Transport-Limited Growth of Flow-Driven Rare-Earth Silicate Tubes

The injection of rare-earth metal salt solutions into sodium silicate solution results in vertically growing tubular precipitate structures. At low input concentrations reaction kinetics is the rate-detemining process, leading to linear growth rates independent of injection rates. At higher concentrations, flow drives the precipitate growth, characterized by jetting mechanism. Among the studied rare-earth metal silicates, dysprosium silicate is found to have the most rigid structure with visible growth even at higher injection rates. The outer surface of the hollow tubes is smooth, on which rare-earth hydroxide – based on the result of the energy dispersive X-ray spectroscopy measurements – aggregates into globules.