The magnetization of superconducting La_1.85Sr _0.15Cu_1-xV_xO_4-∂

Oxides of the type La_1.85Sr_0.15Cu_1-xV _xO_4-∂ were prepared with vanadium contents, x, ranging from 0 to 0.10 in increments of 0.01. Vanadium entered into solid solution in the tetragonal K-phase structure at concentrations up to x=0.05. Further additions of vanadium resulted in the formation of SrV₅O ₁₁ and an orthorhombic distortion of the K-phase structure. An increase in the irreversibility of the magnetization at 4.2 K, at a vanadium concentration of x=0.01, was attributed to increased flux pinning due to solid solution hardening. Reduced magnetic irreversibilities and critical temperatures were observed at higher vanadium concentrations, and attributed to a loss of strontium from the K phase due to the formation of SrV₅O ₁₁.