Static pressure measurements in the Diamond Anvil Cell up to 200 GPa  are  based on the ruby pressure scale. Recent calibrations of the ruby scale have been based on the compression curves of few materials (diamond, Mgo, B2-NaCl, Au, Pt and other metals). This same corpus of data has been self-consistently fitted with different weights by few groups.  Slight differences exist between the various calibrations. One task of the IPPS is to agree on the extraction for the Ruby-scale 2019.

New design of the DAC have been proposed to generate static pressures much above 200 GPa  up to the TPa range [1;2]. For pressures above 200 GPa,  pressure measurements in laboratory are based on the shift of the Raman diamond phonon mode at the tip. The Akahama pressure scale is used[3].  In front of synchrotron, the volume of Re is used to estimate pressure, essentially two calibration are used Dubrovinsky [1] and Anzellini [4].

In this talk :

• We will present  a short review of the current corpus of  xray data on which to adjust  the ruby pressure scale and we will present our view on how to perform an optimum extraction of a ruby calibration.
• We will discuss the current calibrations of the Re volume and the C Raman pressure gauges for measurements above 200 GPa.
• We will propose a set of measurements to constitute a corpus of compression data above 200 GPa with which a calibration of an ultrahigh pressure scale could be reliably made.

References:

[1] L. Dubrovinsky et al, Nat. Commun. 3, 1163 (2012).

[2] A. Dewaele et al, Nat. Commun. 9, 2913 (2018).

[3] Y. Akahama et al, J. Phys. Conf. Ser. 215, 012195 (2010).

[4] S. Anzellini et al, J. Appl. Phys. 115, 043511 (2014).