Synthesis of 1-D Nanostructures of ZnFe<sub>2</sub>O<sub>4</sub> and ZnO by a Low Cost Self-Catalyzed CVD Method

Abstract

Zinc ferrite (ZnFe2O4) is a commercially important material and has wide applications. We report the synthesis of nanostructured ZnFe2O4 and Fe-doped ZnO nanorods via a low cost, open to atmosphere self catalyzed Chemical Vapor Deposition(CVD) method which uses the Vapor-Liquid-Solid (VLS) Mechanism for growth. A mixture of Zinc Oxide, Graphite and Zinc powder, along with the substrates were put at the closed end of a quartz tube and placed in a preheated furnace. The parameters varied were 1.)molar ratios 2.)types of substrates and 3.)the furnace temperature. The characterization was done using FE-SEM, TEM,and XRD. The growth morphology varies along the temperature gradient in the tube, resulting in the formation of ZnFe2O4 nanoribbons (800-750 0C), nanoellipsoids (700 0C) and nanowires (650 0C). Fe- doped ZnO nanorods have also formed as scattered bundles along with the zinc ferrite nanoribbons. This is the first reported synthesis of nanoribbon morphology of ZnFe2O4 . The effective diameter:width ratio of the morphology and the Zn atomic percentage decreases along the temperature gradient. Optimized parameters were:1.)mild steel substrates, 2.)furnace temperature 800 0C and 3.)1:1:0.05 molar ratio of ZnO:C:Zn in the reaction mixture. When stainless steel and gold sputtered steels were used as substrates there was no growth. This proves that iron from the substrate takes an active part in the reaction and is critical for the growth. The simplicity of the setup, control over growth morphology and cheap reagents used give the method potential commercial applications.