Electronic-Ionic Conductivity of Lithium- Vanado- Phosphate Glasses

2017 ◽  
Vol 14 (1) ◽  
pp. 9-14
Author(s):  
Eraiah B
Keyword(s):  
Activation Energy ◽  
Ionic Conductivity ◽  
Structural Changes ◽  
Glass Network ◽  
Phosphate Glasses ◽  
Melt Quenching ◽  
Calculated Activation Energy ◽  
Quenching Method ◽  
Increasing Temperature ◽  
Calculated Activation

The new glassesof glass system x Li 2 O-50 V 2 O 5 -(50-x) P 2 O 5 were prepared by using conventional melt quenching method. The densities of these glasses have been measured by Archimedes method and corresponding molar volumes have also been calculated. The conductivity of these glasses was measured as a function of temperature and composition. The variations of conductivity versus temperature follow Arrehenius type relationship. Conductivity decreases with increasing Li 2 O content and increase with increasing temperature. The calculated activation energy decreases up to 15mol% of Li 2 O, it increases from 15mol% to 30 mol% of Li 2 O and again it suddenly drops at 40 mol% of Li 2 O. This may be due to structural changes in glass network and these glasses exhibit both electronic and ionic conductivity.

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.

Annealing Behavior of the Compressed AZ31 Magnesium Alloy with Different Strain

2007 ◽  
Vol 546-549 ◽  
pp. 267-270
Author(s):  
Tian Mo Liu ◽  
Pan Xiao ◽  
Fu Sheng Pan ◽  
Qing Liu
Keyword(s):  
Activation Energy ◽  
Annealing Temperature ◽  
Hardness Test ◽  
Test Results ◽  
Annealing Behavior ◽  
Different Temperatures ◽  
Calculated Activation Energy ◽  
Calculated Activation ◽  
Crystallographic Orientations ◽  
Microhardness Tester

The cold-compressed AZ31 magnesium alloys with different (2.5%, 5%, 7.5%, 10%, 12.5% and 15%) were annealed at different temperatures (573, 623 and 673K) for different time. With aid of the optical microscopy, and microhardness tester, the microstructural evolution during annealing at different temperature of the compressed AZ31 has been investigated. The microstructural characterized results were further related to the hardness test results and the calculated activation energy. The results showed that for the compressed AZ31, the recrystallization can occur on the samples with the strain just above 10% and the deformation twinning plays an important role on the nucleation and grain growth of the recrystallization. It was found that the twinning boundary was the location of the recrystallization nuclei and a lot of recrystallized grains with equiaxed shape were found along the twinning boundaries. The relationships among the nuclei orientations and the crystallographic orientations on both sides of the twining boundary have been statistically investigated. The effects of the compressed strain and the annealing temperature on annealing behavior were also discussed based on the experimental results.

scholarly journals Vibrational Studies of Calcium Magnesium Ultraphosphate Glasses

2014 ◽  
Vol 5 (1) ◽  
Author(s):  
Rosli Hussin ◽  
Musdalilah Ahmad Salim ◽  
Nur Shahira Alias ◽  
Mutia Suhaibah Abdullah ◽  
Suhailah Abdullah ◽  
...  
Keyword(s):  
Glass Network ◽  
Phosphate Glasses ◽  
Molar Ratio ◽  
Luminescent Materials ◽  
Melt Quenching ◽  
Complementary Information ◽  
Host Matrix ◽  
Hygroscopic Nature ◽  
Calcium Magnesium ◽  
Ir And Raman

