Structural phase transformations of Mg(3)N(2) at high pressure: experimental and theoretical studies.
The structural behavior of Mg(3)N(2) has been investigated up to 40.7 GPa at room temperature by means of angle-dispersive X-ray diffraction. A reversible, first-order structural phase transition from the ambient cubic phase (Ia3) to a high-pressure monoclinic phase (C2/m) is found to start at approximately 20.6 GPa and complete at approximately 32.5 GPa for the first time. The equation of state determined from our experiments yields bulk moduli of 110.7(2) and 171.5(1) GPa for the cubic and monoclinic phases, respectively, indicating higher incompressibility of the high-pressure phase of Mg(3)N(2). First-principles calculations reproduced the phase stability and transition pressure determined in our experiment. In addition, a second phase transition from the monoclinic phase to a hexagonal phase (P3m(1)) was predicted around 67 GPa for Mg(3)N(2). The electronic band structures of three phases of Mg(3)N(2) are also calculated and discussed.
Hao
Jian
J
State Key Laboratory of Superhard Materials, Jilin University, Changchun 130012, People's Republic of China.
Li
Yinwei
Y
Zhou
Qiang
Q
Liu
Dan
D
Li
Min
M
Li
Fangfei
F
Lei
Weiwei
W
Chen
Xiaohui
X
Ma
Yanming
Y
Cui
Qiliang
Q
Zou
Guangtian
G
Liu
Jing
J
Li
Xiaodong
X