The melting curve of Ni to 1 Mbar

Lord, O. T.; Wood, I. G.; Dobson, David P.; Vočadlo, Lidunka; Wang, Weiwei; Thomson, A. P. J.; Wann, Elizabeth T H; Morard, Guillaume; Mézouar, M.; Walter, Michael J.

doi:10.1016/j.epsl.2014.09.046

Cited by 68 publications

(88 citation statements)

References 69 publications

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“…Due to our concerns with interpreting the melting data obtained in the synchrotron x-ray studies above 70 GPa, we reinvestigated the melting temperature between 60 and 100 GPa using the appearance of plateaus as a function of laser power as a diagnostic of the melting event [14]. Such data have been calibrated against x-ray diffraction results in previous Comparison of temperature profiles in two separate Sn melting experiments using KBr as insulating material.…”

Section: Resultsmentioning

confidence: 99%

“…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: 99%

“…3). This melting criterion has been applied in many previous investigations to determine melting in a wide variety of substances [20][21][22] and it has been directly correlated with the appearance of liquid S(Q) during in situ x-ray diffraction experiments in the LH-DAC [14,20].…”

Section: B Thermal Signal Processingmentioning

confidence: 99%

“…The experimental loading procedure was similar to that described above, except that the sample consisted of high-purity Sn wire (99.99% Aldrich) and MgO was used as the PTM and thermal insulation [14]. One experiment was also performed using KBr as the PTM to provide a comparison with the ESRF experiments.…”

Section: B Thermal Signal Processingmentioning

confidence: 99%

“…Pressure was monitored during compression before and after laser heating using the fluorescence of submicron Cr:Al 2 O 3 (ruby) grains dispersed within the sample chamber, with thermal pressure corrections to the final pressures. Further details of typical sample assemblies along with the laser heating and temperature measurement system are described in Lord et al [14]. Samples were heated using an on-axis double-sided geometry using two 100W diode pumped TEM 00 Yb 3 doped fiber lasers (λ = 1070 nm).…”

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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Section: Resultsmentioning

confidence: 99%

Section: γ-Snmentioning

confidence: 99%

Section: B Thermal Signal Processingmentioning

confidence: 99%

Section: B Thermal Signal Processingmentioning

confidence: 99%

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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Shock Compression and Melting of an Fe‐Ni‐Si Alloy: Implications for the Temperature Profile of the Earth's Core and the Heat Flux Across the Core‐Mantle Boundary

et al. 2018

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Understanding the melting behavior and the thermal equation of state of Fe‐Ni alloyed with candidate light elements at conditions of the Earth's core is critical for our knowledge of the region's thermal structure and chemical composition and the heat flow across the liquid outer core into the lowermost mantle. Here we studied the shock equation of state and melting curve of an Fe‐8 wt% Ni‐10 wt% Si alloy up to ~250 GPa by hypervelocity impacts with direct velocity and reliable temperature measurements. Our results show that the addition of 10 wt% Si to Fe‐8 wt% Ni alloy slightly depresses the melting temperature of iron by ~200–300 (±200) K at the core‐mantle boundary (~136 GPa) and by ~600–800 (±500) K at the inner core‐outer core boundary (~330 GPa), respectively. Our results indicate that Si has a relatively mild effect on the melting temperature of iron compared with S and O. Our thermodynamic modeling shows that Fe‐5 wt% Ni alloyed with 6 wt% Si and 2 wt% S (which has a density‐velocity profile that matches the outer core's seismic profile well) exhibits an adiabatic profile with temperatures of ~3900 K and ~5300 K at the top and bottom of the outer core, respectively. If Si is a major light element in the core, a geotherm modeled for the outer core indicates a thermal gradient of ~5.8–6.8 (±1.6) K/km in the D″ region and a high heat flow of ~13–19 TW across the core‐mantle boundary.

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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 melting curve of Ni to 1 Mbar

Cited by 68 publications

References 69 publications

High-pressure melting behavior of tin up to 105 GPa

High-pressure melting behavior of tin up to 105 GPa

Shock Compression and Melting of an Fe‐Ni‐Si Alloy: Implications for the Temperature Profile of the Earth's Core and the Heat Flux Across the Core‐Mantle Boundary

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

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