期刊
JOURNAL OF SOLID STATE CHEMISTRY
卷 246, 期 -, 页码 150-159出版社
ACADEMIC PRESS INC ELSEVIER SCIENCE
DOI: 10.1016/j.jssc.2016.11.018
关键词
Magnetically ordered materials; Chemical synthesis; Vacancy formation
资金
- SERB Department of Science and Technology, Government of India under the Fast Track Scheme for Young Scientists [SB/FTP/PS-180/2013]
Future spintronics technologies based on diluted magnetic semiconductors (DMS) will rely heavily on a sound understanding of the microscopic origins of ferromagnetism in such materials. It remains unclear, however, whether the ferromagnetism in DMS is intrinsic - a precondition for spintronics - or due to dopant clustering. For this, we include a simultaneous doping from transition metal (Ni, Cu) and rare earth (Ce) ions in ZnO nanoparticles that increase the antiferromagnetic ordering to achieve high-T-c ferromagnetism. Rietveld refinement of XRD patterns indicate that the dopant ions in ZnO had a wurtzite structure and the dopants, Ni2+, Cu2+, Ce3+ ions, are highly influenced the lattice constants to induce lattice defects. The Ni, Cu, Ce ions in ZnO have nanoparticles formation than nanorods was observed in pure sample. FTIR involve some organic groups to induce lattice defects and the metal-oxygen bonding of Zn, Ni, Cu, Ce and O atoms to confirm wurtzite structure. Raman analysis evaluates the crystalline quality, structural disorder and defects in ZnO lattice with doping. Photoluminescence spectra have strong near-band-edge emission and visible emission bands responsible for defects due to oxygen vacancies. The energy band gap is calculated using Tauc relation. Room temperature ferromagnetism has been described due to bound magnetic polarons formation with Ni2+, Cu2+, Ce3+ ions in ZnO via oxygen vacancies. The zero field and field cooling SQUID measurement confirm the strength of antiferromagnetism in ZnO. The field cooling magnetization is studied by Curie-Weiss law that include antiferromagnetic interactions up to low temperature. The XPS spectra have involve +3/+4 oxidation states of Ce ions to influence the observed ferromagnetism.
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