Electric quadrupole interaction of 139La in 139La2-xSrxCuO4 at high pressures: experiment and theory

In the 4.2-290 k and 0-17 kbar ranges by the spin echo method experimentally is investigated the 139La nuclear quadrupole resonance in 139La2-xSrxCuO4 ceramic oxides (x=0; 0.1). The baric dependences of the quadrupole coupling constant are compared with theoretical calculations in the point ion model and by the statistical method. It is shown that the electric field gradient behaviour under compression is satisfactory described by the method. A strong effect of La-Sr osides lattice instability on the hyperfine electric interactions is established