Electrical transport and thermoelectric properties of Ni-doped perovskite-type YCo1-xNixO3(0 ≤ x ≤ 0.07) prepared by sol-gel process

摘要

Electrical transport and thermoelectric properties of Ni-doped YCo1-xNixO3(0 ≤ x ≤ 0.07),prepared by using the sol-gel process,are investigated in a temperature range from 100 to 780 K.The results show that with the increase of Ni doping content,the values of DC resistivity of YCo1-xNixO3 decrease,but carrier concentration increases.The temperature dependences of the resistivity for YCo1-xNixO3 are found to follow a relation of lnρ ∝ 1/T in a low-temperature range (LTR) (T ＜～ 304 K for x =0; ～ 230 K ＜ T ＜～ 500 K for x =0.02,0.05,and 0.07) and high-temperature range (HTR)(T ＞～ 655 K for all compounds),respectively.The estimated apparent activation energies for conduction Ea1 in LRT and Ea2 in HTR are both found to decrease monotonically with doping content increasing.At very low temperatures (T ＜～230 K),Mott's law is observed for YCo1-xNixO3(x≥ 0.02),indicating that considerable localized states form in the heavy doping compounds.Although the Seebeck coefficient of the compound decreases after Ni doping,the power factor of YCo1-xNixO3 is enhanced remarkably in a temperature range from 300 to 740 K,i.e.,a 6-fold increase is achieved at 500 K for YCo0.98Ni0.02O3,indicating that the high-temperature thermoelectric property of YCoO3 can be improved by partial substitution of Ni for Co.