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.

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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.

In perovskite manganites La0.7−xNdxCa0.3MnO3 (x=0, 0.05, 0.1, 0.15, and 0.20) prepared by the sol–gel technique, large magnetocaloric effects have been observed. The maximum of the magnetic entropy change peaks at the magnetic ordering temperature. Compared to La0.7Ca0.3MnO3, an enhancement of the magnetocaloric effect has been obtained in the samples with Nd3+ dopant (for La0.5Nd0.2Ca0.3MnO3, the maximum of ΔSM is about −2.31 J/kg K).

Nanosized La0.7Sr0.3MnO3/Pr0.5Sr0.5MnO3 (LSMO1−xPSMOx) ceramic composites are prepared using solid-sate sintering. Their microstructural, electro- and magnetotransport properties are characterized by means of various techniques. It is found that the antiferromagnetic/ferromagnetic coupling between PSMO/LSMO at low temperature and the weak ferromagnetic order of PSMO at high temperature results in enhanced low-field magnetoresistance (LFMR) of the composites. With increasing temperature up to 250 K the observed LFMR decays more slowly than that for pure LSMO and this behavior may be explained by the spin coupling near boundaries between LSMO and PSMO grains.

We have determined the dependence of exchange coupling on the antiferromagnetic layer thickness (tAF) in FeMn/NiFe bilayers, where the FeMn layer varies from 0.5 to 32 nm, and the NiFe is constant at 30 nm. For tAF>3 nm, the exchange field Hex varies as (1/tAF)0.3 at both 80 and 300 K, whereas the coercivity is insensitive to tAF. The value of Hex displays a simple angular dependence of cos θ.

An array of nickel nanowires enveloped in polyaniline nanotubules was prepared by the “second-order-template” method. As the first step, an array of the polyaniline nanotubules was synthesized in the pores of an alumina membrane, then nickel nanowires were fabricated by electrochemical deposition of the nickel into the polyaniline nanotubules. The composite nanostructure was characterized by x-ray powder diffraction, and scanning electron micrography. Its magnetic properties were measured by a vibrating sample magnetometer. The coercivity and remanence are of high anisotropy with a maximum at θ=90° (parallel to the nanowires).