Entangled Zn-ZnO nanorods and urchin-like microstructures were synthesized by the hot filament chemical vapor deposition technique at 825 and 1015°C, respectively. X-ray diffraction results showed a mixture of ZnO and Zn phases in both nanorods and urchin-like structures. The presence of Zn confirms the chemical dissociation of the ZnO solid source. The Z-ZnO nanorods with diameter of about 100？nm showed dispersed-like morphology. The urchin-like structures with micrometer diameters exhibited porous and rough morphology with epitaxial formation of nanorods. 1. Introduction Several techniques have been employed in obtaining nanostructured materials due to their potential applications in electronics, optoelectronics, and chemical gas sensing [1–4]. Recently, micro- and nanoscale composite materials with core-shell structure have stimulated a lot of attention due to their interesting properties such as large surface area and quantum confinement effects. Zn-ZnO core-shell structures are of special interest since heterojunctions can be formed at the interface. These structures offer great promise for fabrication of devices as nanotransducers [5], in solar energy conversion [6], and field emission [7], among others. Nowadays several methods are commonly applied to prepare Zn-ZnO core-shell structures such as urchin-like [6], nanoparticles [8], and nanorods [9]. Chemical vapor deposition (CVD) and its different experimental configurations such as metal organic CVD, plasma enhanced CVD, laser enhanced CVD, low pressure CVD, and HFCVD have shown versatility and reliability in obtaining a large variety of films, coatings, and recently nanostructures. The HFCVD method requires only a filament and a current source to decompose hydrogen molecules into atomic hydrogen . These radicals assist the fast decomposition of several types of gas phase and solid raw materials. In the present work is reported the formation of Zn-ZnO nanorods and urchin-like microclusters by the HFCVD technique, using catalytic produced hydrogen atoms as reducing agent. 2. Materials and Methods Zn-ZnO nanorods and urchin-like microclusters were fabricated by the HFCVD technique by using ZnO powders as reactant material. Although the main characteristic of the HFCVD system is that it uses a metallic filament, it is known that by contact with SiH4 or H2 it yields hydrogen atoms when it is heated at 1600°C and above [10, 11]. The aim of using hydrogen atoms was to produce Zn and OH gases from a ZnO solid source in a short period of time in relation to other methods. Actually, the amount of
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