Conductivity of Potassium and Rubidium Dihydrogen Phosphates at High Temperature and Pressure
Bibliographic record
Abstract
The high-temperature behavior of KH 2 PO 4 and RbH 2 PO 4 has been investigated by several methods. Simultaneous differential scanning calorimetry and thermal gravimetry, combined with evolved gas analysis, was carried out from 25 to 500 °C under ambient pressure. The initial dehydration events in KH 2 PO 4 and RbH 2 PO 4 occur at 233 and 257 °C, respectively, with no indication of either solid−solid or solid−liquid transitions prior to weight loss. Application of pressure suppresses this dehydration. Impedance spectroscopy performed under 1 GPa revealed a highly reproducible superprotonic phase transition in RbH 2 PO 4 at 327 °C, at which the conductivity increased several orders of magnitude to a value of 6.8 × 10 - 2 Ω - 1 cm - 1 at 340 °C. The activation energy for proton transport in the superprotonic phase is Δ H a of 0.232 ± 0.008 eV and the pre-exponential factor A, 3.4 ± 0.6 × 10 3 Ω - 1 cm - 1 K. No superprotonic solid−solid phase transition was observed in KH 2 PO 4 . However, a sharp increase in conductivity to a value of 1.8 × 10 - 2 Ω - 1 cm - 1 at 345 °C was observed upon melting ( T m ∼ 325 °C). The liquid phase exhibited Arrhenius behavior comparable to that of superprotonic RbH 2 PO 4, with Δ H a = 0.227 ± 0.004 eV and A = 5. 2 ± 0.5 × 10 3 Ω - 1 cm - 1 K.
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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 | 0.001 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.000 | 0.000 |
| Bibliometrics | 0.000 | 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".