Abstract
A fiber optic magnetic field sensor is proposed and experimentally demonstrated. Pristine and Co doped ZnO nanorods of different Co concentrations (5, 10, 15 and 20 at%) were synthesized using a hydrothermal method. The synthesized nanorods were subjected to various characterization methods like X-ray diffraction (XRD), optical absorption, scanning electron microscopy, energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, vibrating sample magnetometry and X-ray photoelectron spectroscopy (XPS). XRD and XPS analysis confirms that the Co ions were successfully incorporated into the Zn site of the wurtzite ZnO lattice without altering the structure. The pristine and Co doped ZnO nanorods showed remarkable changes in the M–H loop where the diamagnetic behavior of ZnO changes to paramagnetic when doped with Co. The sensor structure is composed of cladding modified fiber coated with Co doped ZnO nanorods as a sensing material. The modified cladding is proportionally sensitive to the ambient magnetic field because of the magneto-optic effect. Experimental results revealed that the sensor has an operating magnetic field range from 17 mT to 180 mT and shows a maximum sensitivity of ∼18% for 15 at% Co doped ZnO nanorods. The proposed magnetic field sensor would be attractive due to its low cost fabrication, simplicity of the sensor head preparation, high sensitivity and reproducibility.
Highlights
Nanostructured metal oxides have acquired a signi cant role in the scienti c world due to their efficient technological applications in the eld of solar cells, optoelectronic devices, gas sensors and spintronics.[1,2,3,4,5] ZnO is a unique wide band gap (3.37 eV) semiconductor with a large exciton binding energy (60 meV) and good chemical stability.[6]
Among the various TM ions, Co has its own importance in that (i) it is more reconcilable with Zn while doping, (ii) it can amend the morphology and optical properties of ZnO nanostructures, (iii) soluble in ZnO nanostructures, (iv) it has a strong magnetic moment compared with other transition metals and (v) the ionic radius of Zn2+ (0.60 A) is nearly same as Co2+ (0.58 A).[9]
5, 10, 15 and 20 at% Co doped ZnO nanorods are represented as ZC1, ZC2, ZC3 and ZC4 respectively
Summary
Nanostructured metal oxides have acquired a signi cant role in the scienti c world due to their efficient technological applications in the eld of solar cells, optoelectronic devices, gas sensors and spintronics.[1,2,3,4,5] ZnO is a unique wide band gap (3.37 eV) semiconductor with a large exciton binding energy (60 meV) and good chemical stability.[6]. Diluting non-magnetic ZnO with transition metal dopants such as Mn2+, Co2+, Ni2+ and Fe2+ could deliver different magnetic properties. This new genre of semiconductor is entitled as dilute magnetic semiconductors.[7,8]. Among the various TM ions, Co has its own importance in that (i) it is more reconcilable with Zn while doping, (ii) it can amend the morphology and optical properties of ZnO nanostructures, (iii) soluble in ZnO nanostructures, (iv) it has a strong magnetic moment (mCo 1⁄4 1.8 mB) compared with other transition metals and (v) the ionic radius of Zn2+ (0.60 A) is nearly same as Co2+ (0.58 A).[9] Many research groups have synthesized Co
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