Influence of doping effect on structure and superconducting properties of MgB2
(1. Department of Mechanical Engineering,
Tsinghua University, Beijing 100084, China
2. Department of Physics, Tsinghua University, Beijing 100084, China)
Tsinghua University, Beijing 100084, China
2. Department of Physics, Tsinghua University, Beijing 100084, China)
Abstract: Mg1-xMxB2(M=Li or deficiency) compounds were prepared and their structure and superconducting properties were studied. The results show that nearly single-phased Mg1-xLixB2 samples have been obtained while x≤0.3. With increasingx, lattice parameters a decreases and c shows no obvious change, and the superconducting transition temperature Tc of Mg1-xLixB2 decreases. Moreover, loss of superconductivity occurs for sample with x=0.5. For Mg1-xB2 nearly single-phased samples can be obtained at x=0. MgB2 coexists with MgB4 phase and some minor impurity phases while 0＜x＜0.5. With the increase of x, a and c of MgB2 decreases and increases, respectively, and Tc decreases. The obvious difference in the superconductivity of Mg1-xLixB2 and Mg1-xB2 suggests that Li indeed dopes into the structure of MgB2.
Key words: Mg1-xLixB2; Mg1-xB2; lattice parameter; superconducting transition temperature