Thermal Decomposition of Nanostructured Bismuth Subcarbonate

Nanostructured (BiO)₂CO₃ samples were prepared, and their thermal decomposition behaviors were investigated by thermogravimetric analysis under atmospheric conditions. The method of preparation and Ca²⁺ doping could affect the morphologies of products and quantity of defects, resulting in different thermal decomposition mechanisms. The (BiO)₂CO₃ nanoplates decomposed at 300-500 °C with an activation energy of 160-170 kJ/mol. Two temperature zones existed in the thermal decomposition of (BiO)₂CO₃ and Ca-(BiO)₂CO₃ nanowires. The first one was caused by the decomposition of (BiO)₄(OH)₂CO₃ impurities and (BiO)₂CO₃ with surface defects, with an activation energy of 118-223 kJ/mol, whereas the second one was attributed to the decomposition of (BiO)₂CO₃ in the core of nanowires, with an activation energy of 230-270 kJ/mol for the core of (BiO)₂CO₃ nanowires and 210-223 kJ/mol for the core of Ca-(BiO)₂CO₃ nanowires. Introducing Ca²⁺ ions into (BiO)₂CO₃ nanowires improved their thermal stability and accelerated the decomposition of (BiO)₂CO₃ in the decomposition zone.