Nonisothermal Kinetics Study with Isoconversional Procedure and DAEM: LiCoPO₄ Synthesized from Thermal Decomposition of the Precursor

Abstract

The precursor of LiCoPO 4 was synthesized by solid-state reaction at low-heating temperature using LiOH•H 2 O and NH 4 CoPO 4 •H 2 O as raw materials. LiCoPO 4 was obtained by calcining the precursor. Based on isoconversional procedure and the distributed activation energy model (DAEM), the activation energies calculated indicate that the thermal process involves two regions, of which Region II (α = 0.38−0.90) is a kinetically complex process but Region I (α = 0.10−0.38) is a single-step process. The most probable mechanism for the Region I is two-dimensional diffusion. The distributed activation energy model (DAEM) was applied to study the Region II of decomposition process of the precursor. The distributions of activation energy, f(E α ) and values of pre-exponential factor A of the Region II of the thermal decomposition of precursor were obtained on the basis of the DAEM. The reliability of the DAEM for the Region II was tested by the comparison between experimental plots and calculated plots. The results show that the prediction of DAEM is reliable.

Solid State Reaction Mechanisms of the LiMnPO4 Formation Using Special Function and Thermodynamic Studies

“…8,9,18 The nonisothermal (isoconversional) kinetic model is a model-free method, which involves measuring temperatures (T) corresponding to the fixed value of extent of conversion (α) at different heating rates (β, β = (dT/dt)/°C min −1 , t is time/min). The α-values from thermogravimetric analysis may be defined as the ratio of actual mass loss to the total mass loss corresponding to the investigated process:…”

Thermal stability and non‐isothermal kinetics of poly(ethyl cyanoacrylate) nanofibers

“…The iso‐temperature method assumes that the activation energy does not depend on α and Eqn () takes the form: where x = E a / RT and h ( x ) is expressed by the fourth Senum and Yang approximation formula 39 : The logarithmic form of Eqn () is used for the assignment of the most correct reaction mechanism, i.e. the g ( α ) function 30, 38,40,41 : To relate a thermal degradation mechanism to a certain g ( α ) function, a plot of ln g ( α ) versus ln q must be a straight line with a slope equal to −1.0000, and a linear coefficient of determination R 2 close to unity. The values of E a and A have no impact on the shape of the most correct reaction mechanism function determined if the temperature remains constant, so as not to change x = E a / RT and h ( x ).…”

“…The logarithmic form of Eqn ( 8) is used for the assignment of the most correct reaction mechanism, i.e. the g(⊍) function 30,38,40,41 :…”

Kinetic analysis on the synthesis of Mg0.95Zn0.05TiO3 microwave dielectric ceramic by polymeric precursor method

“…Kinetic analysis technique received considerable attention to study the thermal decomposition process of substances [15][16][17][18][19]. Study of the kinetics of the reaction and mechanism is important because the degree of reaction and controlling step affect the final product and hence the performance of the material.…”