Phase evolution in PLD MgB2 films during the in situ annealing process

The transformation of zero-field-cooled (ZFC) magnetization curves of PLD MgB2 films annealed in situ for different dwell times and at different temperatures is studied within the context of structural analysis. The PLD films were deposited using an off-axis geometry followed by two series of annealing conditions: the dwell time series and the annealing temperature series. ZFC magnetization curves were obtained in an MPMS magnetometer from samples that had been cut into similar shapes. XRD scans on the two series of film samples show enhanced (001) and (002) MgB2 peaks till a dwell time of 9 min at a 650 ◦C and a 800 ◦C annealing temperature. TEM results show a granular transformation from an un-annealed film to a 700 ◦C 9 min in situ annealed film. The possible structural development with annealing time and annealing temperature is then discussed. (Some figures in this article are in colour only in the electronic version)