Physicochemical properties of Mn Incorporated Spinels
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Bibliographic record
Abstract
This thesis is aimed at tuning chemical and physical properties of spinels via a novel approach of manganese incorporation. Oxide spinels benefit from 1) hosting diverse cations at 4 and 6-coordinated sites; and 2) dual functionality of shared anionic oxygen in electron transport and surface reactivity. In other words, redox reactions over transition metal oxide spinels take advantage of charge transport in the bulk and mass exchange phenomena on the surface. Both rates of bulk charge transport and surface mass exchange depend on anion-cation interaction. Variability of manganese oxidation state and the impact of Jahn-Teller active Mn3+O6 are the most significant features affecting bulk properties as well as surface reactivity. This thesis establishes a meaningful correlation between activation energy of electron hopping and the rate of oxygen evolution reaction. Both features follow a volcano plot versus eg occupancy at octahedral site in the range of 0-2. Such a correlation is one of the novelties brought about by this thesis. \nThe effect of calcination and post calcination on the structural and electrical properties of MgFe2O4 is investigated. An oxygen free atmosphere is introduced as the most suitable environment to collect densified crystallites of magnesium ferrite at 850 ˚C. A DC electrical conductivity instrument was developed to evaluate the mechanism of electron hopping under controlled atmospheres. The instrumental approach allows us to evaluate the electron exchange interaction managed by cation-anion interactions. In situ evaluation of redox kinetics of such ceramic material is another feature of the instrument, providing novel insights into additional chemical and electrical properties. \nBoth single and multi-phase approaches of manganese incorporation in MgFe2O4 are considered here, along with applications pertaining to catalysis, electrocatalysis, energy storage, and sensors. In this thesis, an advanced composite of porous Mn3O4 in dense MgFe2O4 matrix is introduced and the effect of Mn diffusion into ferrite spinel is further investigated.
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Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.000 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.001 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 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 it