Study on the Kinetics of Non-isothermal Dehydration of Alkaline Earth Metal Selenites

Vlaev, L. T.; Nikolova, Maria M.; Gospodinov, G. G.

doi:10.1007/s00706-005-0352-5

Cited by 10 publications

(7 citation statements)

References 22 publications

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“…The algebraic expressions of these functions of the most common reaction mechanisms of solid-state reactions are described elsewhere [9,23,[30][31][32][33][34]. Coats and Redfern [35] reported that the temperature-containing integral has no exact analytical solution, therefore, they used an approximation.…”

Section: Theoretical Approach and Mathematical Backgroundmentioning

confidence: 99%

“…If the correct g(α) function is used, the corresponding plots should give a straight line with high coefficient of the linear regression analysis. It is well known that the formal expressions of the functions g(α) depend on the conversion mechanism and its mathematical model [23,28,31]. Both the activation energy and pre-exponential factor are mutually correlated.…”

Section: Theoretical Approach and Mathematical Backgroundmentioning

confidence: 99%

“…Taking into account the relationship between the activation energy E A and ΔH / = for the reactions [2,23,31,[39][40][41][42]]…”

Section: Theoretical Approach and Mathematical Backgroundmentioning

confidence: 99%

“…In our case, n is equal to unity, ΔH / = is the change of the enthalpy of activation, and e = 2.7183 is the Neper number. From the comparison of the Arrhenius equation (2) with (12) it is clear that the frequency factor A is equal to the next term [23,31,42]:…”

Section: Theoretical Approach and Mathematical Backgroundmentioning

confidence: 99%

“…Using (11) about the value of the change of enthalpy ΔH / = and using the well-known Gibbs-Helmholtz thermodynamic relationship [2,23,31,[40][41][42]:…”

Section: Theoretical Approach and Mathematical Backgroundmentioning

confidence: 99%

See 4 more Smart Citations

Kinetics of Nonisothermal Degradation of Some Polymer Composites: Change of Entropy at the Formation of the Activated Complex from the Reagents

Turmanova

Genieva

Vlaev

2011

Journal of Thermodynamics

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Studying the nonisothermal kinetics of degradation of rice husks in air or nitrogen atmosphere, polypropylene and tetrafluoroethylene-ethylene copolymer filled with different quantities of rice husks flour or the products of its thermal degradation, namely "white" or "black" rice husks ash, a linear dependence was observed between the ln A and E A , known as the kinetic compensation effect or theta rule. A linear relationship was also established between E A and the change of the entropy ΔS / = for the formation of the activated complex from the reagents. These dependences are related to the assumption of identical kinetic mechanisms of thermal degradation of the composites studied. The negative values of ΔS / = obtained show that the activated complex is a "more organized" structure than the initial reactants and that these reactions may be classified as "slow" ones. It may be concluded that the products of the thermal degradation of rice husks in a fluidized bed reactor can successfully replace the more expensive synthetic fillers to obtain different polymer composites. These polymer composites can lead to the futuristic "organic-inorganic hybrid materials" with specific properties.

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Section: Theoretical Approach and Mathematical Backgroundmentioning

confidence: 99%

Section: Theoretical Approach and Mathematical Backgroundmentioning

confidence: 99%

“…Taking into account the relationship between the activation energy E A and ΔH / = for the reactions [2,23,31,[39][40][41][42]]…”

Section: Theoretical Approach and Mathematical Backgroundmentioning

confidence: 99%

Section: Theoretical Approach and Mathematical Backgroundmentioning

confidence: 99%

“…Using (11) about the value of the change of enthalpy ΔH / = and using the well-known Gibbs-Helmholtz thermodynamic relationship [2,23,31,[40][41][42]:…”

Section: Theoretical Approach and Mathematical Backgroundmentioning

confidence: 99%

See 3 more Smart Citations

Kinetics of Nonisothermal Degradation of Some Polymer Composites: Change of Entropy at the Formation of the Activated Complex from the Reagents

Turmanova

Genieva

Vlaev

2011

Journal of Thermodynamics

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Sr(Sn,Se)O3 modified Bi0.5K0.5TiO3 ferroelectric ceramics: structural, electrical and leakage current characteristics

2022

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Studies of structural and electrical characteristics of multi-substituted Bi0.5Na0.5TiO3 ferroelectric ceramics

Arya

Choudhary

2021

J Mater Sci: Mater Electron

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In this communication, preliminary structural and detailed electrical characteristics of the CaSnO3/CaSeO3 modified Bi0.5Na0.5TiO3 ceramics of a general chemical composition (1-2x) [Bi0.5Na0.5TiO3] + x (CaSnO3) + x (CaSeO3) with x= 0, 0.05, 0.10, 0.15, prepared by hightemperature solid-state reaction method with calcination and sintering temperature 925 o C and 950 o C respectively for 5 h, have been reported. Structural and electrical characteristics of the parent compound have significantly been tailored by the addition of the equal percentage of CaSnO3, CaSeO3 over a wide range of temperature (25 o C -400 o C) as well as frequency (1 kHz-1MHz). Analysis of room temperature X-ray diffraction (XRD) data confirmed the development of single-phase compound (with rhombohedral symmetry) with very small amount of impurity phase with higher concentrations (x). In the dielectric spectroscopy, two dielectric peaks are observed at around temperatures 210 o C and 320 o C indicating multiple phase transitions of different types including the ferroelectric to para-electric through anti-ferroelectric. Impedance analysis of data exhibits both negative/positive temperature coefficient of temperature (i.e., semiconductor behavior) of the materials. The Nyquist plots determine the grain and grain boundary effect in capacitive and resistive properties of the materials, and also the non-Debye type of relaxation. The room temperature hysteresis loop confirms the existence of ferroelectricity in the materials. The leakage current characteristics also determine the Ohmic behavior of the materials.

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Study on the Kinetics of Non-isothermal Dehydration of Alkaline Earth Metal Selenites

Cited by 10 publications

References 22 publications

Kinetics of Nonisothermal Degradation of Some Polymer Composites: Change of Entropy at the Formation of the Activated Complex from the Reagents

Kinetics of Nonisothermal Degradation of Some Polymer Composites: Change of Entropy at the Formation of the Activated Complex from the Reagents

Sr(Sn,Se)O3 modified Bi0.5K0.5TiO3 ferroelectric ceramics: structural, electrical and leakage current characteristics

Studies of structural and electrical characteristics of multi-substituted Bi0.5Na0.5TiO3 ferroelectric ceramics

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