Abstract Motivated by the recent experimental exfoliation of tellurium thin film, and the amazing physical and chemical properties of various theoretically tellurene allotropes, we design a novel and stable pentagonal… Click to show full abstract
Abstract Motivated by the recent experimental exfoliation of tellurium thin film, and the amazing physical and chemical properties of various theoretically tellurene allotropes, we design a novel and stable pentagonal structure of tellurene (SP-type Te), and make a detailed comparison with other possible Te allotropes, related to their mechanical, electronic and thermoelectric properties. SP-type Te shows the higher expandability than other Te allotropes, due to its lower layer modulus and Young’s modulus. More interestingly its Poisson’s ratio along x (y) direction is unusually negative ( ∼ -0.01) which can be further decreased by applying coaxial strain. Three-layers SP-type Te can turn into a topological insulator (TI) with a nontrivial band gap ∼ 0.03 eV when uniaxial compressional strain σ x =-7 % . Moreover the higher the number of layers in SP-type Te, the lower σ x inducing its topological transition requires. At room temperature, lattice thermal conductivity k L of SP-type Te is the lowest in all Te allotropes, and meanwhile its peak ZT for n-type doping even can reach up to 2.84. Thus if SP-type Te can be synthesized in future, these extraordinary properties would promote it with great potential in designing low-dimensional mechanical, spintronic and thermoelectric devices.
               
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