Flame synthesis of molybdenum oxide whiskers

The spectacular growth of molybdenum oxide hollow and solid whiskers with rectangular and circular cross-section is reported. The synthesis is performed using molybdenum probes inserted in an opposed-flow methane oxy-flame. The solid rectangular and circular whiskers with characteristic cross-sectional dimensions from 100 nm to 4 μm and hollow rectangular channels with wall thickness from 50 to 100 nm are grown on 1-mm diameter probes inserted at the high temperature zone on the oxidizer side of the flame front. The shape and structural parameters of grown whisker materials strongly depend on the flame position (temperature) and probe diameter. Well-defined elongated crystal structures with a large number of facets and complex symmetry were grown on the probes with a diameter of 0.25 mm.