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Effect of Holding Temperature on Growth of Ruby Crystal Films via Molybdenum Trioxide Flux Evaporation–Solubility of Aluminum Oxide, Growth Rate, and Material Balance
journal contribution
posted on 2020-02-21, 19:10 authored by Shunsuke Ayuzawa, Sayaka Suzuki, Miki Hidaka, Shuji Oishi, Katsuya TeshimaRuby
(Al2O3:Cr) is used not only for jewelry
but also in various industrial materials because of its excellent
mechanical, optical, and chemical properties. Ruby crystals have been
grown using the molybdenum trioxide (MoO3) flux evaporation
method. Herein, we report the effect of holding temperature on the
growth of ruby crystal films via MoO3 flux evaporation.
All temperature effects were investigated considering the epitaxial
growth of ruby crystal film on sapphire crystal substrates. First,
the solubility curve of aluminum oxide (Al2O3) in MoO3 flux was examined in the temperature range 1050–1200
°C. The difference in solubilities between 1050 and 1200 °C
was ∼0.4 mol %. However, higher temperatures increased the
crystal film growth rate due to increased flux evaporation rate. The
difference in the crystal growth rate produced a difference in the
surface pattern of the ruby crystal films. The surface of the ruby
crystal films exhibited ellipsoidal patterns with a wide step interval
at 1100 °C and circular patterns with a narrow step interval
at 1200 °C. Finally, the material balance between the dissolved
mass supplied by the dissolution of the substrates and the mass of
grown ruby crystals was investigated. All dissolved solutes were found
to be crystallized in ruby crystals, either in film or in particle
form.