New Al₂O₃ Membranes and Catalyst Substrates: Nanoporous Alumina and Corundum for Ultra- and Microfiltration

Optical Properties of Porous Alumina Assisted Niobia Nanostructured Films–Designing 2-D Photonic Crystals Based on Hexagonally Arranged Nanocolumns

“…Alumina is transparent in the visible spectrum region, thermally stable material, characterized by high hardness and low chemical reactivity [ 1 , 2 , 3 , 4 ]. Alumina is applied in the production of ceramics, sitalls, glasses [ 4 ], refractory materials [ 5 , 6 , 7 ], abrasive materials [ 2 ], adsorbents [ 2 , 4 , 8 ], including chromatography [ 2 , 9 ], catalyst carriers and catalytic active [ 2 , 4 , 10 ], and filter materials [ 6 ]. Niobium entities, including oxides, are distinguished by even higher chemical stability [ 1 ], and are promising for application in heterogeneous catalysis [ 11 , 12 , 13 ].…”

“…The optical, structural, and electrochromic properties of the different crystalline polymorphic forms of the niobia films make them attractive for optical applications [ 19 , 20 ]. There are various methods for the oxide materials synthesis, in particular, alumina and niobia: the metal thermal oxidation with oxygen to obtain an oxide in the highest oxidation state [ 18 , 21 ] and metal subsequent sintering (sinter) with higher oxide in vacuum in required proportion to obtain oxides in an intermediate oxidation state [ 20 ], spray pyrolysis deposition [ 22 , 23 ], atomic-layer deposition [ 24 , 25 ], and plasma-enhanced atomic layer deposition [ 26 ], magnetron sputtering technique [ 18 , 27 , 28 , 29 ], and reactive magnetron sputter process [ 30 ], chemical precipitation from solution [ 18 , 31 ], the controlled precipitation method [ 16 ], sol-gel method [ 4 , 10 , 18 , 32 , 33 ], polymeric precursors (Pechini) method [ 32 ], hydro-thermal (in water) and solvothermal (in other solvents such as acetone and isopropyl alcohol) synthesis techniques [ 18 ], extraction from natural minerals [ 4 ], chemical vapor deposition [ 19 , 34 ], and plasma-enhanced chemical vapor deposition [ 35 ], pulsed laser deposition [ 36 , 37 , 38 ], electron beam evaporation [ 22 ], molecular beam epitaxy [ 39 ], electrodeposition [ 18 ].…”