2005/12/22 by M. Naeem, Muhammad Azhar Naeem, S. K. Hasanain +7 · 1 citation
Engineering · Materials Science · Physics and Astronomy · #Copper-based nanomaterials and applications #Gas Sensing Nanomaterials and Sensors #ZnO doping and properties #cond-mat.mtrl-sci #cond-mat.other
paper · pdf · doi:10.1088/0957-4484/17/10/039
published as Nanotechnology 17 (2006) 2675--2680 · 11 pages, 6 figures, submitted to Nanotechnology IOP
arxiv created 2005/12/22 · openalex publication_date 2006/05/08 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/07/30
We report the crystal structure and magnetic properties of Zn(1-x)Co(x)O (0≤x≤0.10) nanoparticles synthesized by heating metal acetates in organic solvent. The nanoparticles were crystallized in the wurtzite ZnO structure after annealing in air and in a forming gas (Ar95% + H5%). The x-ray diffraction and x-ray photoemission spectroscopy (XPS) data for different Co content show clear evidence for the Co(2+) ions in tetrahedral symmetry, indicating the substitution of Co(2+) in the ZnO lattice. However, samples with x = 0.08 and higher cobalt content also indicate the presence of Co metal clusters. Only those samples annealed in the reducing atmosphere of the forming gas, that showed the presence of oxygen vacancies, exhibited ferromagnetism at room temperature. The air annealed samples remained non-magnetic down to 77 K. The essential ingredient in achieving room temperature ferromagnetism in these Zn(1-x)Co(x)O nanoparticles was found to be the presence of additional carriers generated by the presence of the oxygen vacancies.