SECONDARY ION MASS SPECTROMETRIC ANALYSIS OF OXYGEN SELF-DIFFUSION IN SINGLE-CRYSTAL MgO.

Single-crystal layers of Mg**1**8O were grown epitaxially on substrates of normal MgO through chemical transport with HCl. Exchange between **1**8O in the crystals and the **1**6O present in air was produced by annealings in the temperature range of 1000-1650 degree C, and diffusion coefficients were determined from concentration gradients measured with the aid of secondary ion mass spectrometry. The temperature dependence of the oxygen self-diffusion coefficients so obtained may be represented by an activation energy of 3. 24 plus or minus 0. 13 eV and D//o of (1. 8// minus //1//. //1** plus **2**. **9) multiplied by 10** minus **6 cm**2/s. The magnitude of the diffusivities is lower than that first obtained by exchange measurements but agrees well with recent values obtained from gradients established through proton activation analysis. (Author abstract. )