scholarly journals Effect of Manganese Ions on Spectroscopic and Insulating Properties of Aluminophosphate Glasses

2021 ◽  
Vol 2021 ◽  
pp. 1-11
Author(s):  
B. Kassa ◽  
J. Leta Tesfaye ◽  
B. Bulcha ◽  
R. Kiran ◽  
T. Deepak ◽  
...  
Keyword(s):  
Glass Network ◽  
Dielectric Analysis ◽  
Manganese Ions ◽  
Melt Quenching ◽  
Dta Analysis ◽  
Tan Δ ◽  
The Stability ◽  
Aluminophosphate Glasses ◽  
Insulating Properties ◽  
Phosphate Groups

The melt-quenching technique was used to produce 39CdO–10Al2O3-(51-x) P2O5: xMnO glasses (x = 0, 0.1, 0.2, 0.3, and 0.4 wt.%). Various stability factors were calculated and presented from DTA analysis. The stability of the glass network appears to increase with the increase of MnO concentration, according to the findings. IR spectral analysis of these glasses exhibited several symmetrical and asymmetrical bands due to phosphate groups. The observed change in these band intensities with the rise in MnO concentrations, ranging from 0.1 wt.% to 0.4 wt.%, shows an increase in the stability of the glass network. Optical absorption analyses of these glasses revealed an absorption band that shifted from 500 to 488 nm as the concentration of manganese oxide (MnO) increased from 0.1 wt.% to 0.4 wt.%, indicating that Mn2+ ions were gradually converted into Mn3+ ions. EPR spectra of these glasses were characterized by two signals due to Mn2+ and Mn3+ ions. Observations on these signal intensity variations revealed an increase in stability of the glass network with the increase of MnO concentration from 0.1 wt.% to 0.4 wt.%. Parameters, which describe the insulating characteristics, for example, dielectric constant, ε, dielectric loss, tan δ, and AC conductivity σac, were determined in relation to frequency (103 Hz to 105 Hz) and temperature (20°C to 400°C) and presented in the dielectric analysis of these glasses.

Comparative TG/DTG/DTA+FTIR Studies Concerning the Stability of Some Mineral and Vegetable Electro-Insulating Fluids

2018 ◽  
Vol 69 (9) ◽  
pp. 2366-2371
Author(s):  
Andrei Cucos ◽  
Petru Budrugeac ◽  
Iosif Lingvay ◽  
Adriana Mariana Bors ◽  
Andreea Voina
Keyword(s):  
Vegetable Oils ◽  
Electrical Equipment ◽  
Inert Atmosphere ◽  
Oxidation Products ◽  
Gaseous Products ◽  
Mineral Oils ◽  
Ftir Studies ◽  
Dta Analysis ◽  
Anti Oxidant ◽  
The Stability

Thermal TG/DTG/DTA analysis coupled with FTIR spectroscopy was applied to some sorts of mineral and vegetable oils used in electrical equipment. On heating in inert atmosphere, it was observed that the mineral oils vaporize, while the vegetable oils undergo hydrolysis, yielding fatty acids as main volatiles, as indicated by FTIR. In synthetic air, the FTIR spectra of gaseous products confirm the presence of similar oxidation products, both for mineral and vegetable oils. The TG results indicated that the vegetable-based oils exhibit a substantially higher thermal stability than the mineral oils. The presence or absence of anti-oxidant inhibitors in these oils greatly influences the onset of the oxidation process in air environment factor, as results from the DTA results.

scholarly journals Combination of Self-Healing Butyl Rubber and Natural Rubber Composites for Improving the Stability

Polymers ◽  
2021 ◽  
Vol 13 (3) ◽  
pp. 443
Author(s):  
Kunakorn Chumnum ◽  
Ekwipoo Kalkornsurapranee ◽  
Jobish Johns ◽  
Karnda Sengloyluan ◽  
Yeampon Nakaramontri
Keyword(s):  
Natural Rubber ◽  
Dynamic Mechanical Properties ◽  
Attenuated Total Reflection ◽  
Rubber Matrix ◽  
Self Healing ◽  
Mechanical And Electrical Properties ◽  
Natural Rubber Composites ◽  
Tan Δ ◽  
The Stability ◽  
Physical And Chemical

