Trigonal Centre of Gd³⁺ in CdS Investigated by Variable‐Frequency EPR

Abstract

For the new axial centre of Gd3+ in hexagonal CdS, reported recently, a more detailed analysis of results obtained by variable-frequency E P R is carried out, establishing trigonal symmetry and giving spin-Hamilton parameters bg = +I853 x ern-%, bi = (+)2.6 x x em-'. The model of Newman and Urban has been applied to estimate b!j for various local arrangements and these are compared with the experimental values of all three axial centres reported so far for Gd3+ in CdS. Das kurzlich in CdS gefundene

Superposition Model Analysis of the Spin Hamiltonian Parameters of Two Gd3+ Doped Thorium Dichalcogenides

“…It is apparent that the two exponents power law is very sensitive to the position of the Gd 3+ and that the undistorted case gives the most reasonable solution. In fact, it is in agreement with the previous literature [17], where it is assumed that the value of 62 (-Ro) for the Gd-S pair is of the same order as that for Gd-0. The case of equal displacements along b and c seems to give a not bad result, which, on the other hand, is less reasonable, because would lead to too large distortions in the case of ThOS, as it will appear in the following Section.…”

“…In particular, it is ^4<0 and tA<.tß-In fact, this assumption is the only one consistent with the previous literature, in particular as regards the negative sign for b2(Bo) [1,17]. Equation (3) contains five independent parameters, namely A, B, tß and Bq.…”

“…In fact, the value of the intrinsic parameter obtained for TI1S2 has been used to fit the data in a compound of different structure and symmetry, that is ThOS. Moreover, in this procedure, the possibility to reveal environmental distortions, as those induced by the impurity ion [17] has been pointed out.…”