Thermal Expansion of Metal Oxides in Silicate Melts: A Simple Theoretical Analysis

Clicks: 3
ID: 308706
2024
Free PDF
Article Quality & Performance Metrics
Overall Quality
Not rated
Combines reader engagement with the AI quality analysis. This article has not been analysed, so there is no overall score — reader engagement is measured and shown alongside.
AI Quality Assessment
Not analyzed
Readership in this journal
Emerging

Ranked #725 of 8,486 articles by views in american journal of science

Most read Least read

Bar heights use a square-root scale. Only the 120 most-read articles are drawn; the journal has 8,486 in total.

Mint this article as an NFT
Not yet minted

Create a permanent, verifiable on-chain record of this article on the Scimatic Network. The NFT is held in your Journament account, and you can withdraw it to your own wallet at any time.

5 SUSD one-off · no wallet required
Sign in to mint
Abstract
The isobaric, isochemical coefficient of thermal expansion ( α) is the proportionality constant relating ∂V/V and ∂T. Noting that ∂V/V equals ∂lnV at constant pressure and composition (i.e., P and X): α=(∂VV∂T)P,X=(∂lnV∂T)P,X A polynomial expression for the temperature dependence of lnV yields direct and accurate calculation of α of melts and glasses. Using the approach, α G of Na-silicate glasses is shown to be constant between 300 and ∼650 K (P and X constant), but it increases linearly with Na 2 O content, indicating that α is controlled mostly by Na behaviour. Values of α for a melt or glass are necessarily (thermodynamically) related to the coefficients of thermal expansion of its ‘N’ melt components ( αN) by: α=α1θ1+α2θ2+α3θ3+⋯+αNθN where θ represents volume fraction of a component. Calculated αNa2O and αSiO2 values compare satisfactorily with reported values for melts containing ∼40–60 mole% Na 2 O but are less satisfactory for highly siliceous melts, implying need for refinement of α values. The Coulombic force of attraction between cation and anion is the primary determinant of the magnitude of α values of alkali and alkaline earths oxides. Their values represent a lower bound on α of 3d and 4f modifier oxides. Values larger than this lower bound likely result from a change in coordination number (CN) from higher to lower CN values of modifier cations. Experimental and molecular dynamics studies indicate that partial charges on NBO (O of Si-O-M moieties) and BO (O of Si-O-Si moieties) are about −0.96 and −0.64 respectively, thus NBOs should be incorporated into the first coordination spheres of modifier cations in preference to BOs. A simple mechanism is proposed whereby NBO-BO exchange occurs and CN of the modifier cation decreases with minimal topological adjustment or energetic cost to the melt.
Reference Key
openalex_W4396213938 Use this key to autocite in the manuscript while using SciMatic Manuscript Manager or Thesis Manager
Authors H.W. Nesbitt, Pascal Richet, Grant S. Henderson, G.M. Bancroft
Journal american journal of science
Year 2024
DOI
10.2475/001c.115477
URL
https://ajsonline.org/article/115477.pdf
Keywords Keywords not found

Citations

No citations found. To add a citation, contact the admin at info@scimatic.org

Comments

No comments yet. Be the first to comment on this article.