Abstract:Nanocrystalline NiFe 2 O 4 spinel ferrites were synthesized by sol-gel method. The structural and magnetic properties were investigated using X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy, Scanning Electron Microscopy (SEM) and Vibrating Sample Magnetometer (VSM). Annealing temperature showed prominent effect on the grain size. The average grain size of NiFe 2 O 4 was observed to increase from 31 nm to 54 nm as the annealing increased from 500˚C to 1000˚C. The IR spectra showed the ab… Show more
“…Due to development of pores at higher annealing temperatures samples have the decrease in saturation magnetization. Moreover, samples experience an induced spin-reorientation transition, by a temperature change and reduced by an external magnetic field 25 .Figure 5Hysteresis loops for NiZnFe 2 O 4 ( a ) 900 °C, ( b ) 1100 °C; and NiZnFe 2 O 4 /CdS with NiZnFe 2 O 4 ( c ) 900 °C, ( d ) 1100 °C; at room temperature with different particle sized shell. dχ/dH curves of NiZnFe 2 O 4 /CdS nanostructures with varying CdS QDs layers with 0.2 g NiZnFe 2 O 4 loading ( e ) 900 °C, ( f ) 1100 °C; and with 0.05 g NiZnFe 2 O 4 loading (g) 900 °C, ( h ) 1100 °C.…”
The selected and controlled preparation of core@shell nanostructures, which unite the multiple functions of ferromagnetic Ni-Zn ferrite core and CdS shell in a single material with tuneable fluorescence and magnetic properties, have been proposed by the seed mediated aqueous growth process. The shell particle thickness and core of nanostructures were precisely tuned. Current work exhibits the comparative study of core@shell multifunctional nanostructures where core being annealed at two different temperatures. The core@shell nanostructure formation was confirmed by complementary structural, elemental, optical, magnetic and IR measurements. Optical and magnetic characterizations were performed to study elaborative effects of different structural combinations of core@shell nanostructures to achieve best configuration with high-luminescence and magnetic outcomes. The interface of magnetic/nonmagnetic NiZnFe2O4/CdS nanostructures was inspected. Unexpectedly, in some of the core@shell nanostructures presence of substantial exchange-bias was observed in spite of the non-magnetic nature of CdS QDs which is clearly an “optically-active” and “magnetically-inactive” material. Presence of “exchange-bias” was confirmed by the change in “magnetic-anisotropy” as well as shift in susceptibility derivative. Finally, successful formulation of stable and efficient core@shell nanostructures achieved, which shows no exchange-bias and shift. Current findings suggest that these magneto-fluorescent nanostructures can be used in spintronics; and drug delivery-diagnosis-imaging applications in nanomedicine field.
“…Due to development of pores at higher annealing temperatures samples have the decrease in saturation magnetization. Moreover, samples experience an induced spin-reorientation transition, by a temperature change and reduced by an external magnetic field 25 .Figure 5Hysteresis loops for NiZnFe 2 O 4 ( a ) 900 °C, ( b ) 1100 °C; and NiZnFe 2 O 4 /CdS with NiZnFe 2 O 4 ( c ) 900 °C, ( d ) 1100 °C; at room temperature with different particle sized shell. dχ/dH curves of NiZnFe 2 O 4 /CdS nanostructures with varying CdS QDs layers with 0.2 g NiZnFe 2 O 4 loading ( e ) 900 °C, ( f ) 1100 °C; and with 0.05 g NiZnFe 2 O 4 loading (g) 900 °C, ( h ) 1100 °C.…”
The selected and controlled preparation of core@shell nanostructures, which unite the multiple functions of ferromagnetic Ni-Zn ferrite core and CdS shell in a single material with tuneable fluorescence and magnetic properties, have been proposed by the seed mediated aqueous growth process. The shell particle thickness and core of nanostructures were precisely tuned. Current work exhibits the comparative study of core@shell multifunctional nanostructures where core being annealed at two different temperatures. The core@shell nanostructure formation was confirmed by complementary structural, elemental, optical, magnetic and IR measurements. Optical and magnetic characterizations were performed to study elaborative effects of different structural combinations of core@shell nanostructures to achieve best configuration with high-luminescence and magnetic outcomes. The interface of magnetic/nonmagnetic NiZnFe2O4/CdS nanostructures was inspected. Unexpectedly, in some of the core@shell nanostructures presence of substantial exchange-bias was observed in spite of the non-magnetic nature of CdS QDs which is clearly an “optically-active” and “magnetically-inactive” material. Presence of “exchange-bias” was confirmed by the change in “magnetic-anisotropy” as well as shift in susceptibility derivative. Finally, successful formulation of stable and efficient core@shell nanostructures achieved, which shows no exchange-bias and shift. Current findings suggest that these magneto-fluorescent nanostructures can be used in spintronics; and drug delivery-diagnosis-imaging applications in nanomedicine field.
“…Then the solution was heated on a hot plate with a continuous stirring at about 100 ∘ C until viscous gel is formed. Then the temperature was raised to about 200 ∘ C, which leads to the self-propagating combustion reaction resulted in the formation of a loose powder [24][25]. Then the obtained powder was divided into five equal proportions.…”
A single composition of erbium-doped nickel zinc ferrite Ni0.5Zn0.5Fe1.95Er0.05O4 is synthesized by the sol-gel autocombustion process. The prepared composition was divided into five equal parts. One of the parts was an as-prepared sample, and remaining four other parts were calcinated at 600, 700, 800, and 900 ∘C to investigate the variation in structural and optical properties with the calcination temperature. The structural characterization was performed using XRD and SEM. Optical properties were analyzed using FTIR and UV-Visible spectral data. XRD patterns confirm the spinel cubic crystal structure and the Fd3m space group. The crystallite size was minimum for the as-prepared sample (17.9452 nm), and the crystallite size was maximum for the sample calcinated at 900 ∘C (29.8481 nm). SEM images revealed the grain size in the interval from 55.38 nm to 177.73 nm, and certain nanotubes were formed in the sample calcinated at 800 ∘C. Optical energy band gap was observed in the interval from 5.556 eV to 3.969 eV. All these testifies to the variations in structural and optical properties of Ni0.5Zn0.5Fe1.95Er0.05O4 with the calcination temperature.
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