ISO 80000-12:2009

Overview

ISO 80000-12:2009 - Quantities and units - Part 12: Solid state physics specifies standardized names, symbols and definitions for quantities and units used in solid state (condensed matter) physics. Where appropriate, the standard provides conversion factors and guidance on presenting numerical values and uncertainties. Tables in the document pair quantities (left-hand pages) with their corresponding units (right-hand pages) to promote consistency in publications, instrumentation and data exchange.

Key topics

• Standardized quantities and symbols for solid state physics, including:
  • Lattice vectors and fundamental translation vectors (a1, a2, a3)
  • Reciprocal lattice vectors and angular wavenumber (k, q)
  • Lattice plane spacing (d) and Bragg angle (θ)
  • Atomic scattering factor, structure factor and Debye–Waller factor
  • Order parameters (short-range and long-range order), Burgers vector for dislocations
  • Particle position, equilibrium position, and displacement vectors
• Units policy:
  • Coherent SI units are given first; accepted non‑SI units (e.g., ångström) and conversion factors are shown where relevant
  • Rules for dimensionless quantities (unit 1; rad and sr treated as dimensionless derived units)
• Notation and numerical statements:
  • Symbols for exact (=), approximate (≈) and definitional (:=) equality
  • Standard format for reporting measurement uncertainty (e.g., 2.34782(32) m)
• Annex A: Symbols for planes and directions in crystals (normative)

Applications

ISO 80000-12 is practical for:

• Crystallography and X‑ray / neutron diffraction data reporting (Bragg angle, structure factors)
• Materials science and semiconductor research where lattice, defect and phonon descriptions are required
• Instrumentation and software that handle solid state measurements, unit conversion and standardized symbol sets
• Scientific publishing and education, ensuring clear, unambiguous notation across papers, reports and textbooks
• Metrology and standards development, for consistent exchange of physical data

Who uses this standard

• Physicists, crystallographers and materials scientists
• Metrologists and standards engineers
• Instrument manufacturers and software developers (simulation, data analysis)
• Scientific publishers, educators and technical writers

Related standards

ISO 80000-12 is part of the ISO 80000 series on quantities and units. Key related parts include ISO 80000-1 (General), ISO 80000-3 (Space and time), ISO 80000-4 (Mechanics), ISO 80000-5 (Thermodynamics) and IEC/ISO parts on electromagnetism and other fields. These form a consistent framework for units, symbols and numerical presentation across science and engineering.

Keywords: ISO 80000-12, solid state physics, quantities and units, lattice vector, reciprocal lattice, Bragg angle, Debye–Waller, structure factor, SI units, conversion factors.