La1-xBi1+xS3 (x~0.08): An n-Type Semiconductor
arXiv:1606.08002 · doi:10.1021/acs.inorgchem.6b00025
Abstract
The new bismuth chalcogenide La0.92Bi1.08S3 crystallizes in the monoclinic space group C2/m with a = 28.0447(19) à , b = 4.0722(2) à , c = 14.7350(9) à , and $β$ = 118.493(5)°. The structure of La0.92Bi1.08S3 is built up of NaCl-type Bi2S5 blocks, and BiS4 and LaS5 infinitely long chains forming a compact three-dimensional framework with parallel tunnels. Optical spectroscopy and resistivity measurements reveal a semiconducting behavior with a band gap of ~ 1 eV and activation energy for transport of 0.36(1) eV. Thermopower measurements suggest the majority carriers of La0.92Bi1.08S3 are electrons. Heat capacity measurements indicate no phase transitions from 2 to 300 K. Band structure calculations at the density functional theory level confirm the semiconducting nature and the indirect gap of La0.92Bi1.08S3.