Samarium supersensors Piezoelectric materials produce electric charge in response to changes in stress and are thus good sensor materials. One challenge has been growing single-crystal piezoelectrics with uniform properties. As of now, much of the crystal is discarded because of compositional variations. Li et al. synthesized single crystals of samarium-doped Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 that have uniform and extremely high piezoelectric properties (see the Perspective by Hlinka). These crystals are ideal for a variety of sensing applications and could reduce cost by eliminating waste. Science , this issue p. 264 ; see also p. 228

The full set of material constants for relaxor-based ternary single crystals Pb͑In 1/2 Nb 1/2 ͒O 3 -Pb͑Mg 1/3 Nb 2/3 ͒O 3 -PbTiO 3 ͑PIN-PMN-PT͒ were determined and compared to binary Pb͑Mg 1/3 Nb 2/3 ͒O 3 -PbTiO 3 ͑PMNT͒ crystals. The Curie temperature for rhombohedral compositions of PIN-PMN-PT was found to be in the range of 160-200°C with ferroelectric rhombohedral to tetragonal phase transition on the order of 120-130°C, more than 30°C higher than that found for PMNT. The piezoelectric coefficients ͑d 33 ͒ were in the range of 1100-1500 pC/N, with electromechanical coupling factors ͑k 33 ͒ about 89%-92% comparable to PMNT crystals. The coercive field of the ternary crystal was found to be 5.5 kV/cm, double the value of the binary counterparts. The dielectric behavior under varying dc bias exhibited a similar trend as observed in PMNT with a much broader usage temperature range. Together with its enhanced field induced phase transition level, the ternary PIN-PMN-PT crystals are promising candidates for high temperature and high drive transducer applications.

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PbTiO 3 ternary single crystals ͑PIN-PMN-PT͒ were reported to have broader temperature usage range ͑T R-T ͒ and comparable piezoelectric properties to Pb͑Mg 1/3 Nb 2/3 ͒O 3 -PbTiO 3 ͑PMNT͒ crystals. In this work, the orientation dependent dielectric, piezoelectric and electromechanical properties for PIN-PMN-PT crystals were investigated along ͗001͘ and ͗110͘ directions. The electromechanical couplings k 33 and k 32 for ͗110͘ poled crystals were found to be 0.91 and 0.91, respectively, with piezoelectric coefficients d 33 and d 32 on the order of 925 and Ϫ1420 pC/N. Of particular significance was the mechanical quality factor Q 33 for ͗110͘ oriented crystals, which was found to be Ն500, much higher than the Q values of ͗001͘ oriented relaxor-PT crystals ͑Q ϳ 70-200͒. The temperature dependence of the piezoelectric properties exhibited good temperature stability up to their ferroelectric phase transition T R-T ϳ 125°C, indicating ͗001͘ and ͗110͘ oriented PIN-PMN-PT are promising materials for transducer applications, with the latter for high power resonant devices where low loss ͑high Q͒ was required.

Pb(In 0.5 Nb 0.5 )O 3 -Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 (PIN-PMN-PT) ferroelectric crystals attracted extensive attentions in last couple years, due to their higher usage temperatures range (> 30°C) and coercive fields (~5kV/cm), meanwhile maintaining similar electromechanical couplings (k 33 > 90%) and piezoelectric coefficients (d 33~1 500pC/N), when compared to their binary counterpart Pb(Mg 1/3 Nb 2/3 )O 3 -PbTiO 3 . In this article, we reviewed recent developments on the PIN-PMN-PT single crystals, including the Bridgman crystal growth, dielectric, electromechanical, piezoelectric and ferroelectric behaviors as function of temperature and dc bias. Mechanical quality factor Q was studied as function of orientation and phase. Of particular interest is the dynamic strain, which related to the Q and d 33 , was found to be improved when compared to binary system, exhibiting the potential usage of PIN-PMN-PT in high power application. Furthermore, PIN-PMN-PT crystals exhibit improved thickness dependent properties, due to their small domain size, being on the order of 1μm. Finally, the manganese acceptor dopant in the ternary crystals was investigated and discussed briefly in this paper.