Abstract
Sr0.8Ni0.2Fe12−2xMoxO19 (x ≤ 0.35) nanohexaferrites (NHFs) were obtained by a sol–gel combustion route. The phase identification was performed through X-ray powder diffraction (XRD), transmission electron microscopy (TEM), and high-resolution transmission electron microscopy (HR-TEM). The morphological and chemical composition analyses were verified by scanning electron microscope (SEM) and energy dispersive X-rays (EDX), respectively. The crystallite size (DXRD) of all produced samples has been estimated between 31 and 56 nm. Magnetization versus applied magnetic field (M–H) measurements of different products were conducted at 300 K (room temperature, RT) and 10 K, and the results revealed their ferrimagnetic character. Undoped Sr0.8Ni0.2Fe12O19 NHFs have the maximum magnetic parameters at both temperatures. 10 K magnetization data such as MS (saturation magnetization), Mr (remnant magnetization), nB (magneton number), and HC (coercivity) belonging to Sr0.8Ni0.2Fe12O19 NHFs are MS,max = 99.6 emu/g, Mr,max = 48.2 emu/g, nB,max = 18.83 μB, and HC,max = 3406 Oe, respectively. Moreover, the squareness ratio (SQR = Mr/MS) is 0.489 at RT and 0.484 at 10 K. Those magnitudes assign the single-domain structure with uniaxial crystal anisotropy for this hexagonal product at both temperatures. Some magnetic parameters like coercivities (in a range of (286–475) Oe) and Mr (in a range of (7.8–14.1) emu/g) drop sharply due to the Mo6+ doping process. Calculated SQR values are between 0.111 and 0.206, which indicate the multi-domain wall structure for NHFs at both temperatures. Undoped Sr0.8Ni0.2Fe12O19 NHFs can be classified as magnetically hard materials, while Mo-doped samples can be classified as soft magnetic materials.