ISSN:
1551-2916
Source:
Blackwell Publishing Journal Backfiles 1879-2005
Topics:
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
Fully dense disks, each consisting of a single crystal (111) plate of the relaxor-based ferroelectric Pb(Mg1/3Nb2/3)O3-35 mol% PbTiO3 (PMN-35PT) embedded in a 0.48 ± 0.05 µm grain size polycrystalline matrix of the same composition, were formed by hot-pressing at 950°C for 30 min under 20 MPa. Specimens were subsequently annealed to promote migration of the single-crystal boundary through the polycrystal (a process termed seeded polycrystal conversion). An anneal of 10 h at 1150°C using PMN-35PT packing powder resulted in minimal single-crystal boundary migration, and was accompanied by matrix grain coarsening to 1.86 ± 0.20 µm. In contrast, an anneal of 10 h at 1150°C using PbZrO3 (PZ) sacrificial powder resulted in significant migration of the single-crystal boundary through the polycrystal, accompanied by matrix grain coarsening to 13.3 ± 0.3 µm. The shape of the grown crystal relative to the seed plate was consistent with the 〈111〉 direction being the fastest growth direction. Based on the grown crystal dimensions, a lower bound 〈111〉 growth velocity of 0.14 mm/h was calculated. The increased boundary mobility in the specimen that was annealed using PZ sacrificial powder is attributed to a boundary-wetting liquid PbO-based second phase that formed during the anneal. This phase is believed to have formed via PbO absorption from the surrounding vapor phase due to a higher equilibrium PbO vapor pressure above PZ than above PMN-35PT. The grown single crystal exhibited a promising 〈100〉 strain of 0.5% at an applied electric field of 4 MV/m.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1111/j.1151-2916.1999.tb02188.x
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