Layered ferroelectric Bi2SrTa2O9 is attracting much attention as a fat
igue-free material for ferroelectric nonvolatile memory devices. We ha
ve successfully synthesized this single-crystal platelet without any i
mpurity phases by the self-flux method. The largest crystals measure a
bout 1 mm x 1 mm x 5 mu m, and the lattice parameters were estimated t
o be a = 0.5528 nm and c = 2.498 nm, assuming a tetragonal cell. The c
hemical composition is 1.92:1.10:2.00 in an atomic ratio of Bi:Sr:Ta,
from ICP-AES analysis. By wet etching, the crystal structure was found
to be decomposed anisotropically, leaving only the c-axis framework.
The step height of the topmost surface observed by atomic force micros
copy (AFM) was 1.2 to 1.3 nm, which corresponds to half of the c-axis
length (about 2.5 nm). Through thermal analysis, the thermal anomaly o
riginating in ferroelestric-paraelectric phase transition was not obse
rved and there was Little evaporation of Bi compounds.