Calcium tracer diffusion in (La,Ca)CrO3 by SIMS

Calcium tracer diffusion coefficients in (La,Ca)CrO3 were determined by a nitric acid solution application method using 44Ca(NO3)2. The diffusion profiles of 44Ca in the air-sintered (La,Ca)CrO3 were measured by secondary ion mass spectrometry (SIMS) with a bombardment of primary O2+ ion. From the SIMS depth concentration profiles of 44Ca, the diffusion coefficients were determined both for bulk and grain boundary in several annealing conditions. The diffusion coefficients of 44Ca for bulk were ranged from 10−16 to 10−14 cm2 s−1 at the temperature ranges from 1173 to 1373 K. The diffusion coefficients of 44Ca for grain boundary were five to six orders of magnitude larger than those for bulk. The order of the magnitude and the activation energy of 44Ca bulk diffusion coefficient are similar to those of bulk Ca–Sr interdiffusion. Therefore, a similar diffusion mechanism for bulk can be assumed between the tracer diffusion and the chemical interdiffusion in (La,Ca)CrO3. The grain boundary diffusion coefficients of 44Ca showed larger values than those of Ca–Sr interdiffusion.