Shape-Changing Crystals Get Shiftier

Abstract

A talented family of materials has gained some even more gifted members. Piezoelectric crystals have the unique ability to swell or shrink when zapped with electricity, as well as give off a jolt of juice themselves when compressed or pulled apart. Now, by varying the recipe for these materials, researchers have found new ones that display an effect up to 10 times larger than that of current family members.

Ultrahigh electromechanical response in (1−x)(Na0.5Bi0.5)TiO3-xBaTiO3 single-crystals via polarization extension

“…These values are higher than those previously reported for other Pb-free and Pb-containing piezo-ceramics and are comparable to those of Pb-containing relaxor-based single crystals. 1,27,[39][40][41][42][43][44][45] A comparison of the e-E curves along h001i PC (solid line) and h101i PC (dashed line) (at 130 C and 120 C, respectively) is given in Figure 2(d). Three steps are identified in this figure that has notably different slops in the e-E curves with increasing E along both directions.…”

“…Clearly, there is the potential for giant d 33 values in the vicinity of steps B and C: which might exceed that of conventional PZT ceramics 46 and which might be comparable to that of Pb-containing relaxor-based piezo-crystals. 44,45 However, the question must be asked: what is the mechanism of this large response?…”

Three intrinsic relationships of lattice parameters between intermediate monoclinicMCand tetragonal phases in ferroelectricPb[(Wang1 2006Phys. Rev. B781200View full textAdd to dashboardCite

“…[4][5][6] PMN-xPT and PZN-xPT promise to revolutionize the world of piezoelectric and electrostrictive devices. 7 PMN-xPT and PZN-xPT have qualitatively similar temperature-composition phase diagrams: The high-temperature paraelectric phases have a cubic perovskite structure, and the low-temperature ferroelectric phases have a rhombohedral symmetry at low PT content and a tetragonal symmetry at high PT content. The MPB is the boundary of an abrupt structural change between the two forms, 4 i.e., rhombohedral and tetragonal.…”

Phonon localization drives polar nanoregions in a relaxor ferroelectric

“…Relaxor ferroelectrics 2 in particular exhibit a large electromechanical response that makes them useful in medical ultrasonics, military sonar and has potential for future-generation actuators and motors [3][4][5] . Burns and Dacol 6 proposed polar nanoregions PNRs and the upper temperature of their stability range, the Burns temperature (T d ), to explain changes in the optical index of refraction and the onset of relaxor behaviour, which occurs several hundred degrees above the Curie temperature, T C .…”