Non-Tetrahedrally Bonded Elements and Binary Compounds I

It is a core problem in any field to reliably tell how close two objects are to being the same, and once this relation has been established we can use this information to precisely quantify potential relationships, both analytically and with machine learning (ML). For inorganic solids, the chemical composition is a fundamental descriptor, which can be represented by assigning the ratio of each element in the material to a vector. These vectors are a convenient mathematical data structure for measuring similarity, but unfortunately, the standard metric (the Euclidean distance) gives little to no variance in the resultant distances between chemically dissimilar compositions. We present the Earth Mover’s Distance (EMD) for inorganic compositions, a well-defined metric which enables the measure of chemical similarity in an explainable fashion. We compute the EMD between two compositions from the ratio of each of the elements and the absolute distance between the elements on the modified Pettifor scale. This simple metric shows clear strength at distinguishing compounds and is efficient to compute in practice. The resultant distances have greater alignment with chemical understanding than the Euclidean distance, which is demonstrated on the binary compositions of the Inorganic Crystal Structure Database (ICSD). The EMD is a reliable numeric measure of chemical similarity that can be incorporated into automated workflows for a range of ML techniques. We have found that with no supervision the use of this metric gives a distinct partitioning of binary compounds into clear trends and families of chemical property, with future applications for nearest neighbor search queries in chemical database retrieval systems and supervised ML techniques.

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Magnetic and structural properties of pseudo-binary compounds CrAs1−P

Journal of Alloys and Compounds ◽

10.1016/j.jallcom.2004.04.055 ◽

2004 ◽

Vol 383 (1-2) ◽

pp. 189-194 ◽

Cited By ~ 9

Author(s):

K. Kanaya ◽

S. Abe ◽

H. Yoshida ◽

K. Kamigaki ◽

T. Kaneko

Keyword(s):

Structural Properties ◽

Binary Compounds

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Phase transitions beyond post-perovskite in NaMgF3 to 160 GPa

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1909446116 ◽

2019 ◽

Vol 116 (39) ◽

pp. 19324-19329 ◽

Cited By ~ 1

Author(s):

Rajkrishna Dutta ◽

Eran Greenberg ◽

Vitali B. Prakapenka ◽

Thomas S. Duffy

Keyword(s):

Phase Transitions ◽

Diamond Anvil Cell ◽

Extrasolar Planets ◽

High Pressures ◽

Model System ◽

Similar Sequence ◽

Deep Interior ◽

Diamond Anvil ◽

Binary Compounds ◽

Pressure Phase

Neighborite, NaMgF3, is used as a model system for understanding phase transitions in ABX3 systems (e.g., MgSiO3) at high pressures. Here we report diamond anvil cell experiments that identify the following phases in NaMgF3 with compression to 162 GPa: NaMgF3 (perovskite) → NaMgF3 (post-perovskite) → NaMgF3 (Sb2S3-type) → NaF (B2-type) + NaMg2F5 (P21/c) → NaF (B2) + MgF2 (cotunnite-type). Our results demonstrate the existence of an Sb2S3-type post-post-perovskite ABX3 phase. We also experimentally demonstrate the formation of the P21/c AB2X5 phase which has been proposed theoretically to be a common high-pressure phase in ABX3 systems. Our study provides an experimental observation of the full sequence of phase transitions from perovskite to post-perovskite to post-post-perovskite followed by 2-stage breakdown to binary compounds. Notably, a similar sequence of transitions is predicted to occur in MgSiO3 at ultrahigh pressures, where it has implications for the mineralogy and dynamics in the deep interior of large, rocky extrasolar planets.

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