To explore novel vanadate formulations, i.e. newly effective cathode active material for sodium-ion battery (SIB), relationships among the local structure, electrical conductivity, and cathode ...performance of xNa2O•10 P2O5•(85-x)V2O5•5Fe2O3 and xNa2O•10 P2O5•(85-x) V2O5•5SnO2 (5 <x < 45 mol%) glasses and glass-ceramics nanocomposite abbreviated as xFeV and xSnV, respectively, were systematically investigated before and after heat treatment at 500 ℃ for 100 min. Measurements of 57Fe- and 119Sn Mössbauer spectra (FeMS, SnMS, respectively), X-ray absorption fine structure (XAFS), X-ray diffraction patterns (XRD), Fourier Transform Infrared spectroscopy (FTIR), differential thermal analysis (DTA), electrochemical impedance spectra (EIS) and charge-discharge capacity were carried out in this study. From DTA curves, decreases in glass transition temperature (Tg) and crystallization temperature (Tc) were observed for xFeV and xSnV glasses as ‘x’ increased from 5 to 45 mol% Na2O content. This indicates that the introduction of Na2O reduces thermal stability. Furthermore, the DC conductivity for xFeV and xSnV glasses and glass-ceramics nanocomposite, decreases from 2.82 • 10−5 to 6.61 • 10−7 S cm−1 and from 1.26 • 10−5 to 4.27 • 10−7 S cm−1, respectively, with increasing Na2O content from 5 to 45 mol%. The values of electrical conductivity of xFeV and xSnV are higher than that of xNa2O•10 P2O5•(90-x)V2O5, abbreviated as xV glasses. This indicates that the introduction of Fe2O3 and SnO2 produces an increase in electrical conductivity. 57Fe-Mössbauer spectra of xFeV glass showed decreased quadrupole splitting from 0.73 to 0.63 mm s−1, indicating that FeIII ion forms less distorted tetrahedra upon increasing ‘x’ from 5 to 45 mol%. Additionally, a high capacity of about 200 mAh g−1 was achieved for the SIB made of 5FeV glasses as a cathode. This capacity was larger than the previously reported value of 158 mAh g−1 in Na1.25V3O8. It can be concluded that the introduction of Fe or Sn ions into the phospho-vanadate glass as a cathode causes an increase in durability and conductivity, so these glasses can be considered promising for a high-performance cathode active material with significant improvement of cyclability in SIBs.
•The thermal stability and electrical conductivity of xV glasses significant increased after adding the Fe2O3 and SnO2.•The Na0.282V2O5, Na1.1V3O7.9 and Na0.33V2O5 crystalline phases were detected in xFeV and xSnV glass- ceramics, known as vanadium bronzes.•The 25FeV and 5SnV glasses are good candidates for use as a cathode for Na-ion batteries because of the large capacity of 142 and 162 mAh g−1.
57
Fe conversion electron Mössbauer (CEM) spectroscopy, SEM and magnetization measurements were used to study the effect of swift heavy ion irradiation on metallic
57
Fe (10 nm) thin layer vacuum ...deposited onto SiO
2
/Si. About 85% of the total iron content of the surface layer detected by CEM was present as metallic, crystalline alpha iron before the irradiation, while upon irradiation with 160 MeV Xe ions, with a fluence of 5 × 10
13
ion cm
−2
, ~ 21% was converted to amorphous iron and ~ 47% to silicon-containing iron oxide phases. The presence of pure iron in the amorphous state was evidenced by CEM in agreement with magnetization measurements. Temperature dependence of CEM measurements and the FC/ZFC curves of the irradiated deposit indicated superparamagnetic nature of the iron-silicon-oxide phases. The results are discussed in terms of the thermal spike model for the formation of the amorphous iron phase that can be essential for the formation of silicon-iron-oxides.
Graphical abstract
Glass samples with composition xFe2O3・yAl2O3・(100-x-y)SiO2 abbreviated as xFyAS for photo-Fenton catalyst were prepared by a sol-gel method and heat-treated at 1000 °C for 100 min. It was found that ...when alumina was added to the Fe2O3 + SiO2 glass matrix, the photo-Fenton activity tested with methylene blue degradation increased, so did the photoactivity with visible light. From Mössbauer and XRD results, it was noticed that hercynite phase appeared that showed higher photoactivity even for the samples having lower hematite content and that the Fe+3 (Td) content increased with Al2O3 content. In these samples, the more Fe+3 (Td) found, the more effective was the photo-Fenton degradation.
