Comparative nanoindentation study of biogenic and geological calcite
Comparative nanoindentation study of biogenic and geological calcite
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生物方解石和地质方解石的比较纳米压痕研究
DOI：
10.1016/j.jmbbm.2022.105538
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发表时间：
2023
影响因子：
3.9
通讯作者：
Li, Ling
中科院分区：
文献类型：
--
作者：
Deng, Zhifei;Chen, Liuni;Li, Ling
据报道，生物成因的矿物往往比地质矿物更坚硬。然而，它们的机械性能，特别是断裂韧性的定量比较，仍然是有限的。在这里，我们提供了一个系统的比较地质和生物方解石（软体动物壳Atrina rigida棱镜和胎盘板条）通过纳米压痕在干燥和90%的相对湿度条件下。利用Berkovich纳米压痕技术研究了地质方解石在不同晶面上的力学各向异性，即折合模量Er {104}≥ Er {108}> Er {001}和硬度H {001}≥ H {104}≥ H {108}，生物方解石与地质方解石具有相似的模量，但硬度增加。基于锥形纳米压痕，我们阐明，塑性变形激活在地质方解石在低负荷制度（< 20 mN），涉及r {104}和f {012}位错滑移以及e {018}孪生，而解理断裂占主导地位，在较高的负荷下，通过沿着{104}面开裂。相比之下，生物方解石往往会发生断裂，而晶间有机界面有助于损伤约束。此外，湿度的增加对地质方解石和单晶A的性质没有明显的影响。然而，与刚性棱柱相比，胎盘木板条的层压复合材料（层厚，约250-300 nm）表现出增加的韧性和降低的硬度和模量。我们相信这项研究的结果可以为未来的生物矿物和生物启发材料的研究提供一个基准。
Biogenic minerals are often reported to be harder and tougher than their geological counterparts. However, quantitative comparison of their mechanical properties, particularly fracture toughness, is still limited. Here we provide a systematic comparison of geological and biogenic calcite (mollusk shell Atrina rigida prisms and Placuna placenta laths) through nanoindentation under both dry and 90% relative humidity conditions. Berkovich nanoindentation is used to reveal the mechanical anisotropy of geological calcite when loaded on different crystallographic planes, ie, reduced modulus E r {104}≥ E r {108}> E r {001} and hardness H {001}≥ H {104}≥ H {108}, and biogenic calcite has comparable modulus but increased hardness than geological calcite. Based on conical nanoindentation, we elucidate that plastic deformation is activated in geological calcite at the low-load regime (< 20 mN), involving r {104} and f {012} dislocation slips as well as e {018} twinning, while cleavage fracture dominates under higher loads by cracking along {104} planes. In comparison, biogenic calcite tends to undergo fracture, while the intercrystalline organic interfaces contribute to damage confinement. In addition, increased humidity does not show a significant influence on the properties of geological calcite and the single-crystal A. rigida prisms, however, the laminate composite of P. placenta laths (layer thickness,∼ 250–300 nm) exhibits increased toughness and decreased hardness and modulus. We believe the results of this study can provide a benchmark for future investigations on biominerals and bio-inspired materials.