Improvement in fatigue properties of ferroelectric Bi/sub 4/Ti/sub 3/O/sub 12/ thin films by heat treatment in O/sub 2/ gas at high pressure

Abstract

Fabrication of ferroelectric Bi/sub 4/Ti/sub 3/O/sub 12/ thin films was carried out by spin-coating pyrolysis process of metal naphthenates. The films were finally sintered at 800/spl deg/C for 30 min in O/sub 2/ gas with the pressures ranging from 0.1 to 0.4 MPa. In any conditions, ferroelectric Bi/sub 4/Ti/sub 3/O/sub 12/ thin films with complete c-axis orientation were obtained. Remanent polarizations of the films were improved with increasing O/sub 2/ gas pressure in sintering while coercive fields were constant. The Bi/sub 4/Ti/sub 3/O/sub 12/ thin film sintered at the O/sub 2/ gas pressure of 0.4 MPa exhibited good ferroelectric properties: the remanent polarization of 2.1 /spl mu/C/cm/sup 2/ and the coercive field of 66 kV/cm. The remanent polarization of the film sintered at 0.4 MPa was observed to be 95 % of the initial value after the polarization reversal of 1/spl times/10/sup 9/ cycles while that of the film sintered at 0.1 MPa was reduced to about half of the initial one after 1/spl times/10/sup 7/ cycles. Sintering at high O/sub 2/ gas pressure had a great influence on the improvement of fatigue properties of ferroelectric Bi/sub 4/Ti/sub 3/O/sub 12/ thin films.