Meryem Berrada, Siheng Wang, Bin Chen, Vitali Prakapenka, Stella Chariton, Marc M. Hirschmann, Jie Li
{"title":"Pressure–volume equation of state of Fe18Pt82","authors":"Meryem Berrada, Siheng Wang, Bin Chen, Vitali Prakapenka, Stella Chariton, Marc M. Hirschmann, Jie Li","doi":"10.1007/s00269-024-01275-8","DOIUrl":null,"url":null,"abstract":"<div><p>Platinum-iron (Pt-Fe) alloys have long served as oxygen fugacity sensors in high-temperature experiments investigating Earth and planetary interiors, relying on the equilibrium between Fe within the alloy and FeO in coexisting oxides or silicates. Despite their significance, studies on intermediate compositions remain limited. This investigation focuses on compressibility of Fe<sub>18</sub>Pt<sub>82</sub> up to <span>\\(\\sim\\)</span> 40 GPa at ambient temperature and explores the pressure-dependent characteristics of the oxygen fugacity relationship. In-situ X-ray diffraction measurements confirm the stability of the <i>fcc</i> phase in Fe<sub>18</sub>Pt<sub>82</sub> across the pressure range. The fit to the compression data by the third-order Birch–Murnaghan equation of state results in <span>\\({V}_{0}=59.14 \\pm 0.08\\)</span>Å<sup>3</sup>, <span>\\({K}_{0}=266 \\pm 13\\)</span> GPa, and <span>\\({K}_{0}^{\\prime}=4.7 \\pm 0.7\\)</span>. The differences between this fit and the Vinet and Kunc equations of state fall within the range of uncertainty. Comparing results with reported data for other Pt-Fe alloys reveals a nearly linear trend between volume and the Fe content in Pt-Fe alloys at ambient pressure. Unlike more iron-rich alloys, the excess volume of mixing of Fe<sub>18</sub>Pt<sub>82</sub> (<span>\\(\\sim\\)</span> 0.21 cm<sup>3</sup>/mol) remains nearly constant across the examined pressure range. Estimates of the excess Gibbs free energy suggest diminishing non-ideal contributions to thermodynamic activities as pressure increases.</p></div>","PeriodicalId":20132,"journal":{"name":"Physics and Chemistry of Minerals","volume":null,"pages":null},"PeriodicalIF":1.2000,"publicationDate":"2024-07-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Physics and Chemistry of Minerals","FirstCategoryId":"89","ListUrlMain":"https://link.springer.com/article/10.1007/s00269-024-01275-8","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q4","JCRName":"MATERIALS SCIENCE, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
Platinum-iron (Pt-Fe) alloys have long served as oxygen fugacity sensors in high-temperature experiments investigating Earth and planetary interiors, relying on the equilibrium between Fe within the alloy and FeO in coexisting oxides or silicates. Despite their significance, studies on intermediate compositions remain limited. This investigation focuses on compressibility of Fe18Pt82 up to \(\sim\) 40 GPa at ambient temperature and explores the pressure-dependent characteristics of the oxygen fugacity relationship. In-situ X-ray diffraction measurements confirm the stability of the fcc phase in Fe18Pt82 across the pressure range. The fit to the compression data by the third-order Birch–Murnaghan equation of state results in \({V}_{0}=59.14 \pm 0.08\)Å3, \({K}_{0}=266 \pm 13\) GPa, and \({K}_{0}^{\prime}=4.7 \pm 0.7\). The differences between this fit and the Vinet and Kunc equations of state fall within the range of uncertainty. Comparing results with reported data for other Pt-Fe alloys reveals a nearly linear trend between volume and the Fe content in Pt-Fe alloys at ambient pressure. Unlike more iron-rich alloys, the excess volume of mixing of Fe18Pt82 (\(\sim\) 0.21 cm3/mol) remains nearly constant across the examined pressure range. Estimates of the excess Gibbs free energy suggest diminishing non-ideal contributions to thermodynamic activities as pressure increases.
期刊介绍:
Physics and Chemistry of Minerals is an international journal devoted to publishing articles and short communications of physical or chemical studies on minerals or solids related to minerals. The aim of the journal is to support competent interdisciplinary work in mineralogy and physics or chemistry. Particular emphasis is placed on applications of modern techniques or new theories and models to interpret atomic structures and physical or chemical properties of minerals. Some subjects of interest are:
-Relationships between atomic structure and crystalline state (structures of various states, crystal energies, crystal growth, thermodynamic studies, phase transformations, solid solution, exsolution phenomena, etc.)
-General solid state spectroscopy (ultraviolet, visible, infrared, Raman, ESCA, luminescence, X-ray, electron paramagnetic resonance, nuclear magnetic resonance, gamma ray resonance, etc.)
-Experimental and theoretical analysis of chemical bonding in minerals (application of crystal field, molecular orbital, band theories, etc.)
-Physical properties (magnetic, mechanical, electric, optical, thermodynamic, etc.)
-Relations between thermal expansion, compressibility, elastic constants, and fundamental properties of atomic structure, particularly as applied to geophysical problems
-Electron microscopy in support of physical and chemical studies
-Computational methods in the study of the structure and properties of minerals
-Mineral surfaces (experimental methods, structure and properties)