Habit Changes of Y3Al5O12 and Y3Ga5O12 Grown from a PbO-PbF2 Flux

摘要

The habit of single crystals of Y3Al5O12 and Y3Ga5O12, when grown from a PbO - PbF2 flux, is dependent on both the PbO-to-PbF2 ratio and the Y2O3-to-Al2O3 or -Ga2O3 ratio in the melt. Y3Ga5O12 crystals have a pure (211) habit when grown from either a Y2O3- or PbO-rich melt. The crystals develop small (110) faces when grown from a Ga2O3- or PbF2-rich melt. Y3Al5O12 crystals have a pure (110) when grown from either a PbF2- or Al2O3-rich melt and develop (110) faces as well in a PbO- or Y2O3-rich melt. The crystals incorporate Pb (replacing Y in the lattice) when grown from PbF2-, Al2O3-, or Ga2O3-rich melts. It is believed that the habit variations are caused by changes in either the surface diffusion or step propagation, due to Pb contamination, that favor the development of (110) faces. In addition, the crystals habits of the mixed system Y3(Al,Ga)5O12 were studied and found to be directly dependent on the Al2O3-toGa2O3 melt ratio. (Author)