Synthesis and characterization of mullite (3Al2O3.2SiO2) sol by sol-gel route using inorganic salts
Bibliographic record
Abstract
Mullite, also referred to as 3Al2O3.2SiO2, is recognized as the only chemically stable intermediate phase in the SiO2–Al2O3 system, as indicated by mineralogical studies. Several synthesis techniques can be employed to obtain mullite. In this research, the synthesis of mullite particles is aimed to be achieved via the sol-gel route using inexpensive materials, specifically silica sol and aluminum nitrate hydrate [(Al(NO3)3.9H2O] as sources for silica and alumina, respectively. The article is organized into two sections which describe and discuss the systematic synthesis of the mullite sol. The first section emphasizes the influence of the stoichiometric values of Al and Si elements on the formation of the mullite phase at 1200 °C. The effects of sintering temperature on the microstructure and composition of the synthesized mullite sol, with a 3:1 alumina-to-silica ratio, are discussed in the following section. This includes pH, density, solid content, particle size distribution, thermal analysis, phase evolution with temperature, nature of bonds, and microstructural analysis. The XRD results for the mullite sol with a 3:1 alumina-to-silica ratio show strong crystalline diffraction peaks of the mullite phase and the absence of a free silica phase at 1200 °C. The solution exhibits a clear, stable, and homogeneous appearance, with a density of 1.17 g/cm3, a pH ranging from 4 to 5, and a solid content of approximately 15%, measured after heating at 1000 °C for 2 h.
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How this classification was reachedexpand
Full frame machine prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. The Gemma side is a direct model label for every work in the frame, read from the title-only record. The Codex side is a classifier learned from the 10,348 direct Codex labels and calibrated to design-weighted sample rates; fields without enough sample support carry no Codex call. Candidate is the union of the two sides; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels.
Distilled classifier scores by category (both heads)
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.001 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.001 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one source (direct Gemma or distilled Codex), not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".