Mg_(3)Bi_(2-x)Sb_(x)(0≤x≤2)have gained significant attention due to their potential in thermoelectric(TE)applications.However,there has been much debating regarding their structural properties and phase diagram as a...Mg_(3)Bi_(2-x)Sb_(x)(0≤x≤2)have gained significant attention due to their potential in thermoelectric(TE)applications.However,there has been much debating regarding their structural properties and phase diagram as a function of pressure,which is crucial for understanding of their TE properties.Here,we investigate a unified phase diagram of Mg_(3)(Bi,Sb)_(2) materials up to 40 GPa at room temperature using high-pressure X-ray diffraction.Two high-pressure phases with the structural transition succession of P3m1→C2/m→P21/n are observed,which is valid for all Mg_(3)Bi_(2-x)Sb_(x)(0≤x≤2)compounds.We further explore the low-pressure phase P3m1 and report that alloying does not change the quasi-isotropic compression of the unit lattice parameters nor has effect on the anisotropic bond compressibility,as recently reported for the end-members.Our study presents a comprehensive picture of Mg_(3)Bi_(2–x)Sb_(x) as a function of pressure and chemical composition providing a solid foundation for the future experimental and theoretical studies searching for the most efficient TE compound in Mg_(3)(Bi,Sb)_(2).展开更多
基金W.Xu acknowledges the National Natural Science Foundation of China(Grants no.12075273)Y.Pan acknowledges the financial support from Alexander von Humboldt Foundation.S.Liu acknowledges National Natural Science Foundation of China under Grant No.51872133Shenzhen Key Program for Long-Term Academic Support Plan 20200925164021002.
文摘Mg_(3)Bi_(2-x)Sb_(x)(0≤x≤2)have gained significant attention due to their potential in thermoelectric(TE)applications.However,there has been much debating regarding their structural properties and phase diagram as a function of pressure,which is crucial for understanding of their TE properties.Here,we investigate a unified phase diagram of Mg_(3)(Bi,Sb)_(2) materials up to 40 GPa at room temperature using high-pressure X-ray diffraction.Two high-pressure phases with the structural transition succession of P3m1→C2/m→P21/n are observed,which is valid for all Mg_(3)Bi_(2-x)Sb_(x)(0≤x≤2)compounds.We further explore the low-pressure phase P3m1 and report that alloying does not change the quasi-isotropic compression of the unit lattice parameters nor has effect on the anisotropic bond compressibility,as recently reported for the end-members.Our study presents a comprehensive picture of Mg_(3)Bi_(2–x)Sb_(x) as a function of pressure and chemical composition providing a solid foundation for the future experimental and theoretical studies searching for the most efficient TE compound in Mg_(3)(Bi,Sb)_(2).
