研究目的
To investigate the oxygen vacancy induced ferromagnetism in ball milled Zn0.97Ni0.03O and confirm it through electron spin resonance.
研究成果
The nanocrystalline Ni-doped ZnO synthesized by ball milling method exhibits room temperature long range ferromagnetic ordering due to long range Ni2+-Ni2+ ferromagnetic coupling mediated by shallow donor electrons. The ESR spectrum validates the observation of room temperature ferromagnetism because of the presence of oxygen vacancies as well as the occurrence of cationic interactions.
研究不足
The study does not quantify the oxygen vacancies in undoped and Ni-doped ZnO as Micro-Raman analysis provides only qualitative analysis of structure and defects.
1:Experimental Design and Method Selection:
The study synthesized Zn1?xNixO (x =
2:03) nanoparticles using a ball milling technique to investigate the ferromagnetic properties induced by oxygen vacancies. Sample Selection and Data Sources:
Commercial ZnO nanopowders (
3:99%, Aldrich) and 3% Nickel oxide (99%, Aldrich) powder were used as starting materials. List of Experimental Equipment and Materials:
Retsch PM-100 planetary ball mill with 5 mm tungstate carbide balls, X-ray diffractometer with Cu-ka radiation, Renishaw In Via micro-Raman spectrometer, vibrating sample magnetometer, and ESR spectrometer.
4:Experimental Procedures and Operational Workflow:
The ball milling was carried out in dry medium at fixed rotations per minute (rpm) of 350 for three hours. The grinded product was recovered and separated from the balls using a filtrated system.
5:Data Analysis Methods:
The crystal structure was analyzed by XRD, structural and defect analysis by micro-Raman, magnetic properties by VSM, and electron spin resonance by ESR spectrometer.
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