# Magnetic Nanoparticles as Mediators for Magnetic Hyperthermia Therapy Applications: A Status Review
## 3 Results and Discussion
### X-ray Diffraction Analysis  
Figures 1-7 show the XRD patterns of as-prepared maghemite and maghemite particles covered with CM-dextran MNPs, (Mg, Ti)-ferrite MNPs, as-prepared NiCu MNPs, NiCu MNPs embedded in SiO\({}_{2}\) matrix, and as-prepared NiCr NPs heat-treated. XRD measurements were performed with a D5005 diffractometer (Bruker Siemens) and analyzed with Topas software (Bruker, AXS). All presented MNPs with selected compositions are well crystallized. Crystalline sizes were determined from XRD line broadening using the Sherrer equation (Table 1):  
\[d_{\rm x}=\frac{(0.94\cdot\lambda)}{(\beta\cdot cos\theta)}, \tag{1}\]  
where \(d_{\rm x}\) is crystallite size; \(\lambda\) is the wavelength of the radiation; \(\beta\) is the line broadening at half the maximum intensity (FWHM) in radians and \(\theta\) is the corresponding diffraction angle. Figure 1: XRD spectra of as-prepared maghemite particles (A) and the particles covered with CM-dextran (B). Figure 4: XRD powder diffraction patterns of Ni\({}_{1-x}\)Cu\({}_{x}\) (Ni\({}_{67.5}\)Cu\({}_{32.5}\) (A), Ni\({}_{62.5}\)Cu\({}_{37.5}\) (B), Ni\({}_{60}\)Cu\({}_{40}\) (C)) alloy MNPs embedded in the silica matrix (sol–gel method). Figure 3: XRD spectra of (a) as-prepared Ni\({}_{0.725}\)Cu\({}_{0.275}\) MNPs and (b) particles thermally homogenized in NaCl matrix (microemulsion method). Figure 2: XRD spectra of the (Mg, Ti)-ferrite sample (x = 0.37). The curves of the crystalline and nanocrystalline spinel phases are shown below. Figure 5: XRD patterns of Cu\({}_{1-x}\)Ni\({}_{x}\) samples (milled 20 h) with various compositions. The patterns are compared with the pattern of a Cu–Ni physical mixture, where samples are: A = Cu\({}_{40}\)Ni\({}_{60}\), B = Cu\({}_{30}\)Ni\({}_{70}\), C = Cu\({}_{27.5}\)Ni\({}_{27.5}\), D = Cu\({}_{27}\)Ni\({}_{73}\), E = Cu\({}_{25}\)Ni\({}_{75}\), F = Cu\({}_{20}\)Ni\({}_{80}\). Figure 6: XRD patterns of synthesized Cr\({}_{20}\)Ni\({}_{80}\) alloy, as-prepared and at different temperatures (microemulsion technique). The X-ray diffraction patterns of the as-prepared maghemite MNPs (A) and the particles coated with CM-dextran (B) are shown in Figure 1. The diffraction peaks correspond to the cubic phase of maghemite (JCPDS No. 39-1346). Figure 1 clearly shows that the particles are crystalline. Using the Sherrer equation, we estimated the size of the maghemite nanoparticles to be around 16 nm (sample A) and the size of the nanoparticles coated with CM-dextran to be around 11.8 nm (sample B). The size of the nanoparticles is consistent with the analysis of TEM, but one of the main reasons that the coated particles are smaller than the uncoated ones is due to centrifugation, which removed the larger particles [27]. The X-ray diffraction patterns of milled (Mg, Ti)-ferrite sample (x = 0.37) are shown in Figure 2[26]. The diffraction patterns are consistent with the peaks characteristic of MgFe\({}_{2}\)O\({}_{4}\) but the diffraction peaks are slightly shifted. The diffraction peaks of MgFe\({}_{2}\)O\({}_{4}\) (JCPDS 36-0398) have a lattice constant of \(a\) = 8.387 A, those of the (Mg, Ti)-ferrite sample (x = 0.37) have a larger lattice constant of \(a\) = 9.418 A. The XRD data were fitted with a nanoscale crystalline component in addition to a crystalline component, and we can see that the powder consists of two types of crystallites. The crystalline spinel phase with sharp XRD peaks is shown in blue in Figure 2, while the spinel phase is shown in black. The size of nanoparticles is also different in different phases. The size of the nanoparticles in the crystalline spinel phase is about 200 nm, while the size of the nanocrystallites is about 20 nm. According to the XRD analysis, the size of the individual unit cells also varies. The 2\(\theta\) diffraction angles in Figure 3 correspond to the (111), (200), and (220) planes of NiCu alloy crystallites, single FCC phase [41].