Bi₂O₃–BiFeO₃ Glass-Ceramic: Controllable β-/γ-Bi₂O₃ Transformation and Application as Magnetic Solar-Driven Photocatalyst for Water Decontamination

Abstract

Glass and glass-ceramic materials containing photoactive and magnetic crystalline phases were prepared from Fe2O3 and Bi2O3 using the conventional melt method. All samples were characterized in terms of formed phases, morphological analyses, optical properties, and magnetic properties. Formation of the photoactive tetragonal β- and body-centered cubic γ-Bi2O3 phases along with the magnetic BiFeO3 and Fe3O4 phases was revealed. However, the crystalline structure relied on the composition and the applied heat-treatment time. β-/γ-Bi2O3 transformation could be controlled by the heat-treatment time. The samples exhibited variable magnetic properties depending on their composition. All of the samples showed excellent absorbance in visible light with an optical band gap of 1.90–2.22 eV, making them ideal for solar-light-driven photocatalysis. The best performance was recorded for the sample containing equal amounts of Fe2O3 and Bi2O3 due to the formation of γ-Bi2O3/BiFeO3 heterojunction in this sample.

Structural, Optical and Photocatalytic Activity of α-Bi2O3/Bi2O2CO3/(BiO)4CO3(OH)2 Ternary Multi-heterojunction Nanoflakes Synthesized via Submerged DC Electrical Discharge in Urea Solution

“…Thermodynamically α-Bi 2 O 3 is stable between 25˚C and 730˚C and then transformed to face centered cubic δ-Bi 2 O 3 phase at 730˚C and remains stable up to its melting point at 825˚C 19,21 . The tetragonal β-Bi 2 O 3 and body centered cubic γ-Bi 2 O 3 are metastable phases, which formed at high temperature and can be stabilize down to room temperature or transform to α-Bi 2 O 3 at high cooling rates 22,23 . In addition, thermal transformation of α-Bi 2 O 3 and β-Bi 2 O 3 to (BiO) 2 CO 3 and (BiO) 4 CO 3 (OH) 2 were reported previously 24,25 .…”

Facile and reproducible method of stabilizing $$\hbox {Bi}_2\hbox {O}_3$$ phases confined in nanocrystallites embedded in amorphous matrix

“…Hence, an idea of a facile way to inexpensive and facile syntheses of bulk amounts of nanomaterials of nanocrystallites of - embedded in a residual glassy matrix arises. It consists of two stages only: (i) melting pure in silica/alumina crucibles followed by their rapid quenching; (ii) heating the samples to ca 630 C. Later, the same approach was used by Margha et al 9 , who succesfully synthesized glass ceramics of more complex – system, containing the and phases of .…”

Phosphate glasses containing silver nanoparticles for applications in plasmonics

“…A thermal treatment takes place to nucleate crystals within the glass, thus forming the glass-ceramics. Common additives include the semiconductors titanium oxide [49] and zinc oxide [50,51], bismuth oxide to form semiconducting compounds [48,52], or a combination of oxides that will crystallize as perovskites, such as barium titanate [46].…”

“…The targets of the photodegradation processes are organic compounds, usually drugs [45,46] or dyes [47,48,49,50,52], but not restricted to those.…”

“…The glass synthesis may include additional processes or compounds to enhance the photocatalytic activity, such as acid etching to with HF [47], crystallization of a ferromagnetic phase (BiFeO 3 ) in the glass-ceramics [52,53], or yet, as proposed here, synthesis of plasmonic nanoparticles.…”