Synthesis of new Ln4(Al2O6F2)O2 (Ln = Sm, Eu, Gd) phases with a cuspidine-related structure

IUCrJ

Wain-Martin, A.¹  Morn-Ruiz, A.²  Orera, A.³ 

[1] Instituto de Ciencia de Materiales de Aragn (CSIC - Universidad de Zaragoza), C/ Pedro Cerbuna 12, Zaragoza 50009, Spain;Universidad del Pas Vasco (UPV/EHU), Facultad de Ciencia y Tecnologa, Barrio Sarriena S/N, Leioa, Vizcaya 48940, Spain;University of Birmingham, School of Chemistry, Birmingham B15 2TT, UK

关键词: CUSPIDINE-TYPE RARE-EARTH ALUMINATES;    FLUORINATION;    X-RAY DIFFRACTION;    POLY(VINYLIDENE DIFLUORIDE);    RAMAN SPECTROSCOPY;   

DOI  :  10.1107/S205225251801744X

学科分类：数学（综合）

来源: International Union of Crystallography

【 摘 要 】

The first fluorination of the cuspidine-related phases of Ln4(Al2O7□)O2 (where Ln = Sm, Eu, Gd) is reported. A low-temperature reaction with poly(vinyl­idene difluoride) lead to the fluorine being substituted in place of oxygen and inserted into the vacant position between the dialuminate groups. X-ray photoelectron spectroscopy shows the presence of the F 1s photoelectron together with an increase in Al 2p and rare-earth 4d binding energies supporting F incorporation. Energy-dispersive X-ray spectroscopy analyses are consistent with the formula Ln4(Al2O6F2)O2, confirming that substitution of one oxygen by two fluoride atoms has been achieved. Rietveld refinements show an expansion in the cell upon fluorination and confirm that the incorporation of fluoride in the Ln4(Al2O7□)O2 structure results in changes in Al coordination from four to five. Thus, the isolated tetrahedral dialuminate Al2O7 groups are converted to chains of distorted square-based pyramids. These structural results are also discussed based on Raman spectra.

【 授权许可】

CC BY