Definition

1. Adjective:
   • Composed of many small crystals: Describes a solid material whose structure consists of numerous crystalline grains or crystallites, as opposed to a single, continuous crystal (which is monocrystalline).

Usage

• The term is used primarily in materials science, metallurgy, and solid-state physics to describe the microstructure of a substance.
• It is typically used attributively (before a noun) to modify the name of a material.

Examples

• Adjective:
  • Solar panels often use polycrystalline silicon because it is more cost-effective to produce than monocrystalline silicon.
  • The polycrystalline structure of the metal was visible under the microscope.
  • Most common metals, like the steel in this bridge, are polycrystalline.

Advanced Usage

• "Polycrystalline aggregate": A common technical term for a solid composed of many crystalline grains.
  • The rock sample was identified as a polycrystalline aggregate of quartz and feldspar.
• The property of being polycrystalline is referred to as "polycrystallinity".

Variants and Related Words

• Monocrystalline (adj): Composed of a single, continuous crystal. (Antonym)
  • Monocrystalline silicon wafers have higher purity.
• Crystallite (n): A small, individual crystal grain within a polycrystalline material.
  • The size of the crystallites affects the material's strength.
• Grain (n): In this context, synonymous with crystallite; a single crystal region in a polycrystalline material.
  • The grain boundaries are where two crystals meet.

Synonyms

• Multicrystalline (adj): Often used interchangeably, especially regarding silicon for solar cells.
• Granular (adj): Can describe a similar visual or textural quality, though it is less specific to crystalline structure.

Notes

• Polycrystalline materials have grain boundaries, which are the interfaces where crystals of different orientations meet. These boundaries significantly influence the material's mechanical and electrical properties.
• The term is a technical adjective. Its use is almost entirely confined to scientific and engineering contexts describing the microstructure of solids like metals, ceramics, and semiconductors.

Adjective

1. composed of aggregates of crystals
   • polycrystalline metals