STRUCTURAL STABILITY OF THE 1T STRUCTURE ON TRANSITION-METAL DICHALCOGENIDES .1. COMPOUNDS IN THE NBS2-IRS2 SYSTEM

A new family of the 1T compounds is prepared in the NbS2-IrS2 system a nd the NbSe2-IrSe2 system. The end members of the above systems do not crystallize into the 1T structure. In the NbS2-IrS2 system, the struc ture variation from the 2H(a) structure to the pyrite structure throug h 1T structure has been observed as the average number of the valence electrons per atom increases. Also, in the NbSe2-IrSe2 system, the str ucture variation from the 4H(a) structure to the pyrite structure thro ugh 1T structure has been observed as the average number of the valenc e electrons per atom increases. The relative structural stability of t he 1T structure in comparison with the 2H(a) and the pyrite structures is discussed. The electrical resistivity has been measured from room temperature to 30 K, and the magnetic susceptibility has been measured from room temperature to 5 K. The 1T compounds of those systems show semiconductive and weak-paramagnetic behavior. (C) 1997 Academic Press .