Critical supersaturation ratio,
S*, of monodisperse AgCl grains in the controlled double-jet precipitation was experimentally determined on the basis of a potentiometric measurement of supersaturation ratio, S, and theoretical relationships between
S and the supply rate of reactants,
Q. For cubic grains, the relationship is derived as (
S-1) =
Q/12
DConsLs in
S<
S* whereas (
S-1) =
Q/12
DCo (
nsLs+
nnLn) in
S>
S*, where
D the diffusivity,
Co the solubility of bulk solid,
ns and
nn the numbers of seed grains and new nuclei, respectively, and
Ls and
Ln the edge lengths of seed grains and new nuclei, respectively. The critical supersaturation ratio was defined as
S at the inflection point in the relationship between (
S-1) and
Q/nsLs. The definition of
S* was confirmed with transmission electron microscopy. Under the condition of pCl 3.0 and 50°C,
S* was determined as 1.077-1.097 and almost independent of the size and number of seed grains. The critical nucleus size, critical growth rate, and magnitude of driving force of growth were also discussed.
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