Study Of Synthesis,Structure And Magnetic Properties On Phase Separation System Sm_0.5Ca_0.5Mn_1-xGa_xO₃

Strongly-Correlated perovskite manganese oxides as a phase separation system has many couplings and competitions within it,which can exhibit a lot of unique properties.Theoretical models proposed can explain the phenomenon which the Strongly-Correlated perovskite manganese oxides exhibited while in some occasions cannot.Furthermore,the magnetic origin and couplings of Strongly-Correlated perovskite manganese oxides are still not clear which is needed to improve.Sm0.5Ca0.5Mn1-xGaxO3(x = 0、0.025、0.05、0.075、0.10、0.15)serial samples were prepared from semi-doped parent phase Sm0.5Ca0.5MnO3 by high temperature solid-state method with doping different amount of Mn-site with different concentration of Ga.The structures of serial samples were characterized by X-ray diffraction(XRD),scanning electron microscopy(SEM),and Fourier transformation infrared absorption spectroscopy(IR).Afterwards,the curves of dc magnetization changes with temperature(M-T)and hysteresis loop(M-H)of the serial samples were analysised by the physical property measurement system(PPMS)for the magnetic properties and,especially,the effects of whether doping of Ga and the amount of doped Ga on the magnetic properties of parent phase sample.XRD analysis showed high quality of the synthesized samples which all exhibited a single-phase orthogonal structure without distinct effects of Ga doping.SEM results presented that serial samples doped with Ga are more compact compared to parent phase samples.IR results presented the effects in parent phase samples of the doping of the different doping amount of Ga on Mn06 octahedron which could be one of the reasons of the distortion of Mn06 octahedron.The charge ordering peak was appeared at Tco = 277 K in apparent phase sample shown by the results of M-T.With decreasing temperature,bifurcation of FC and ZFC curves appeared at Tirr= 150 K.In Ga-doped samples,the charge ordering peaks appeared at the doping level of 2.5%,with moving towards low temperature zone.When the doping amount exceeded 5%,the charge ordering peaks disappeared with the destroy of charge ordering.With temperature decreased,all the Ga-doped samples and parent phase sample exhibited bifurcation,with Tirr move toward low temperature zone,right after which magnetic ordering freezes appeared on the ZFC curves instead of the parent phase sample curve.In the parent phase sample rather than Ga-doped samples,a small peak at 240 K was observed which could be a "Pseudo "-CE type long-range antiferromagnetic order.The M-H results of the serial samples showed the weak ferromagnetism of the parent phase sample,indicating the poor correlation of charge ordering anti-ferromagnetic component of parent phase sample.Increasing amount Ga doped didnot furtherly induce the phenomenon of metamagnetic phase transition but hysteresis strengthened.With increasing of amount of Ga doping,increase of ferromagnetism could also be observed from M-T and M-H curves.