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Growth of Pb(Mg1/3Nb2/3)O3‐35 mol% PbTiO3 Single Crystals from (111) Substrates by Seeded Polycrystal Conversion
Author(s) -
Khan Ajmal,
Meschke Frank A.,
Li Tao,
Scotch Adam M.,
Chan Helen M.,
Harmer Martin P.
Publication year - 1999
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/j.1151-2916.1999.tb02188.x
Subject(s) - materials science , crystallite , grain boundary , single crystal , crystal (programming language) , annealing (glass) , crystallography , phase boundary , analytical chemistry (journal) , phase (matter) , ferroelectricity , microstructure , mineralogy , composite material , metallurgy , chemistry , optoelectronics , organic chemistry , chromatography , computer science , dielectric , programming language
Fully dense disks, each consisting of a single crystal (111) plate of the relaxor‐based ferroelectric Pb(Mg 1/3 Nb 2/3 )O 3 ‐35 mol% PbTiO 3 (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 PbZrO 3 (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.