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Structural and optical characterization of Er‐doped CaMoO 4 down‐converting phosphors
Author(s) -
Kaur Puneet,
Kumar Rajesh,
Davessar Shreya,
Khanna Atul
Publication year - 2020
Publication title -
acta crystallographica section b
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.604
H-Index - 33
ISSN - 2052-5206
DOI - 10.1107/s2052520620011397
Subject(s) - tetragonal crystal system , raman spectroscopy , phosphor , materials science , rietveld refinement , crystal structure , bond length , octahedron , doping , crystallography , analytical chemistry (journal) , monoclinic crystal system , molecular geometry , chemistry , molecule , optics , optoelectronics , physics , organic chemistry , chromatography
x Er 2 O 3 –(1− x )CaMoO 4 ( x = 1, 3, 5, 7 and 10 mol%) nanoparticles were synthesized by solid‐state sintering at 800°C. X‐ray diffraction studies confirmed the tetragonal crystal structure of CaMoO 4 , while the doped samples show the co‐existence of cubic Er 2 O 3 and tetragonal CaMoO 4 and rule out the replacement of Ca 2+ by Er 3+ in the structure. The crystal unit‐cell dimensions, phase concentration and atomic position coordinates were determined by Rietveld refinement. The short‐range structure of CaMoO 4 consists of tetrahedral MoO 4 and snub disphenoid deltahedral CaO 8 units, while the unit cell of Er 2 O 3 consists of two types of ErO 6 octahedral units. All MoO 4 units contain Mo—O bonds of equal lengths, whereas two types of slightly different Ca—O bond lengths exist in CaO 8 . Raman spectra of the doped samples show only Mo—O vibrational modes and the Raman peaks of Er 2 O 3 are masked by Mo—O bond vibrations. CaMoO 4 shows bluish‐green emission at 500 nm, while Er‐doped samples show strong green emission under UV excitation. UV irradiation (380 nm) induces down‐conversion green emission at 531 nm and 552 nm and good color purity in 1 mol% Er 2 O 3 –CaMoO 4 sample which makes it a potential candidate for applications in optical devices.