Structure–property correlations in Eu-doped tetra calcium phosphate phosphor: A key to solid-state lighting application

Komuro, Naoyuki; Mikami, Masayoshi; Saines, Paul J.; Cheetham, Anthony K.

doi:10.1016/j.jlumin.2015.02.006

Cited by 9 publications

(9 citation statements)

References 24 publications

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“…We have previously reported Ca 6 BaP 4 O 17 :Eu 2+ , 5 which is a rare bright yellow phosphor that can be excited using blue light and is importantly the first example reported in a phosphate system. We have also reported that Ca 4 (PO 4 ) 2 O:Eu 2+ (hereafter referred to as TTCP:Eu 2+ ), which has the longest excitation wavelength amongst phosphate systems, emits deep red light at room temperature and considerably broad emission from 500 nm to 800 nm at 77 K. 6 The relationship between the crystal structure and the unique emission characteristics of TTCP:Eu 2+ was discussed, differentiating the eight Ca sites. The importance of the anion polarizability and the distortions of the coordination polyhedra were also highlighted.…”

Section: Introductionmentioning

confidence: 97%

Deep red emission in Eu²⁺-activated Sr₄(PO₄)₂O phosphors for blue-pumped white LEDs

Komuro

Mikami²,

Saines

et al. 2015

J. Mater. Chem. C

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The deep red phosphor Sr 4 (PO 4 ) 2 O:Eu 2+ , which has an excitation peak around 450 nm for blue LED applications, is reported. This behavior is unusual for most phosphate phosphors. The crystal structure of Sr 4 (PO 4 ) 2 O:Eu 2+ is found to be monoclinic P2 1 and isotypic with Ca 4 (PO 4 ) 2 O:Eu 2+ , which also shows deep red emission. Sr 4 (PO 4 ) 2 O:Eu 2+ has a larger lattice volume than Ca 4 (PO 4 ) 2 O:Eu 2+ , but their emission and excitation spectra at room temperature are very similar. The key factors are discussed for achieving a large redshift of the 5d levels of Eu 2+ ion in order to emit red light. In particular, the importance of the anion polarizability and the distortions of the metal coordination polyhedra are discussed, including the effective coordination number. Importantly, Sr 4 (PO 4 ) 2 O:Eu 2+ lacks the yellow emission at 77 K, which is found in Ca 4 (PO 4 ) 2 O:Eu 2+ . The differences in thermal quenching behavior for Eu 2+ dopants in Sr 4 (PO 4 ) 2 O:Eu 2+ and Ca 4 (PO 4 ) 2 O:Eu 2+ are attributed to the degree of auto/photo-ionization due to differences in the band gaps of these compounds. The importance of the large band gap of the host lattice in avoiding non-radiative processes of energy relaxation was confirmed.

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Section: Introductionmentioning

confidence: 97%

Deep red emission in Eu²⁺-activated Sr₄(PO₄)₂O phosphors for blue-pumped white LEDs

Komuro

Mikami²,

Saines

et al. 2015

J. Mater. Chem. C

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“…This phenomenon results from the doping of Eu 2+ ions, which changes the crystal field environment and affects the vibrational level of the electrons in the outer shell . Additionally, although the radii of Ce 3+ and Eu 2+ are both compatible with the ionic radius of Ba 2+ , doping of these rare‐earth ions with different radii are considered to locate at different types of Ba1 or Ba2 lattice sites randomly, which may influence the electron transition and the optical properties of phosphors . Therefore, the photoluminescence spectra of the same phosphor may exhibit varying excitation wavelengths or the differences in intensity.…”

Section: Resultsmentioning

confidence: 99%

Luminescent properties of single‐phase Ba_{2‐x‐1.5y‐1.5z}P₂O₇:xEu²⁺,yCe³⁺, zTb³⁺ phosphors for white light‐emitting diode

