Experimental and theoretical investigations on the electric field gradient at the Br site in Sr(BrO3)2 · H2O and Ba(BrO3)2 · H2O

Abstract

Single-crystal Zeeman effect studies have been done using 79Br NQR in Sr(BrO3)2 · H2O and Ba(BrO3)2 · H2O and the electric field gradient (EFG) parameters at the Br site have been determined. The point-charge model for the evaluation of EFG at the Br site, when applied to these systems, has not yielded satisfactory results. In another model, the total EFG is obtained as the sum of the covalent contribution and the inter-ionic contribution. To obtain the covalent contribution CNDO/2 MO calculations have been done for the (BrO3)− ions of these systems. There is excellent agreement with the experimental values in the case of Sr(BrO3)2 · H2O, while the results on Ba(BrO3)2 · H2O indicate that the structural data on this crystal need refinement.