X-Ray Study of the Room Temperature Structure in Monoclinic TlS

抄録

TlS is known as a mixed valence compound containing monovalent and trivalent thallium ions. The structure of the newly found monoclinic TlS has been analyzed using three-dimensional single crystal diffraction data. Space group C2: a=11.018(6), b=11.039(15), c=60.16(7) Å, β=100.69°(4) and Z=128. The structure is characterized by layers formed of corner-connected Tl⁺³S₄ tetrahedra. Monovalent Tl¹⁺ ions are located between the layers and have trigonal prismatic coordination of the sulfur ions. The structure is a variation of the TlGaSe₂ type with fourfold modulation along the c-axis. The modulation is caused by cooperative distortion of trigonal prisms around the monovalent Tl¹⁺ ions.