•Sol-gel synthesized and heated 30FyAS, 40FyAS and 50FyAS samples with ‘y’ of 10, 15, and 20 resulted in the precipitation of hematite and hercynite (FeAl2O4) with photocatalytic properties.•As for the photo-Fenton degradation ability by adding H2O2, the best sample was 40F20AS yielding the highest first-order rate constant of 8.61 × 10−2 min−1.•These results indicate that Fe3+ ions also show photo-Fenton catalytic abilities and light-scattering ability caused by the introduction of Al2O3 is effective for the visible light photocatalytic activity.
In this review, the structure of iron-containing soda-lime aluminosilicate glass–ceramics prepared by domestic waste slag from waste combustion plants in Japan and its simulated composite was ...investigated by
57
Fe-Mössbauer spectroscopy. The photo-Fenton catalytic ability of the samples was evaluated by a degradation test using an aqueous methylene blue (MB) solution. The photo-Fenton catalytic efficacy of the specimens was assessed through a degradation examination employing an aqueous methylene blue (MB) solution. The MB degradation test recorded a
k
value of 2.25–2.65 × 10
–3
min
−1
using the composite of (silicate + iron oxide nanoparticles) prepared from domestic waste slag. The
57
Fe-Mössbauer spectra were mainly composed of three sextets due to nanoparticles of Fe
3
O
4
and α-Fe
2
O
3
. After exploring the chemical composition of soda lime iron aluminosilicates as domestic waste-modeled slag, we revealed that heat-treated simulated slag samples of 5Na
2
O-41.4CaO-20Al
2
O
3
-27.6SiO
2
-6Fe
2
O
3
glass showed the largest
k
value of 115 × 10
–3
min
−1
under photo-Fenton reaction which highly covalent distorted Fe
III
O
4
caused. It is concluded that municipal waste slag can be a starting material for the Photo-Fenton catalyst with high activity, which contributes purification of wastewater.
The relationship between local structure and visible-light activated photocatalytic effect of simulated domestic waste slag glass–ceramics (R-NaWSFe) was investigated. The largest pseudo-first-order ...rate constant of 9.75 × 10
−3
min
−1
was estimated for methylene blue decomposition test under the visible-light irradiation using R-NaWSFe with additional 30 mass% of Fe
2
O
3
heat-treated at 900 °C for 100 min. The reason for the high photoactivity of this sample was mainly due to nanoparticles of CaFe
2
O
4
and α-Fe
2
O
3
confirmed by the Mössbauer spectrum measured at 77 K. It is concluded that the nanoparticles of magnetic components in silica are essential for exhibiting visible-light activated catalytic effect.
Dioximes as ligands are used as analytical reagents and serve as models for biological systems as well as catalysts in chemical processes. A number of novel mixed complexes of the type Fe(DioxH)
2
...(amine)
2
have been prepared and characterised by FTIR,
57
Fe Mössbauer and mass spectroscopy by us. We have found strong Fe–N donor acceptor interactions and iron occurred in low-spin Fe
II
state in all complexes. Later, we have also found that the incorporation of branching alkyl chains (isopropyl) in the complexes alters the Fe–N bond length and results in high-spin iron(II) state 1, 2. The question arises: can the spin state of iron be manipulated generally by replacing the short alkyl chains with high volume demand ones in Fe-azomethine-amine complexes? To answer the question we have synthetized novel iron-bis-glioxime and iron-tris-gloxime complexes when long chain alkyl or aromatic ligands replaced the short alkyl ones and studied by
57
Fe Mössbauer spectroscopy, MS, FTIR, UV-VIS, TG-DTA-DTG and XRD methods. Novel iron-bis-glyoxime and iron-tris-glyoxime type complexes, Fe(Diethyl-Diox)
3
(BOH)
2
, Fe(Diethyl-Diox)
3
(BOEt)
2
and Fe(phenyl-Me-Diox)
3
(BOEt)
2
, were synthesized similarly as described in 2. The FTIR, UV-VIS, TG-DTA-DTG and MS measurements indicated that the expected novel complexes could be successfully synthesized.
