Low-field dynamic magnetic alignment and templated grain growth of diamagnetic PMN–PT ceramics

A novel combination of low-field magnetic alignment (MA) and templated grain growth (TGG) was used to fabricate highly textured diamagnetic 0.72Pb(Mg 1/3 Nb 2/3 )O 3 –0.28PbTiO 3 (0.72PMN–0.28PT) ceramics. Samples were produced by nonaqueous slip casting of PMN–PT slurries, in which diamagnetic plate-like 0.4(Na 1/2 Bi 1/2 )TiO 3 –0.6PbTiO 3 (0.4NBT–0.6PT) template particles were aligned by dynamic MA in a 2.2-T permanent magnet array. Template alignment improved as slurry viscosity increased, with a 32-vol% solid loading (a viscosity of ∼0.1 Pa s at 0.1 s −1 ) giving optimal texture quality (7.85° FWHM, f = 92 vol%) after sintering and TGG. Alignment was stable for more than 3 h during slip casting, allowing fabrication of ∼1-cm thick textured ceramics with high piezoelectric response ( d 33 = 1222 pC/N). The success of dynamic MA at low magnetic field (2.2 T) is attributed to an increase in driving force for alignment of large (5–10 μm) template particles relative to the randomizing effect of Brownian motion (i.e., thermal energy k B T ).