodensity and velocity maps were obtained for both lines and these maps were superimposed. Results show a good correlation between the H-alpha and C IV velocities with a surge being observed for 10 minutes. The base of the surge was determined to be located in a bright point in C IV and H-alpha, while the escaping matter followed the same channel ('absorbing' in H-alpha, 'emitting' in C IV). It was found that the velocity along the surge was about 80 km/s in H-alpha and 100 km/s in C IV. In addition, a loop appeared in C IV during the surge. It is concluded that the vertical pressure gradient was capable of driving the surge.
Observations of the 158 microns fine-structure line of C(+) toward the nuclei of six gas-rich galaxies are presented. The observations are compared with observations of the CO J = 1-0 and H I 21 cm lines, observations of far-IR continuum emission, and observations of forbidden C II emission with the Galaxy. The forbidden C II line comes from dense, warm gas in UV-illuminated photodissociation regions at the surfaces of molecular clouds. This line is probably optically thin in all but the brightest of galactic sources. The variation of forbidden C II brightness from source to source and its ratio to the integrated infrared continuum intensity agree well with the theoretical prediction that UV absorption by dust controls the C(+) column density. The forbidden C II line is a tracer of molecular clouds, especially those near intense sources of UV radiation.
Various multiple strain-anneal cycles (1000 C) were imposed on specimens of the directionally solidified eutectic (DSE) alloy gamma/gamma prime-alpha to identify thermomechanical processing methods (TMP) which would improve the creep behavior. Specimens of the Ni-32.3Mo-6.3Al wt pct alloy were grown with a modified Bridgeman technique. Some of the cylindrical specimens were alternately heat-treated at 900 C, then strained, or heat-treated only, while other specimens were annealed at 900 C after swaging and then worked at ambient temperature. The specimens were all examined microstructurally using transmission electron microscopy, some before and after being exposed to constant-load compression tests at 1000 C. The creep strain increased for all TMP specimens for strain rates of at least 2 millionths per sec. Strain rates of about 2 ten millionths per sec were only improved with strain annealing with 13 percent work at ambient temperature. A slight improvement, compared to as-grown materials, was observed in the 1000 C creep behavior of materials annealed at 900 C. Strain-annealing was found to introduce three-dimensional dislocation networks into the gamma-prime matrix.