Andrzej Grzechnik, Vaclav Petříček, Dmitry Chernyshov, Charles McMonagle, Tobias Geise, Hend Shahed, Karen Friese
{"title":"Incommensurate structures and radiation damage in Rb<sub>2</sub>V<sub>3</sub>O<sub>8</sub> and K<sub>2</sub>V<sub>3</sub>O<sub>8</sub> mixed-valence vanadate fresnoites.","authors":"Andrzej Grzechnik, Vaclav Petříček, Dmitry Chernyshov, Charles McMonagle, Tobias Geise, Hend Shahed, Karen Friese","doi":"10.1107/S2052520623000999","DOIUrl":null,"url":null,"abstract":"<p><p>The structures and phase transitions to incommensurate structures in Rb<sub>2</sub>V<sub>3</sub>O<sub>8</sub> and K<sub>2</sub>V<sub>3</sub>O<sub>8</sub> mixed-valence vanadate fresnoites are studied with synchrotron single-crystal diffraction at low temperatures and ambient pressure. Although mixed satellite reflections are absent, the modulated structure of K<sub>2</sub>V<sub>3</sub>O<sub>8</sub> below 115 K is better described in (3 + 2)- than in (3 + 1)-dimensional space. The geometries of the VO<sub>4</sub> and VO<sub>5</sub> building units are rigid and it is mainly slight rotations of these polyhedra and small variation of the intermediate K-O distances that are modulated. Prolonged exposure to the high-brilliance synchrotron beam suppresses the incommensurate phase. The previously postulated phase transition to the incommensurate phase in Rb<sub>2</sub>V<sub>3</sub>O<sub>8</sub> at 270 K was not observed. One of the reasons could be that the intense radiation also affects the modulation in this material. Strategies to collect and analyse single-crystal diffraction data measured with very intense synchrotron radiation using modern low-noise pixel area detectors are discussed.</p>","PeriodicalId":7320,"journal":{"name":"Acta crystallographica Section B, Structural science, crystal engineering and materials","volume":null,"pages":null},"PeriodicalIF":1.3000,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10088480/pdf/","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Acta crystallographica Section B, Structural science, crystal engineering and materials","FirstCategoryId":"92","ListUrlMain":"https://doi.org/10.1107/S2052520623000999","RegionNum":3,"RegionCategory":"化学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"CHEMISTRY, MULTIDISCIPLINARY","Score":null,"Total":0}
引用次数: 0
Abstract
The structures and phase transitions to incommensurate structures in Rb2V3O8 and K2V3O8 mixed-valence vanadate fresnoites are studied with synchrotron single-crystal diffraction at low temperatures and ambient pressure. Although mixed satellite reflections are absent, the modulated structure of K2V3O8 below 115 K is better described in (3 + 2)- than in (3 + 1)-dimensional space. The geometries of the VO4 and VO5 building units are rigid and it is mainly slight rotations of these polyhedra and small variation of the intermediate K-O distances that are modulated. Prolonged exposure to the high-brilliance synchrotron beam suppresses the incommensurate phase. The previously postulated phase transition to the incommensurate phase in Rb2V3O8 at 270 K was not observed. One of the reasons could be that the intense radiation also affects the modulation in this material. Strategies to collect and analyse single-crystal diffraction data measured with very intense synchrotron radiation using modern low-noise pixel area detectors are discussed.
期刊介绍:
Acta Crystallographica Section B: Structural Science, Crystal Engineering and Materials publishes scientific articles related to the structural science of compounds and materials in the widest sense. Knowledge of the arrangements of atoms, including their temporal variations and dependencies on temperature and pressure, is often the key to understanding physical and chemical phenomena and is crucial for the design of new materials and supramolecular devices. Acta Crystallographica B is the forum for the publication of such contributions. Scientific developments based on experimental studies as well as those based on theoretical approaches, including crystal-structure prediction, structure-property relations and the use of databases of crystal structures, are published.