title: Generating MnO2 nanoparticles using simulated amorphization and recrystallization.
abstract: Models of MnO2 nanoparticles, with full atomistic detail, have been generated using a simulated amorphization and recrystallization strategy. In particular, a 25,000-atom "cube" of MnO2 was amorphized (tension-induced) under molecular dynamics (MD). Long-duration MD, applied to this system, results in the sudden evolution of a small crystalline region of pyrolusite-structured MnO2, which acts as a nucleating "seed" and facilitates the recrystallization of all the surrounding (amorphous) MnO2. The resulting MnO2 nanoparticle is about 8 nm in diameter, conforms to the pyrolusite structure (isostructural with rutile TiO2, comprising 1 x 1 octahedra) is heavily twinned and comprises a wealth of isolated and clustered point defects such as cation vacancies. In addition, we suggest the presence of ramsdellite (2 x 1 octahedra) intergrowths. Molecular graphical snapshots of the crystallization process are presented.
authors.affiliation: DEOS, Cranfield University, Defense Academy of the U.K., Shrivenham, Swindon, UK.
authors.forename: Thi X T
authors.initials: TX
authors.lastname: Sayle
authors.forename: C Richard A
authors.initials: CR
authors.lastname: Catlow
authors.forename: R Regina
authors.initials: RR
authors.lastname: Maphanga
authors.forename: Phuti E
authors.initials: PE
authors.lastname: Ngoepe
authors.forename: Dean C
authors.initials: DC
authors.lastname: Sayle
mesh_terms: D003460:Crystallization; D018360:Crystallography, X-Ray; D017895:Manganese Compounds / Q000737:chemistry*; D008958:Models, Molecular; D049329:Nanostructures / Q000737:chemistry*; D010087:Oxides / Q000737:chemistry*; D013997:Time Factors
chemical_list: D017895:Manganese Compounds; D010087:Oxides; C016552:manganese dioxide