Synthesis, Structure, and Magnetic Properties of the Layered Copper(II) Oxide Na<sub>2</sub>Cu<sub>2</sub>TeO<sub>6</sub>
Bibliographic record
Abstract
A new quaternary layered transition-metal oxide, Na2Cu2TeO6, has been synthesized under air using stoichiometric (with respect to the cationic elements) mixtures of Na2CO3, CuO, and TeO2. Na2Cu2TeO6 crystallizes in the monoclinic space group C2/m with a = 5.7059(6) A, b = 8.6751(9) A, c = 5.9380(6) A, beta = 113.740(2) degrees, V = 269.05(5) A3, and Z = 2, as determined by single-crystal X-ray diffraction. The structure is composed of infinity(2)[Cu2TeO6] layers with the Na atoms located in the octahedral voids between the layers. Na2Cu2TeO6 is a green nonmetallic compound, in agreement with the electronic structure calculation and electrical resistance measurement. The magnetic susceptibility shows Curie-Weiss behavior between 300 and 600 K with an effective moment of 1.85(2) muB/Cu(II) and theta(c) = -87(6) K. A broad maximum at 160 K is interpreted as arising from short-range one-dimensional antiferromagnetic correlations. With the aid of the technique of magnetic dimers, the short-range order was analyzed in terms of an alternating chain model, with the surprising result that the stronger intrachain coupling involves a super-superexchange pathway with a Cu-Cu separation of >5 A. The J2/J1 ratio within the alternating chain refined to 0.10(1), and the spin gap is estimated to be 127 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 | 0.000 |
| 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 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".