Biogenic single crystals have been widely demonstrated to incorporate macromolecules to achieve extra damage tolerance, spurring investigations on their synthetic analogs with enhanced mechanical properties as well as...Biogenic single crystals have been widely demonstrated to incorporate macromolecules to achieve extra damage tolerance, spurring investigations on their synthetic analogs with enhanced mechanical properties as well as the enhancement mechanism（s） behind. And the investigations rely on both rational design of the single-crystal composites and, equally importantly, nanoscale and in-situ characterization strategy. Here, composite structures are constructed inside the calcite single-crystal host by incorporating guest materials of agarose fibers, multi-walled carbon nanotubes （MWCNTs）, and graphene oxide （GO）, through crystallization in agarose gel media. Further, transmission electron microscopy-scanning probe microscopy （TEM-SPM） method, coupling compression measurements with nanoscale imaging, shows that the obtained single-crystal composites exhibit improved toughness, compared to the solution-grown pure single crystals. Particularly, the rupture time increases by 1.25 times after the gel-networks and MWCNTs are incorporated. More importantly, the in-situ observation of the crystal deformation suggests that the guest incorporation toughens the single-crystal host by the shielding effect of nanofiber on crack-bridging at nanoscale. As such, this work may have implications for understanding the damage tolerance of biominerals as well as towards the development of new mechanically reinforced single-crystal composite materials.展开更多
It is well known that in biomineralization, the inorganic solids crystallized in the presence of organic phases, which are generally recognized as additives and matrix, leading to the crystal morphology modification. ...It is well known that in biomineralization, the inorganic solids crystallized in the presence of organic phases, which are generally recognized as additives and matrix, leading to the crystal morphology modification. However, the synergy effects of both soluble additive and insoluble matrix on regulating the morphology of synthetic single-crystals are less studied. Here, we examine the morphological revolution of calcite single crystals induced by the additive, citrate（CIT）, or/and the matrix, agarose gel network. The agarose gel matrix is inert to the crystal morphology in the sense that the agarose gelgrown calcite crystals maintain in characteristic rhombohedra. In contrast, CIT additives are active in crystal morphology modification and crystals begin to exhibit curved rough surfaces when grown in solution with the concentration of CIT coated Au nanoparticles（[CIT-Au NPs]） of more than 2.25 mg/mL.Interestingly, once agarose gel and CIT-Au NPs are simultaneously introduced, the curved morphological feature emerges at a much lower [CIT-Au NPs] of around 0.2 mg/mL. Increasing the gel concentrations further reduce the [CIT-Au NPs] needed to trigger calcite morphological modification, suggesting that the gel networks reduce the CIT diffusion and thereby enhance the kinetic effects of CIT on crystallization. As such, this work may have implications for understanding the mechanism of hierarchical biominerals construction and provide rational strategy to control single-crystal morphologies.展开更多
Synthetic calcite single crystals,due to their strong crystal habit,tend to grow into characteristic rhombohedra.In the nature,biogenic calcite crystals form composites together with biomacromolecular materials,spurri...Synthetic calcite single crystals,due to their strong crystal habit,tend to grow into characteristic rhombohedra.In the nature,biogenic calcite crystals form composites together with biomacromolecular materials,spurring investigations of how the growing calcite single crystals change their habit to satisfy the curvature of the organic phase.In this work,we examine calcite crystallization on a flat surface of glass slide and a curved surface of polystyrene（PS） sphere.The crystals exhibit tiny contact area onto the glass substrate that is averagely only 15%of their projected area on the substrate.In sharp contrast,the contact area greatly increase to above 75%of the projected area,once magnesium ions or agarose gel networks are introduced into the crystallization media.Furthermore,the calcite crystals form rough and step-like interfaces with a curved surface.However,the interfaces become smooth and curved as the crystals grow in presence of magnesium ions or agarose gel networks.The discrepancy between the interfacial structures implies kinetic effects of the additives on the crystallization around the surfaces.This work may provide implications for understanding the formation mechanisms of single-crystal composite materials.展开更多
