Assessing glass‐ceramic homogeneity and nucleation self‐correlation by crystallization statistics

In this work, we implemented and tested a statistical method to evaluate the microstructural uniformity of partially crystallized glasses employing the aggregation index (R‐index), a parameter derived from the Poisson distribution function, which has mainly been used in Ecology studies. Since the cr...

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Bibliographic Details
Published in:Journal of the American Ceramic Society 2021-09, Vol.104 (9), p.4459-4470
Main Authors: Ramírez Acosta, María Helena, Raphael Rodrigues, Lorena, Guarin Castro, Edgar David, Dutra Zanotto, Edgar
Format: Article
Language:English
Subjects:
Ceramics
Chemical composition
Chemical elements
chemical homogeneity
Crystallization
Crystals
Distribution functions
Evaluation
Glass
glass‐ceramic
Homogeneity
nearest‐neighbor index
Nucleation
Photomicrographs
Poisson distribution
Statistical analysis
Statistical methods
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Summary:In this work, we implemented and tested a statistical method to evaluate the microstructural uniformity of partially crystallized glasses employing the aggregation index (R‐index), a parameter derived from the Poisson distribution function, which has mainly been used in Ecology studies. Since the crystal nucleation rate strongly depends on the chemical composition, the spatial crystal distribution in glass‐ceramics can be used to infer their chemical homogeneity. We also tested the hypothesis, advanced by some authors, of preferential secondary nucleation close to preexisting crystals (even in chemically homogeneous samples). To this end, we conducted a nearest‐neighbor statistical analysis of the spatial crystal distribution in partially crystallized Li2Si2O5 and Ba5Si8O21 glasses, used as model materials, by inspecting optical micrographs obtained at different magnifications. The resultant R‐indexes indicate a very high degree of homogeneity of the crystal number distribution, reflecting the uniform distribution of the chemical elements in the parent glasses. Moreover, the results for both glasses refute the suggestion that crystal nucleation is self‐correlated. These outcomes allow us to suggest the R‐index as a valuable and easily implemented tool to evaluate the chemical homogeneity of glasses that undergo internal nucleation, such as those used for glass‐ceramics.
ISSN:0002-7820
1551-2916
DOI:10.1111/jace.17815