Phosphate glasses in a system of magnesium calcium phosphate for host matrix luminescent materials wereinvestigated. The glass samples in a series of xMgO–(40- x)CaO–60P2O5 in molar ratio (0x40 mol%) were preparedusing melt-quenching technique. The effect of Mg and Ca content on the structure and glass stability againstcrystallization in the system of MgO–CaO–P2O5 ultraphosphate has been investigated using XRD, Infrared and Ramanspectroscopy. The compositions containing up to 40 mol% of CaO and /or MgO formed glasses and no crystallinephases were detected by XRD. The results of IR and Raman spectroscopy suggest that the phosphate network of theseglasses is composed of middle (Q2) and branching (Q3) phosphate tetrahedral and other calcium/magnesium anions.All the symmetric and asymmetric stretching vibrations of POP and PO2 observed in the spectra are characteristic ofQ3 and Q2 groups. The glass network, especially the Q2 units can be modified by the presence of Ca and Mg ions. Thismodification is primarily associated with the phosphate and the Q2 and Q3 phosphate units randomly distributed in thenetwork. Spectroscopic results shows that the modification of the phosphate network is higher for the Ca containingglasses with respect to the Mg ones, at the same alkali earth content, due to the well defined Ca properties as amodifying cation. Formation of P–O–H bond expresses the hygroscopic nature of the phosphate glasses. This studyshows that the vibrational spectroscopy (Infrared and Raman) are provide useful, complementary information aboutthe network structures of ultraphosphate glasses.

scholarly journals DTA Evaluation of Spruce Wood Degradation Process

2017 ◽  
Vol 25 (40) ◽  
pp. 41-48
Author(s):  
Ivan Hrušovský ◽  
Peter Rantuch ◽  
Jozef Martinka ◽  
Simona Dzíbelová
Keyword(s):  
Activation Energy ◽  
Room Temperature ◽  
Degradation Process ◽  
Heating Rates ◽  
Wood Degradation ◽  
Wood Sawdust ◽  
Spruce Wood ◽  
Calculated Activation Energy ◽  
Two Stages ◽  
Calculated Activation

Abstract The decomposition stages of spruce wood sawdust were analyzed by means of sequential differential calorimetry. Two stages of decomposition were identified and activation energy of one stage was calculated using the Kissinger method. The DTA was conducted by means of SEDEX safety calorimeter. Sample was analyzed under three heating rates of 10, 20 and 45 °C/h in temperature range from room temperature to 400 °C. The calculated activation energy for the last and most clear decomposition peak was 122.63 KJ/mol. The results are comparable with the data calculated by J.V. Rissanen et al., who calculated activation energy for Spruce hemicellulose as 120 KJ/mol.

A method of preparation of x-casein and some observations on its nature

1962 ◽  
Vol 29 (2) ◽  
pp. 163-171 ◽  
Author(s):  
G. C. Cheeseman
Keyword(s):  
Activation Energy ◽  
Calcium Ions ◽  
Ion Concentration ◽  
Gel Formation ◽  
Protein Nitrogen ◽  
First Order ◽  
Electrophoretic Patterns ◽  
Calculated Activation Energy ◽  
Milk Coagulation ◽  
Calculated Activation

SummaryDetails are given of the method used in this laboratory for the preparation of k-casein. The recovery is about 25% and the material has a purity, estimated from electrophoretic patterns, of about 90% with β-casein as the main contaminant. Higher temperatures and lower ion concentration caused precipitation of k-casein in the presence of calcium ions, 0·1m-acetate buffer at pH 6·5 being sufficient to stabilize a 0·5% solution in the presence of 0·01–0·2m-CaCl2 at 20 and 30°C but not at all calcium concentrations at 40°C. It was also found that solutions of para-k-casein did not aggregate in the presence of concentrations of electrolytes above about 0·25m.The rate of release of non-protein nitrogen and decline in viscosity during the enzymic stage of gel formation in solutions of k-casein and rennin had similar apparent first order constants (0·087 ± 0·03 min—1 and 0·086 ± 0·021 min—1, respectively, at 25°C). A gel could be formed by rennin action in a solution containing as little as 6·25mg of the protein per litre. In the non-enzymic stage of gelling of k-casein solutions the calculated activation energy over the range of 20–40°C was much lower than that obtained from the non-enzymic stage of milk coagulation.

