Transition metal chalcogenides (TMCs) continue to gain interest and popularity due to their broad spectra of properties and applications. Although the TMC family is quite large, its chemical space remains unexplored in comparison to transition metal oxides (TMOs), with a ratio of approximately 450 TMCs to 2500 TMOs registered in the Inorganic Crystal Structure Database (ICSD). Additionally, within the chemical space of TMCs, there remains much to be understood about ternary transition metal selenides (TMSe). Recent efforts in exploring TMSe compounds are highlighted by the computational and experimental work of Narayan and coworkers in which 24 phase diagrams are computed for stable ternary selenides and sulfides, and by the work of Kanatzidis and coworkers, for the discovery of low dimensional Na-Cu-Se materials NaCu6Se4 (mixed valency metal), NaCu4Se3 (2D metal) and NaCu4Se4 (2D metal with giant magnetoresistance). Here, we study the crystal structure, stability, and electronic structure of a new material, Na2MoSe4. We employ the Hautier method of data-mining + ionic substitution to predict the crystal structure of Na2MoSe4, generating an initial pool of 64 NaMoSe crystal structures, of which 21 are candidates for Na2MoSe4. By means of plane-wave Density Functional Theory (DFT), we study the five candidates with highest likelihood of being stable at the GGA-PBEsol level of theory. The material was synthesized through a solvothermal reaction method, and was characterized by powder X-Ray Diffraction (XRD) and Raman vibrational spectroscopy. We discuss a comparison of our experimental and theoretical findings, in addition to phonon dispersion, electronic density of states and band structure. In summary, we present a theoretical and experimental investigation of a new material Na2MoSe4, the first Na-Mo-Se compound to be registered in the ICSD. An understanding of Na2MoSe4 not only expands the library of known TMSes, but provides insight into the chemistry of chemical analogs such to be explored.

New ternary transition metal selenide Na2MoSe4: Computational and experimental study

2019 Fall National Meeting

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