Aluminum nitride nanostructures are attractive for many promising applications in semiconductor nanotechnology. Herein we report on vapor-solid growth of quasi-aligned aluminum nitride nanocones on catalyst-coated wafers via the reactions between AlCl3 vapor and NH3 gas under moderate temperatures around 700 degrees C, and the growth mechanism is briefly discussed. The as-prepared wurtzite aluminum nitride nanocones grow preferentially along the c-axis with adjustable dimensions of the sharp tips in the range of 20-60 nm. The photoluminescence spectrum reveals a broad blue emission band with a fine photon structure while the field emission study shows a notable emission current with a moderate turn-on field as expected, suggesting their potential applications in light and electron emission nanodevices.

Metallic nanowires protected from oxidation and corrosion by a sheath of polyaniline have been prepared in arrays on an alumina membrane support. The cobalt wire/polyaniline tubule nanocomposite structures (see Figure), which are produced by using the polyaniline tubules as a template for the growth of the metal wires, have potential in applications such as magnetic antenna materials.

No abstract

Two novel complexes trans-[Fe(MBPT) 2 (NCS) 2 ] (1) and cis-[Fe(mMBPT) 2 (NCS) 2 ] (2) have been synthesized and their structure characterized at 293 K by single-crystal X-ray crystallography [MBPT (or mMBPT) ) 4-p(or m)-methylphenyl-3,5-bis(pyridin-2-yl)-1,2,4triazole]. Complexes 1 and 2 are isomers, and 1 crystallizes in the triclinic space group P1 h with Z ) 1, a ) 9.120(3) Å, b ) 9.2563(18) Å, c ) 11.576(2) Å, R ) 76.256(15)°, β ) 76.405-(18)°, γ ) 84.983(19)°, and V ) 922.1(4) Å 3 in contrast to 2 in the monoclinic space group C2/c with Z ) 4, a ) 21.851(3) Å, b ) 13.4113(15) Å, c ) 16.859(3) Å, β ) 128.153( 9)°, and V ) 3885.0(9) Å 3 . Both complexes have a similar pseudo-octahedral [FeN 6 ] core with the NCSgroups in the trans arrangement in 1 but cis in 2. Variable-temperature magnetic susceptibility and IR spectral measurements reveal that 1 shows an abrupt high-spin T low-spin (HS T LS) transition centered at T 1/2 around 231 K, in contrast to 2 staying in a high-spin state in the observed temperature range of 75-300 K. The extended X-ray absorption fine structures (EXAFS) spectra confirm that the average Fe-N distance for the HS state in 1 is ≈0.2 Å longer than that of the LS state. Complex 1 represents the first spin-crossover iron(II) complex with triaryltriazole and trans-thiocyanate ligands.