Browsing by Author "Ghani, A. A"

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    Structure, magnetic and magnetocaloric properties of nano crystalline perovskite La0.8Ag0.2MnO3
    (ELSEVIER SCIENCE BV, 2019-06) AboZieda, Abd El-Rahman T.; Ghani, A. A; Ali, Ahmed I; Salaheldin, Taher A
    Nano crystalline La0.8Ag0.2MnO3 perovskite compound was prepared using sol-gel method. The synthesized nano compound was characterized using X-ray Diffraction (XRD) and High Resolution - Transmission Electron Microscope (HR-TEM). The magnetic and magnetocaloric properties were studied in a broad temperature range, and confirmed the presence of ferromagnetic-paramagnetic (FM-PM) transition around Curie temperature (T-C = 306 K). We reported a maximum magnetic entropy change vertical bar Delta S-M vertical bar(max) = 0.96 J/kg.K with relative cooling power (RCP) = 39.98 J/kg at magnetic field 2 T. Such results could be a significant practical application in magnetic refrigeration. The observed magnetic phase transition in the sample was testified a second order. The critical exponent analysis which define the magnetic transition revealed values 0.4025 for beta, 3.33 for delta and 0.93 for gamma. These values are closely related to those obtained by the mean field model. The second order magnetic phase transition is further confirmed by constructing a universal curve for variation of vertical bar Delta S-M vertical bar/vertical bar Delta S-max vertical bar vs rescaled temperature (theta) for various magnetic field values.