Formation and stability of pyrochlore in sputtered SBT thin films

摘要

In magnetron sputtering of SrBi_2Ta_2O_9 (SBT) thin films, bismuth deficiency tends to result in formation of an unwanted pyrochlore phase. In this paper, the dependence of deposition parameters on phase evolution in Sr deficient SBT thin films is studied. Only when bismuth is over stoichiometric (Sr_(0.74)Bi_(2.2)Ta_2O_(9+x)) can one obtain pure SBT structure. Decreasing the Bi content encourages formation of the Bi deficient pyrochlore phase. At 1.04 of Bi, only the pyrochlore phase forms. The pyrochlore phase is very stable even at 900 deg C.