Nuclear Science and Techniques ›› 2019, Vol. 42 ›› Issue (2): 20101-020101.doi: 10.11889/j.0253-3219.2019.hjs.42.020101

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In-situ high-pressure single crystal X-ray diffraction of natural pyromorphite and mimetite

Xi CHEN1,Xun XU1,Fei QIN2,Yingxin LIU1()   

  1. 1. School of Gemmology, China University of Geosciences, Beijing 100083, China
    2. School of Earth and Space Sciences, Peking University, Beijing 100871, China
  • Received:2018-09-06 Revised:2018-11-16 Online:2019-02-10 Published:2019-02-19
  • Contact: Yingxin LIU E-mail:liuyingxin@cugb.edu.cn
  • About author:CHEN Xi, female, born in 1995, graduated from Institute of Disaster Prevention Science and Technology in 2016, master student, focusing on gemology|CHEN Xi, female, born in 1995, graduated from Institute of Disaster Prevention Science and Technology in 2016, master student, focusing on gemology|LIU Yingxin, E-mail:<email>liuyingxin@cugb.edu.cn</email>
  • Supported by:
    Supported by National Natural Science Foundation of China (No.41202027), the Fundamental Research Funds for the Central Universities (No.2652017090)

Abstract: Background

Pyromorphite [Pb5(PO4)3Cl] and mimetite [Pb5(AsO4)3Cl] are phosphate minerals with a typical apatite structure [A5(BO4)3X], which have many substitutions of both metal cations and anionic complexes. Therefore, it is important to figure out the effect of substitutions of different elements on compressibility by studying their high pressure structures.

Purpose

This study aims to reveal the crystal structure and compressibility of the natural pyromorphite and mimetite under high pressure.

Methods

High pressure single crystal X-ray diffraction experiments on pyromorphite [Pb5(PO4)3Cl] and mimetite [Pb5(AsO4)3Cl] were performed with the pressure up to 11.51 GPa at ambient temperature. Both the in-situ high pressure synchrotron radiation X-ray diffraction and diamond anvil cell were applied to the experimental tests.

Results

No phase transition of pyromorphite and mimetite was observed within the experimental pressure range. The P-V data was fitted by the third-order Birch-Murnaghan Equations of State (BM-EoS), where K 0=52.3(17) GPa, V 0=0.638 4(5) nm3, K 0'=8.9(6) for pyromorphite and K 0=87.4(37) GPa, V 0=0.673 3(7) nm3, K 0'=1.2(6) for mimetite.

Conclusion

The substitutions of B in BO4 tetrahedron have little effects on its cell parameters and bulk modulus, but have great influences on the axial compressibility.

Key words: Pyromorphite, Mimetite, Synchrotron radiation, High pressure, Structure

CLC Number: 

  • TL99