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K2CaV2O7: a pyrovanadate with a new layered type of structure in the A2BV2O7 family
Alexander P Tyutyunnik1, Boris V Slobodin, Rina F Samigullina
1Institute of Solid State Chemistry, Ural Branch of the Russian Academy of Sciences, 91 Pervomayskaya str., Ekaterinburg GSP-145, 620990, Russia.
Dalton Transactions (Cambridge, England : 2003)
|November 1, 2012
Summary
The crystal structure of potassium calcium divanadium heptoxide (K(2)CaV(2)O(7)) was determined using X-ray powder diffraction. This pyrovanadate features undulating layers of calcium and vanadium oxides, with potassium ions situated between them.
Area of Science:
- Solid-state chemistry
- Crystallography
- Materials science
Background:
- Potassium calcium divanadium heptoxide (K(2)CaV(2)O(7)) is an inorganic compound.
- Understanding its crystal structure is crucial for exploring related materials.
Purpose of the Study:
- To determine the crystal structure of K(2)CaV(2)O(7) synthesized via solid-state reaction.
- To analyze the structural features and bonding within the compound.
- To investigate the stability of alkali metal calcium pyrovanadates.
Main Methods:
- Conventional solid-state reaction for synthesis.
- X-ray powder diffraction (XRD) for data collection.
- Direct methods and Rietveld refinement for crystal structure solution and analysis.
- Energy-dispersive X-ray (EDX) analysis for chemical composition confirmation.
- First-principles calculations for stability analysis.
Main Results:
- K(2)CaV(2)O(7) crystallizes in the triclinic space group P1.
- The structure consists of undulating CaV(2)O(7)(2-) layers with CaO(6) octahedra and V(2)O(7) pyrogroups.
- Potassium atoms occupy interstitial sites with distorted nine-fold coordination.
- Structural findings were corroborated by EDX analysis.
Conclusions:
- The detailed crystal structure of K(2)CaV(2)O(7) has been elucidated.
- The compound exhibits a layered structure with specific coordination environments for potassium ions.
- The stability of related pyrovanadates can be understood through cation-anion size correlations and theoretical calculations.
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