Influence of Samarium on the Optical Response of Zinc Phosphate Glass

2015 ◽  
Vol 1107 ◽  
pp. 403-408 ◽  
Author(s):  
Siti Amlah Mohamad Azmi ◽  
M.R. Sahar ◽  
Ramli Arifin ◽  
Sib Krishna Ghoshal
Keyword(s):  
Excited States ◽  
Zinc Phosphate ◽  
Rapid Quenching ◽  
Phosphate Glasses ◽  
Relaxation Processes ◽  
Melt Quenching ◽  
Zinc Phosphate Glass ◽  
Amorphous Nature ◽  
Quenching Method ◽  
Xrd Patterns

Samarium doped zinc phosphate glasses of the form 40ZnO-(60-x) P2O5-xSm2O3, with 1.0 ≤ x ≤ 5.0 mol% were prepared using the melt quenching method. The XRD patterns confirmed the amorphous nature of the glass. The Archimedes method was used to measure the density, which was used to calculate the molar volumes. The density was found to vary in the range of 2.839 to 3.138 gm/cm3 while the molar volume varied between 40.80 and 42.21cm3/mol. The effect of samarium on the optical absorption and emission characteristics were examined. The absorption spectra exhibit two dominant absorption peaks corresponding to the transitions from 6H5/2 ground state to 4I11/2 and 4F7/2 excited states, respectively. Photoluminescence emission consisting of 4G5/2 à 6H5/2, 6H7/2, 6H9/2 and 6H11/2 transitions display significant enhancement with the increase of Sm3+ concentration up to 3.0 mol% followed by a rapid quenching beyond this concentration which is ascribed to the nonradiative energy transfer and multi-phonon relaxation processes.

Dynamic Thermal Diffusivity Measurements – A Tool for Studying Gas-Solid Reactions

2011 ◽  
Vol 312-315 ◽  
pp. 217-222
Author(s):  
Hesham M. Ahmed ◽  
Nurini N. Viswanathan ◽  
Seshadri Seetharaman
Keyword(s):  
Thermal Diffusivity ◽  
Laser Flash ◽  
Diffusivity Measurements ◽  
Calculated Activation Energy ◽  
Laser Flash Technique ◽  
Flash Technique ◽  
The Difference ◽  
Increasing Temperature ◽  
Cold Pressed ◽  
Calculated Activation

In the present work, the thermal diffusivity measurements of uniaxially cold pressed NiWO4 has been carried out. The measurements were performed isothermally at temperatures between 973 and 1273 K under H2 gas using the laser flash technique. The experimental thermal diffusivity values were found to increase with the reduction progress as well as with increasing temperature. The calculated activation energy was found to be higher than that for chemically controlled reaction. The difference has been attributed to factors like agglomeration of the product as well as sintering of the precursor along with the chemical reaction. In order to sort out the sintering effect on the thermal diffusivity values, complementary experiments have been done on pressed NiWO4 and Ni-W, produced by the reduction of NiWO4 at 1123K, under Argon gas. The porosity change and its effect on thermal diffusivity values have been studied.

scholarly journals Polaronic Conductivity in Iron Phosphate Glasses Containing B2O3

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2505
Author(s):  
Luka Pavić ◽  
Stjepko Fazinić ◽  
Hüseyin Ertap ◽  
Mevlüt Karabulut ◽  
Andrea Moguš-Milanković ◽  
...  
Keyword(s):  
Master Curve ◽  
Structural Changes ◽  
Strong Dependence ◽  
Glass Structure ◽  
Glass Network ◽  
Iron Phosphate ◽  
Phosphate Glasses ◽  
Nominal Composition ◽  
Number Density ◽  
Iron Phosphate Glasses

We report on the electrical properties of glasses with nominal composition xB2O3–(100 − x)[40Fe2O3–60P2O5],x = 2–20, mol.%. The conduction transport in these glasses is polaronic and shows a strong dependence on Fe2O3 content and polaron number density. The changes in DC conductivity are found not to be directly related to B2O3, however structural changes induced by its addition impact frequency-dependent conductivity. All glasses obey Summerfield and Sidebottom procedures of scaling conductivity spectra indicating that the polaronic mechanism does not change with temperature. An attempt to produce a super-master curve revealed that shape of the conductivity dispersion is the same for glasses with up to 15.0 mol.% B2O3 but differs for glass with the highest B2O3 content. This result could be related to the presence of borate units in the glass network. Moreover, the spatial extent of localized polaron motions increases with the decrease of polaron number density, however, this increase shows a larger slope than for previously reported iron phosphate glasses most probably due to the influence of B2O3 on glass structure and formation of polarons. While Summerfield scaling procedure fails, Sidebottom scaling yields a super-master curve, which indicates that polaronic hopping lengths also change with changing polaron number density in these glasses.

