Asymmetry ratio as a parameter of Eu 3+ local environment in phosphors

Luminescence properties of novel Eu3+‐doped tantalate NaCaTiTaO6 red‐emitting phosphors for solid‐state lighting

“…To assess the site symmetry of Eu 3+ ions, the integrated emission intensity ratio (asymmetry ratio) ( 5 D 0 → 7 F 2 )/( 5 D 0 → 7 F 1 ) [R = I( 5 D 0 → 7 F 2 )/ I( 5 D 0 → 7 F 1 )=I 0-2 /I 0-1 ] was analyzed to describe the degree of distortion. 24 The asymmetry ratio of NaCaTiTaO 6 25,26 This result indicated it had potential in high red color purity. Figure 5B showed the energy level scheme of the sample.…”

“…Commonly, the I 0‐2 / I 0‐1 emission ratio was used as a viable way to describe the environment of a cation in lanthanide‐based systems. To assess the site symmetry of Eu 3+ ions, the integrated emission intensity ratio (asymmetry ratio) ( 5 D 0 → 7 F 2 )/( 5 D 0 → 7 F 1 ) [R = I( 5 D 0 → 7 F 2 )/I( 5 D 0 → 7 F 1 )= I 0‐2 / I 0‐1 ] was analyzed to describe the degree of distortion . The asymmetry ratio of NaCaTiTaO 6 :0.30Eu 3+ was 3.38.…”

Highly Efficient Extraction of Trivalent f‐Cations Using Several N‐Pivot Tripodal Diglycolamide Ligands in an Ionic Liquid: The Role of Ligand Structure on Metal Ion Complexation

“…It is well known that the 5 D 0 → 7 F 1 transitions (589 nm) of Eu 3+ are not perturbed by the local environment around the central metal ion, but the transition due to 5 D 0 → 7 F 2 (612 nm) is hypersensitive in nature and perturbed by the coordination of the ligands around the Eu 3+ cation . The “ asymmetry factor ” which is calculated as the ratio of the peak intensity at 612 nm to that at 589 nm has been used for qualitative explanation . It is evident from Figure that reducing the spacer length between the central N atom and the DGA moieties (–C 3 H 6 – in L I and –C 2 H 4 – in L II ) makes the complex more asymmetric as the hypersensitive 612 nm peak is highly sensitized in L II (Table ).…”

“…The asymmetry ratio is defined as the ratio of the intensities of the 613 nm and 589 nm emission peaks …”

Optical Investigation of Eu3+ Doped Bi12GeO20 (BGO) Crystals

“…Furthermore, the asymmetry parameter (calculated from the room temperature emission spectrum) R is defined as the ratio between the integral intensities of the 5 D 0 → 7 F 2 and 5 D 0 → 7 F 1 transition bands, R = I( 5 D 0 → 7 F 2 )/I( 5 D 0 → 7 F 1 ) may be considered as an indication of the Eu 3+ ion symmetry. Specifically, the further from a centrosymmetric geometry luminescent center is located, the higher the value of the asymmetry parameter R [15,27]. As expected, the determined R parameter for Eu 3+ :BGO specimens increases for samples with higher concentration of Europium 3+ , as the Eu 3+ ion somewhat disrupts lattice symmetry, which is due to the difference between the ionic radii of Bi 3+ (0.96 Å) and Eu 3+ (1.07 Å) ions, as indicated in Table 1.…”