The NiSi melting curve to 70GPa

Lord, O. T.; Wann, Elizabeth T H; Hunt, Simon A.; Walker, Andrew; Santangeli, J. R.; Walter, Michael J.; Dobson, David P.; Wood, Ian G.; Vočadlo, Lidunka; Morard, Guillaume; Mézouar, M.

doi:10.1016/j.pepi.2014.05.005

Cited by 39 publications

(29 citation statements)

References 49 publications

(2 reference statements)

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“…3. Figure 3 indicates that the calculated phase boundary corresponds reasonably well with the experimentally constrained phase boundary (Lord et al 2012(Lord et al , 2014Dobson et al 2016) in that both calculations and experiments show a negative Clapeyron slope of similar magnitude at high temperature, and a similar transition pressure at low temperature. The experimental data are, however, fairly sparse.…”

Section: Lattice Dynamics Calculations In the Nisi Systemsupporting

confidence: 65%

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High-temperature ab initio calculations on FeSi and NiSi at conditions relevant to small planetary cores

2017

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Section: Lattice Dynamics Calculations In the Nisi Systemsupporting

confidence: 65%

“…dP/dT tends to 0 as T tends to 0). The experimentally determined melting curve is shown in blue (Lord et al 2014) and the boundaries of the MnP, Pmmn, ε-FeSi and CsCl phases in black (from Dobson et al 2016, with symbols defined therein). The ε-FeSi to CsCl phase boundary from these experiments is dashed to show extrapolation to zero K …”

Section: Discussionmentioning

confidence: 99%

High-temperature ab initio calculations on FeSi and NiSi at conditions relevant to small planetary cores

2017

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“…In the present study we have reexamined the melting relations in the same high P-T range using LH-DAC melting experiments with the onset of melting determined by the first appearance of liquid scattering [S(Q)] in the synchrotron x-ray diffraction patterns. We have also carried out additional melting studies between 74-105 GPa using discontinuities during thermal signal processing to diagnose melting [14,15]. Our new results indicate that the melting line continues with a shallow dT m /dP slope, rising slightly above the previous melting curve.…”

Section: γ-Snmentioning

confidence: 82%

“…Sample pressures were recorded before and after laser heating and a thermal pressure correction was applied using P T H = αK T (T m − T 300 ) for NaCl. For KBr loadings, the thermal pressure was corrected using an experimentally determined empirical formula as described in Lord et al [15].…”

Section: A In Situ X-ray Diffractionmentioning

confidence: 99%

“…The power to the lasers was automatically increased in a linear fashion as a function of time, with a constant offset designed to equalize the initial temperature at the two sample surfaces. Temperature cross sections were determined using spectroradiometry from both sides of the sample, whereas imaging radiometry was used to measure 2-D temperature maps on the left-hand side only [15]. The onset of melting was established from the appearance of plateaus or other related distinctive features in the relationship between the incident laser power and temperature recorded in the experiments (see Fig.…”

Section: B Thermal Signal Processingmentioning

confidence: 99%

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High-pressure melting behavior of tin up to 105 GPa

et al. 2017

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The melting curve of Sn initially rises steeply as a function of pressure but exhibits a decrease in slope (dT m /dP ) above 40 GPa to become nearly flat above 50 GPa. Previous studies have argued that a body-centered tetragonal (bct) to cubic (bcc) phase transition occurs in this range at room temperature. However, our investigations have shown that the phase behavior is more complex in this region with orthorhombic (bco) splitting of reflections occurring in the x-ray diffraction pattern above 32 GPa and coexisting diffraction signatures of bco and bcc structures are observed between 40 and 70 GPa. Here we have documented the simultaneous presence of bco and bcc reflections up to the melting point, negating the possibility that their coexistence might indicate a kinetically hindered first-order phase transformation. In this paper we have extended the observation of Sn melting relations into the megabar (P > 100 GPa) range using the appearance of liquid diffuse scattering in x-ray diffraction patterns and discontinuities during thermal signal processing to diagnose the occurrence of melting. Both techniques yield consistent results that indicate the melting line maintains the same low slope up to the highest pressure examined and does not flatten. The results below approximately 40 GPa agree well with the melting relations produced recently using a multiphase equation of state fitted to available or assumed data. Above this pressure the experimental melting points lie increasingly below the predicted crystal-liquid phase boundary, but above the flat melting from past studies, indicating that the thermodynamic properties of the body-centered "γ "-Sn structure remain to be clarified.

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The Melting Curve of Nickel Up to 100 GPa Explored by XAS

et al. 2017

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Precise knowledge of the melting temperatures of iron, nickel, and their alloys at pressures of the deep Earth would allow us to better constrain the parameters used for the Earth's heat budget and dynamics. However, melting curves of transition metals at pressures approaching 100 GPa and above are still controversial. To address this issue, we report new data on the melting temperature of nickel in a laser‐heated diamond anvil cell up to 100 GPa obtained by X‐ray absorption spectroscopy (XAS), a technique rarely used at such conditions. We couple this for the first time to ex situ analysis of the sample, providing a further validation of the melting criterion adopted here. Finally, a Simon‐Glatzel fit to the melting data obtained in this work, combined with those obtained in the most recent X‐ray diffraction experiments, gives TM(K)=1727×[]PM17±3+112.5±0.1, defining the most up‐to‐date X‐ray‐determined melting curve for Ni. This result confirms that Ni could be ignored in the discussion on melting properties and thermal profile of the Earth's core, as it should affect the Fe melting point by only 10–20 K at 90 GPa.

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The NiSi melting curve to 70GPa

Abstract: 1The melting curve of NiSi has been determined to 70 GPa on the basis of laser-heated 2 diamond anvil cell (LH-DAC) experiments in which changes in the gradient of temperature vs. laser 3 power functions were used as the melting criterion. The melting curve was corroborated with in situ 4

Cited by 39 publications

References 49 publications

High-temperature ab initio calculations on FeSi and NiSi at conditions relevant to small planetary cores

High-temperature ab initio calculations on FeSi and NiSi at conditions relevant to small planetary cores

High-pressure melting behavior of tin up to 105 GPa

The Melting Curve of Nickel Up to 100 GPa Explored by XAS

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