基金supported by the 973 Program (No. 2014CB643503)the National Natural Science Foundation of China (Nos.51625304,51461165301)financial support from the China Scholar Council
文摘Biogenic single crystals have been widely demonstrated to incorporate macromolecules to achieve extra damage tolerance, spurring investigations on their synthetic analogs with enhanced mechanical properties as well as the enhancement mechanism（s） behind. And the investigations rely on both rational design of the single-crystal composites and, equally importantly, nanoscale and in-situ characterization strategy. Here, composite structures are constructed inside the calcite single-crystal host by incorporating guest materials of agarose fibers, multi-walled carbon nanotubes （MWCNTs）, and graphene oxide （GO）, through crystallization in agarose gel media. Further, transmission electron microscopy-scanning probe microscopy （TEM-SPM） method, coupling compression measurements with nanoscale imaging, shows that the obtained single-crystal composites exhibit improved toughness, compared to the solution-grown pure single crystals. Particularly, the rupture time increases by 1.25 times after the gel-networks and MWCNTs are incorporated. More importantly, the in-situ observation of the crystal deformation suggests that the guest incorporation toughens the single-crystal host by the shielding effect of nanofiber on crack-bridging at nanoscale. As such, this work may have implications for understanding the damage tolerance of biominerals as well as towards the development of new mechanically reinforced single-crystal composite materials.
基金supported by the 973 Program (No. 2014CB643503)the National Natural Science Foundation of China (Nos. 51625304, 51461165301)
文摘It is well known that in biomineralization, the inorganic solids crystallized in the presence of organic phases, which are generally recognized as additives and matrix, leading to the crystal morphology modification. However, the synergy effects of both soluble additive and insoluble matrix on regulating the morphology of synthetic single-crystals are less studied. Here, we examine the morphological revolution of calcite single crystals induced by the additive, citrate（CIT）, or/and the matrix, agarose gel network. The agarose gel matrix is inert to the crystal morphology in the sense that the agarose gelgrown calcite crystals maintain in characteristic rhombohedra. In contrast, CIT additives are active in crystal morphology modification and crystals begin to exhibit curved rough surfaces when grown in solution with the concentration of CIT coated Au nanoparticles（[CIT-Au NPs]） of more than 2.25 mg/mL.Interestingly, once agarose gel and CIT-Au NPs are simultaneously introduced, the curved morphological feature emerges at a much lower [CIT-Au NPs] of around 0.2 mg/mL. Increasing the gel concentrations further reduce the [CIT-Au NPs] needed to trigger calcite morphological modification, suggesting that the gel networks reduce the CIT diffusion and thereby enhance the kinetic effects of CIT on crystallization. As such, this work may have implications for understanding the mechanism of hierarchical biominerals construction and provide rational strategy to control single-crystal morphologies.
基金supported by 973 Program(No.2014CB643503)National Natural Science Foundation of China(Nos.51625304,51373150,51461165301)Zhejiang Province Natural Science Foundation(No.LZ13E030002)
文摘Synthetic calcite single crystals,due to their strong crystal habit,tend to grow into characteristic rhombohedra.In the nature,biogenic calcite crystals form composites together with biomacromolecular materials,spurring investigations of how the growing calcite single crystals change their habit to satisfy the curvature of the organic phase.In this work,we examine calcite crystallization on a flat surface of glass slide and a curved surface of polystyrene（PS） sphere.The crystals exhibit tiny contact area onto the glass substrate that is averagely only 15%of their projected area on the substrate.In sharp contrast,the contact area greatly increase to above 75%of the projected area,once magnesium ions or agarose gel networks are introduced into the crystallization media.Furthermore,the calcite crystals form rough and step-like interfaces with a curved surface.However,the interfaces become smooth and curved as the crystals grow in presence of magnesium ions or agarose gel networks.The discrepancy between the interfacial structures implies kinetic effects of the additives on the crystallization around the surfaces.This work may provide implications for understanding the formation mechanisms of single-crystal composite materials.
