Morphological aspects of some symmetrical crystal aggregates grown by silica gel technique

Rationally Designed Complex, Hierarchical Microarchitectures

“…4A) (44). The basic shapes, including single-and double-spirals, globular and leaf-like structures, are consistent with the curling mode of growth and resemble those reported previously (28)(29)(30). In contrast to the pronounced gradient of structural variation observed in Regime 1, here even a single set of bulk conditions gives rise to a tremendous diversity of structures that not only grow next to each other but even appear together as part of composite structures.…”

“…Strategies inspired by biomineralization have been explored as potential routes to controlling growth and self-assembly from the molecular level via tailored microenvironments, epitaxy and inorganic or organic additives (13)(14)(15)(16)(17)(18)(19)(20)(21)(22)(23)(24). Yet although these have produced some interesting spherical, spiral, leaf-like, and other shapes (25)(26)(27)(28)(29)(30)(31)(32), it is rather disappointing that the appearance of various forms in synthetic systems is often unexpected and the attempts to identify the mechanisms of their formation are generally assessed a posteriori..…”

Additive-induced morphological tuning of self-assembled silica–barium carbonate crystal aggregates

“…Although growing attention has been paid to these materials over recent years, resulting in manifold complex architectures, still little is known about their physical origin [15][16][17][18][19][20][21][22][23][24][25][26]. This is not least due to the many parameters governing the precipitation process, all cooperating and changing simultaneously on different time and length scales during the growth process.…”

“…The self-assembly of alkaline-earth metal carbonates in the presence of silicate is an outstanding example in this context, as purely inorganic precursors cooperate in this case to constitute hierarchical structures and shapes strongly reminiscent of biological forms [15][16][17][18][19]. Precipitation of barium carbonate (witherite) from alkaline silica solutions or gels results in a variety of complex curved, non-crystallographic ultrastructures, including helicoidal filaments and sinuous sheets.…”

New insights into the early stages of silica-controlled barium carbonate crystallisation

“…[5][6][7] Such studies are typically inspired by natural biomineralisation, where an organic matrix controls the crystallisation of inorganic matter to produce superior hybrid structures. [14][15][16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31] Under the influence of dissolved silicate as a crystallisation modifier, metal carbonates (usually BaCO 3 ) can indeed assemble spontaneously into a range of sinuously shaped non-crystallographic aggregates (such as regular helicoids), which mimic products from biomineralisation closely in terms of morphology and internal hierarchy, and therefore were termed "silica-carbonate biomorphs". Among these, the processes observed during precipitation of alkaline-earth carbonates into alkaline, silica-containing media are probably the most prominent and well-studied case.…”