Interplay between Thermally Induced Aragonite–Calcite Transformation and Multistep Dehydration in a Seawater Spiral Shell (Euplica scripta)

While heating a seawater spiral shell (Euplica scripta), thermally induced aragonite–calcite (A–C) transformation occurred within the temperature region of multistep thermal dehydration. Here, kinetic interplay between A–C and dehydration was studied as possible cause reduction in temperatures. The kinetics systematically investigated under isothermal conditions by powder X-ray diffractometry linear nonisothermal Fourier transform infrared spectroscopy. characterized partially overlapping, three-step process thermogravimetry–differential analysis coupled with mass spectroscopy for evolved gases. range final part second step initial third step. were contracting geometry-type models, which respective transformations regulated constant advancement rate diffusional removal water vapor, respectively. Based on results, mutual interaction those processes is discussed temperature.