Ag Deposited La _0.67 Ca _0.33 MnO ₃ Preparation And Properties

Strong correlated oxide Lao.67Cao.33MnO3 has been widely used as an important material to make light detection and magnetic electronic devices, due to its colossal magneto-resistance (CMR) effect and laser-induced voltage (LIV) effect. Ag doping can significantly improve the material properties. But the doping amount and doping mechanism of Ag still need further study. In this thesis, Lao.67Cao.33MnO3:Agx (LCMO:Agx, x= 0.00,0.02,0.04,0.06,0.08,0.10 and 0.20, x is the Molar content of Ag) were taken as the research object. LCMO:Agx powder were prepared by sol-gel method. And then, suppressed and sintered to make the targets. At last, LCMO:Agx films were prepared on (LaAlO3)o.3-(SrAlTa06)o.7 (LSAT) single crystal substrate by pulsed laser deposition (PLD) technique. Furthermore, the experiment tends to investigate preparation technology and material properties of powder, target and film by analyzing test methods of X Ray Diffraction (XRD), Resistance and Temperature (R-T), scanning electron microscopy (SEM), atomic force microscope (AFM) and X-ray photodectron spectroscopy (XPS) etc.Pure LCMO powder can be synthesized by sol-gel method at 600 ℃. XRD pattern shows that LCMO phase structure of the powder calcined at 600 ℃ were attained the requirement. Then we doped Ag into LCMO with a mole ratio x=0.00,0.02,0.04, 0.06,0.08,0.10 and 0.20 as the second phase, laser particle size analyzer indicate that Ag doping can reduce particle size of powder obviously.Suppressed LCMO:Agx powder to wafer, and then sintered at 950℃ to make the targets. All targets’grains size are very uniform, Ag doping can significantly reduce glass phase and the resistivity. When Ag doping x=0.1, the target has the minimum resistivity, relatively high metal-insulator transition temperature (Tp) and temperature coefficient of resistance (TCR).By studying on the mechanism of Ag-doped, we know Ag doping mechanism mainly are subsitutional doping and grain boundary doping. By analyzing the different growth condition for the preparation of LCMO films, the optimum process parameters for preparation of LCMO films are as follows:growth temperature is 790 ℃, growth oxygen pressure is 45 Pa, annealing temperature is 790 ℃. TCR of the films are reached to 9% by the optimum process parameters. The metal-insulator transition temperature (Tp) is significantly enhanced with Ag doping, due that La3+/Ca2+ is substituted for Ag which improved the Mn4+/Mn3+proportion. Laser-induced voltage (LFV) effect test results show that, the best tilt angle is 10°, Ag doping can reduce the peak voltage (Up) of the LCMO material.