TY - JOUR
T1 - Pressure induced solid-solid reconstructive phase transition in LiGaO 2 dominated by elastic strain
AU - Hu, Qiwei
AU - Yan, Xiaozhi
AU - Lei, Li
AU - Wang, Qiming
AU - Feng, Leihao
AU - Qi, Lei
AU - Zhang, Leilei
AU - Peng, Fang
AU - Ohfuji, Hiroaki
AU - He, Duanwei
N1 - Funding Information:
We thank Ignacio Hernandez for helpful discussions. The authors acknowledge support from the National Natural Science Foundation of China (Grants No. 11774247 and No. 11704014), the Science Foundation for Excellent Youth Scholars of Sichuan University (Grant No. 2015SCU04A04), the Research Foundation of Key Laboratory of Neutron Physics (Grant No. 2015BB03), and the Joint Usage/Research Center PRIUS (Ehime University, Japan). The high-pressure ADXRD experiments were supported by the Chinese Academy of Sciences (Grant No. 2017-BEPC-PT-000568).
Publisher Copyright:
© 2018 American Physical Society.
PY - 2018/1/25
Y1 - 2018/1/25
N2 - Pressure induced solid-solid reconstructive phase transitions for graphite-diamond, and wurtzite-rocksalt in GaN and AlN occur at significantly higher pressure than expected from equilibrium coexistence and their transition paths are always inconsistent with each other. These indicate that the underlying nucleation and growth mechanism in the solid-solid reconstructive phase transitions are poorly understood. Here, we propose an elastic-strain dominated mechanism in a reconstructive phase transition, β-LiGaO2 to γ-LiGaO2, based on in situ high-pressure angle dispersive x-ray diffraction and single-crystal Raman scattering. This mechanism suggests that the pressure induced solid-solid reconstructive phase transition is neither purely diffusionless nor purely diffusive, as conventionally assumed, but a combination. The large elastic strains are accumulated, with the coherent nucleation, in the early stage of the transition. The elastic strains along the (100) and (001) directions are too large to be relaxed by the shear stress, so an intermediate structure emerges reducing the elastic strains and making the transition energetically favorable. At higher pressures, when the elastic strains become small enough to be relaxed, the phase transition to γ-LiGaO2 begins and the coherent nucleation is substituted with a semicoherent one with Li and Ga atoms disordered.
AB - Pressure induced solid-solid reconstructive phase transitions for graphite-diamond, and wurtzite-rocksalt in GaN and AlN occur at significantly higher pressure than expected from equilibrium coexistence and their transition paths are always inconsistent with each other. These indicate that the underlying nucleation and growth mechanism in the solid-solid reconstructive phase transitions are poorly understood. Here, we propose an elastic-strain dominated mechanism in a reconstructive phase transition, β-LiGaO2 to γ-LiGaO2, based on in situ high-pressure angle dispersive x-ray diffraction and single-crystal Raman scattering. This mechanism suggests that the pressure induced solid-solid reconstructive phase transition is neither purely diffusionless nor purely diffusive, as conventionally assumed, but a combination. The large elastic strains are accumulated, with the coherent nucleation, in the early stage of the transition. The elastic strains along the (100) and (001) directions are too large to be relaxed by the shear stress, so an intermediate structure emerges reducing the elastic strains and making the transition energetically favorable. At higher pressures, when the elastic strains become small enough to be relaxed, the phase transition to γ-LiGaO2 begins and the coherent nucleation is substituted with a semicoherent one with Li and Ga atoms disordered.
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U2 - 10.1103/PhysRevB.97.014106
DO - 10.1103/PhysRevB.97.014106
M3 - Article
AN - SCOPUS:85041190794
VL - 97
JO - Physical Review B
JF - Physical Review B
SN - 2469-9950
IS - 1
M1 - 014106
ER -