LiGaGe2Se6: a new IR nonlinear optical material with low melting point.
The new compound LiGaGe(2)Se(6) has been synthesized. It crystallizes in the orthorhombic space group Fdd2 with a = 12.501(3) Å, b = 23.683(5) Å, c = 7.1196(14) Å, and Z = 8. The structure is a three-dimensional framework composed of corner-sharing LiSe(4), GaSe(4), and GeSe(4) tetrahedra. The compound exhibits a powder second harmonic generation signal at 2 μm that is about half that of the benchmark material AgGaSe(2) and possesses a wide band gap of about 2.64(2) eV. LiGaGe(2)Se(6) melts congruently at a rather low temperature of 710 °C, which indicates that bulk crystals can be obtained by the Bridgman-Stockbarger technique. According to a first-principles calculation, there is strong hybridization of the 4s and 4p orbitals of Ga, Ge, and Se around the Fermi level. The calculated birefractive index is Δn = 0.04 for λ ≥ 1 μm, and the calculated major SHG tensor elements are d(15) = 18.6 pm/V and d(33) = 12.8 pm/V. This new material is promising for application in IR nonlinear optics.
Center for Crystal Research and Development, Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190, People's Republic of China.
Dajiang
D
Mei
Wenlong
W
Yin
Kai
K
Feng
Zheshuai
Z
Lin
Lei
L
Bai
Jiyong
J
Yao
Yicheng
Y
Wu