Characteristics of La0.7Sr0.3MnO3−δ films treated by oxygen plasma immersion ion implantation

The magnetron sputtered La0.7Sr0.3MnO3−δ films were implanted with oxygen ions at a dose of 1×1016ions/cm2 and various negative pulsed voltages (10–50kV) by plasma immersion ion implantation (PIII), and followed by air annealing at 973K for 1h. The structure, metal–insulator transition and room temperature emittance property of the treated films were investigated. The results indicate that the length of MnO bond of the films shortens and (100) preferred orientation growth of the films becomes more obvious when implantation voltage increases. The effects of implantation with oxygen on the structure of the films cannot be removed by annealing in air. Compared with annealing treatment, oxygen implantation-annealing can effectively decrease the vacancy defects in the implantation depth of the films. The post-implantation annealed films have higher metal–insulator transition temperatures (TMI) than the annealed film does because of the enhanced double-exchange interaction resulting from the shortening of the MnO bond length, the decrease of vacancy defects and the improvement of microstructure. The TMI of the treated films depends on the implantation voltage and the TMI of the film implanted at 50kV is higher 99K than that of the annealed film. However, oxygen implantation has only a small effect on the room temperature emissivity of the films. Thus oxygen plasma immersion ion implantation can be used to adjust effectively the TMI, near where the emittance properties of La0.7Sr0.3MnO3−δ films significantly change, for meeting the demands of different thermal control applications. ► Oxygen implantation-annealing decreases effectively the vacancy defects of the films. ► Annealing cannot remove the effect of oxygen implantation on the structure of films. ► Oxygen PIII can adjust effectively TMI of the La0.7Sr0.3MnO3−δ films. ► The higher TMI of films results from the enhancement of double-exchange interaction. ► Oxygen implantation has a small effect on room temperature emissivity of the films.