A facile hydrothermal method was developed to synthesize boehmite nanorods with a length of 50-2000 nm, a diameter of 6-20 nm, and a preferential growth along [100] by treating the Al(OH)(3) gel in acidified sulfate solutions at 240 degrees C. Studies on the hydrothermal treatment of Al(OH)(3) gel in sulfate solutions showed that the morphology and the composition of the hydrothermal products were connected with the sulfate concentration and the pH of the hydrothermal solution. The aspect ratio of the boehmite nanorods increased to 300 as the initial H(2)SO(4) concentration increased to 0.043 mol x L(-1), whereas boehmite nanorods and (H(3)O)Al(3)(SO(4))(2)(OH)(6) cubic particles coexisted in the case of the initial H(2)SO(4) concentration > or = 0.054 mol x L (-1). Sole boehmite nanoflakes with a diameter of about 50 nm were formed under alkaline conditions (pH 10.5) despite the existence of the sulfate. The chemical and Raman analyses indicated that SO(4)(2-) in acidified solutions adsorbed on the boehmite surface via H-bonds. On the basis of the above results, the growth of boehmite along the [100] direction was attributed to the selective adsorption of SO(4) (2-) on the (010) and (001) planes of boehmite.

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Magnesium borate hydroxide (MgBO2(OH)) nanowhiskers with a diameter of 20–50 nm and a length of 0.5–3 μm were synthesized via a facile hydrothermal route, using MgCl2·6H2O, H3BO3, and NaOH as the reactants. Mg7B4O13·7H2O with poor crystallinity was formed after coprecipitation of the reactant solutions at room temperature, the hydrothermal treatment of the slurry at 240 °C for 18 h led to the formation of uniform MgBO2(OH) nanowhiskers with high crystallinity and preferential growth direction along the (200) plane.

We investigate the optical property of bent ZnO nanowires ͑NWs͒ obtained by low energy argon ion milling. At room temperature, the bent NWs demonstrates an enhanced near band edge ultraviolet emission, while the deep level green emission is totally suppressed. Temperature dependent photoluminescence measurements were carried out between 10 and 300 K for both the as-grown and the bent ZnO NWs. It is found that the emission peak energy of the bent NWs systematically shifts to lower energy compared to the as-grown NWs in the whole measured temperature range. Our results indicate that the redshift in the emission peak is related to the uniaxial tensile strain and the enhanced exciton-phonon coupling strength in the bent ZnO NWs.