Dynamics of anions and cations in cesium hydrogensulfide (CsHS, CsDS): Neutron and x-ray diffraction, calorimetry and proton NMR investigations
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Bibliographic record
Abstract
Protonated and deuterated samples of the hydrogensulfide of cesium were studied by high-resolution neutron powder diffraction, calorimetry and proton NMR investigations in a wide temperature range. Primarily due to reorientational disorder of the anions, three modifications of the title compounds are known: an ordered low-temperature modification—LTM (tetragonal, I4/m, Z=8), a dynamically disordered middle-temperature modification—MTM (tetragonal, P4/mbm, Z=2), and a high-temperature modification—HTM (cubic, Pm3̄m, Z=1). The LTM⇄MTM phase transition is continuous. Its order parameter, related to an order/disorder and to a displacive part of the phase transition, coupled bilinearly, follows a critical law. The critical temperature TC=123.2±0.5 K determined by neutron diffraction of CsDS is in good agreement with TC=121±2 K obtained by calorimetric investigations. For the protonated title compound a shift to TC=129±2 K was observed by calorimetric measurements. The entropy change of this transition is (0.24±0.04) R and (0.27±0.04) R for CsHS and CsDS, respectively. The MTM⇄HTM phase transition is clearly of first order. The transition temperatures of CsHS and CsDS are T=207.9±0.3 K and T=213.6±0.3 K with entropy changes of (0.86±0.01) R and (0.81±0.01) R, respectively. Second moments (M2) of the proton NMR absorption signal of MTM and HTM are in reasonable agreement with M2 calculated for the known crystal structures. A minimum in spin-lattice relaxation times (T1) in the MTM could not be assigned by dipolar coupling to a two-site 180° reorientation of the anions, a model of motion presumed by the knowledge of the crystal structure. The activation enthalpies determined by fits of T1 presuming a thermal activated process are in the order of molecular reorientations (Ea=13.5±0.5 kJ mol−1 for the MTM and Ea=9.3±0.3 kJ mol−1 for the HTM). In the HTM at T>330 K translational motion of the cations determines T1 (Ea=13.8±0.4 kJ mol−1).
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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) | 0.000 | 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) | 0.000 | 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