Structure and stability of 2.4 nm period amorphous Ni-Nb/C multilayers

Amorphous Ni-Nb/C multilayers with a period of 2.4 nm were prepared by puls ed laser ablation deposition. The as-deposited multilayers were found to ha ve an interdiffused Ni1/3Nb1/3C1/3 layer present at the two interfaces; Ni1 /2Nb1/2/C and C/N1/2Nb1/2. The specular reflectivity and diffuse scattering studies show that the interface roughness is chemical and not morphologica l in origin. The structural studies performed using X-ray scattering techni ques after a period of 2.5 years from deposition show that the behaviour do es not change with time. These results indicate that the multilayered struc ture is temporally stable in spite of the strong composition dependent driv ing force for chemical homogenization. The structural stability against hom ogenization is due to the presence of an amorphous Ni1/3Nb1/3C1/3 layer pre sent at the interfaces which acts as a diffusion barrier. (C) 1999 Elsevier Science S.A. All rights reserved.