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IrTe crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Ir is bonded in a 6-coordinate geometry to two equivalent Ir and six equivalent Te atoms. Both Ir–Ir bond lengths are 2.83 Å. All Ir–Te bond lengths are 2.76 Å. Te is bonded in a 6-coordinate geometry to six equivalent Ir atoms.
Dy7Ir2Te2 crystallizes in the orthorhombic Imm2 space group. The structure is three-dimensional. there are four inequivalent Dy sites. In the first Dy site, Dy is bonded in a 4-coordinate geometry to three equivalent Ir and one Te atom. There are two shorter (2.86 Å) and one longer (3.11 Å) Dy–Ir bond lengths. The Dy–Te bond length is 3.18 Å. In the second Dy site, Dy is bonded in a 4-coordinate geometry to two equivalent Ir and two equivalent Te atoms. Both Dy–Ir bond lengths are 2.89 Å. Both Dy–Te bond lengths are 3.21 Å. In the third Dy site, Dy is bonded in a 3-coordinate geometry to three Te atoms. There are one shorter (3.17 Å) and two longer (3.18 Å) Dy–Te bond lengths. In the fourth Dy site, Dy is bonded in a 5-coordinate geometry to two equivalent Ir and three Te atoms. Both Dy–Ir bond lengths are 2.85 Å. There are one shorter (3.13 Å) and two longer (3.22 Å) Dy–Te bond lengths. Ir is bonded in a 7-coordinate geometry to seven Dy atoms. There are two inequivalent Te sites. In the first Te site, Te is bonded in a 8-coordinate geometry to eight Dy atoms. In the second Te site, Te is bonded in a 7-coordinate geometry to seven Dy atoms.
Er7(IrTe)2 crystallizes in the orthorhombic Imm2 space group. The structure is three-dimensional. there are four inequivalent Er sites. In the first Er site, Er is bonded in a 5-coordinate geometry to two equivalent Ir and three Te atoms. Both Er–Ir bond lengths are 2.83 Å. There are one shorter (3.11 Å) and two longer (3.19 Å) Er–Te bond lengths. In the second Er site, Er is bonded in a 4-coordinate geometry to three equivalent Ir and one Te atom. There are two shorter (2.84 Å) and one longer (3.09 Å) Er–Ir bond lengths. The Er–Te bond length is 3.17 Å. In the third Er site, Er is bonded in a 4-coordinate geometry to two equivalent Ir and two equivalent Te atoms. Both Er–Ir bond lengths are 2.85 Å. Both Er–Te bond lengths are 3.17 Å. In the fourth Er site, Er is bonded in a 3-coordinate geometry to three Te atoms. There are two shorter (3.17 Å) and one longer (3.19 Å) Er–Te bond lengths. Ir is bonded in a 7-coordinate geometry to seven Er atoms. There are two inequivalent Te sites. In the first Te site, Te is bonded in a 8-coordinate geometry to eight Er atoms. In the second Te site, Te is bonded in a 7-coordinate geometry to seven Er atoms.
The baseline definition of the Space Tug discussed herein is the one necessary to meet current payload mission model requirements in the mid-1980's for the least risk and development investment. This baseline Space Tug is a nominal 15-ft diameter, 30-ft long, LOX/LH2 stage with a main propellant capacity of about 50,000 lbs. Once deployed from the Space Shuttle in orbit, it is designed to automatically deliver spacecraft to a predetermined position and velocity and/or rendezvous and dock with prepositioned spacecraft for servicing or retrieval. The Tug would normally be returned to the vicinity of the Shuttle Orbiter, with or without spacecraft, to be retrieved and returned to earth in the Shuttle. Design characteristics, performance requirements, projected activities, and subsystems features are described.