Room-temperature compression and equation of state of body-centered cubic zirconium

Abstract

Zirconium (Zr) has properties conducive to nuclear applications and exhibits complex behavior at high pressure with respect to the effects of impurities, deviatoric stress, kinetics, and grain growth which makes it scientifically interesting. Here, we present experimental results on the 300 K equation of state of ultra-high purity Zr obtained using the diamond-anvil cell coupled with synchrotron-based x-ray diffraction and electrical resistance measurements. Based on quasi-hydrostatic room-temperature compression in helium to pressure P = 69.4(2) GPa, we constrain the bulk modulus and its pressure derivative of body-centered cubic (bcc) β-Zr to be K = 224(2) GPa and K′ = 2.6(1) at P = 37.0(1) GPa. A Monte Carlo approach was developed to accurately quantify the uncertainties in K and K′. In the Monte Carlo simulations, both the unit-cell volume and pressure vary according to their experimental uncertainty. Our high-pressure studies do not indicate additional isostructural volume collapse in the bcc phase of Zr in the 56–58 GPa pressure range.

Comment on the Evidence of Isostructural Phase Transitions in Elemental Zirconium

“…There is no logic in comparing the experiments performed with Ne PTM to experiments using Zr or Au PTMs. The experiment of Pigott et al [5], performed with hydrostatic He-PTM (Fig. 3), shows clearly the first order ω → β volume collapse which is not observed when using Ne PTM.…”

“…The statement "no evidence for isostructural phase transitions in Zr metal" claimed by O'Bannonet al [1] contradicts two independent experimental evidences [2,3]. The DAC experiment with Ne PTM leads to denying the existence of the ω → β first order phase transition which was reported by five independent experiments [2,3,5,10,11].…”

“…J.S. Pigott et al [5], re-measured the Zr 300 K isotherm under hydrostatic (He-PTM) conditions and re-confirmed the existence of the ω → β first order collapse, evidencing the existence bcc βzirconium phase at ~ 68 GPa. These results are depicted in Fig.…”

“…Further on, Pigott et al (2020) confirmed the existence of the bcc Zr-β phase. By using hydrostatic helium PTM [5], the ω → β transformation erupted at ~68 GPa. The experiment reported by E.F. O'Bannon et al [1] does not observe the ω → β transition, then obviously, the no evidence isostructural phase transitions in compressed Zr could be claimed.…”

Experimental melting curve of zirconium metal to 37 GPa

“…phase and then to the body-centered cubic (bcc) (β) phase. The solid-solid phase transitions in zirconium have been studied extensively using techniques such as the diamond-anvil cell (DAC) and large-volume press compression coupled with xray diffraction (XRD) or x-ray absorption spectroscopy [1][2][3][4][5][6][7][8][9]. The static compression work has been complemented by shock compression, ramp compression [10], and first-principles calculations [11].…”