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.