Showing papers by "Pham Thanh Phong published in 2019"
TL;DR: Zinc-substituted cobalt ferrites Co1−xZnxFe2O4 (x = 0.0 to 0.7) nanoparticles have been synthesized using the hydrothermal method as mentioned in this paper.
Abstract: Zinc-substituted cobalt ferrites Co1−xZnxFe2O4 (x = 0.0 to 0.7) nanoparticles have been synthesized using the hydrothermal method. The pure cubic spinel powder samples prepared were characterized by X-ray diffraction, Fourier transform infrared spectroscopy and Raman spectroscopy. It is found that the lattice parameter increases with Zn substitution. The average crystallite size of the particles decreases gradually from 20 to 10 nm with the increase in Zn-content, which is confirmed by transmission electron spectroscopy micrographs. The direct and indirect band gap of Co1−xZnxFe2O4 determined from UV–Vis measurements decreases with the increase of Zn concentration. The magnetic properties have been investigated by physical property measurement system and vibrating sample magnetometer. The saturation magnetization increases slightly from 71.38 emu g−1 (x = 0) to 77.59 emu g−1 (x = 0.1), then decrease with the increase in Zn substitution. Nevertheless, the coercivity significantly decreases with Zn concentrations, which can be explained using Yafet–Kittel model and the distribution of Fe3+ ions among octahedral and tetrahedral sites in samples. This result is further confirmed by photoluminescence emission spectra.
23 citations
TL;DR: In this article, the critical behavior of La0.8Ca0.2MnO3 nanoparticles was studied around its Curie temperature, and the estimated critical exponents were close to those expected for mean-field model.
19 citations
TL;DR: In this article, the Griffith-like phase over a wide range of x in La 0.7Sr0.3Mn1−xCoxO3 was assessed, which occurs due to the quenched disorder arising from the random distribution of Co-O-Mn antiferromagnetic bonds in a ferromagnetic background.
Abstract: The appearance of the Griffith-like phase over a wide range of x in La0.7Sr0.3Mn1−xCoxO3 is assessed in this study.
This phase occurs due to the quenched disorder arising from the random distribution of Co-O-Mn antiferromagnetic bonds in a ferromagnetic background. Based on the present study, a modified magnetic phase diagram for the La0.7Sr0.3Mn1−xCoxO3 system has been constructed.
5 citations
TL;DR: In this article, the critical exponents and magnetocaloric properties of La0.7Sr0.3Mn1−xTixO3 have been explored via magnetic measurements.
Abstract: The critical exponents and magnetocaloric properties of La0.7Sr0.3Mn1−xTixO3 with x = 0 and 0.05 have been explored via magnetic measurements. The magnetic data analyzed in the critical region by using modified Arrott plots, the Kouvel–Fisher method, and the scaling hypothesis reveal values for the critical parameters of β = 0.3165 and 0.3027, γ = 1.1121 and 1.203, and δ = 4.7556 and 4.833 for x = 0 and x = 0.05 respectively. These values are in agreement with the three-dimensional (3D) Ising model. The n values obtained from the law $$ \Delta S_{\rm{max} } = a(\mu_{0} H)^{n} $$
are 0.648 and 0.685. The maximum values of the magnetic entropy change are 1.65 J/kg K and 1.46 J/kg K under a magnetic field change of 10 kOe for x = 0.00 and 0.05, respectively. These results can be explained in the scenario of the short-range interaction and the phase separation as well as the diluted magnetic effect in manganites.
4 citations