ORALS

SESSION: GeochemistryTueAM-R8	Navrotsky International Symposium (2nd Intl. Symp. on Geochemistry for Sustainable Development)
Tue. 28 Nov. 2023 / Room: Coral Reef
Session Chairs: Wenhao Sun; Manisha Rane-Fondacaro; Session Monitor: TBA

12:50: [GeochemistryTueAM04] OS
ENTHALPIES OF MIXING FOR ALLOYS LIQUID BELOW ROOM TEMPERATURE DETERMINED BY OXIDATIVE SOLUTION CALORIMETRY
Michael Bustamante¹ ; Alexandra Navrotsky² ; Kristina Lilova³ ; Jean-Philippe Harvey⁴ ; Oishi Kentaro⁵ ; ¹Arizona State U., Tempe, United States; ²Arizona State University, Phoenix, United States; ³ARIZONA STATE UNIVERSITY, Tempe, United States; ⁴Chemical Engineering Department, CRCT Polytechnique Montréal, Montréal, Canada; ⁵Chemical Engineering Department, Montréal, Canada;
Paper Id: 31 [Abstract]

Fusible alloys, and gallium-based liquid metal alloys (Ga-LMA) in particular, have applications in soft robotics, microelectronics, self-healing battery components, and 2D materials synthesis, making the study of their thermodynamic properties critical to improvement and development of hybrid materials. To determine the enthalpies of formation/mixing of the binary Ga-In, the ternary Ga-In-Sn, and the quaternary Ga-In-Sn-Zn eutectics, a novel experimental calorimetric technique based on oxidative solution calorimetry was developed. The experimental results for the binary alloy are consistent with previous data obtained by direct reaction and solution calorimetry, demonstrating the viability and precision of the experimental technique, which is applicable to a large variety system that are liquid at or below room temperature. The heats of mixing in the ternary and quaternary systems represent the first reported experimental values. Both the standard geometrical models and FactSage were used to define enthalpy analogs for these systems which agreed with the experimental data, providing a foundation to analyze the thermodynamics of other unknown Ga-based alloys.

SESSION: GeochemistryTuePM1-R8	Navrotsky International Symposium (2nd Intl. Symp. on Geochemistry for Sustainable Development)
Tue. 28 Nov. 2023 / Room: Coral Reef
Session Chairs: Megan Householder; Zi-Kui Liu; Session Monitor: TBA

14:05: [GeochemistryTuePM105] OS
MEASUREMENT OF NANOPARTICLE SURFACE ENERGIES WITH APPLICATION TO NUCLEATION AND CONDENSATION IN EXOPLANET ATMOSPHERES
Megan Householder¹ ; Alexandra Navrotsky¹ ; Kristina Lilova² ; ¹Arizona State University, Phoenix, United States; ²ARIZONA STATE UNIVERSITY, Tempe, United States;
Paper Id: 52 [Abstract]

Exoplanets orbit stars other than our own sun. Aerosols are a prominent feature of exoplanet atmospheres, sometimes obscuring the spectral determination of atmospheric gas composition [1]. Hot Jupiters are studied because they are the hottest of exoplanets, so emit the most radiation and therefore, give the most spectral information on exoplanets. Because it is not yet possible to definitively determine aerosol composition and formation through astronomical observations, it is important to model aerosol production accurately [2]. A key factor in the determination of nucleation and condensation rate is the surface energy of the nucleating material [3]. High surface energy materials, such as forsterite, will nucleate much more slowly compared to lower surface energy materials, such as sulfides. Despite their importance, few surface energies of rock-forming minerals have been measured [4]. In this work, surface energies were measured using oxide melt solution calorimetry of materials with different surface areas for likely exoplanet atmosphere condensates including zinc sulfide (ZnS) [5] and enstatite (MgSiO3), with other measured surface energies taken from experimental rather than estimated data. This work inputs the accurate measured surface energy data to calculate a model of nucleation rates for each of the proposed cloud species of a hot Jupiter exoplanet with atmospheric metallicity of 10x solar, a total atmospheric pressure of 10 bar and a saturation ratio of 10. These corrected surface energy values show drastically different nucleation rates for a variety of condensates in the atmospheres, which lead to different atmospheric compositions of these exoplanets than previous models.

References:
[1] D. Adams, P. Gao, I. de Pater, and C. V. Morley, “Aggregate Hazes in Exoplanet Atmospheres,” Astrophys. J., vol. 874, no. 1, p. 61, Mar. 2019, doi: 10.3847/1538-4357/ab074c.
[2] A. Navrotsky and M. Householder, “New worlds, new chemistry, new ceramics,” Int. J. Ceram. Eng. Sci., vol. 3, no. 6, pp. 252–266, Nov. 2021, doi: 10.1002/CES2.10104.
[3] P. Gao, M. S. Marley, and A. S. Ackerman, “Sedimentation Efficiency of Condensation Clouds in Substellar Atmospheres,” Astrophys. J., vol. 855, no. 2, p. 86, Mar. 2018, doi: 10.3847/1538-4357/aab0a1.
[4] S. Chen and A. Navrotsky, “Calorimetric study of the surface energy of forsterite,” Am. Mineral., vol. 95, no. 1, pp. 112–117, 2010, doi: 10.2138/am.2010.3339.
[5] T. Subramani, K. Lilova, M. Householder, S. Yang, J. Lyons, and A. Navrotsky, “Surface energetics of wurtzite and sphalerite polymorphs of zinc sulfide and implications for their formation in nature,” Geochim. Cosmochim. Acta, vol. 340, pp. 99–107, 2022, doi: 10.1016/j.gca.2022.11.003.