Comparative study on nano-mechanics and thermodynamics of fish otoliths

Fish otolith is a kind of typical natural biomineral, which is composed of calcium carbonate and organic matrix. In fresh water carp otolith, the inorganic phase of lapillus is pure aragonite, and for asteriscus it is pure vaterite. In this research, the phase composition, phase transformation, mechanical property and solubility of lapillus and asteriscus were studied. And results showed that, the organic content of lapillus was higher than that of asteriscus; the phase-transition temperature of lapillus (aragonite–calcite) and asteriscus (vaterite–calcite) both happened between 520 and 640 °C; the nano-mechanical property of lapillus was better than that of asteriscus; the solubility of asteriscus powder was higher than that of lapillus powder.

► The nano-mechanical property of lapillus (aragonite) was better than that of asteriscus (vaterite).
► The phase-transition temperature of lapillus and asteriscus were both between 520 and 640 °C.
► The solubility property of asteriscus powder was better than that of lapillus powder.