scholarly journals Structures and Dissolution Behaviors of Quaternary CaO-SrO-P2O5-TiO2 Glasses

Materials ◽  
2021 ◽  
Vol 14 (7) ◽  
pp. 1736
Author(s):  
Sungho Lee ◽  
Fukue Nagata ◽  
Katsuya Kato ◽  
Takayoshi Nakano ◽  
Toshihiro Kasuga
Keyword(s):  
Bone Formation ◽  
Network Structure ◽  
Glass Network ◽  
Chemical Durability ◽  
Phosphate Glasses ◽  
Mixed Composition ◽  
Mixed Cation ◽  
Glass Series ◽  
Strontium Ions ◽  
Quenching Method

Calcium phosphate glasses have a high potential for use as biomaterials because their composition is similar to that of the mineral phase of bone. Phosphate glasses can dissolve completely in aqueous solution and can contain various elements owing to their acidity. Thus, the glass can be a candidate for therapeutic ion carriers. Recently, we focused on the effect of strontium ions for bone formation, which exhibited dual effects of stimulating bone formation and inhibiting bone resorption. However, large amounts of strontium ions may induce a cytotoxic effect, and there is a need to control their releasing amount. This work reports fundamental data for designing quaternary CaO-SrO-P2O5-TiO2 glasses with pyro- and meta-phosphate compositions to control strontium ion-releasing behavior. The glasses were prepared by substituting CaO by SrO using the melt-quenching method. The SrO/CaO mixed composition exhibited a mixed cation effect on the glassification degree and ion-releasing behavior, which showed non-linear properties with mixed cation compositions of the glasses. Sr2+ ions have smaller field strength than Ca2+ ions, and the glass network structure may be weakened by the substitution of CaO by SrO. However, glassification degree and chemical durability of pyro- and meta-phosphate glasses increased with substituted all CaO by SrO. This is because titanium groups in the glasses are closely related to their glass network structure by SrO substitution. The P-O-Ti bonds in pyrophosphate glass series and TiO4 tetrahedra in metaphosphate glass series increased with substitution by SrO. The titanium groups in the glasses were crosslink and/or coordinate phosphate groups to improve glassification degree and chemical durability. Sr2+ ion releasing amount of pyrophosphate glasses with >83% SrO substitution was larger than 0.1 mM at day seven, an amount that reported enhanced bone formation by stimulation of osteogenic markers.

Calculations of activation energy and frequency factors for corn leafs pyrolysis using excel solver: new concept

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Omar Salim Al-Ayed ◽  
Mohammad Waleed Amer ◽  
Sura Al-Harahshah ◽  
Birgit Maaten ◽  
Muhammad Sajjad Ahmed
Keyword(s):  
Activation Energy ◽  
Apparent Activation Energy ◽  
Frequency Factor ◽  
Heating Rates ◽  
First Order ◽  
First Order Kinetics ◽  
Calculated Activation Energy ◽  
Apparent Activation Energies ◽  
Excel Solver ◽  
Calculated Activation

Abstract Thermal degradations of biomass corn leaves were studied for kinetic modeling. Thermogravimetric-differential analyzer runs at 5, 10, 20, and 30 °C min−1 heating rates were employed. Apparent activation energy and frequency factor values were calculated for first-order kinetics using several procedures. The procedure of Coats and Redfern showed 28.89 to 31.78 kJ mol−1 apparent activation energy and 15.5 to 157.12 min−1 frequency factor, respectively. Calculation of the apparent activation energy and frequency factor using Kissinger–Akahira–Sunose procedure gave 229.9–364.2 kJ/mol and 8.567 × 1023 and 1.13 × 1031 (min−1), respectively as the conversion increased from 0.1 to 0.9. The newly introduced excel solver procedure indicates a distribution activation energy over the entire range of conversion. For first-order reaction kinetics, the calculated apparent activation energy magnitudes ranged between 5.0 kJ mol−1 with frequency factor equals to 0.239 and 196.2 kJ mol−1 with frequency factor 2.89 × 1012 in the studied range. The low or high magnitudes of the calculated activation energy are not associated with a particular value of the conversion. The calculated apparent activation energies are related to the direct solution of the simultaneous equations that constitute the basis of the excel solver.

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