Structure, magnetic, electrical and thermal transport properties of Dy-doped Ca3Co2O6 ceramics

The effects of Dy doping on the structure, magnetic, electrical and thermal transport properties of Ca3-xDyxCo2O6 (x=0-0.4) ceramics have been investigated. All samples show the rhombohedral structure with space group R (3) over barc. The lattice parameter c is found to increase whereas a decreases in the Dy-doped samples by the Rietveld refinement on the powder x-ray diffraction patterns. The magnetization at high temperatures increases slightly with increasing Dy-doping content, whereas the low-temperature magnetization decreases. The variations of the magnetization in the high- and low-temperature range are considered to be related to the paramagnetism of the doped Dy3+ ions and the weakened ferromagnetic (FM) interaction along the spin-chains, respectively. The resistivity decreases initially and then increases slightly with increasing Dy-doping level. The competition between the increased carrier concentration and the enhanced disorder in the Dy-doped samples may be the origin of the observed phenomenon. The low-temperature thermopower increases considerably in the Dy-doped samples, although its value has a decreasing trend at high temperatures. The result shows that the magnetic ion doping may be an effective method to tune the low-temperature thermoelectric properties of these spin chain compounds. (C) 2016 Elsevier Ltd and Techna Group S.r.l. All rights reserved.