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Tuning the Energy Transfer Efficiency between Ce 3+ and Ln 3+ Ions (Ln=Tm, Sm, Tb, Dy) by Controlling the Crystal Phase of NaYF 4 Nanocrystals
Author(s) -
Adusumalli Venkata N. K. B.,
Koppisetti Heramba V. S. R. M.,
Ganguli Sagar,
Sarkar Shyam,
Mahalingam Venkataramanan
Publication year - 2017
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201604316
Subject(s) - luminescence , ion , materials science , crystal (programming language) , phase (matter) , hexagonal phase , photon upconversion , nanocrystal , excited state , lanthanide , crystal structure , crystallography , doping , crystal field theory , analytical chemistry (journal) , chemistry , hexagonal crystal system , nanotechnology , atomic physics , optoelectronics , physics , organic chemistry , chromatography , computer science , programming language
NaYF 4 is a superior host matrix to study the luminescence properties of lanthanide (Ln 3+ ) ions. Ln 3+ ions in hexagonal‐phase NaYF 4 (β‐phase) nanocrystals (NCs) exhibit strong luminescence via an upconversion process compared to cubic NaYF 4 (α‐phase) NCs. However, in Ce 3+ /Ln 3+ ‐doped NaYF 4 NCs (Ln=Tm, Tb, Sm, Dy) the α‐phase NaYF 4 NCs shows strong luminescence compared to their counterpart β‐phase NCs despite the latter being much larger in size. This is attributed to comparatively large overlap between Ce 3+ ions emission band with excited energy levels of those Ln 3+ ions in α‐phase compared to β‐phase NCs. This difference is attributed to different crystal‐field splitting of Ce 3+ ions 4f–5d band in different crystal environments of the α‐phase (cubic crystal field environment) and β‐phase (trigonal prismatic with equatorials crystal field environment) NaYF 4 NCs with respect to their barycenter. The enhanced luminescence from α‐phase NaYF 4 NCs is advantageous as they are prepared at a relatively lower temperature and shorter reaction times compared to β‐NaYF 4 NCs.