title: Combined Theoretical and in Situ Scattering Strategies for Optimized Discovery and Recovery of High-Pressure Phases: A Case Study of the GaN-Nb2O5 System.
abstract: The application of pressure in solid-state synthesis provides a route for the creation of new and exciting materials. However, the onerous nature of high-pressure techniques limits their utility in materials discovery. The systematic search for novel oxynitrides-semiconductors for photocatalytic overall water splitting-is a representative case where quench high-pressure synthesis is useful and necessary in order to obtain target compounds. We utilize state of the art crystal structure prediction theory (USPEX) and in situ synchrotron-based X-ray scattering to speed up the discovery and optimization of novel compounds using high-pressure synthesis. Using this approach, two novel oxynitride phases were discovered in the GaN-Nb2O5 system. The (Nb2O5)0.84:(NbO2)0.32:(GaN)0.82 rutile structured phase was formed at 1 GPa and 900 °C and gradually transformed to a α-PbO2-related structure above 2.8 GPa and 1000 °C. The low-pressure rutile type phase was found to have a direct optical band gap of 0.84 eV and an indirect gap of 0.51 eV.
authors.forename: William R
authors.initials: WR
authors.lastname: Woerner
authors.forename: Guang-Rui
authors.initials: GR
authors.lastname: Qian
authors.forename: Artem R
authors.initials: AR
authors.lastname: Oganov
authors.forename: Peter W
authors.initials: PW
authors.lastname: Stephens
authors.forename: H A Naveen
authors.initials: HA
authors.lastname: Dharmagunawardhane
authors.forename: Alexandra
authors.initials: A
authors.lastname: Sinclair
authors.affiliation: Photon Sciences, Brookhaven National Laboratory , Upton, New York 11934, United States.
authors.forename: John B
authors.initials: JB
authors.lastname: Parise