The Study On Diversity Morphology And FTIR Anlysis Of Nacre In Atrina Rigida

Firstly, we focus on nacre in Atrina Rigida combining Optical Microscopy, Scanning Electron Microscopy, High Resolution Transmission Electron Microscopy, X-Ray Diffraction and Fourier Transform Infrared Spectroscopy analytical techniques to investigate its microstructure characteristics and its aragonite tablets’diverse morphologies. Secondly, we used FTIR fully to study nacre’s biogenic aragonite in Atrina Rigida. The research mainly includes three parts:1) The FTIR anlysis of raw samples; 2) The FTIR anlysis of grinding samples; 3) The FTIR anlysis of heat treating samples. Finally, based on previous studies and results in this paper, we discussed factors in diverse morphologies’formation mechanisms and frequency shift of biogenic aragonite respectively.Main conclusions are drawn as follows:1. In the previous studies, they believed that aragonite tablets’morphologies in nacre should be the same in different stages. However, we first find that aragonite tablets’ morphologies in Atrina Rigida are various, which mean that calcium carbonate’s crystallization in Atrina Rigida has the character of diversity.2. SEM and TEM data show a new morphology of aragonite tablets in Atrina Rigida’s nacre which look like H-like shape. These new tablets all have a preferred orientation and H-like shape, and also locate at the narrowed area in prism-nacre transition / nacre melt zone. Interestingly, we first observe pre-designed template regulated by organic matrix and many mineral nanogranules are assembling and aggregating around the organic template. Due to the observation, we believe that the new tablets may be an intermediate state in nacre growth process.3. The results obtained by the raw samples, the grinding samples and the heat treating samples collected are all analyzed by FTIR.The conclusions prove that there are frequency shifts in biogenic aragonite of Atrina Rigida. In fact, v3 and v2 both change indexs strongly.At last, particle size reducing, lattice distortion and phase transformation are discussed, which may mainly result in the frequency shift of biogenic aragonite in Atrina Rigida.