Anodic oxidation of aluminum in acidic electrolytes is widely used for the formation of porous oxide films with a regular structure on the metal surface. Despite the century-old history of this...

One-dimensional photonic crystals (1D PhCs) obtained by aluminium anodizing under oscillating conditions are promising materials with structure-dependent optical properties. Electrolytes based on sulphuric, oxalic, and selenic acids have been utilized for the preparation of anodic aluminium oxide (AAO) 1D PhCs with sub-100-nm pore diameter. AAO films with larger pores can be obtained by anodizing in phosphorous acid at high voltages. Here, for the first time, anodizing in phosphorous acid is applied for the preparation of AAO 1D PhCs with nonbranched macropores. The sine wave profile of anodizing voltage in the 135–165 V range produces straight pores, whose diameter is above 100 nm and alternates periodically in size. The pore diameter modulation period linearly increases with the charge density by a factor of 599 ± 15 nm·cm²·C⁻¹. The position of the photonic band gap is controlled precisely in the 0.63–1.96 µm range, and the effective refractive index of AAO 1D PhCs is 1.58 ± 0.05.

In the study, a technique for formation of planar microheaters that make it possible to heat an active zone to a temperature higher than 500°С is proposed and successfully implemented. The developed...

Synthesis from mixed-anionic aqueous solutions is a novel approach to obtain active powders for bioceramics production in the CaO-SiO₂-P₂O₅-Na₂O system. In this work, powders were prepared using precipitation from aqueous solutions of the following precursors: Ca(NO₃)₂ and Na₂HPO₄ (CaP); Ca(NO₃)₂ and Na₂SiO₃ (CaSi); and Ca(NO₃)₂, Na₂HPO₄ and Na₂SiO₃ (CaPSi). Phase composition of the CaP powder included brushite CaHPO₄‧2H₂O and the CaSi powder included calcium silicate hydrate. Phase composition of the CaPSi powder consisted of the amorphous phase (presumably containing hydrated quasi-amorphous calcium phosphate and calcium silicate phase). All synthesized powders contained NaNO₃ as a by-product. The total weight loss after heating up to 1000 °C for the CaP sample—28.3%, for the CaSi sample—38.8% and for the CaPSi sample was 29%. Phase composition of the ceramic samples after the heat treatment at 1000 °C based on the CaP powder contained β-NaCaPO₄ and β-Ca₂P₂O₇, the ceramic samples based on the CaSi powder contained α-CaSiO₃ and Na₂Ca₂Si₂O₇, while the ceramics obtained from the CaPSi powder contained sodium rhenanite β-NaCaPO₄, wollastonite α-CaSiO₃ and Na₃Ca₆(PO₄)₅. The densest ceramic sample was obtained in CaO-SiO₂-P₂O₅-Na₂O system at 900 °C from the CaP powder (ρ = 2.53 g/cm³), while the other samples had densities of 0.93 g/cm³ (CaSi) and 1.22 (CaPSi) at the same temperature. The ceramics prepared in this system contain biocompatible and bioresorbable phases, and can be recommended for use in medicine for bone-defect treatment.