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系统地研究单相Co掺杂自旋梯子化合物Sr14-xCaxCu24-yCoyO41(x=9:y=0,1,2,3;x=6:y=0,3)系列样品的晶体结构、电阻率以及热电势随Co含量的变化。随着y(Co)掺杂量的增加,晶格常数a,b,c几乎线性增加。电阻测量发现所有样品的电阻率温度关系均为半导体型,电阻率随着Co掺杂量的增加而增加。除了x=9,y=0样品外,其他样品的电阻率均可以用热激活公式ρ=ρ0exp(Δ/kBT)拟合。热电势测量发现,x=9,y=0样品的热电势显示金属型行为,其余样品均显示半导体行为,并且热电势随Co含量增加而明显增大。认为Co掺杂引入了无序、电子,并且引起空穴载流子由导电性较好的自旋梯子向导电性较差的自旋链的转移,从而减少参与导电空穴的数目,使得能隙、电阻率以及热电势增加。
The crystal structure of the single-phase Co-doped spin-ladder compound Sr14-xCaxCu24-yCoyO41 (x = 9: y = 0,1,2,3; x = 6: y = 0,3) As well as the thermoelectric power with the Co content change. With the increase of y (Co) doping amount, the lattice constants a, b and c increase almost linearly. Resistance measurements found that the resistivity of all samples temperature dependence of the semiconductor type, the resistivity increases with increasing the amount of Co doping. The resistivities of other samples except the x = 9 and y = 0 samples can be fitted by the heat activation formula ρ = ρ0exp (Δ / kBT). Thermoelectric measurements showed that the thermoelectric properties of samples with x = 9 and y = 0 showed metallic behavior, while the other samples showed semiconducting behavior, and the thermoelectric power increased with the increase of Co content. It is believed that Co doping introduces disordered, electrons and causes the transfer of hole carriers from the less conductive spin ladder to the less conductive spin chain thereby reducing the number of participating voids so that Gap, resistivity and thermoelectricity increase.