Wang G.,Anhui Key Laboratory of Spintronic and Nanometric Materials Cultivating Base |
Wang G.,Suzhou University |
Yan G.,Anhui Key Laboratory of Spintronic and Nanometric Materials Cultivating Base |
Yan G.,Suzhou University |
And 12 more authors.
Rare Metals | Year: 2012
A series of the samples La 1-x(Sr 1-yNa y) xMnO 3 (y=0.0, 0.2, 0.4, 0.6, 0.8, 1.0) were prepared by the solid-state reaction method. Magnetoresistance enhancement and temperature stability of magnetoresistance in the system La 1-x(Sr 1-yNa y) xMnO 3 with unchanged Mn 3+/Mn 4+ ratio through the doping of both monovalent and divalent elements at A site were studied through the measurements of X-ray diffraction (XRD) patterns, resistivity-temperature (ρ-T) curves and magnetoresistance-temperature (MR-T) curves. The results indicate that with the increase of Na doping amount, the peak value of MR increases, and it increases from 12.4% for y=0.2 to 50.6% for y=1.0 in the magnetic field B=0.8 T; ρ-T curves exhibit the double-peak phenomenon, which comes from the competition between the resistivity of surface phase and that of body phase; for the sample of y=0.8, MR increases slowly from 8.3% to 9.4% in the temperature range from 259 to 179 K, and MR is so stable in such a wide temperature range, which provides reference for the research on the temperature stability of MR.© The Nonferrous Metals Society of China and Springer-Verlag Berlin Heidelberg 2012.
Wang W.-Q.,Anhui Key Laboratory of Spintronic and Nanometric Materials Cultivating Base |
Wang W.-Q.,Suzhou University |
Wang G.-Y.,Anhui Key Laboratory of Spintronic and Nanometric Materials Cultivating Base |
Wang G.-Y.,Suzhou University |
And 8 more authors.
Chinese Rare Earths | Year: 2013
The two-phase composites of (1-x)La0.80Sr0.05 K0.15MnO3/xCuO (x=0.00, 0.04, 0.08, 0.10, 0.20, 0.30) were prepared by solid-state reaction method. Their structure was detected by X-ray diffraction and scanning electron microscope, and the result indicates that intact perovskite phase and CuO phase are formed, CuO is distributed between perovskite grains, and perovskite grains are surrounded by CuO. Electric transport property and magnetoresistance effect were studied through the measurements of resistivity-temperature (p-T) curves in zero field and in applied field, and of magnetoresistance-temperature (MR-T) curves, and the result indicates that the influence of composite CuO on electric transport and magnetoresistance effect of La0.80Sr0.05K0.15MnO3 is very large. Magnetoresistance peak appears in high temperature range, which is the character of intrinsic magnetoresistance; magnetoresistance increases continuously with the decrease of temperature in low temperature range, which is the character of tunneling magnetoresistance induced by grain boundary; the total magnetoresitance is the addition between intrinsic magnetoresistance and tunneling magnetoresistance; the temperature stability of magnetoresistance appears in the intermediate temperature range.