Phase transitions and equation of state of CsI under high pressure and the development of a focusing system for x-rays

Wu, Yan

doi:10.2172/6299092

Title: Phase transitions and equation of state of CsI under high pressure and the development of a focusing system for x-rays

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Abstract

The phase transitions and equation of state of ionic solid cesium iodide were studied under high pressure and room temperature in a diamond anvil cell. The studies were carried out using both energy dispersive and angular dispersive diffraction methods on synchrotron radiation sources over the pressure range from atmospheric pressure to over 300 gigapascals (3 million atmospheres). CsI undergoes a distinct phase transition at about 40 GPa, a pressure that is much lower than the reported insulator-metal transition at 110 GPa, from the atmospheric pressure B2(CsCl) structure to an orthorhombic structure. At higher pressures, a continuous distortion in the structure was observed with a final structure similar to a hcp lattice under ultra high pressure. No volume discontinuity was observed at the insulator-metal transition. The newly found transition sequence is different from the result of previous static compression studies. The current structure has a smaller unit cell volume than the previous assignment. This has resolved a long existing controversy among the previous static compression studies, the dynamic compression studies, and the theoretical studies. The current results also explain the apparent discrepancy between the present study and the previous static studies. We also present the development of a focusing system formore »« less

Authors:: Wu, Yan

Publication Date:: Thu Nov 01 00:00:00 EST 1990

Research Org.:: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

Sponsoring Org.:: DOE/ER

OSTI Identifier:: 6299092

Report Number(s):: LBL-29844
ON: DE91007646; TRN: 91-004577

DOE Contract Number:: AC03-76SF00098

Resource Type:: Technical Report

Resource Relation:: Other Information: Thesis (Ph.D.)

Country of Publication:: United States

Language:: English

Subject:: 36 MATERIALS SCIENCE; CESIUM IODIDES; EQUATIONS OF STATE; PHASE TRANSFORMATIONS; X RADIATION; FOCUSING; CRYSTAL STRUCTURE; PRESSURE EFFECTS; VERY HIGH PRESSURE; X-RAY DIFFRACTION; ALKALI METAL COMPOUNDS; CESIUM COMPOUNDS; COHERENT SCATTERING; DIFFRACTION; ELECTROMAGNETIC RADIATION; EQUATIONS; HALIDES; HALOGEN COMPOUNDS; INORGANIC PHOSPHORS; IODIDES; IODINE COMPOUNDS; IONIZING RADIATIONS; PHOSPHORS; RADIATIONS; SCATTERING; 360602* - Other Materials- Structure & Phase Studies; 360603 - Materials- Properties

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                    Wu, Yan. Phase transitions and equation of state of CsI under high pressure and the development of a focusing system for x-rays.  United States: N. p., 1990. 
        Web.  doi:10.2172/6299092.

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                    Wu, Yan. Phase transitions and equation of state of CsI under high pressure and the development of a focusing system for x-rays.  United States.  https://doi.org/10.2172/6299092

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                    Wu, Yan. 1990.  
        "Phase transitions and equation of state of CsI under high pressure and the development of a focusing system for x-rays".  United States.  https://doi.org/10.2172/6299092.  https://www.osti.gov/servlets/purl/6299092.

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@article{osti_6299092,

  title        = {Phase transitions and equation of state of CsI under high pressure and the development of a focusing system for x-rays},

  author       = {Wu, Yan},

  abstractNote = {The phase transitions and equation of state of ionic solid cesium iodide were studied under high pressure and room temperature in a diamond anvil cell. The studies were carried out using both energy dispersive and angular dispersive diffraction methods on synchrotron radiation sources over the pressure range from atmospheric pressure to over 300 gigapascals (3 million atmospheres). CsI undergoes a distinct phase transition at about 40 GPa, a pressure that is much lower than the reported insulator-metal transition at 110 GPa, from the atmospheric pressure B2(CsCl) structure to an orthorhombic structure. At higher pressures, a continuous distortion in the structure was observed with a final structure similar to a hcp lattice under ultra high pressure. No volume discontinuity was observed at the insulator-metal transition. The newly found transition sequence is different from the result of previous static compression studies. The current structure has a smaller unit cell volume than the previous assignment. This has resolved a long existing controversy among the previous static compression studies, the dynamic compression studies, and the theoretical studies. The current results also explain the apparent discrepancy between the present study and the previous static studies. We also present the development of a focusing system for high energy x-rays (> 12 keV) that is particularly suited for high pressure diffraction studies. This system uses a pair of multilayer coated spherical mirrors in a Kirkpatrick-Baez geometry. A focused beam size less than 10 micron in diameter can be readily achieved with sufficient intensity to perform diffraction studies. 93 refs., 46 figs., 15 tabs.},

  doi          = {10.2172/6299092},

  url          = {https://www.osti.gov/biblio/6299092},
  journal      = {},
number       = ,

  volume       = ,

  place        = {United States},

  year         = {Thu Nov 01 00:00:00 EST 1990},

  month        = {Thu Nov 01 00:00:00 EST 1990}

}

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