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Crystal Structure and Site Symmetry of Undoped and Eu 3+ Doped Ba 2 LaSbO 6 and BaLaMSbO 6 Compounds (M=Mg,Ca): Tuning Europium Site Occupancy to Develop Orange and Red Phosphor
Author(s) -
Phatak Rohan,
Pathak Nimai,
Muhammed Shafeeq,
Sali Sanjay K.,
Das Amitabh
Publication year - 2018
Publication title -
chempluschem
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.801
H-Index - 61
ISSN - 2192-6506
DOI - 10.1002/cplu.201800514
Subject(s) - octahedron , crystal structure , crystallography , monoclinic crystal system , europium , rietveld refinement , photoluminescence , ion , phosphor , electronegativity , chemistry , tetragonal crystal system , materials science , analytical chemistry (journal) , optoelectronics , organic chemistry , chromatography
Double perovskite antimonates of the type BaLaMSbO 6 (M=Mg, Ca) were synthesized by a standard solid‐state route. The compounds were characterized by X‐ray crystallography and the structures were refined using Rietveld method. BaLaMgSbO 6 and BaLaCaSbO 6 crystallized in monoclinic space groups ( I2/m ) and ( P2 1 /n ), respectively. In both compounds, La occupied the A‐site of perovskite, which is 12‐coordinated as compared to Ba 2 LaSbO 6 where La ion shifts to the B‐site octahedral coordination due to the larger size of Ba as compared with Mg and Ca. The samples were further characterized using FTIR and the frequency of the octahedral vibration is correlated to the electronegativity of the B‐site ions. Photoluminescence study of the title compounds and Ba 2 LaSbO 6 was carried out upon doping with 2 atom% Eu 3+ ion, which confirmed that Eu 3+ occupies distorted 12‐coordinated A‐site in BaLaMSbO 6 (M=Mg, Ca) and symmetrical octahedral B‐site in Ba 2 LaSbO 6 . Furthermore, the emission spectrum corresponding to each Eu 3+ ion at different crystal site was successfully isolated through a TRES study. This site selective occupancy of Eu 3+ ion also has a direct impact on the light emission, which was found to change from orange to red in a dark room in the order Ba 2 LaSbO 6 : Eu→BaLaCaSbO 6 : Eu→BaLaMgSbO 6 : Eu. Such an outcome will have high impact in designing new commercial Eu 3+ ion doped phosphor materials and tailoring of their optical properties.