Crystal Structure of Gallium Antimonide Complex, LaGaSb and YGaSb
Gallium antimonide is used in infrared detectors, infrared LEDs, lasers and transistors, and thermophotovoltaic systems. It can be used as a component in photoresists and other composite materials that require a high refractive index. This article will introduce the crystal structures of two compounds of gallium antimonide, LaGaSb and YGaSb.
The figure above shows the crystal structure of YGaSb(left)[1] and LaGaSb(right)[2].
Most of the atomsin La12Ga3.26Sb24.02 structure are located on two mirror planes perpendicular to [100]. Small deviations from the plane positions for Ga1 and Sb7 are eventually realized for better packing of the small Ga and Sb atoms around larger lanthanum species. The main feature of La12Ga3.26Sb24.02 structure is the presence of pseudo-trigonal fragments formed by lanthanum atoms around triangular GaSb3 planar units. This structural units are also an inherent feature of the structure of La13Ga8Sb21 and series of hexagonalstructures R6Ni2Si3 (R =La - Sm, Gd). Trigonal-prismatic channels formed by La atoms are outlined by corrugated Sb nets interconnected by Ga atoms. The disorder in the structure of La12Ga3.26Sb24.02 around the position 2c (½½0) is caused by the implantation of Sb atoms (partially occupied Sb10 position) and local symmetry breaking due to an alternating location of atoms on the splitted Ga8 and Sb8 positions. The distance between Ga8 and Sb8 sites of 2.70 Å agrees very well with the values 2.61 - 2.63 Å observed between Ga1 and Sb1 atoms within GaSb3 triangle unit. The shift of Ga8 and Sb8 atoms from the ideal 4g position correlates to the displacement of the Sb atoms around Sb9a and Sb9b sites caused by in the three-fold and strongly distorted tetrahedral coordination for Sb8 and Ga8, resprectively.[2]
Reference
[1] Crystal structure of yttrium gallium antimonide, Y5Ga1.24Sb2.77. DOI:10.1515/ncrs-2016-0312
[2] Crystal structure of lanthanum gallium antimonide, La12Ga3.26Sb24.02. NCS 225 (2010) 229-230. DOI:10.1524/ncrs.2010.0099
