Characterization, thermal dehydration kinetic, and thermodynamic study of synthesized cesium borate (CsB₅O₈·4H₂O)

Abstract

Cesium borate was synthesized via hydrothermal method by using the sources of Cs₂CO₃ and H₃BO₃. The synthesized sample was identified as CsB₅O₈·4H₂O with the powder diffraction file number of “00-051-0232.” The decomposition of the hydrated compound was studied between 90 and 235 °C by using the Coats–Redfern non-isothermal kinetic method. According to the thermal results, the dehydration behavior of the synthesized cesium borate hydrate can be explained with the chemical reaction order of 1.5 and the mass loss of 18.6%. The activation energy was estimated as 97.2 kJ/mol. According to the morphological changes, by the increase in temperature from 30 °C to 600 °C the particles sizes decreased from 18–50 µm to 12–20 µm. In the thermodynamic study, the positive values of enthalpy and Gibbs energy changes (ΔH and ΔG) can be interpreted with an endothermic and non-spontaneous reaction, whereas the negative value of ΔS signified the reaction was slow and decreased the system disorder.

Keywords:

• Borates
• thermal kinetic
• thermodynamic
• XRD
• spectroscopy