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TiS3 crystallizes in the trigonal R3m space group. The structure is one-dimensional and consists of three TiS3 ribbons oriented in the (0, 0, 1) direction. Ti2+ is bonded to six equivalent S+0.67- atoms to form distorted face-sharing TiS6 pentagonal pyramids. All Ti–S bond lengths are 2.39 Å. S+0.67- is bonded in a distorted L-shaped geometry to two equivalent Ti2+ atoms.
TiS3 crystallizes in the monoclinic P2_1/m space group. The structure is two-dimensional and consists of one TiS3 sheet oriented in the (0, 0, 1) direction. Ti2+ is bonded in a 8-coordinate geometry to eight S+0.67- atoms. There are a spread of Ti–S bond distances ranging from 2.47–2.67 Å. There are two inequivalent S+0.67- sites. In the first S+0.67- site, S+0.67- is bonded in a 2-coordinate geometry to two equivalent Ti2+ atoms. In the second S+0.67- site, S+0.67- is bonded to four equivalent Ti2+ atoms to form a mixture of distorted edge and corner-sharing STi4 trigonal pyramids.
We investigate the behavior of the metal-insulator transition (MIT) in TiS 3 nanowire field-effect transistors, in the strongly nonequilibrium limit that has, thus far, largely been neglected. Under high electric fields within the TiS 3 channel (≤115 kV/cm), we observe the emergence of a critical fixed point, separating insulating and metallic regions in the transfer curves of the device. The critical gate voltage that defines this fixed point evolves systematically with the drain bias (field), allowing us to map out a phase diagram that identifies the conditions for metallicity or for insulating behavior. Dependent upon the choice of the gate voltage used to tune the carrier concentration in the nanowire, the existence of the field-induced MIT allows the TiS 3 to be either insulating or metallic over an extensive range of temperature. The possible connection of this strongly nonequilibrium state to some form of charge density wave is discussed.