The self-healing composites were prepared from the combination of bromobutyl rubber (BIIR) and natural rubber (NR) blends filled with carbon nanotubes (CNT) and carbon black (CB). To reach the optimized self-healing propagation, the BIIR was modified with ionic liquid (IL) and butylimidazole (IM), and blended with NR using the ratios of 70:30 and 80:20 BIIR:NR. Physical and chemical modifications were confirmed from the mixing torque and attenuated total reflection-fourier transform infrared spectroscopy (ATR-FTIR). It was found that the BIIR/NR-CNTCB with IL and IM effectively improved the cure properties with enhanced tensile properties relative to pure BIIR/NR blends. For the healed composites, BIIR/NR-CNTCB-IM exhibited superior mechanical and electrical properties due to the existing ionic linkages in rubber matrix. For the abrasion resistances, puncture stress and electrical recyclability were examined to know the possibility of inner liner applications and Taber abrasion with dynamic mechanical properties were elucidated for tire tread applications. Based on the obtained Tg and Tan δ values, the composites are proposed for tire applications in the future with a simplified preparation procedure.

Formation and stability of porphyrin and phthalocyanine self-assembled monolayers on ZnO surfaces

2016 ◽  
Vol 20 (08n11) ◽  
pp. 1264-1271 ◽  
Author(s):  
Hanna Hakola ◽  
Essi Sariola-Leikas ◽  
Paavo Jäntti ◽  
Thomas Mokus ◽  
Kati Stranius ◽  
...  
Keyword(s):  
Thin Films ◽  
Zno Nanorods ◽  
Self Assembled Monolayers ◽  
Layer Formation ◽  
Zno Film ◽  
Assembled Monolayers ◽  
Self Assembled ◽  
Anchoring Groups ◽  
The Stability ◽  
Phosphate Groups

Formation of self-assembled monolayers (SAMs) of three porphyrin and one phthalocyanine derivatives on thin ZnO film was studied by monitoring absorption spectra of the samples. The compounds were equipped with carboxylic or phosphate groups to bind to the surface. The SAM formation was found to be fast. The layer was formed in less than 15 min for all studied porphyrins, and 30 min was sufficient to form phthalocyanine layer. For porphyrins with different anchor groups the SAM formation was too fast to see any difference between the anchoring groups. The stability of SAMs was tested then by immersing the samples into neat solvents. Upon immersion the SAMs were gradually losing the absorbance for all the compounds with degradation trends being in line with p[Formula: see text] values of the binding groups of the same type. However, even for the weakest binding group the SAM was relatively stable after a few tens of minutes of washing, which was sufficient to remove physisorbed compounds but the SAM was essentially not destroyed. Comparison of SAMs on thin films with SAMs on ZnO nanorods and TiO2 nanoparticle films indicated the same fast layer formation but relatively weaker SAMs stability, showing 20–40% faster absorption losses during the washing.

AC CONDUCTION PHENOMENON OF Li2O–WO3–B2O3 GLASSES DOPED WITH V2O5

2013 ◽  
Vol 06 (03) ◽  
pp. 1350032 ◽  
Author(s):  
LINGANABOINA SRINIVASA RAO ◽  
NALLURI VEERAIAH ◽  
TUMU VENKATAPPA RAO
Keyword(s):  
High Temperatures ◽  
Ac Conductivity ◽  
Conduction Mechanism ◽  
Glass Composition ◽  
Melt Quenching ◽  
Frequency Exponent ◽  
Spreading Factor ◽  
Cbh Model ◽  
Tan Δ ◽  
Ac Conduction

The glass composition 40 Li 2 O –5 WO 3–(55−x) B 2 O 3: x V 2 O 5 for x = 0.2, 0.4, 0.6 and 0.8 is chosen for the present study. The glass samples were synthesized by conventional melt-quenching technique. The dielectric properties such as constant (ε′), loss (tan δ) and ac conductivity (σac) are carried out as a function of temperature (30–270°C) and frequency (102–105 Hz). The glass sample (at x = 0.6) exhibited highest ac conductivity (σac) and spreading factor (β) among all the samples. All glasses exhibited mixed conduction (both electronic and ionic) at high temperatures. The frequency exponent s denotes the ac conduction mechanism is associated with both QMT model (at low temperatures) and CBH model (at high temperatures).

