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Dynamic compression of glassy GeO$2$ up to the TPa range and first observation of shock induced crystallization

R. Torchio, J. A. Hernandez, A. Cordone, S. Balugani, T. Vinci, C. Pepin, N. Sevelin-Radiguet, E. Guillam, F. Dorchies, A. Benuzzi

Abstract

In this work we present an extensive study of glassy GeO$_2$ under laser induced dynamic compression. New VISAR and SOP data provide the extension of Hugoniot EoS up to the TPa range for this material including temperature measurements. Reflectivity data at both 532 and 1064 nm wavelenght are also reported. In the low compression range we observe changes of the optical properties from transparent, to opaque, to metallic state. The second part of this work describes a further laser shock experiment combined with in-situ X-ray diffraction. Here we observe, for the first time, the laser shock-induced crystallization of glassy GeO$_2$ to a structure compatible with the rutile phase at pressure higher than 20 GPa and melting occurring at around 75 GPa.

Dynamic compression of glassy GeO$2$ up to the TPa range and first observation of shock induced crystallization

Abstract

In this work we present an extensive study of glassy GeO under laser induced dynamic compression. New VISAR and SOP data provide the extension of Hugoniot EoS up to the TPa range for this material including temperature measurements. Reflectivity data at both 532 and 1064 nm wavelenght are also reported. In the low compression range we observe changes of the optical properties from transparent, to opaque, to metallic state. The second part of this work describes a further laser shock experiment combined with in-situ X-ray diffraction. Here we observe, for the first time, the laser shock-induced crystallization of glassy GeO to a structure compatible with the rutile phase at pressure higher than 20 GPa and melting occurring at around 75 GPa.

Paper Structure

This paper contains 13 sections, 10 equations, 15 figures, 1 table.

Table of Contents

  1. Introduction
  2. METHODS
  3. Experimental setup
  4. Target design
  5. Hugoniot measurements
  6. Hugoniot measurements in the Low Energy regime
  7. Hugoniot measurements in the High Energy regime
  8. Reflectivity and temperature
  9. In situ-X-ray diffraction
  10. Results and discussion
  11. Hugoniot curve, reflectivity and temperature
  12. Microstructural analysis
  13. Conclusions

Figures (15)

  • Figure 1: Scheme of the experimental setup for the EoS measurements.
  • Figure 2: Scheme of the experimental setup for the X-ray diffraction campaign.The collimation of the X-ray source was ensured by a 500 $\mu$m tantalum or lead pinhole.
  • Figure 3: targets designs for EoS (left and center) and combined shock/XRD experiment (right).
  • Figure 4: Example of hydrodynamic simulation at 2 10$^{12}$ W/cm$^2$ laser intensity. The dotted areas represent the probed times with X-rays on the Hugoniot and in re-shock conditions. The X-ray pulse duration is around 0.8 ns.
  • Figure 5: Compression induced changes of optical properties for the LE target: from transparent (left) to opaque (center) to metallic (right). The two dashed lines on the left side of the target indicate the double shock structure due to the elastic wave originated in the SiO$_2$ quartz substrate. The dashed line on the right side indicates the free surface.
  • ...and 10 more figures