COMPUTER MODELS OF DEALLOYING IN BINARY METAL NANOPARTICLES

Abstract

Two alternative molecular dynamics models (programs) involving the Gupta (tight-binding) potential have been used to reproduce the dealloying phenomenon in the Au – Ag nanoalloy. Program I successively removes Ag atoms from the particle surface layer (we simulated nanoparticles consisting initially of 1500 Au and 1500 Ag atoms). Program II proposes search and removing atoms with lowest specific binding energies. We have found that as a result of dealloying the particle surface layer is really enriched with Au atoms. However the particle core keeps in general the structure of the initial nanoalloy. We have also established that dealloying results in formation a defected particle structure (vacancies, first of all). Presumably, just such an effect yields the porous structure of bigger Au – Ag particles in laboratory experiments on dealloying.

Keywords

• dealloying phenomenon
• molecular dynamics method
• binary metal nanoparticles
• segregation
• defects
• core-shell structures