Supervariate Ceramics: Demineralization via Gelation in Neutral Nontoxic Solutions

Demineralization is essential in various fields, from ocean acidification to orthopaedics. Currently, demineralization is generally ascribed to etching by corrosive acids. Herein, the “supervariate” strategy for the demineralization of calcite (the most abundant biomineral on Earth, and a major component of Earth's crust) is disclosed, in which nontoxic solutions of multiple ionic species are used to convert calcite into a multi‐ionic amorphous gel that exhibits moderate flowability, which means it can be conveniently collected, stored, transferred, and moulded. This transformation is enabled by the facile formation of highly stable “supervariate” gels featuring high entropy (as a result of their disordered structure, containing various ionic and hydration species) and high resistance to crystallization. Overall, a novel, safe, generic method for etching, gelatinating, and processing solid ceramics is described. Nontoxic aqueous solutions of common salts are used to convert calcite into a multi‐ionic amorphous gel, which can be conveniently collected, stored, transferred, or moulded.