Construction of Bulk Inorganic Ionic Materials by Nonclassical Reactive Precursors

Conspectus Inorganic ionic compounds, exemplified by minerals and ceramics, are essential materials for construction, optics, structural engineering, and biomedicine. The processing of these materials into bulk forms relies predominantly on conventional sintering; however, this process typically requires extreme temperatures and pressures. Furthermore, the limited ion diffusivity in crystalline particle precursors often leads to internal structural discontinuities, including pores and other defects. These imperfections compromise critical performance metrics, most notably mechanical strength and optical transparency, posing a significant challenge for the development of high-performance monolithic inorganic ionic materials. Recent advances in nonclassical crystallization indicate that inorganic materials can be generated through alternative pathways involving nonclassical inorganic precursors beyond monatomic ions. Upon controlled crystallization, these precursors can endow inorganic materials with optimized mechanical, optical, and bioactive properties. Our recent studies further demonstrate that nonclassical crystallization provides feasible pathways for manufacturing monolithic inorganic ionic materials. For example, inorganic ionic oligomers can be polymerized into moldable monolithic inorganic ionic materials. Amorphous solid particles can fuse in a liquid-like manner under pressure, forming hard and transparent bulk inorganic ionic materials. These achievements indicate that the rational selection of inorganic precursors with controllable crystallization pathways can expand the methodological toolbox for the construction of bulk inorganic ionic materials. In this Account, we categorize inorganic precursors into three typical classes based on their structural characteristics and reactivity–stability profiles, namely inorganic ionic clusters, amorphous solids, and crystalline particles. Inorganic ionic clusters, exemplified by inorganic ionic oligomers, represent highly reactive molecule-like species. These precursors enable a molecular-level processing route for inorganic materials, facilitating precise and continuous bottom-up fabrication of bulk inorganic solids across multiple scales. Amorphous solids represent an intermediate state in which disordered structures facilitate ion diffusion and structural rearrangement, thereby enabling their fusion into bulk inorganic ionic materials. Crystalline particles exhibit the highest thermodynamic stability but the lowest reactivity among the precursors; their conversion into continuous bulk materials typically requires surface activation or enhanced mass transport to promote effective fusion and ordered assembly. We summarize the unique advantages of these precursors for manufacturing monolithic inorganic ionic materials and propose future directions for their further development, focusing on the chemical regulation of reactivity and the establishment of controllable pathways for bulk fabrication. Alongside these scientific advancements, future efforts should address key practical requirements such as scale-up production, industrial feasibility, and the long-term structural integrity and stability of the resulting bulk materials. We emphasize that integrating nonclassical crystallization concepts with conventional processing strategies offers a promising pathway toward bulk inorganic ionic materials with superior structural precision, functionality, and applicability.