EPR and Ionic Thermocurrents Experiments on Cubic Solid Solutions Sr1-xEuxF2+x

Abstract

In this paper we report about the results of EPR and ionic thermocurrents (ITC) experiments on cubic solid solutions of the type Sr 1- x Eu x F 2+ x . A part of the Eu-ions is in the divalent state; these ions can be detected easily with EPR. From the EPR results we conclude that for 0≦ x ≦0.115 the long range order is still cubic and the lattice parameter does not vary appreciably. The interactions between distant Eu 3+ -F - i dipoles and the Eu 2+ probes is estimated; from this we conclude that for \(x{\gtrsim}0.044\) clustering of trivalent Eu-ions cannot be excluded. The ITC results are in line with those obtained from EPR. In addition we note that for small values of x nearest neighbor (NN) Eu 3+ -F - i complexes are the dominant defects. For x >5.10 -3 NNN dipoles are present also. Apart from the reorientation bands associated with the above mentioned defects we observe with ITC a depolarization peak, ascribed to space charge phenomena. The behavior of the dipole peaks and the space charge peak is d...