Strain state of bismuth zinc niobate pyrochlore thin films

The anisotropic strain of bismuth zinc niobate (BZN) cubic pyrochlore thin films deposited on Si, sapphire, MgO, and Vycor glass substrates is characterized through four circle X-ray diffraction and Raman spectroscopy. Based on the X-ray measurements, it is found that all the films exhibit a hydrostatic compressive strain component with those on MgO substrate exhibiting the highest compressive strain component (0.4%). The effect of the compressive state on the local environment for the ions was investigated through Raman spectroscopy. The observed shifts in the peak position for Raman-active modes are consistent with the measured strain states and correlate well with previously reported dielectric properties for BZN films on MgO, Si, and sapphire.