Abstract
In this study, dehydration I and II, polycondensation, and decarbonization processes of the thermal solid-state reaction between CoHPO4⋅3H2O and Li2CO3 were observed and the LiCoPO4 nanoparticles were obtained. For the sample characterization, the TG/DTG/DTA, FTIR, and AAS/AES techniques were applied. Structures and morphologies were investigated by the XRD and SEM techniques, respectively. To calculate the variable activation energy (\(E_{\alpha }\)) value, various isoconversional equations were used. In addition, the iterative isoconversional equations were also used to obtain the more reliable \(E_{\alpha }\) values of 64.04 ± 3.20, 78.54 ± 3.23, 100.41 ± 6.00, and 140.07 ± 5.02 kJ mol−1 for the first (regions I and II), second, and final steps, respectively. The first (regions I and II) as well as the second and final steps were confirmed to be a single-step kinetic process with the unique kinetic parameters. The double function \(y(\alpha )\) and \(z(\alpha )\) method was used to confirm the reaction mechanisms and found to be \(R_{2}\), \(R_{3}\), \(A_{3}\), and \(P_{3}\) corresponding to contracting cylinder, contracting sphere, assumed random nucleation (and its subsequent growth), and nucleation processes, respectively. The studied processes lead to the formation of the final nanoparticle product LiCoPO4. The four pre-exponential factors calculated using \(E_{\alpha }\) and mechanism functions were found to be 1.01 (±0.016) × 107, 7.80 (±0.009) × 107, 4.52 (±0.010) × 105, and 1.03 (±0.003) × 106 s−1, respectively. The related standard thermodynamic functions of the transition-state complexes were evaluated by using the calculated kinetic parameters.
Published Version
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