Structural and magnetic characterization of La0.8Sr0.2MnO3 nanoparticles prepared via a facile microwave-assisted method

Synthesis and ESR Study of Transition from Ferromagnetism to Superparamagnetism in La0.8Sr0.2MnO3 Nanomanganite

“…Significant reduction in Ms. for the sample (a) compared to samples (b, c) is coherent with both ESR measurements (low factor g) and core-shell model [68]. The core-shell model assumes the formation of a magnetically dead layer of thickness t, which increases with size reduction and can be estimated using the following formula [48]: (1) where t is dead layer thickness and d is crystallite size. As a necessary condition for superparamagnetism, nanoparticles must be formed by small magnetic volumes without exchange interaction [68].…”

“…To rely on the core-shell model with a single magnetic core, in order that the magnetic core keeps the same volume, the thickness of the dead layer must increase with increasing crystallite size. This hypothesis is in contradiction with the literature which reveals that the thickness of the shell decreases [18,34,48]. To explain these experimental data, we resorted to the phenomena of magnetic phase separation, which is a usual phenomenon observed in manganites [69,70].…”

“…Strontium doping transforms La 1−x Sr x MnO3 manganites into a ferromagnetic state at room temperature, due to the reinforcement of the double exchange (DE) interactions between Mn 3 + and Mn 4 + ions, which is a ferromagnetic interaction. The ferromagnetic transition depends on the strontium content [43,44]. The Curie temperature (TC) increases monotonically with x, and TC is increased from 220 to 325 K for values of x between 0 and 0.2 [18,45].…”

“…First, the percentage of dead layer increases with increased surface/volume ratio. In addition to that, the shell thickness increases and the volume of the magnetic core decreases [34,48]. Magnetization of the shell is considered as null, and the contributory portion of each crystallite to the magnetization is the core.…”

Improving the crystallinity and magnetocaloric effect of the perovskite La0.65Sr0.35MnO3 using microwave irradiation

“…A few methods demonstrate the advantageous use of MWs in the synthesis of LSMO, including a MW-hydrothermal method 36 , MW sintering 37 , and the use of combined MW Pechini synthesis and calcination. 38 Microwave (MW) irradiation is a promising materials processing method, offering advantages in terms of shorter reaction times, smaller particle sizes and narrower size distributions compared with conventional methods of heating. 20 Electrical dipole moments found in polar materials (e.g.…”