Cryogenic dielectric and piezoelectric activities in rhombohedral (1-x)Pb(Mg1/3Nb2/3)O3-xPbTiO3 single crystals with different crystallographic orientations

We report the cryogenic dielectric and piezoelectric activities in [0 0 1]-, [1 1 0]-and [1 1 1]-oriented rhombohedral (1-x) Pb(Mg1/3Nb2/3)O-3-xPbTiO(3) single crystals for temperatures down to -200 degrees C. Unusual dielectric relaxation resulting from collective pinning of randomly distributed point defects to ferroelectric macrodomain walls is observed instead of a phase transition in all the poled crystals below -150 degrees C rather than in the unpoled ones. Stiffening of the poled crystals by the cryogenic temperature-induced pinning effect leads to a characteristic decrease in the piezoelectric coefficient (d(31)) and the compliance coefficient (s(11)(E)), along with a similar quantitative increase in frequency constant (N-31). An almost temperature-independent property region is revealed in a wide temperature range of -50 to -150 degrees C, enabling applications of the crystals in cryogenic fields.