Rutile VO2 nanorods have been synthesized by the precursor morphology controlled formation. The precursor single-crystal VO2 hydrate nanorods have been obtained via the hydrothermal reaction of KOH, V2O5, and hydrazine in a sealed autoclave at low temperature. The reducing agent N2H4 plays a key role in the control of one-dimensional morphology. According to the data of differential scanning calorimetry and thermogravimetric analysis, rutile VO2 nanorods have been formed when the precursor VO2 hydrate is heated at 340 °C for 1 day in flowing N2 and maintaining the morphology of the precursor. The products have been characterized by means of X-ray powder diffraction, transmission electron microscopy, high-resolution electron microscopy, selected area electron diffraction, and X-ray energy-dispersive spectroscopy techniques. It is shown that these rutile VO2 nanorods are self-assembled by VO2 nanocrystalline domains with the same crystallographic direction along the rod axis. The reaction details and features are described and discussed.

The normal state resistivtity, upper critical field H c2 and Hall coefficientAbove 70 K, ρ(T ) fits well curve predicted by Bloch-Grüneisen theory consistently with electron-phonon scattering. H c2 (0) was estimated to be about 15.0 Tesla within the weak-coupling BCS theory, and the superconducting coherence length ξ(0) is approximately 47Å. R H of M gCN i 3 is negative for the whole temperature range which definitely indicates that the carrier in M gCN i 3 is electron-type. R H is temperature independent between T c and ∼ 140 K. Above ∼ 140 K, the magnitude of R H decreases as temperature rises. At T = 100 K, the carrier density is 1.0 × 10 22 /cm 3 , which is comparable with that in perovskite (Ba, K)BiO 3 , and less than that of the metallic binary M gB 2 .

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The thermopower and thermal conductivity of superconducting perovskite M gCN i 3 (T c ≈ 8 K) have been studied. The thermopower is negative from room temperature to 10 K. Combining with the negative Hall coefficient reported previously, the negative thermopower definetly indicates that the carrier in M gCN i 3 is electron-type. The nonlinear temperature dependence of thermopower below 150 K is explained by the electron-phonon interaction renormalization effects. The thermal conductivity is of the order for intermetallics, larger than that of borocarbides and smaller than M gB 2 . In the normal state, the electronic contribution to the total thermal conductivity is slightly larger than the lattice contribution. The transverse magnetoresistance of M gCN i 3 is also measured. It is found that the classical Kohler's rule is valid above 50 K. An electronic crossover occures at T * ∼ 50K, resulting in the abnormal behavior of resistivity, thermopower, and magnetoresistance below 50 K.