Wenjing Dong,Tianyi Xie,Haiyi Peng,Haishen Ren,Huixing Lin
BiOBr photocatalytic active coatings on bismuth-boron-zinc glass carrier using acid etching synthesis were obtained. The effect of direct and indirect corrosion of the glass layer on the bonding ability of the coatings and the substrate were studied. Specially, the BiOBr photocatalytic coating obtained by acid etching after crystallization of the glass has stronger bonding ability with the glass substrate. This is because the needle-like crystal structure after crystallization can be used as a transition layer to closely combine the glass and the photocatalytic coating. In this paper, the concept of plant cultivation was introduced to explain that the coating prepared by the indirect method had a better bonding force with the substrate. This research solves the traditionally difficult recycling problem of degrading organic pollutants in the form of powder, and the preparation method is simple and suitable for industrial mass production.
Glasses in the system xBi2O3–(100 – x)NaPO3 were prepared using transitional melting–quenching and characterized using solid state nuclear magnetic resonance (SSNMR), X-ray photoelectron spectroscopy (XPS), and Fourier-transform infrared spectroscopy (FT-IR). The addition of Bi2O3 results in the depolymerization of the phosphorus chain and the formation of Q(n) (n = 0, 1, 2) phosphorus species, where n represents the number of P–O–P bonds that can be quantified using 31P magic angle spinning (MAS) NMR and constant-time double-quantum based dipolar recoupling effects nuclear alignment reduction (CT-DQ-DRENAR). The 23Na{31P}, 31P{23Na}, and XPS results consistently prove that both Na+ and Bi3+ ions are bounded by phosphorus tetrahedron [PO4]3–. Unlike other trivalent ions such as Ga3+ and Al3+, which connect with the phosphorus tetrahedron by corner-sharing, Bi3+ ions were first proved to share edge with the phosphorus tetrahedron by the analysis of 31P spectra, taking the charge balance and bond valence consideration into account. Such a difference in connectivity results in significant structural differences.
Ruili Zhang,Delong Ma,Jianrong Wang,Yang Chen,Xun Hu
A detailed structural investigation of a series of phosphate laser glasses with composition x Bi 2 O 3 – y Al 2 O 3 –(100 − x – y )NaPO 3 ( x = 0, 10; y = 0, 5, 10, 15, 20) has been conducted using solid-state nuclear magnetic resonance (NMR) techniques and X-ray photoelectron spectroscopy (XPS). 31 P MAS NMR spectroscopy demonstrates that the addition of Bi 2 O 3 and Al 2 O 3 leads to the depolymerization of the phosphorus chain in the process of Q 2 → Q 1 → Q 0 . The various phosphorus species (Q n , n = 0, 1, 2) are identified by 31 P single pulse, 31 P{ 27 Al} rotational echo adiabatic passage double resonance, 31 P{ 27 Al} J-coupling-based heteronuclear multiple-quantum coherence, and 1D refocused INADEQUATE experiments. The results of 23 Na{ 31 P}, 31 P{ 23 Na}, 27 Al{ 31 P} rotational echo double resonance, and XPS consistently confirm that Na + , Al 3+ , and Bi 3+ ions are all bound by phosphorus tetrahedron [PO 4 ] 3− . No bond is formed between these glass modifiers. Based on the complementary evidence from previous experiments, comprehensive local structure models are developed for these Bi 2 O 3 –Al 2 O 3 –NaPO 3 glasses.
Joining is an indispensable process for expanding the application of ceramics and composites. Recently, glasses have been extensively explored for ceramic/composite joining owing to their unique functional needs. However, the difficulty in detecting amorphous materials and lack of enthalpy data make the interfacial reaction mechanism challenging to investigate. In this study, the interfacial reaction mechanism of joints of SiO 2f /SiO 2 composite-brazed bismuth glass was thoroughly explored. SiO 2 was dissolved from the matrix and used throughout the brazing process. In the initial stage, silica reacts with the brazing glass to form Bi 4 (SiO 4 ) 3 . Then, owing to the decomposition of Bi 4 (SiO 4 ) 3 , the silicate glass replaced the bismuth glass. Finally, some precipitation of SiO 2 occurred at the brazing seam owing to an entropy–enthalpy dominating mode. This study may instigate the design of brazing glasses for joining SiO 2f /SiO 2 composites.
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