Research ArticleMATERIALS SCIENCE

Sculpted grain boundaries in soft crystals

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Science Advances  29 Nov 2019:
Vol. 5, no. 11, eaax9112
DOI: 10.1126/sciadv.aax9112
  • Fig. 1 Engineered C-shaped soft crystal surrounded by a differently oriented soft crystal.

    (A) Nematic liquid crystal (LC) host (MLC2142) and chiral dopant (S811) for BP material; unit cell structures and disclination lines for BPI and BPII; disclination line structure of BPII viewed along three lattice planes (top) and their corresponding director fields (bottom). (B) Fabrication scheme for soft heteroepitaxy chemical patterns on a silicon substrate. BP material confined between octadecyltrichlorosiline (OTS)–coated top glass (homeotropic anchoring) and chemically patterned substrate (alternating homeotropic and planar anchoring) with a gap of 3.5 μm. (C) A SP surface designed as a “C” surrounded by a RP background. Left: Scanning electron microscopy (SEM) image marked with six different areas. Right: Detailed pattern information. (D) Reflection optical microscopy images with Kossel diagrams corresponding to BPII(100)—or BPI(110)—inside the “C” region and BPII(110)—or BPI(200)—outside. (E) Reflection optical microscopy images showing the optical response of the material at 39.8°C (i.e., within the BPI temperature range) when a voltage of 3.5 V is applied.

  • Fig. 2 Grain boundaries at pattern boundaries.

    SP adjacent to (A) RP regions, (B) homeotropic (unpatterned), and (C) CP regions. Reflection optical microscopy images of the corresponding patterned areas are also shown, along with simulation results of the disclination lines for the BPII(100)-BPII(110) and BPII(100)-BPII(111) interfaces, respectively.

  • Fig. 3 Engineered rectangular grains.

    (A) Chemically patterned surface designed as an SP area surrounded by an RP region. Red regions correspond to homeotropic anchoring, and blue regions correspond to planar anchoring. (B) Reflection optical microscopy images of the system at different temperatures during heating. (C) Kossel diagrams indicating the BPII symmetry corresponding to different pattern regions marked in (B).

  • Fig. 4 Binary pattern array as a stimuli responsive platform.

    (A) Chemically patterned surface designed as 60 μm by 60 μm SP area within a uniform homeotropic anchoring background. Reflection optical microscopy images of BPI and BPII on the uniform homeotropic anchoring surface. (B) Chemically patterned surface designed as an SP area surrounded by an RP background. (C) Optical setup for diffraction detection. A 445-nm laser light is converted to circularly polarized light after successively passing through a linear polarizer (LP) and a quarter waveplate (QWP). The circularly polarized light impinges on the sample by passing through a beam splitter (BS), generating the diffraction pattern. The diffractive light was projected on a black screen. (D and E) Reflection optical microscopy images of system array 1 (D) and array 2 (E), with their corresponding diffraction patterns at different temperatures during the cooling process.

Supplementary Materials

  • Supplementary material for this article is available at http://advances.sciencemag.org/cgi/content/full/5/11/eaax9112/DC1

    Continuum simulations

    Estimation of the grain boundary free energies

    Fig. S1. Pattern characteristics.

    Fig. S2. Schematic for estimating the grain boundary energies.

    Fig. S3. Grain boundary variation during phase transition by heating.

    Fig. S4. Lateral dimension of grain boundary.

    Fig. S5. Binary array pattern during phase transitions by thermal process.

    Fig. S6. Martensitic transformations during cooling process.

    Fig. S7. Simulated optical diffraction patterns.

    Movie S1. C-shaped grain-boundary under electric field.

    References (3133)

  • Supplementary Materials

    The PDFset includes:

    • Continuum simulations
    • Estimation of the grain boundary free energies
    • Fig. S1. Pattern characteristics.
    • Fig. S2. Schematic for estimating the grain boundary energies.
    • Fig. S3. Grain boundary variation during phase transition by heating.
    • Fig. S4. Lateral dimension of grain boundary.
    • Fig. S5. Binary array pattern during phase transitions by thermal process.
    • Fig. S6. Martensitic transformations during cooling process.
    • Fig. S7. Simulated optical diffraction patterns.
    • Legend for movie S1
    • References (3133)

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    Other Supplementary Material for this manuscript includes the following:

    • Movie S1 (.mp4 format). C-shaped grain-boundary under electric field.

    Files in this Data Supplement:

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