Abstract
Controlling crystalline phases in polymorphic materials is critical not only for the fundamental understanding of the physics of phase formation but also for the technological application of forbidden, but potentially useful physical properties of the nominally unstable phases. Here, using tin oxide (SnO2) as a model system, we demonstrate a new way to enhance the mechanical hardness of an oxide by stabilizing a high-pressure dense phase through nitrogen integration in the oxide. Pristine SnO2 has a tetragonal structure at the ambient pressure, and undergoes phase transitions to orthorhombic and cubic phases with increasing pressure. Leveraging the enhanced reactivity of nitrogen in plasma, we are able to synthesize tin oxynitride (SnON) thin films with a cubic phase same as the high-pressure phase of SnO2. Such nitrogen-stabilized cubic SnON films exhibit a mechanical hardness of ∼23 ± 4 GPa, significantly higher than even the nitride counterpart (Sn3N4) as the result of the shortened atomic distance of the denser, high-pressure cubic phase. Moreover, SnON has a heavily doped, n-type semiconducting property with a controllable optical bandgap. Our work will provide new opportunities to search for and to utilize beneficial, but hidden physical properties that exist in a particular phase stable only at extreme conditions.
Original language | English |
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Pages (from-to) | 7051-7057 |
Number of pages | 7 |
Journal | Chemistry of Materials |
Volume | 28 |
Issue number | 19 |
DOIs | |
Publication status | Published - 2016 Oct 11 |
Bibliographical note
Funding Information:The authors gratefully acknowledge the financial support of the Korea Institute of Science and Technology (KIST) through 2E26370.
Publisher Copyright:
© 2016 American Chemical Society.
ASJC Scopus subject areas
- General Chemistry
- General Chemical Engineering
- Materials Chemistry