In situ characterization of the high pressure – high temperature melting curve of platinum

Abstract

In this work, the melting line of platinum has been characterized both experimentally, using synchrotron X-ray diffraction in laser-heated diamond-anvil cells, and theoretically, using ab initio simulations. In the investigated pressure and temperature range (pressure between 10 GPa and 110 GPa and temperature between 300 K and 4800 K), only the face-centered cubic phase of platinum has been observed. The melting points obtained with the two techniques are in good agreement. Furthermore, the obtained results agree and considerably extend the melting line previously obtained in large-volume devices and in one laser-heated diamond-anvil cells experiment, in which the speckle method was used as melting detection technique. The divergence between previous laser-heating experiments is resolved in favor of those experiments reporting the higher melting slope.

Resistivity, Seebeck coefficient, and thermal conductivity of platinum at high pressure and temperature

“…2(a)]. At high temperatures, isoresistivity curves become parallel to the melting curve determined by Belonoshko and Rosengren [43], which is consistent with the recent laser-heated diamond-anvil cell measurement and theoretical calculations [44][45][46]. This gives a constant resistivity value of ∼70 μ cm along the melting curve.…”

Experimental and theoretical confirmation of an orthorhombic phase transition in niobium at high pressure and temperature

“…Above that T, we observe rapid changes in the relative intensities of the Bragg peaks in consecutive diffraction patterns, which are due to the recrystallization of the sample. This phenomenon has also been observed in other metals under HP conditions at several hundred degrees below T m [21][22][23][24][25] . It is probably caused by an increase in the grain size in polycrystalline material at HT.…”

“…At 117 GPa the same effect is detected at 4900 K. Such phenomena have previously been attributed to a signature of the onset of melting 31 . However, this observation alone could lead to an overestimation of T m 23,24 . Likewise, the T plateau, another signature of melting, may correspond to T higher than the actual T m , which is the case for titanium, as discussed below.…”

“…However, their phase diagrams have remained virtually unknown over decades of research. More recently, advances in theoretical [1][2][3][4][5][6][7][8][9][10] and experimetal [11][12][13][14][15][16][17][18][19][20][21][22][23][24][25] techniques started offering the possibility to gain better understanding of the high-pressure (HP) and high-temperature (HT) behavior of transition metals and to elucidate the fundamental mechanisms responsible for the physical appearance of their HP-HT phase diagrams. Of special interest is HP-HT polymorphism in the bcc transition metals of Group 4B (Cr, Mo, and W) and Group 5B (V, Nb, and Ta), which is related to laser-heated diamond anvil cell (DAC) melting experiments bringing up a small slope (dT/dP) of the corresponding melting curves in the pressure-temperature (P-T) coordinates in the megabar P range [11][12][13][14][15][16][17]19 .…”

Oxidation of High Yield Strength Metals Tungsten and Rhenium in High-Pressure High-Temperature Experiments of Carbon Dioxide and Carbonates

“…A small and perfectly centered heater foil will minimize this possibility. Something similar occurs with soft Cu [49] or Pt [50,51]. (iii) A convenient approach is heating the optically transparent samples with a CO 2 laser, λ = 10.6 µm.…”