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In this work, an attempt is made to study \( Pb_{1 - x} Y_x \left( {Zr_{0.53} Ti_{0.47} } \right)O_3 \) system with x=0.0125, 0.025, 0.050, 0.075 and 0.1. It was shown that there is limited solid solubility (0.625 mol %) of \( Y_2 O_3 \) or 1.25 mol % of \( Y^{3 + } \) in PZT(53/47). For higher levels of dopant, mainly two other extra second phases were detected. The first was a Zr-rich phase in which some \( Y_{^2 } O_3 \) and small amounts of \( TiO_2 \) was dissolved. The second one was a Pb solid solution \(\left( {PbO_{SS} }\right)\) composed of mainly PbO, \(Y_2 O_3 \) and \(ZrO_2 \) which was initially also seen in calcined samples. The formation of Zr-rich phase is thought possibly to originate due to the sublimation of Pb from \(PbO_{SS}\) source during the sintering process. For higher x values, a structural shift towards Ti-rich region of PZT's phase diagram is seen. All piezoelectric parameters of the doped samples such as \(d_{33}\), \(g_{33}\) are seen to decline sharply compared to that of undoped samples. Increasing the level of dopant gave rise to the increase of conductivity and dielectric loss of sintered samples. The formation of non-ferroelectric extra phases, and the Zr/Ti change of the main formed phase is believed to be responsible for this behavior.