scholarly journals Mechanism of hopping conduction in Be–Fe–Al–Te–O semiconducting glasses and glass–ceramics

2022 ◽  
Author(s):  
Natalia A. Wójcik ◽  
Nagia S. Tagiara ◽  
Doris Möncke ◽  
Efstratios I. Kamitsos ◽  
Sharafat Ali ◽  
...  
Keyword(s):  
Glass Ceramics ◽  
Theoretical Models ◽  
Wide Frequency Range ◽  
Ion Concentration ◽  
Iron Ions ◽  
Polaron Hopping ◽  
Valence States ◽  
Temperature Dependence Of Conductivity ◽  
Schnakenberg Model ◽  
Alumina Dissolution

AbstractElectrical properties of beryllium-alumino-tellurite glasses and glass–ceramics doped with iron ions were studied using impedance spectroscopy. The conductivity was measured over a wide frequency range from 10 mHz to 1 MHz and the temperature range from 213 to 473 K. The D.C. conductivity values showed a correlation with the Fe-ion concentration and ratio of iron ions on different valence states in the samples. On the basis of Jonscher universal dielectric response the temperature dependence of conductivity parameters were determined and compared to theoretical models collected by Elliott. In glasses, the conduction process was found to be due to the overlap polaron tunneling while in glass–ceramics the quantum mechanical tunneling between semiconducting crystallites of iron oxides is proposed. The D.C. conductivity was found not to follow Arrhenius relation. The Schnakenberg model was used to analyze the conductivity behavior and the polaron hopping energy and disorder energy were estimated. Additionally, the correlation between alumina dissolution and basicity of the melts was observed.

scholarly journals Optical glass-ceramics based on nanosized crystals of magnesium aluminate spinel doped with iron ions

2020 ◽  
Vol 1697 ◽  
pp. 012156
Author(s):  
V Bukina ◽  
O Dymshits ◽  
I Alekseeva ◽  
M Tsenter ◽  
S Zapalova ◽  
...  
Keyword(s):  
Optical Glass ◽  
Glass Ceramics ◽  
Magnesium Aluminate ◽  
Magnesium Aluminate Spinel ◽  
Iron Ions ◽  
Nanosized Crystals

Assessment of role of iron ions on the physical and spectroscopic properties of multi-component Na2O−PbO−Bi2O3−SiO2 glass ceramics

2017 ◽  
Vol 91 (1) ◽  
pp. 92-107 ◽  
Author(s):  
M. V. Sambasiva Rao ◽  
A. Suneel Kumar ◽  
G. Chinna Ram ◽  
Ch. Tirupataiah ◽  
D. Krishna Rao
Keyword(s):  
Glass Ceramics ◽  
Spectroscopic Properties ◽  
Iron Ions ◽  
Sio2 Glass

MAGNETIC BEHAVIOR OF IRON IONS IN THE P2O5·CaO GLASS MATRIX

2003 ◽  
Vol 17 (24) ◽  
pp. 1271-1275 ◽  
Author(s):  
I. ARDELEAN ◽  
C. ANDRONACHE ◽  
P. PǍŞCUŢǍ
Keyword(s):  
Magnetic Susceptibility ◽  
High Temperature ◽  
Magnetic Moment ◽  
Glass Matrix ◽  
Magnetic Behavior ◽  
Iron Ions ◽  
Ion Content ◽  
Dipole Interactions ◽  
Valence States ◽  
Temperature Susceptibility

The temperature dependence of the magnetic susceptibility of x Fe 2 O 3·(100-x)-[ P 2 O 5· CaO ] glasses with 0<x≤50 mol % have been investigated. These data revealed that the valence states and the distribution of iron ions in the glass matrix depend on the Fe 2 O 3 content. For the glasses with x≤1 mol % only Fe 3+ ions are evidenced. In the case of the glasses with 3≤x≤35 mol % both Fe 3+ and Fe 2 ions co-exist in the P 2 O 5· CaO glass matrix, the Fe 2+ ion content is higher than that of the Fe 3+ ions for glasses with x≥10 mol %. For the glasses with x>35 mol %, the evaluated values of the μ eff indicate either the presence of Fe + ions or the coordination influence on the magnetic moment of iron ions, but the presence of small quantities of the antiferromagnetic or ferrimagnetic interactions between iron ions in studied temperature range cannot be excluded. The high temperature susceptibility results indicate that the iron ions are isolated or participate in dipole-dipole interactions for glasses with x≤35 mol % and are antiferromagnetically coupled for higher contents of Fe 2 O 3.

The Charge State of Iron Ions Implanted Into Sapphire

1988 ◽  
Vol 100 ◽  
Author(s):  
C. J. Mchargue ◽  
P. S. Sklad ◽  
C. W. White ◽  
G. C. Farlow ◽  
A. Perez ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Single Crystals ◽  
Charge State ◽  
Room Temperature ◽  
Local Environment ◽  
Rutherford Backscattering ◽  
Iron Ions ◽  
Valence States ◽  
Transmission Electron

ABSTRACTSingle crystals of α-Al2O3 were implanted with 57Fe+ at room temperature to fluences ranging from 1016 to 1017 ions/cm2. The damage in the implanted zone and the valence states and local environment of implanted ions were studied by transmission electron microscopy, Rutherford backscattering-channelling, and conversion electron Mössbauer spectroscopy. The implanted iron was distributed among the three charge states Fe2+, Fe3+, and Fe°(metallic clusters) with the relative amount of each varying with concentration of implanted iron.

