Definition

Noun: A specific analytical technique, also known as the powder method or X-ray powder diffraction (XRPD), used primarily to identify the crystalline phases present in a material. In this process, a finely powdered sample is exposed to a beam of X-rays. The resulting diffraction pattern, consisting of concentric rings on a photographic film or detector, is unique to the crystal structure and is used as a fingerprint for identification.

Usage

This term is used in scientific contexts, particularly in chemistry, geology, materials science, and solid-state physics, to describe a standard method for phase identification of crystalline substances.

Examples

• Noun:
  • The mineralogist used powder photography to determine the composition of the unknown rock sample.
  • Before the advent of digital detectors, powder photography was the primary method for obtaining X-ray diffraction data.

Advanced Usage

• The technique is foundational for creating powder diffraction files, which are international reference databases used to match unknown patterns.
• While "powder photography" historically referred to the use of photographic film, the modern digital equivalent is more commonly called X-ray powder diffraction (XRPD) or simply powder diffraction.

Variants and Related Words

• Powder method: A more general synonym for the technique.
• X-ray powder diffraction (XRPD): The modern, more precise term encompassing both film and digital detection.
• Powder diffraction pattern: The specific set of rings or peaks produced by the analysis.
• Debye-Scherrer method: A historical name for the same technique, named after its developers.

Synonyms

• X-ray powder diffraction (XRPD)
• Powder diffraction
• Powder method

Notes

• The term is highly specialized and is not used in everyday language. It is a compound noun where "powder" refers to the sample's physical state and "photography" refers to the original method of recording the diffraction pattern.
• The process is crucial for distinguishing between materials that may have the same chemical composition but different crystal structures (polymorphs).

Noun

1. a process for identifying minerals or crystals; a small rod is coated with a powdered form of the substance and subjected to suitably modified X-rays; the pattern of diffracted rings is used for identification