Structure and Electronic Properties of the Quasi-One-Dimensional Ba2Co1-xZnxS3 Series

This work focuses on the structure and physical properties of the solid solution Ba2Co1-xZnxS3 (0 ≤ x ≤ 1), a family of quasi-one-dimensional sulfides with end members Ba2CoS3 and Ba2ZnS3. The structure of selected compounds with increasing Zn2+ content has been analyzed using neutron diffraction, transmission electron microscopy, and extended X-ray absorption fine structure, and the physical properties have been analyzed via magnetic susceptibility and resistivity measurements. The progressive substitution of the nonmagnetic Zn2+ cation for Co2+ rapidly destroys the antiferromagnetic transition present at 46 K in the quasi-one-dimensional Ba2CoS3, leading to paramagnetic behavior down to the lowest investigated temperature (5 K) for compounds with x > 0.25. For compounds with x ≥ 0.4, a pure Curie-Weiss regime is recovered around 300 K, yielding effective moments consistent with the g factor of the tetrahedrally coordinated Co2+ previously determined for Ba2CoS3. The substitution of Zn2+ for Co2+ also removes the metallic-like behavior of Ba2CoS3, causing an increase in the value of the resistivity with all the Ba2Co1-xZnxS3 compounds showing semiconducting behavior. The negative magnetoresistance of Ba2CoS3 is improved by the substitution of Zn2+ for Co2+, with values of -6% for Ba2Co0.75Zn0.25S3, -9% for Ba2Co0.5Zn0.5S3, and -8% for Ba2Co0.25Zn0.75S3. However, there does not seem to be a correlation between the values of resistivity and magnetoresistance and the content of Zn2+, leading to the hypothesis that transport properties may be linked more closely to extrinsic properties.