Valence states of iron ions in nanostructured yttrium iron garnet Y3Fe5O12 studied by means of soft X-ray absorption spectroscopy

2012 ◽  
Vol 185 (12) ◽  
pp. 598-601 ◽  
Author(s):  
V.V. Mesilov ◽  
V.R. Galakhov ◽  
B.A. Gizhevskii ◽  
N.I. Lobachevskaya ◽  
M. Raekers ◽  
...  
Keyword(s):  
Absorption Spectroscopy ◽  
Yttrium Iron Garnet ◽  
Iron Ions ◽  
Yttrium Iron ◽  
X Ray ◽  
Valence States ◽  
Iron Garnet ◽  
X Ray Absorption

scholarly journals Metallo-Supramolecular Hydrogels from the Copolymers of Acrylic Acid and 4-(2,2′:6′,2″-terpyridin-4′-yl)styrene

Polymers ◽  
2019 ◽  
Vol 11 (7) ◽  
pp. 1152 ◽  
Author(s):  
Huiqin Zhang ◽  
Pan Liu ◽  
Zheng Chi ◽  
Xuegang Chen
Keyword(s):  
Transition Metal ◽  
Acrylic Acid ◽  
Metal Ions ◽  
Self Assembly ◽  
Wavelength Region ◽  
Transition Metal Ions ◽  
Ion Concentration ◽  
Iron Ions ◽  
Absorption Intensity ◽  
Dilute Aqueous Solution

Hydrophilic copolymers containing 2,2′:6′,2″-terpyridine moieties and acrylic acid (AA) units poly (acrylic acid-co-4-(2,2′:6′,2″-terpyridin-4′-yl)styrene) (P(AA-co-TPY)) were synthesized and characterized. Coordinated with different transition metal ions, the dilute aqueous solution of the copolymers exhibited red-shifted UV-vis absorption peaks of π-π* transition from 317 to 340 nm. Further, interacting with iron ions, the copolymer showed new absorption peaks at a longer wavelength region (570 nm) and the absorption intensity enhanced with increase of the ion concentration. When enough ions were added to coordinate with the 2,2′:6′,2″-terpyridine moieties, novel metallo-supramolecular hydrogels were obtained due to the formation of metal coordination bonds between polymer back bones and transition metal ions (Ni2+, Zn2+, Cd2+, Fe2+ and Cu2+), which acted as self-assembly crosslinking structures. The mechanical strength and morphology of the resulting metallo-supramolecular hydrogels have been investigated.

Prevention of Material Deterioration in ECM of Sintered Carbide with Iron Ions (2ndReport)

2017 ◽  
Vol 11 (5) ◽  
pp. 829-834
Author(s):  
Sicong Wang ◽  
Akihiro Goto ◽  
Atsushi Nakata ◽  
◽  
Keyword(s):  
High Speed ◽  
Present Report ◽  
Electrochemical Machining ◽  
Ion Concentration ◽  
Iron Ions ◽  
Conductive Liquid ◽  
Sintered Carbide ◽  
Fe Ions ◽  
Electrical Source

This study focuses on electrochemical machining as a method of processing sintered carbide at high speed. Previous studies have suggested the possibility of using electrochemical machining to achieve the high-speed machining of sintered carbide. However, there has been strong resistance from industry against bringing sintered carbide into contact with a conductive liquid. This is because the material quality of sintered carbide is degraded by the elution of Co when in contact with a conductive liquid. In previous reports, the authors have shown that it is possible to control the two modes of Co elution occurring during electrochemical machining: the elution from sintered carbide in contact with an electrolyte and the selective elution of Co arising from differences in the speeds of the dissolution of tungsten carbide and the elution of Co when sintered carbide is connected to an electrical source for processing. It is possible to control the elution of Co from sintered carbide in contact with an electrolyte by adding Co ions to the electrolyte, which increases the Co ion concentration. In addition, the excessive elution of Co can be prevented by using a bipolar electrical source for machining. Although we have shown that it is possible to carry out the electrochemical machining of sintered carbide without degrading its quality, the addition of large amounts of Co ions to the electrolyte is expensive. Therefore, we attempted to prevent the degradation in the quality of sintered carbide by adding iron ions instead of Co ions, and we confirmed that the addition of Fe ions has the desired effect. However, the Fe2+ions in the solution are easily oxidized to Fe3+ions with time, and the Fe3+ions yield no protective effect for sintered carbide. In our previous report, we discussed a method to bring the electrolyte into contact with Fe to prevent the oxidation of Fe2+ions to Fe3+ions and proposed the use of an iron filter. In the present report, we verify the effect of the iron filter.