et al. 2017

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Abstractpoor color rendering index and low stability of CCT. [1,4] Given that issue, it is necessary to explore single-phase white emissive phosphors for application in w-LEDs.Numerous efforts have previously been made to develop codoped single-phase white-emitting phosphors. [5,6] However, with the tri-doped phosphor it is easier to achieve tri-chromatic (RGB) emission with complete coverage when compared with co-doped phosphors. It is well known that the mixture of RGB emissions is more beneficial to generate an ideal warm white-light emission according to trichromatic theory. [7] Hence, more researchers have devoted themselves to developing the more complex tri-doped single-phase white-emitting phosphors. For example, Jiang and colleagues [8] It is a known reality that most phosphors are prepared via a conventional solid-state route, which has unavoidable disadvantages such as high synthesis temperature, nonhomogeneous mixtures and uncontrollable morphology. In particular, the obtained particles are very large with sizes in the range 1-10 μm. [9,10] In recent years, more researchers have focused on the co-precipitation method, which can overcome the above disadvantages and obtain nanophosphors with excellent luminescence properties. [9][10][11][12][13][14] Among these, Yi and colleagues [15] short, the co-precipitation method is very safe, energy-saving, timesaving option.At present, the most common hosts are aluminate and silicate systems with high stability and high QE. [16] But their synthesis conditions are harsh, in particular the synthesis temperatures are often as high as 1300°C. [17] Other materials, such as tungsten phosphate and rare earth oxides, can be easily synthesized, however they are chemically instable.[18] Barium pyrophosphate is a promising host for luminescent materials due to its low sintering temperature and stability. [18][19][20] Among the trivalent rare earth ions, Tb 3+ ion has been used frequently as the green emission center owing to its predominant 5 D 4 ! 7 F 5 transition with a peak centered at 545 nm. However, because of the forbidden transition and the weak absorption of Tb 3+ ion in the NUV region, the emission efficiency is low. [20,21] As is well known, Ce 3+ and Eu 2+ are often considered as the most important activator and effective sensitizer for Tb 3+ because of their unique electronic energy levels. [22][23][24][25] To the best of our knowledge, the crystal structures and lumines- | CharacterizationThe crystal phase of phosphor sample was analyzed by a SHIMADZU XRD-6000 diffractometer (Shimadzu Co., Japan) with Ni-filtered Cu single-phase. Ba 2 P 2 O 7 crystallized as a hexagonal structure with a space group p-62m and the lattice parameters were determined to be a = b = 9.415Å, c = 7.078Å, the crystal structure diagram of which is presented in Figure 2(a). The hexagonal form of Ba 2 P 2 O 7 signified that the sample host was at a higher temperature phase as σ-Ba 2 P 2 O 7 .Ba ions have two different types of coordination environments, in which one is coordinated b...

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“…[5,6] Among these ions, europium (Eu) is favoured by researchers because of its two different valence states. [7][8][9][10] The luminescence of divalent Eu 2+ ions is greatly influenced by its crystalline environment, unlike Eu 3+ , which has a stable red light emission in different substrates, so the luminescence of divalent Eu 2+ is very colourful and tunable. [11][12][13] Europium generally exists in the form of Eu 3+ in nature, so both the acquisition and utilization of Eu 2+ have become an important subject of research.…”

Section: Introductionmentioning

confidence: 99%

In‐air self‐reduction synthesis and luminescence properties from Mg₂₁Ca₄Na₄(PO₄)₁₈:Eu²⁺–Eu³⁺ excited using ultraviolet light

Peng

Huang

et al. 2021

Luminescence

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A series of Mg 21 Ca 4 Na 4 (PO 4 ) 18 :Eu 2+ -Eu 3+ phosphors was successfully synthesized using a high-temperature solid-state method in an air atmosphere. The phase structures and luminescence properties of the samples were studied in detail. The phosphors exhibited strong visible light emission under different wavelengths of ultraviolet light excitation. By harmonizing the doping concentration of Eu 3+ to adjust the relative luminescence intensity of Eu 2+ and Eu 3+ , a colourful emission of phosphors could be achieved. In addition, the colour coordinates of the International Commission on lighting indicated that Mg 21 Ca 4 Na 4 (PO) 18 :Eu 2+ -Eu 3+ could be considered as a potential blue, orange and red phosphor for white light-emitting diode applications.

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Structure–property correlations in Eu-doped tetra calcium phosphate phosphor: A key to solid-state lighting application

Cited by 9 publications

References 24 publications

Deep red emission in Eu²⁺-activated Sr₄(PO₄)₂O phosphors for blue-pumped white LEDs

Deep red emission in Eu²⁺-activated Sr₄(PO₄)₂O phosphors for blue-pumped white LEDs

Luminescent properties of single‐phase Ba_{2‐x‐1.5y‐1.5z}P₂O₇:xEu²⁺,yCe³⁺, zTb³⁺ phosphors for white light‐emitting diode

In‐air self‐reduction synthesis and luminescence properties from Mg₂₁Ca₄Na₄(PO₄)₁₈:Eu²⁺–Eu³⁺ excited using ultraviolet light

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Structure–property correlations in Eu-doped tetra calcium phosphate phosphor: A key to solid-state lighting application

Cited by 9 publications

References 24 publications

Deep red emission in Eu2+-activated Sr4(PO4)2O phosphors for blue-pumped white LEDs

Deep red emission in Eu2+-activated Sr4(PO4)2O phosphors for blue-pumped white LEDs

Luminescent properties of single‐phase Ba2‐x‐1.5y‐1.5zP2O7:xEu2+,yCe3+, zTb3+ phosphors for white light‐emitting diode

In‐air self‐reduction synthesis and luminescence properties from Mg21Ca4Na4(PO4)18:Eu2+–Eu3+ excited using ultraviolet light

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Deep red emission in Eu²⁺-activated Sr₄(PO₄)₂O phosphors for blue-pumped white LEDs

Deep red emission in Eu²⁺-activated Sr₄(PO₄)₂O phosphors for blue-pumped white LEDs

Luminescent properties of single‐phase Ba_{2‐x‐1.5y‐1.5z}P₂O₇:xEu²⁺,yCe³⁺, zTb³⁺ phosphors for white light‐emitting diode

In‐air self‐reduction synthesis and luminescence properties from Mg₂₁Ca₄Na₄(PO₄)₁₈:Eu²⁺–Eu³⁺ excited using ultraviolet light