STRESS-INDUCED NUCLEAR QUADRUPOLE SPLITTINGS IN MGO - MN2+ AND CAF2 - EU2+

Stress-induced nuclear quadrupolar splittings are reported for Mn2+ and Eu2+ in MgO and CaF2, respectively, using ENDOR techniques. The magnitude of all observed splittings are shown to be in agreement with point-charge estimates, in the absence of any correction for the difference between local and bulk compressibilities. An overlap contribution to the pressure-induced electric field gradient at the nucleus is calculated, and shown to be a factor of 2 smaller than the point-charge contribution. A pressure-induced dipolar contribution, appropriate to CaF2 stressed along a [111] direction, though calculated to be large (twice the point-charge value), is shown to be absent experimentally. © 1968 The American Physical Society.