Anelastic relaxation and phase transition internal friction properties of La2-x Ndx CuO4+δ (0.1≤x≤1.2) compounds

The low-frequency internal frictions of La2-xNdxCuO4+8(0.1 <= x <= 1.2) compounds are measured. The results show that the relaxation internal friction peak related to the excess oxygen atoms appears around 250K with 0.1 <= x <= 1.0. And the peak becomes higher with the value of x increasing for 0.1 <= x <= 0.4 and all these compounds have orthorhombic structures. When 0.5 <= x <= 1.0, the compounds have all tetragonal structures on a macro scale and the peak reduces as the value of x increases. However, the sample with x = 1.2 exhibits tetragonal structure but the relaxation internal friction peak is not found. Further more, when 0.1 <= x <= 0.8, there exists a phase transition internal friction peak around 550K. The transition temperature shifts toward high temperature zone as the value of x increases and relative shear modulus M is enlarged. But for x = 1.0 and 1.2, there appears no phase transition internal friction peak in the measurement range. We find that all these phase transition internal friction peaks are related to the transition between the orthorhombic structure and the tetragonal structure.