Browsing by Author "Sun, DH"

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    Cooling field tuned magnetic phase transition and exchange bias-like effect in Y0.9Pr0.1CrO3
    (AIP Publishing, 2015-09-11) Deng, DM; Zheng, JS; Yu, DH; Wang, BM; Sun, DH; Avdeev, M; Feng, Z; Jing, C; Lu, B; Ren, W; Cao, SX; Zhang, JC
    Cooling magnetic field dependence of magnetic phase transition has been observed in Y0.9Pr0.1CrO3. GzFx order (spin structure of PrCrO3) is dominant after zero field cooling (ZFC), whereas GxFz order (spin structure of YCrO3) is dominant after cooling under a field higher than 100 Oe. Positive/negative exchange bias-like effect, with large vertical shift and small horizontal shift, has been observed after FC/ZFC process. The vertical shift can be attributed to the frozen ordered Pr3+ and Cr3+ spins in magnetic domains, because of the strong coupling between Pr3+ and Cr3+ sublattices; while the horizontal shift is a result of the pinning of spins at the interfaces. The frozen structure is generated by the field used for the measurement of the initial magnetization curve of M(H) for the ZFC cooled sample, while it is generated by the cooling field for the sample cooled under a cooling field higher than 100 Oe. © 2015 AIP Publishing LLC.
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    New high-pressure polymorph of non-linear optical crystal BaTeMo2O9
    (American Chemical Society, 2015-06-17) Yu, DH; Sun, DH; Avdeev, M; Wu, Q; Tian, XX; Gu, QF; Tao, XT
    High-pressure synchrotron X-ray diffraction on the nonlinear optical crystal α-BaTeMo2O9 (α -BTM) has revealed a new polymorph of γ-BTM having a monoclinic space group of P21. This first order phase transition from the orthorhombic Pca21 to the new monoclinic P21 structure occurs at 3.8 GPa pressure. The mechanism of the phase transition under high pressure is attributed to the anisotropic pressure response along different crystallographic directions. © 2015 American Chemical Society
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    Understanding the unusual response to high pressure in KBe2BO3F2
    (Springer Nature, 2017-06-22) Yu, DH; Avdeev, M; Sun, DH; Huston, LQ; Shiell, TB; Sun, QB; Lu, T; Gu, QF; Liu, H; Bradby, JE; Yie, N; Liu, Y; Wang, JY; McIntyre, GJ
    Strong anisotropic compression with pressure on the remarkable non-linear optical material KBe2BO3F2 has been observed with the linear compression coefficient along the c axis found to be about 40 times larger than that along the a axis. An unusual non-monotonic pressure response was observed for the a lattice parameter. The derived bulk modulus of 31 ± 1 GPa indicates that KBe2BO3F2 is a very soft oxide material yet with stable structure up to 45 GPa. A combination of high-pressure synchrotron powder X-ray diffraction, high-pressure Raman spectroscopy, and Density Functional Theory calculations points to the mechanism for the unusual pressure response being due to the competition between the K-F bond length and K-F-K bond angle and the coupling between the stretching and twisting vibration modes. This article is licensed under a Creative Commons Attribution 4.0 International License.