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Condensed Matter

  • I7-01: CRYSTAL MODELS - SET OF 2

    I7-01
    Set of two simple crystal models.
    The following crystals are modeled here, from left to right: (1) face-centered cubic, such as common salt, where sodium is black and chlorine is white, (2) an apparently indeterminate structure, which can nevertheless be studied for its symmetries.

  • I7-02: CRYSTAL MODELS - BRAVAIS SET OF 14

    I7-02
    Models of crystals
    This set of 14 crystal models includes: triclinic, monoclinic primitive, monoclinic base-centered, orthorhombic primitive, orthorhombic base-centered, orthorhombic face-centered, orthorhombic body-centered, tetragonal primitive, tetragonal body-centered, rhombohedral, hexagonal unit cell, cubic primitive, cubic face-centered, and cubic body-centered.
    Disp2

  • I7-03: CRYSTAL MODELS - BRAVAIS SUPPLEMENTAL SET OF 16

    I7-03
    Models of crystals.
    This set of 18 crystal models has all the other kinds not in the first set of 14 (Demonstration I7-02)
    Disp1

  • I7-04: CRYSTAL MODELS - CALCITE

    I7-04
    Model a calcite crystal with a sample of the real thing
    The model indicates the basic structure of calcite (calcium carbonate or CaCO3). A sample of the actual crystal is also included (photograph at right) so that the crystal structure can be observed directly.
    I7

  • I7-05: CRYSTAL MODELS - LARGE

    I7-05
    Large models of crystals.
    Models include (1) salt and (2) graphite. These models are easily seen in the large lecture halls; note that they are not suitable for passing around the class, as they are fragile. Please handle with care.
    Disp1

    i7-05ai7-05b

  • I7-06: CRYSTAL MODELS - LARGE UNIVERSAL

    I7-06
    Set of components to form a large number of crystal types.
    This system can be used to illustrate the structure of a large number of crystals. The model can be changed from one type to another very easily in a matter of seconds, eliminating the need for expensive and space-consuming crystal models like those in Demonstrations I6-01 through I6-05. Of course, you have to know what you are doing.

  • I7-07: CLOSE-PACKED CRYSTALLITE

    I7-07
    Display the low index surfaces of face-centered cubic or hexagonal close-packed crystals
    Each plane is a two-dimensional hexagonal array. By stacking either abab or abcabc one obtains a hexagonal close-packed or face-centered cubic crystal, respectively. The face-centered cubic arrangement, for example, can expose (111),(100) and (110) surfaces simultaneously.
    I7

  • I7-08: CRYSTAL MODEL WITH FAULTS

    I7-08
    Visualization of a crystal fault within a simple crystal structure.
    A monolayer of BBs sandwiched between two glass plates forms this crystal model. When it is moved around and/or oriented vertically the BBs form a "crystal" arrray with a hexagonal structure and lots of "faults," as seen in the photograph.
    I7

  • I7-09: Spontaneous Ordering - Crystal Formation Models

    I7-09
    Demonstrates the formation of crystal patterns from disordered objects

    A pair of wooden frames can hold a collection of hexagonal objects. When shaken, the objects gradually form into a hexagonal grid, conforming the the container.

    One of the frames has a few additional hexagons fixed to the base; try comparing the time/work required to form a lattice with or without these seeding points.

    Donated by Dr. Stephen Parks.
    I7

  • I7-11: FERMI SURFACE OF ALUMINUM

    I7-11
    Illustrate the Fermi surface of aluminum.
    Model of Fermi surface of aluminum.
    I7

  • I7-21: SUPERCONDUCTOR - MAGNET LEVITATION

    I7-21
    Demonstrate levitation of a magnet above a high-temperature superconductor
    A one-inch diameter superconducting disc is set on a conducting base in a bath of liquid nitrogen. A cubic samarium cobalt magnet levitates above the superconductor. Note that to show the Meissner effect you must place the magnet on the disc before cooling it down. When the superconductor passes through its transition temperature the magnet rises up by itself and levitates. For large groups, a camera can be provided.
    I7, I0

  • I7-22: Phonon Propagation - Simple 1D Model

    i7-22
    To illustrate the concept of phonons
    This model consists of a series of suspended masses joined by springs, forming a one-dimensional lattice. A pulse can be generated by hand and propagated along the line.
    FS2

  • I7-23: Magnetic Track and Superconductor

    I7-23
    To illustrate levitation of a superconductor and magnetic pinning
    A chilled superconducting puck is levitated above a magnetic track. Despite the curve and slope of the track, the puck will remain above the track as it moves.

    This is an illustration of the diamagnetic and magnetic pinning effects of a superconducting material. When setting up, be sure to chill the puck in the position you want it above the track for maximum efficiency.

    The University of Cambridge has made available a helpful video lecture on magnetic pinning: https://ascg.msm.cam.ac.uk/lectures/fundamentals/pinning.php.

  • I7-31: FILLED CONDUCTION BANDS

    I7-31
    Demonstrate that filled bands and empty bands are non-conductive; only partially filled bands are active.
    Three identical cola bottles are (1) empty, (2) filled completely, and (3) partially filled. Shake the bottles. Only the partially filled bottle responds to the external force.
    I7

  • N1-31: SUN DOG - MODEL

    N1-31
    Show how a "sun dog" is formed.
    A prism is mounted below a fast rotator, approximating the effect of hexagonal ice crystals. Rotation of the crystal has the same effect as scattering off many flat hexagonal ice crystals aligned along the horizontal plane but rotated randomly in that plane (See demonstration N1-32 ICE CRYSTALS - PAPER MODELS). The "sun dog" consists of a relatively sharp cutoff at 22 degrees, the minimum angle of dispersion for ice crystals, with a long tail of decreasing intensity. For the prism the deflection angle is greater than 22 degrees because the index of refraction of glass is greater than that of ice. The outer thirds of each face of the equilateral prism is covered by tape, making it appear to the incoming light more like a hexagonal ice crystal.

     

    n1-31an1-31b

  • N1-32: ICE CRYSTALS - PAPER MODELS

    N1-32
    Illustrates how two types of ice crystals formed high in the atmosphere float downward through the air with preferred orientations.
    Ice crystals may be formed in the upper atmosphere and float downward through the air. Pencil shaped hexagonal crystals fall with their axis of symmetry horizontal, while flat crystals float with their axes vertical (flat area horizontal). This can be seen by throwing the crystals in the air and observing how they fall.

    Pencil shaped and flat hexagonal ice crystals made of paper and foam are provided for this demonstration.

    Scattering and refraction of light by these crystals creates several important natural atmospheric phenomena: (1) The sun pillar is formed by reflections of the sunlight by the flat surfaces of flat crystals when the sun is near the horizon, (2) The 22 degree halo around the moon is formed by refraction with the minimum angle of deviation from pencil ice crystals when the moon is very high in the sky, (3) The sun dog is formed to the side of the sun by refraction from flat ice crystals when the sun is low in the sky.

  • Q3-01: Helix Diffraction

    Q3-01
    To model the structure of a helical molecule
    The spiral structure of DNA was discovered through diffraction. This demonstration shows a simplified model, diffraction through a single (rather than double) helix. Several springs are mounted to enable the laser to be pointed at each in turn, including one distorted to show the effect of changing the angle.
    (photo credit: Mary Chessey, UMD)