Synthesis of silicate coating by layer-by-layer self-assembly of Yb2O3 and SiO2 particles

Multilayer particle assemblies that contained both Yb₂O₃ and SiO₂ particles were prepared on Si substrates by layer-by-layer self-assembly (LBLSA) as a new non-line-of-sight avenue of producing dense and uniform Yb₂O₃-SiO₂ coating microstructures. Morphological characteristics of the multilayer particle assemblies upon viscous sintering in the temperature range of 1300 to 1350 °C were evaluated in reference to those of multilayer assemblies that only contained SiO₂ or Yb₂SiO₅ particles. A 4-layer 0.5-μm SiO₂ particle assembly could be easily transformed to a dense and continuous coating structure after sintering. In contrast, a 4-layer 1.7-μm Yb₂SiO₅ particle assembly could not be consolidated and densified, as anticipated from the absence of the viscous sintering mechanism provided by the SiO₂ phase. Most of the coatings produced from sintering of Yb₂O₃-SiO₂ (0.5 μm) particles assemblies were dense and continuous with Yb₂Si₂O₇ and Yb₂SiO₅ as two predominant phases. The results suggest the feasibility of producing dense and uniform silicate coating structures by integrating the LBLSA concept with the viscous flow sintering mechanism provided by the SiO₂ particles.