Solid-phase reactive inter-diffusion of Mg/B multilayers
Abstract
A better understanding of the reaction of Mg and B in the solid-phase regime is needed for the low-temperature synthesis of MgB2 films. Here, we study the kinetics of reactive inter-diffusion of Mg and B multilayers on glassy carbon substrates in the temperature range of 400 -650 °C. Results show that, at these temperatures, inter-diffusion is characterized by a single activation energy of ∼0.45 eV . The formation of the superconducting MgB2 phase with critical temperatures of 25-31 K occurs at reaction temperatures of 450°C and above, with the rate of inter-diffusion obeying a power law with a kinetic exponent of ∼0.3 . This suggests that rate-limiting processes are the nucleation and growth of MgB2 grains rather than diffusion and interfacial reactions. Implications of these results to the low-temperature synthesis of MgB2 films are discussed.
- Publication:
-
Journal of Applied Physics
- Pub Date:
- February 2019
- DOI:
- 10.1063/1.5082563
- Bibcode:
- 2019JAP...125g5306B