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1. Heterogeneous nucleation of/on nanoparticles: a density functional study using the phase-field crystal model (Animations for Figs. 9, 10, 11, 14, 16 & 18 and for pure Fe). L . Gr áná sy 1,2 , F. Podmaniczky, G . I. Tóth 1 , G. Tegze, & T. Pusztai 1
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1 Heterogeneous nucleation of/on nanoparticles: a density functional study using the phase-field crystal model (Animations for Figs. 9, 10, 11, 14, 16 & 18 and for pure Fe) L. Gránásy1,2, F. Podmaniczky, G. I. Tóth1, G. Tegze, & T. Pusztai1 1Wigner Research Centre for Physics, POB 49, H-1525 Budapest, HU 2BCAST, Brunel University, Uxbridge, Middlesex, UB8 3PH, UK Electronic Supplementary Information for Chem. Soc. Rev. paper. Ppt file downloadable from: http://www.szfki.hu/~grana/rsc_review/Elect_Suppl_Info.ppt
Zhang & Liu, JACS (2007) A. Nucleation ( = 1, single mode-PFC) = 0.1684 0 = 0.25 Red (bcc-like) if q4 [0.02, 0.07] q6 [0.48, 0.52] 256256256 grid Tóth et al.PRL (2011). req= 0.1330 Fig. 9 Starts to solidify as amorphous, then crystallizes! A’la 2D & 3D colloids. Steinhardt, Nelson, Ronchetti, PRB (1983) 2 Please read comment to the slide
qi of Lechner & Dellago qi of Steinhardt et al. B. Structural evolution: Black: bcc Yellow: Icosah. Green: hcp Red: fcc Red (bcc-like) if q4 [0.02, 0.07] q6 [0.48, 0.52] Medium Range Crystalline Order (MRCO) Greenq6 > 0.4 Redq6 [0.28, 0.4] Whiteq6 < 0.28 Kawasaki & Tanaka, PNAS (2010) • Observations: • - PFC does not see MRCO of Kawasaki & Tanaka • - Some grain boundaries are “amorphous” • Am. precursor is structurally like LJ liquid • - Heterogeneous bcc nucleation on am. surfaces Solid bond no.: Pink: low Blue: high 3 Figs. 9, 10, 11 Please read comment to the slide 14
Further structural analysis: 4 Fig. 9 Solid bond no.: Pink: low Blue: high Solid bond number, :
n0 = 0.5125 T = Tf Advanced PFC for Fe: 5 300300300 grid n0 = 0.52 MD am. Fe:Hong, Nanotech. (2009) n0 = 0.55 The appearance of an amorphous precursor prior to crystal nucleation might be fairly general. Please read comment to the slide
(Greeret al., Acta Mater., 2002) T = 17 K d = 30 nm T = 18 K Horizontal: 1 = 75 Vertical: 2 = 175 40 nm 40 nm 40 nm 6 B. Particle induced freezing in 2D and 3D (solving the Euler-Lagrange equation): - Cylindrical particles ~ wet by the crystal on top/bottom, not on sides; (e.g., Al + Al-Ti-B inoculant Ti2B particles with AlTi3 coating on {0001} faces different contact angles on different faces) - Free growth for - PFT simulations Tc 1/d; Tc < classical Please read comment to the slide
= 0.5 as/ = 1.0 = 0.25 7 Single mode PFC modeling of nanoparticle induced crystallization in 2D: (results obtained by solving the Euler-Lagrange equation) EL solutions for increasing driving force: as/ = 1.0 Results: - Small anisotropy: Greer’s model OK - Faceted: free-growth at a much larger driving force Fig. 14 Homogeneous nuclei at the critical driving force Tóth et al.PRL (2012). Please read comment to the slide
8 Single mode PFC of particle induced freezing in 3D (solving the Euler-Lagrange equation): = 0.25 SC substrate Cubic shape 512 512 512 grid Please read comment to the slide Fig. 16 256 256 256 grid Tóth et al.PRL (2012).
= 0.25 0 = 0.32 = 0.1 as/ = 1.39 Heterogeneous crystal nucleation in 2D (solving Equation of Motion): 9 Fig. 18 Realization: - Square lattice (periodic potential) - Noise represents thermal fluctuations. Observation: - Heterogeneous crystal nucleation - Capillary waves on the crystal-liquid front Please read comment to the slide