Research Progress in Area 3 方向 ( 三 ) 課題進展 157 Abstract Themicrostructureandchemicalcompositionof the deep-sea limpet shells are disclosed, which is the first step to investigate their formation mechanism and living environment. The morphology, size, transparency and even microstructures of the calcareous limpet shells will show remarkable distinction at different sea depths. Accordingly, the deep-sea limpet shells are expected to be different with common shallow-sea ones in microstructures and physicochemical characteristics, which will provide insights into their functional properties and biomimetic applications. Herein, Prof. Ning Wang’s team applied materials characterization techniques such as transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), Raman and IR spectroscopy for the first time to investigate the microstructural and chemical composition of deep-sea limpet shells at depth of 3000m in the South China Sea. The layered microstructures were explicitly revealed, the exfoliation characteristics were confirmed, and the crystallographic orientation of each layer’s unit cell was determined to be tilted at a small angle sequentially. The deep-sea limpet shells are unique in containing pure calcite of calcium carbonate polymorph and the trace of phosphate. The crystallographic results further indicated that the deep-sea limpet shell features unexpectedly less compact lattice structure under the deep-sea condition, which confirms effects of the living environment on the structure of deepsea shell organisms. Research Activities and Progress • Revealed the microstructure and crystallography of deep-sea limpet; • Discovered the surface morphology and exfoliation availability of deep-sea limpet shells; • Investigated the chemical composition and CaCO3 polymorph details of deep-sea limpet shells; • Compared the microstructure and chemical composition of common shallow-sea limpet shells with the targeted deep-sea ones; • Developed a new preparation method of crosssectional deep-sea limpet shell samples used for the microscopic study. Key Findings • Several or even single layer lamella of deepsea limpet shell can be prepared by mechanical exfoliation, which is unique compared to the shallow-sea shell; • The crystalline arrangement of adjacent layers of deep-sea limpet shell is not perfectly aligned. The orientation of each layer’s hexagonal unit cell is tilted at small angle sequentially; • Deep-sea limpet shell features unexpectedly less compact lattice structure under the deepsea condition with high static pressure; • Deep-sea limpet shell specifically contains pure CaCO3-calcite while shallow-sea one has two CaCO3 polymorphs, calcite and paragonite; • Both deep-sea and shallow-sea limpet shells contain C, Ca, O, Mg elements, and specifically, deep-sea one has the trace of phosphorus (P) in in the form of phosphate (PO4 3-). Research Output Publication 1 Trained personnel 4 Decipher Shell Structures of Deep-sea Animals by Atomicresolution Electron Microscopy Prof. Ning Wang The Hong Kong University of Science and Technology Fig 1.
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