  Lead-free dielectric thin-film capacitors with desirable energy storage
density are gathering attention due to the increasing environmental concern and
the integrating electronic devices. We here reported a series of new
highly-orientated (1-x)NaNbO3-xBaHfO3 (x<0.15) lead-free thin films prepared by
a sol-gel method, and presented the dependence of their structural, electrical
and energy storage properties on the x level of BaHfO3. The microstructure,
leakage current and breakdown strength of pristine NaNbO3 thin films are
significantly improved by addition of BaHfO3. As a result, the superior energy
storage performances were obtained at x=0.1 with recoverable energy storage
density of 23.1 J/cm3 at 1100 kV/cm, excellent thermal stability from 30 to 210
0C, good fatigue resistance, and the fast charge-discharge rate.
