Premium
Order and Disorder in Powder Mixtures: Spatial Distribution Functions as Tools to Assess Powder Homogeneity
Author(s) -
Mihranyan Albert,
Frenning Göran,
Fransén Nelly,
Welch Ken,
Strømme Maria
Publication year - 2009
Publication title -
particle and particle systems characterization
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.877
H-Index - 56
eISSN - 1521-4117
pISSN - 0934-0866
DOI - 10.1002/ppsc.200701129
Subject(s) - homogeneity (statistics) , amorphous solid , particle (ecology) , range (aeronautics) , correlation function (quantum field theory) , particle size , distribution function , chemistry , particle size distribution , scanning electron microscope , materials science , analytical chemistry (journal) , chemical physics , biological system , crystallography , chromatography , mathematics , thermodynamics , physics , statistics , dielectric , composite material , geology , oceanography , optoelectronics , biology
Abstract In interactive mixtures with small carrier particles, the content variability is often higher than predicted by available models despite the significant degree of interaction visualized with Scanning Electron Microscopy (SEM). The present work details how pair‐correlation functions can be used to reveal information about the spatial distribution of mixture constituents and their interactions. SEM pictures of a 2 % w/w oxazepam/sodium starch glycolate (SSG) mixture were recorded ( n = 14). The constituent coordinates were extracted and pair‐correlation functions as well as the cross‐correlation function were calculated. A significant degree of interaction was observed between the constituents in the experimental mixture, compared to a randomized control system. In particular, the probability of finding an oxazepam particle was especially high inside the perimeter of the carrier particle and along its edges. The observed cross‐correlation between oxazepam and SSG particles was periodic and repeated at distances corresponding to 1–1.5 carrier diameters. It was concluded that interactive mixtures of powders can be compared to disordered/amorphous solids since both exhibit short‐range order, whilst lacking long‐range translational periodicity.