material homogeneity 

https://doi.org/10.1351/goldbook.08025
Uniform structure or composition of a material with respect to one or more specified properties.
Notes:
  1. A material is said to be homogeneous with respect to a specified quantity if the quantity values measured using aliquots of a specified size do not fall outside a specified interval. See minimum sample size.
  2. In the homogeneity study of a candidate reference material, it is distinguished whether the analytical samples are taken from different supply units or from a single supply unit ("termed between-bottle homogeneity" or "within-bottle homogeneity", respectively).
  3. Inhomogeneity is a source of measurement uncertainty.
  4. Detailed guidance for the assessment of homogeneity of reference materials is given in ISO Guide 35.
Source:
PAC, 2021, 93, 997. (Metrological and quality concepts in analytical chemistry (IUPAC Recommendations 2021)) on page 1009 [Terms] [Paper]