THE STRUCTURAL STUDY OF Fe2O3–TeO2–B2O3–SrF2 GLASSES BY EPR AND IR SPECTROSCOPIES

2000 ◽  
Vol 14 (17n18) ◽  
pp. 653-661 ◽  
Author(s):  
I. ARDELEAN ◽  
F. CIORCAS ◽  
M. PETEANU ◽  
I. BRATU ◽  
V. IONCU
Keyword(s):  
Structural Changes ◽  
Mixed Valence ◽  
Ir Absorption ◽  
Iron Ions ◽  
Structural Units ◽  
Spectra Analysis ◽  
Valence States ◽  
Ir Absorption Spectra ◽  
Distorted Octahedral ◽  
Paramagnetic Ions

The local structure of Fe2O3–TeO2–B2O3–SrF2 glasses was studied by recording the EPR and IR absorption spectra. Structural changes and increasing glass stability were evidenced with the addition of Fe2O3 in the sample. The distribution of isolated paramagnetic ions in sites of strongly distorted octahedral symmetry was detected at low concentration (up to 3 mol% Fe2O3) by means of EPR measurements. For x>3 mol% Fe2O3, the clustered iron ions become progressively preponderent in the system. Mixed valence states of iron ions involved in dipole–dipole and superexchange type interactions were also evidenced. The IR spectra analysis revealed the BO3, BO4 and B2O6 units in the structure of tellurite investigated glasses. Among these structural units, those containing the threefold boron atoms are predominant.

Investigation of Room Temperature Mössbauer Spectroscopy and Initial Permeability Properties of Al3+ Substituted Cobalt Ferrites

SPIN ◽  
2018 ◽  
Vol 08 (01) ◽  
pp. 1840005
Author(s):  
Rabia Pandit ◽  
Pawanpreet Kaur ◽  
K. K. Sharma ◽  
Mohd. Hashim ◽  
Ravi Kumar
Keyword(s):  
Loss Factor ◽  
Room Temperature ◽  
Magnetic Hyperfine Field ◽  
Initial Permeability ◽  
Wide Frequency Range ◽  
Ion Concentration ◽  
Frequency Range ◽  
High Frequencies ◽  
Relative Loss ◽  
Cobalt Ferrites

In the present work, Al[Formula: see text] substituted cobalt ferrites (CoFe[Formula: see text]AlxO4, [Formula: see text], 0.4, 0.6, 0.8) have been synthesized via standard solid-state reaction technique. The incorporation of Al[Formula: see text] ions in cobalt ferrite has been shown to play an important role in modifying the magnetic properties. The room temperature (300[Formula: see text]K) [Formula: see text]Fe Mössbauer spectra reveals that the studied samples show two characteristic ferromagnetic zeeman sextets at A and B-sites at lower Al[Formula: see text] ion concentration (i.e., up to [Formula: see text]). However, a paramagnetic relaxation has been noted for higher Al[Formula: see text] substitution (for [Formula: see text] and 0.8) samples. The dependence of the Mössbauer parameters such as isomer shift, quadrupole splitting, line width and magnetic hyperfine field on Al[Formula: see text] ion concentration has also been noted. The variations in initial permeability over a wide frequency range (125[Formula: see text]kHz to 30[Formula: see text]MHz) at 300[Formula: see text]K have been recorded. The fairly constant values of initial permeability and the low values of the relative loss factor of the order of 10[Formula: see text] to 10[Formula: see text] over the wide frequency range are the important findings of the present work. The observed low values of relative loss factor at high frequencies suggest that the studied ferrites are promising materials to be used in microwave applications.

scholarly journals The Influence of Vanadium Ions in Spectral Properties of ZnO–Sb2O3–B2O3 glasses

2020 ◽  
Vol 06 (09) ◽  
pp. 201-207
Author(s):  
N. Narasimha Rao, P. Raghava Rao, B. J.R.S.N. Swamy A. Chitti Babu, T.Sambasiva rao and N.Ch.Ramesh Babu
Keyword(s):  
Optical Absorption ◽  
Glass Network ◽  
Structural Disorder ◽  
Spectroscopic Studies ◽  
Esr Spectra ◽  
Ion Concentration ◽  
Absorption Bands ◽  
Valence States ◽  
Vanadium Ions

Spectroscopic investigations of V2O5 doped ZnO–Sb2O3–B2O3glass system was prepared by melt-quenching technique. ZnO–Sb2O3–B2O3 glasses containing varying concentrations of V2O5 ranging from 0.1 to 1.0 mol% were prepared, here spectroscopic studies such as Optical absorption, IR and ESR spectra have been carried out as a function of vanadium ion concentration. The optical absorption spectrum of glasses has exhibited two broad absorption bands corresponding to 2B2→2B1 and 2B2→2E transitions of VO2+ ions. The appearances of vibration bands in IR spectra are characteristic for B-O-B and V-O-V linkages, showing the network former role of V2O5. Vanadium ions are believed to be present in two possible valence states, namely V4+and V5+. Here with increasing presence of V2 O5 in the glass network, vanadium ions mostly exist in V4+state and occupy modifying positions. Such increase obviously suggests most structural disorder in the network as the concentration of V2 O5 is increased.

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