AI Article Synopsis
- A new oxynitride material called ZnTaON was created using high-pressure techniques and has a unique structure that stays stable at very low temperatures (down to 20 K).
- Researchers used advanced imaging techniques to determine that zinc atoms are disordered in the material's structure, which suggests that this disorganization is key to how the phase transition occurs between two different structural forms.
- The findings indicate that the electron configuration of Zn and the characteristics of the tantalum ion help stabilize the material's structure, and only a small amount of zinc substitution can trigger a notable phase transition, highlighting the close energy relationship between the two structural forms.
Article Abstract
By using a high-pressure reaction, we prepared a new oxynitride ZnTaON that crystallizes in a centrosymmetric (R3̅c) high-temperature LiNbO-type structure (HTLN-type). The stabilization of the HTLN-type structure down to low temperatures (at least 20 K) makes it possible to investigate not only the stability of this phase, but also the phase transition to a noncentrosymmetric (R3c) LiNbO-type structure (LN-type) which is yet to be clarified. Synchrotron and neutron diffraction studies in combination with transmission electron microscopy show that Zn is located at a disordered 12c site instead of 6a, implying an order-disorder mechanism of the phase transition. It is found that the closed d-shell of Zn, as well as the high-valent Ta ion, is responsible for the stabilization of the HTLN-type structure, affording a novel quasitriangular ZnON coordination. Interestingly, only 3% Zn substitution for MnTaON induces a phase transition from LN- to HTLN-type structure, implying the proximity in energy between the two structural types, which is supported by the first-principles calculations.
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| http://dx.doi.org/10.1021/jacs.6b08635 | DOI Listing |
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