The dielectric and field induced strain properties of the antiferroelectric-ferroelectric phase boundary (y = 0.085) and the ferroelectric (y = 0.12) compositions in the Pb0.97Y0.02[(Zr0.6Sn0.4)(1-y)Ti-y]O-3 system have been investigated as a function of excess PbO in the range of 0-5 mol%, The y = 0.085 specimen showed that the double hysteresis loops of the antiferroelectric phase and its transition field (EA<->F) of the antiferroelectric-ferroelectric phase transition increased with the increase of excess PbO. The y = 0.12 specimen showed that the typical ferroelectric hysteresis loop, due to the stable ferroelectric phase and its coercive field, increased due to inhibition of the ferroelectric domain wall motion as the amount of excess PbO increased. The shape memory effect of strain in the y = 0.085 specimen disappeared above 3 mol% of excess PbO. The y = 0.12 specimen maintained the butterfly-type strain curve through the entire range of excess PbO additions. The maximum strain of the y = 0.085 specimen with no excess PbO was about 4 x 10(-3), and it decreased to about 2 x 10(-3) with the addition of 5 mol% excess PbO.