# Magnetic Properties of NiZn Ferrite Nanofibers Prepared by Electrospinning
## 3 Results
Therefore, it is important to check the morphology through a microscopic observation. Figure 3a, Figure 3b, and Figure 3c are FE-SEM images of the as-spun nanofibers of samples A, B, and C, respectively, and Figure 3d, Figure 3e, and Figure 3f show the calcined Ni\({}_{0.5}\)Zn\({}_{0.5}\)Fe\({}_{2}\)O\({}_{4}\) nanofibers. Although as-spun nanofibers were shrunk by calcination, the morphology of isotropic fibers was maintained without breaking the microstructure. Figure 4 shows the EDX mapping results of the nanofiber samples. Figure 3a, Figure 3b, and Figure 3c show the emission distribution of the characteristic X-ray of Fe, Ni, and Zn, respectively. A comparison of the distribution of each element with the SEM image shown in Figure 4d, confirmed that each component was evenly distributed at the position where the nanofiber existed. The density of each pixel was only related to the degree of the nanofiber overlap. The uniform distribution of each element can support XRD analysis results showing a single crystal structure. The EDX spectrum analysis of the mapping results is shown in Table 3. Due to the characteristics of the electron beam source, high analytical reliability for the magnetic powders cannot be expected, but the chemical composition ratio was very similar to the Ni\({}_{0.5}\)Zn\({}_{0.5}\)Fe\({}_{2}\)O\({}_{4}\) phase. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Samples** & **Plane (_hkl_)** & **20 (\({}^{\circ}\))** & **FWHM (\({}^{\circ}\))** & **Average Crystallite Size (nm)** \\ \hline \multirow{2}{*}{Sample A} & (131) & 35.25 & 0.33 & \multirow{2}{*}{20 \(\pm\) 6} \\  & (151) & 56.72 & 0.58 & \\  & (404) & 62.47 & 0.56 & \\ \hline \multirow{2}{*}{Sample B} & (131) & 35.60 & 0.44 & \multirow{2}{*}{16 \(\pm\) 3} \\  & (151) & 56.76 & 0.69 & \\  & (404) & 62.82 & 0.68 & \\ \hline \multirow{2}{*}{Sample C} & (131) & 35.63 & 0.58 & \multirow{2}{*}{13 \(\pm\) 2} \\  & (151) & 56.78 & 0.87 & \\ \cline{1-1}  & (404) & 62.81 & 0.82 & \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Average crystallite size and XRD peak broadening data of each sample. FWHM: full width at half maximum. Figure 3: Field emission-scanning electron microscopes (FE-SEM) images of as-spun and calcined Ni\({}_{0.5}\)Zn\({}_{0.5}\)Fe\({}_{2}\)O\({}_{4}\) nanofibers obtained from various samples: (**a**) As-spun nanofibers of sample A, (**b**) As-spun nanofibers of sample B, (**c**) As-spun nanofibers of sample C, (**d**) Calcined Ni\({}_{0.5}\)Zn\({}_{0.5}\)Fe\({}_{2}\)O\({}_{4}\) nanofibers of sample A, (**e**) Calcined Ni\({}_{0.5}\)Zn\({}_{0.5}\)Fe\({}_{2}\)O\({}_{4}\) nanofibers of sample B, and (**d**) Calcined Ni\({}_{0.5}\)Zn\({}_{0.5}\)Fe\({}_{2}\)O\({}_{4}\) nanofibers of sample C.  
The diameters of Ni\({}_{0.5}\)Zn\({}_{0.5}\)Fe\({}_{2}\)O\({}_{4}\) nanofibers were measured with FE-SEM images. To obtain quantification uniformity, 10 specimens for each sample A, B, and C were prepared and FE-SEM analysis was conducted. Four FE-SEM images were taken from each specimen and 5 points in the image with up, down, left, right, and center parts, were selected to measure the diameter. Figure 5 shows a histogram on the distribution of nanofiber diameters obtained by making 200 measurements of samples A, B, and C. The histogram shows that the average diameter of the samples was formed with a constant difference of about 20 nm within the range  
Figure 6 shows the magnetization behavior of nanofiber samples with different average diameters measured by VSM. In general, the crystalized structure, chemical composition, oxygen vacancies, particle shape, and the interaction of the domain wall with various defects are considered to be the parameters of saturation magnetization [40; 41; 42]. Among them, the presence of non-aligned surface spin derived to thermal fluctuation is regarded as the main factor to reduce saturation magnetization, and it is related to the specific surface area [43].