Fityk change colors6/6/2023 ![]() ![]() In Table 1 common physicochemical properties of corundum are presented. According to Mohs scale corundum hardness is 9. All corundum forms have extremely high hardness. Nickel, titanium, iron (II, III), and manganese impurities yield yellow, blue, orange and reddish pink colors to crystals, correspondingly. Along with blue sapphires there are different colored forms of them. Sapphires occur in a wide variety of colors. Pink color of rubies is provided by chromium presence in a-Al2O3 (up to 0.5 wt.%). Coloration is caused by presence of insignificant amount of chromium impurities of d-elements which enable isomorphically replace alumina in its crystalline structure. Pure corundum is colorless however, some coloured forms like rubies and sapphires occur in nature. Its structure refers to one of superb compact structure of minerals. Corundum lattice represents close hexagonal packing of oxygen ions with insignificant distortions, in which two thirds of octahedral gaps are occupied with aluminum cations. Synthesized pigments can be used as a component of glaze ceramic colors for porcelain.Ĭorundum a-Al2O3 is a crystalline modification of aluminum oxide of hexagonal symmetry. Increasing chrome oxide content to 5 wt.% in initial charge mixture leads to pigment darkening due to inclusions of Cr2O3. Absorption bands of pink corundum in visible reflectance spectrum at X=560 nm (17850 cm-1) and 400 nm (25000 cm-1) correspond to electron transitions 4A2g^4T2g(4F) and 4A2g^4T1g(4F). Pigments based on pink corundum have been obtained by self-propagating high temperature synthesis in Cr2O3-Al2O3-Al system using a small amount of chromium oxide (up to 0.5 wt %) in the composition of the green mixture. 'Tomsk Scientific Centre SB RAS, Tomsk, Russian Federation 2Tomsk State University, Tomsk, Russian FederationĪbstract. Self-propagating High Temperature Synthesis of Pink CorundumĪnastasiya Nazarova1, Nina Radishevskaya1, Nikolay Kasatsky1, and Natalia Karakchieva2
0 Comments
Leave a Reply. |