New conductive glass with a composition of 20BaO·10Fe
2
O
3
·
x
WO
3
·(70 −
x
)V
2
O
5
(
x
= 10–50) was investigated by means of Mössbauer spectroscopy. A marked decrease in quadrupole splitting ...(Δ) was observed after the isothermal annealing at 500 °C for 1,000 min, due to the structural relaxation of 3D-network composed of FeO
4
, VO
4
, and VO
5
units. After the isothermal annealing, a marked increase in the electrical conductivity (
σ
) was observed from 1.7 × 10
−5
to 1.0 × 10
−1
S cm
−1
when “
x
” was 10, whereas comparable
σ
values of 1.1 × 10
−4
and 2.0 × 10
−4
S cm
−1
were observed when “
x
” was 40. These results evidently show that structural relaxation of 3D-network structure involved with a marked increase in
σ
is intrinsic of “vanadate glass”. XRD pattern indicated several weak peaks due to needle-like BaFe
2
O
4
and α-Fe
2
O
3
when the glass sample with “
x
” of 20 was annealed at 500 °C for 1,000 min. SEM study proved the formation of needle-like BaFe
2
O
4
just on the surface of the sample, whereas hexagonal BaFe
12
O
19
were observed in the annealed sample with “
x
” of 40. Chemical durability of WO
3
-containing vanadate glass was investigated by immersing each glass sample into 20 %-HCl solution for 72 h.
Li2O·0.25Fe2O3·0.25NiO·1.5SiO2 glass was prepared with and without 5 wt % sulfur (S) while melting the mixture of the starting materials at 1350 °C for 1 h in air. A part of the as-prepared glass was ...heat treated for 1 h near its crystallization temperature (Tc) as determined from differential thermal analysis. Each glass was also investigated by means of Mössbauer spectroscopy, X-ray diffraction, FTIR, and DC conductivity. The Mössbauer spectra showed ionic Fe2+ and Fe3+ species in the glass as well as in the precipitated phase obtained after heat treatment. XRD patterns demonstrated the glassy phase formation in the as-quenched samples irrespective of the presence of sulfur. The heat treated samples showed different precipitated phases containing iron particles of nanometer size. The electric conductivity measurements showed that sulfur-doped samples had high values of (σ) probably because of small polaron hopping between Fe2+ and Fe3+.
57
Fe Mössbauer spectroscopy and XRD have successfully been applied to show the incorporation of Fe ion into the interlayer space of montmorillonite via treatment with FeCl
3
in acetone. The 78K
57
...Fe Mössbauer spectra of montmorillonite samples reflected magnetically split spectrum part indicating the intercalation of iron into the interlayer of montmorillonite via the treatment with FeCl
3
+acetone and washed with water until the initial pH=2.3 increased to pH=4.14. It was found that the occurrence of intercalated iron in the form of oxide-oxihydroxide in montmorillonite increases with the pH. Intercalation was confirmed by the gradual increase in the basal spacing
d
001
with pH.
Egyptian basalt rock was used to prepare some glasses with different additives of Na
2
O by the melt quenching method. The prepared glasses were characterized applying FTIR, XRD and Mössbauer Effect ...(ME) spectroscopy. XRD indicated that all the samples showed a homogeneous glassy phase except the sample containing 35 mol % of Na
2
O which showed a very small crystalline phase of less than 5 %. FTIR measurements indicated the presence of various structural units including SiO
4,
FeO
4
and AlO
4
. ME hyperfine parameters indicated the presence of both Fe
2+
and Fe
3+
in the low Na
2
O content glasses (the first three samples), while the iron in the high Na
2
O content glasses (the last three samples) showed only the Fe
3+
state. All the glass samples were heated at 900
°
C for 6 h, of which XRD analysis showed different crystallites of nanometer size. ME spectra of the heat-treated (HT) samples indicated the presence of magnesium ferrites as confirmed by XRD study.
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