Al Doped Ta2O5 Thin Films for Microelectronic Applications

2000 ◽  
Vol 654 ◽  
Author(s):  
P. C Joshi ◽  
M. W. Cole ◽  
C. W. Hubbard ◽  
E. Ngo
Keyword(s):  
Thin Films ◽  
Precursor Solution ◽  
Electrical Measurements ◽  
Cross Sectional ◽  
Solution Deposition ◽  
Atomic Force ◽  
The Stability ◽  
Insulating Properties ◽  
Post Deposition

AbstractIn this paper, we report on the fabrication and characterization of pure and Al doped Ta2O5 thin films fabricated by metalorganic solution deposition (MOSD) technique. The pure and Aldoped Ta2O5 thin films were fabricated by spin-coating technique using room temperature processed carboxylate-alkoxide precursor solution. The structure of the films was analyzed by xray diffraction (XRD). The surface and cross-sectional morphology of the films were examined by field emission scanning electron microscope (FESEM) and atomic force microscope (AFM). The electrical measurements were conducted on films in MIM configuration using Pt as the top and bottom electrode. The effects of Al concentration and the post-deposition annealing temperature on the structural, dielectric, and insulating properties were analyzed. The effects of the applied bias and the measurement temperature on the dielectric and insulating properties were also analyzed to establish the stability and reliability of Al doped Ta2O5 thin films.

Structural Studies of Lead Sodium Borate Glasses

2010 ◽  
Vol 93-94 ◽  
pp. 439-442
Author(s):  
Pruittipol Limkitjaroenporn ◽  
Jakrapong Kaewkhao ◽  
Suparat Tuscharoen ◽  
Pichet Limsuwan ◽  
Weerapong Chewpraditkul
Keyword(s):  
Molar Volume ◽  
Glass Network ◽  
Sodium Borate ◽  
Borate Glasses ◽  
Structural Studies ◽  
Melt Quenching ◽  
Network Modifier ◽  
Ir Analysis ◽  
Quenching Method ◽  
Glass Compositions

Glass compositions xPbO : 20Na2O : (80-x)B2O3 (x = 5,10,15,20,25,30,35,40,45,50 and 55 %mol) have been prepared using melt-quenching method. The density and molar volume of these glass samples have been found to be compositional dependent. The results indicate that PbO acts on the glass structures were different between the range 0≤ x ≤ 20 %mol and beyond x = 20 %mol (with inflection at x = 20 %mol). These due to the PbO can enter the glass network both as a network modifier and also as a network former. This role depends on the type of bond between lead and oxide. These results are interpreted in term of IR analysis.

Dielectric analysis of polypropylene (PP) and polylactic acid (PLA) blends reinforced with halloysite nanotubes

2017 ◽  
Vol 31 (8) ◽  
pp. 1042-1053 ◽  
Author(s):  
Krishna Prasad Rajan ◽  
Ahmed Al-Ghamdi ◽  
Selvin P Thomas ◽  
Aravinthan Gopanna ◽  
Murthy Chavali
Keyword(s):  
Dielectric Properties ◽  
Polylactic Acid ◽  
Loss Factor ◽  
Halloysite Nanotubes ◽  
Dynamic Mechanical Properties ◽  
Dielectric Analysis ◽  
Melt Mixing ◽  
Microelectronic Devices ◽  
Base Matrix ◽  
Tan Δ

Polypropylene (PP) and polylactic acid were blended in the ratio 80:20 by weight and compatibilized with 3 wt% of maleic anhydride-grafted-PP. The compatibilized blend was chosen as the base matrix for reinforcement with halloysite nanotubes (HNTs). The nanotube content varied from 0 to 10 wt%. Blend and the nanocomposites were prepared by melt mixing technique. Dielectric analysis of the base matrix and the nanocomposites was carried out using interdigitated electrode sensor in a DEA 288 Epsilon-dielectric analyser. The dielectric properties of the composites were measured at temperatures from 30 to 120°C at various frequencies ranging from 1 Hz to 1 kHz. Permittivity values slightly decreased as the HNT content increased from 0 to 2 wt%. It increased at 4 wt% of HNT and again slightly decreased at 6 wt% of HNT, and with further increase in HNT (HNT 8 and HNT 10) led to increase in permittivity values. Loss factor values decreased slightly as the HNT content in the composites increased from 0 to 4 wt%; but with further increase in HNT, the loss factor showed a sharp increase. Loss tangent (tan δ) values decreased up to 4 wt% of HNT (HNT 4) and then increased up to 8 wt% (HNT 8) of HNT and then decreased slightly (for HNT 10). Analysing the different dielectric properties, consistent properties were shown by 6 wt% of HNT similar to static and dynamic mechanical properties. The analysis showed that the composites can be utilized in microelectronic devices or in microelectronic packaging applications.

