Unconventional Heteroanion Ceramics: 2D Layered Seleno- and Thio-Phosphates

Project: Research project

Description

Heteroanionic ceramics are inorganic compounds containing more than one anionic species in a single phase. Recently, there has been a significantly increased interest in such materials due to the possible arise of new phenomena by combining different anionic characteristics, such as charge, ionic radii, electronegativity, and polarizability, otherwise inaccessible. Precise structural characterization is critical for advancing the knowledge of novel heteroanionic compounds. For example, anion position alters the characteristic charge and electronegativity of the local atomic and electronic structure. As such, determining both local and global anion bonding is imperative for fundamental understanding of newly developed compounds.
Intelectual Merit of the proposed research revolves around synthesis and advanced characterization of layered Seleno- and Thio-Phosphates. Anchored on a variety of possible elemental combination, the synthesized structures will be readily amenable to extensive multimodal characterization and computational methods to map the complex structural characteristics of layered heteroanionic ceramics in conjunction with their measured properties. The scientific questions will be addressed through three fundamental themes: (1) The structures and phases of heteroanionic ceramics 2D layered materials. We will utilize and enhance large-scale DFT databases in conjunction with the experimental observations to create a framework that will involve computational prediction of the phases and structures of heteroanionic ceramics. We expect to map a variety of elemental combinations for synthesizing such materials focusing on the ones that present layered structure. (2) Synthesis and Advanced Characterization of 2D-Layered Seleno and Thio-Phosphate: We will synthesize single crystals of quaternary layered compounds and further apply exfoliation methods to reduce the dimension down to 2-D sheets in order to explore novel phenomena arising from this geometry. We will primarily focus on the MIMII [P2Se6], (MI=Cu,Ag;MII =Cr,Al,Ga,In) compounds. We will utilize advanced scanning and transmission electron microscopy techniques in combination with spectroscopic methods to probe the local atomic and electronic structure. (3) Stability/phase transformations in 2D layered Seleno and Thio-Phosphate: Under external stimuli, these materials are likely to restructure, adapting their geometric and electronic structure to the environment. Here, one key goal is to conduct in-situ S/TEM analysis of the effect of external stimuli (temperature and electric field) on MIMII [P2Se6], (MI=Cu,Ag;MII =Cr,Al,Ga,In) compounds. This is crucial for a complete understanding of the structural and electronic evolution of such compounds, to build a multidimensional phase diagram.
Broader Impacts will cover educational and societal outreach activities, anchored by the unique platform for 2-D heteroanionic discovery, design, optimization, synthesis, and advanced atomic level characterization. The research findings will be distributed through web resources, including Open Quantum Materials Database (OQMD), a collection of more than 500,000 materials calculations constructed at Northwestern. We will incorporate “teaching module” in advance synthesis and characterization methods into existing MSE and Chem courses, especially for Freshmen. We will leverage the NUANCE Center and Shyne facilities (PI is the director), for summer REU and MIN programs. Our team will participate in open houses and hosting of neighborhood visitors. As a capstone DMR outreach, we propose t
StatusActive
Effective start/end date8/15/197/31/23

Funding

  • National Science Foundation (DMR-1929356)

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Phosphates
Electronic structure
Crystal atomic structure
Electronegativity
Anions
Transmission electron microscopy
Inorganic compounds
Computational methods
Discrete Fourier transforms
Phase diagrams
Teaching
Temperature distribution
Phase transitions
Electric fields
Single crystals
Scanning electron microscopy
Geometry