In-Plane Stacking Disorder in Polydisperse Hard Sphere Crystals

Meijer, Janne‐Mieke; Villeneuve, V.W.A. de; Petukhov, Andrei V.

doi:10.1021/la062966f

Cited by 34 publications

(55 citation statements)

References 37 publications

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“…In the following we shall assume that the structure can be still described using the same stacking parameter α as for an infinite crystal. In practice this assumption means that within the irradiated part of the crystalline film one finds many different realizations of the stacking sequence due to the presence of different domains and the presence of in-plane stacking disorder [40,41].…”

Section: Wilson Theory For Thin Crystalline Films With Stacking Dmentioning

confidence: 99%

Periodic order and defects in Ni-based inverse opal-like crystals on the mesoscopic and atomic scale

et al. 2014

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The structure of inverse opal crystals based on nickel was probed on the mesoscopic and atomic levels by a set of complementary techniques such as scanning electron microscopy and synchrotron microradian and wide-angle diffraction. The microradian diffraction revealed the mesoscopic-scale face-centered-cubic (fcc) ordering of spherical voids in the inverse opal-like structure with unit cell dimension of 750 ± 10 nm. The diffuse scattering data were used to map defects in the fcc structure as a function of the number of layers in the Ni inverse opal-like structure. The average lateral size of mesoscopic domains is found to be independent of the number of layers. 3D reconstruction of the reciprocal space for the inverse opal crystals with different thickness provided an indirect study of original opal templates in a depth-resolved way. The microstructure and thermal response of the framework of the porous inverse opal crystal was examined using wide-angle powder x-ray diffraction. This artificial porous structure is built from nickel crystallites possessing stacking faults and dislocations peculiar for the nickel thin films.

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Section: Wilson Theory For Thin Crystalline Films With Stacking Dmentioning

confidence: 99%

Periodic order and defects in Ni-based inverse opal-like crystals on the mesoscopic and atomic scale

et al. 2014

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“…Stacking can subsequently be characterised to distinguish islands, but since stacking across both sides of a line-defect can be HCP and FCC on both sides, a second criterium is necessary. Here we extend the use of the orientational correlation method presented in [21] by incorporating the stacking direction.…”

Section: Identification Of Islandsmentioning

confidence: 99%

“…First of all, a single line-defect separates two lateral islands, but causes stacking islands in the layer above and the layer below as well [21]. Stacking islands should therefore be significantly smaller than lateral islands.…”

Section: -P2mentioning

confidence: 99%

“…-Full details of our experimental methods can be found in [21]. We prepared sedimented crystals of fluorescent, 1.2 diameter µm polymethyl-metacrylate spheres [22], dispersed in two apolar 56001-p1 V. W. A. de Villeneuve et al…”

mentioning

confidence: 99%

“…Our previous studies showed that the different solvents resulted in fractions of FCC α of ∼ 0.6 (TTC) and ∼ 0.7 (De) [21]. Crystals were grown from the sample bottom by sedimentation from intial volume fractions φ 0 of 0.4 (Sample TTC6) and 0.2 (Sample De10), 0.3 (De13) and 0.4 (De14).…”

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confidence: 99%

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Grain size effects on lateral islands in hard-sphere crystals

et al. 2007

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-Due to the lateral stacking disorder, random hexagonally closed-packed hard-sphere crystals consist of lateral islands with different lateral positions A, B, and C, and as a consequence, different stacking. We investigate the extent of lateral stacking disorder as a function of grain size, and as a function of the fraction of FCC-stacked particles α by laser scanning confocal microscopy and Monte Carlo simulations. We compare the simulations and microscopy data to relate stacking islands (2D domains with identical stacking type and direction) to lateral islands. Small crystals mainly contain single hexagonal planes, whereas larger crystals consist of a much larger number of lateral islands. Furthermore, the typical stacking island size is related to the FCC fraction. At high α, more FCC islands nucleate, and these are more likely to combine into larger islands than the HCP islands. Copyright c EPLA, 2007Introduction. -Small crystallites are remarkably different from their large counterparts. The amount of particles at the surface is relatively high, which can drastically affect elastic [1], optical [2], electric [3] and magnetic properties [4]. The change in properties is often coupled to a change in particle configuration. It is extremely difficult to study atomic systems on the single-particle level, but colloidal systems are excellent reference systems: they are very similar to atomic systems [5] and enable 3D studies on the single-particle level by confocal microscopy [6-9] due to large particle size and their relative slowness. The phase diagram of colloidal hard spheres is based on excluded-volume interactions only. The free energy difference between face-centered cubic (FCC) and hexagonally closed packed (HCP) structures is tiny for hard sphere crystals [10][11][12]: less than 10 −3 k B T per particle, where k B T is the thermal energy. As a result, a so-called randomhexagonal close-packed (RHCP) crystal structure is often found in experimental hard sphere systems [13][14][15][16][17][18]: the reorganisation from RHCP to FCC structure is expected to take months to years for experimental systems [18,19]. Due to the variety of possible RHCP configurations, an additional gain in entropy can stabilize the RHCP structure for sufficiently small crystals [20]. The RHCP structure is characterized not only by randomly alternating FCC and HCP layers, but also by lateral islands with

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Ptychographic X‐Ray Imaging of Colloidal Crystals

Lazarev

Besedin

Zozulya

et al. 2017

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dipolar interactions. [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15] The flexibility of colloidal crystals and their response to external stimuli [16][17][18] along with their unique optical properties such as the strongly pronounced structural color and photonic band gap makes them attractive for many applications. [19][20][21][22][23][24][25] Moreover, defects, which determine the mechanical properties of many engineering materials such as metals, [26] can be studied with "atomic" resolution using colloidal crystals. [27][28][29] The high penetration depth of X-rays makes them an ideal tool to access important statistically averaged spatial information about the colloidal crystal structure and disorder over macroscopic sample volume. [7,30,31] Further access to local structure of colloidal crystals can be gained by using microscopy with Fresnel optics and soft X-rays, [32,33] but unfortunately the use of soft X-rays significantly limits the penetration depth. Alternatively, compound refractive lenses (CRLs) can be used as an objective lens for hard X-rays to study thicker samples. [34][35][36] This technique provides full field of view, however, resolution is limited by the resolving power of the optical elements and contrast is limited by using hard X-rays. [37] Ptychographic coherent X-ray imaging is applied to obtain a projection of the electron density of colloidal crystals, which are promising nanoscale materials for optoelectronic applications and important model systems. Using the incident X-ray wavefield reconstructed by mixed states approach, a high resolution and high contrast image of the colloidal crystal structure is obtained by ptychography. The reconstructed colloidal crystal reveals domain structure with an average domain size of about 2 µm. Comparison of the domains formed by the basic close-packed structures, allows us to conclude on the absence of pure hexagonal close-packed domains and confirms the presence of random hexagonal close-packed layers with predominantly face-centered cubic structure within the analyzed part of the colloidal crystal film. The ptychography reconstruction shows that the final structure is complicated and may contain partial dislocations leading to a variation of the stacking sequence in the lateral direction. As such in this work, X-ray ptychography is extended to high resolution imaging of crystalline samples. Ptychography [+]

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In-Plane Stacking Disorder in Polydisperse Hard Sphere Crystals

Cited by 34 publications

References 37 publications

Periodic order and defects in Ni-based inverse opal-like crystals on the mesoscopic and atomic scale

Periodic order and defects in Ni-based inverse opal-like crystals on the mesoscopic and atomic scale

Grain size effects on lateral islands in hard-sphere crystals

Ptychographic X‐Ray Imaging of Colloidal Crystals

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