The dielectric properties and phase transition of (1-x)Pb(Yb1/2Ta1/2)O-3-xPb(Yb1/2Nb1/2)O-3

The dielectric properties and phase transition behaviors of (1-x)Pb(Yb1/2Ta 1/2)O-3-xPb(Yb1/2Nb1/2)O-3 (PYT1-xPYNx) solid solution have been investigat ed. The primary transition that occurs at 310 degreesC of PYT is not affect ed by substitution of Ta5+ by Nb5+. The secondary phase transition of PYT w hich happens to be relaxor-like in character is critically affected by Nb5 substitution. Although the profiles of X-ray diffraction of the. solid sol ution are not noticeably changed by Nb5+ substitution, its selected area el ectron diffraction reveals that the superlattice diffraction spots become i ncommensurate due to Nb-5+ substitution. This incommensuration. coincides w ith disappearance of the secondary phase transition on Nb5+ substitution.