Structural and Magnetic Studies of Nanocrystalline Zn1-xMnxO (x=0 and 0.05) Samples Synthesized by Chemical Vapor Deposition

Abstract

We report on the structural and magnetic properties of the nanocrystalline samples of Zn1-xMnxO (x=0 and 0.05) synthesized by chemical vapor deposition (CVD) technique. X-ray diffraction (XRD) and transmission electron microscopy (TEM) studies of the samples reveal pure wurtzite structure of ZnO with no impurity phase in all the synthesized samples. TEM study reveals that the particle sizes of the Zn1-xMnxO (x=0 and 0.05) samples vary in the range 15–25 nm. Magnetic measurements show weak ferromagnetism for x=0.05 and diamagnetic behavior for x=0 at room temperature. Annealing in Ar/H2 enhances ferromagnetism in Zn0.95Mn0.05O whereas pure ZnO remains diamagnetic. Magnetization versus temperature (M–T) measurements in the temperature range 5–300 K also suggests Curie temperature above room temperature for Ar/H2 annealed (hydrogenated) Zn0.95Mn0.05O samples. The observed room temperature ferromagnetism (RTFM) in the present case may be attributed to the oxygen vacancies produced on annealing the sample in reducing atmosphere (Ar/H2) and is not due to any secondary phases or clusters of Mn.