Characterization of Aluminophosphate Glasses Containing Pr3+, Er3+, Gd3+ and Yb3+ Ions

2008 ◽  
Vol 39-40 ◽  
pp. 61-64 ◽  
Author(s):  
M. Elisa ◽  
Ileana Cristina Vasiliu ◽  
Cristiana Eugenia Ana Grigorescu ◽  
B. Grigoras ◽  
H. Niciu ◽  
...  
Keyword(s):  
Rare Earth ◽  
Absorption Spectra ◽  
Glass Network ◽  
Phosphate Glasses ◽  
Rare Earth Ions ◽  
Electronic Transitions ◽  
Ir Absorption ◽  
Optical Phonons ◽  
Infra Red ◽  
Aluminophosphate Glasses

A wet non-conventional method for preparing aluminophosphate glasses is presented. Aluminophosphate glasses belonging to the oxide system Li2O-BaO-Al2O3-La2O3-P2O5, doped with rare-earth ions (Pr3+, Er3+, Gd3+, and Yb3+) were obtained. The influence of the doping ions on the optical properties of the phosphate glasses has been investigated in relation with micro-structural and local electronic phenomena The optical behavior of Li2O-BaO-Al2O3-La2O3-P2O5 glasses doped with 3% mol. rare-earth ions has been studied by ultra-violet-visible-near-infra-red (UV-VISNIR) spectroscopy. The transmission spectra revealed electronic transitions between 4f and 6s inner orbital of the rare-earth ions. Structural information via optical phonons was provided by infra-red (IR) absorption spectra in the range 400-4000 cm-1. IR optical phonons are characteristic for the vitreous phosphate network, showing out the glass network-forming role of P2O5. The absorption spectra present the main PO2 and P-O-P symmetrical stretch modes besides P-O-P bend mode, P-OH, P=O, PO3 2-, asymmetrical and symmetrical vibration modes. Fluorescence spectra of the rareearth- doped aluminophosphate glasses, in the visible range, were obtained by laser excitation at 514.5 nm. The fluorescence signals revealed specific electronic transitions, which provide visible and near-infra-red emission. Glasses containing rare-earth ions exhibit luminescence at the following wavelengths: Pr3+ ions at 820 nm and 880 nm, Er3+ ions at 520 nm, 550 nm and 560 nm, Gd3+ ions at 530 nm, 540 nm, 550 nm 820 and 880 nm, Yb3+ions at 530 nm, 540 nm, 550 nm and 980 nm.

STRUCTURAL STUDIES ON GALLIUM–BISMUTHATE GLASSES CONTAINING IRON

2004 ◽  
Vol 18 (09) ◽  
pp. 1369-1377
Author(s):  
S. SIMON
Keyword(s):  
Electron Paramagnetic Resonance ◽  
Infrared Spectroscopy ◽  
Glass Network ◽  
Local Order ◽  
Iron Ions ◽  
Structural Studies ◽  
Melt Quenching ◽  
Paramagnetic Resonance ◽  
Network Modifier ◽  
Electron Paramagnetic

Glasses belonging to x Fe2O3·(80-x) Bi2O3·20 Ga2O3system (0≤x≤20 mol %) were prepared using the melt quenching technique. Local order changes were investigated as a function of iron content using electron paramagnetic resonance and infrared spectroscopy results. The glass network mainly consist of [ BiO6] octahedral units. Iron ions enter the glass network by breaking up Bi - O - Bi bonds. Gallium ions also behave as glass network modifier.

Poly(4-methyl-1-pentene)/MWNT nanocomposites

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Prashant A Patil ◽  
Santosh D Wanjale ◽  
Jyoti P. Jog
Keyword(s):  
Storage Modulus ◽  
Multiwall Carbon Nanotubes ◽  
Viscoelastic Behavior ◽  
Complex Viscosity ◽  
Dielectric Analysis ◽  
Melt Compounding ◽  
Tan Δ ◽  
Multiwall Carbon ◽  
Thermal Stability Of ◽  
Scanning Electron

AbstractNanocomposites of poly(4-methyl-1-pentene) (PMP) with various weight fractions of multiwall carbon nanotubes (MWNT’s) were prepared by melt compounding. The nanocomposites are characterized for structure using scanning electron microscopy. The viscoelastic behavior of the nanocomposites is investigated in solid as well as melt state. The study reveals a significant increase in storage modulus especially in the rubbery regime of the polymer matrix and reduced tan δ. Rheological properties in melt show that the complex viscosity and shear storage modulus are increased as a result of incorporation of MWNT. A systematic decrease in the cross over frequency is noted which is attributed to the increased relaxation time. In dielectric analysis, composition dependent enhanced permittivity and conductivity are observed. The thermal stability of the polymer is found to be significantly improved in presence of MWNT’s.

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