New melilite (Ca,Sr,Ba)4MgAl2Si3O14:Eu2+ phosphor: structural and spectroscopic analysis for application in white LEDs (original) (raw)
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Luminescence : the journal of biological and chemical luminescence, 2015
A europium (Eu)-doped di-calcium magnesium di-silicate phosphor, Ca2 MgSi2 O7 :Eu(2+) , was prepared using a solid-state reaction method. The phase structure, particle size, surface morphology, elemental analysis, different stretching mode and luminescence properties were analyzed by X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM) with energy dispersive X-ray spectroscopy (EDX), Fourier transform infrared (FTIR) spectroscopy, photoluminescence (PL) and mechanoluminescence (ML). The phase structure of Ca2 MgSi2 O7 :Eu(2+) was an akermanite-type structure, which belongs to the tetragonal crystallography with space group P4̅21 m; this structure is a member of the melilite group and forms a layered compound. The surface of the prepared phosphor was not found to be uniform and particle distribution was in the nanometer range. EDX and FTIR confirm the components of Eu(2+) -doped Ca2 MgSi2 O7 phosphor. Under UV excitation...
Chemical Physics Letters, 2014
Novel Na 0.60 Ca 0.40 Sc 0.60 Mg 0.40 Si 2 O 6 :Eu 2+ ,Mn 2+ (NCSMS:Eu 2+ ,Mn 2+) phosphors have been prepared, and the structural phase is derived from the solid-solution composition in (Na 1-x Ca x)(Sc 1-x Mg x)Si 2 O 6 (x = 0.4). The as-prepared phosphor shows full-color white emission with a three-band profile, including the 5d-4f transition of Eu 2+ in different emission centers (447 and 533 nm) and the d-d transition of Mn 2+ (654 nm). Energy transfer (ET) from Eu 2+ to Mn 2+ in this system is also discussed. A white LED lamp was fabricated by using the composition-optimized phosphor, and the result verified that the phosphor is a promising candidate for w-LEDs application. Highlights Novel Na 0.60 Ca 0.40 Sc 0.60 Mg 0.40 Si 2 O 6 :Eu 2+ ,Mn 2+ phosphors have been prepared. Full-color white emission can be realized in the single host with different emission centers. A white LED lamp was fabricated to demonstrate good luminescence properties.
Materials Letters, 2009
Eu 3+-activated novel red phosphors, MLa 2 (MoO 4) 4 (M = Ba, Sr and Ca) were synthesized by the conventional solid state method. The excitation and emission spectra indicate that these phosphors can be effectively excited by UV (395 nm) and blue (466 nm) light, and exhibit a satisfactory red performance at 614 nm. Upon excitation with a 466 nm light, our synthesized phosphors have stronger emission intensity than the sulfide red phosphors used in white LEDs. Due to high emission intensity and a good excitation profile, the Eu 3+-doped CaLa 2 (MoO 4) 4 phosphor may be a promising candidate in solid-state lighting applications.
White light-emitting Mg0.1Sr1.9SiO4:Eu2+ phosphors
Journal of Luminescence, 2008
Divalent europium-activated strontium orthosilicate Sr 2 SiO 4 :Eu 2+ and Mg 0.1 Sr 1.9 SiO 4 :Eu 2+ phosphors were synthesized through the solid-state reaction technique. Their luminescent properties under ultraviolet excitation were investigated. The X-ray diffraction (XRD) results show that these phosphors are of a 0 -Sr 2 SiO 4 phase with a trace of b-Sr 2 SiO 4 . Doping of Eu 2+ ion into the crystal lattice results in the lattice constant being expended, while Mg 2+ makes the lattice constant shrinking. A solid solution with the same crystal structure is formed when Eu 2+ or Mg 2+ substitutes part of Sr 2+ ions and occupies the same lattice sites. The Sr 2 SiO 4 :Eu 2+ phosphors show two emission spectra peaked at 535 and 473 nm originated from the 5d-4f transition of Eu 2+ ion doped in two different Sr 2+ sites in the host lattice. By substitution of 0.1 mol of Sr 2+ with Mg 2+ , these two emission bands are tuned to be in the blue and yellow region (459 and 564 nm for Mg 0.1 Sr 1.88 SiO 4 :Eu 0.02 ), respectively. The tuning effect is discussed. With a combination of the blue and yellow emission bands the phosphors show white color, indicating that these phosphors may become promising phosphor candidates for white lightemitting diodes (LEDs).
Journal of Radiation Research and Applied Sciences, 2015
A new orangeered europium doped di-calcium magnesium di-silicate (Ca 2 MgSi 2 O 7 :Eu 3þ) phosphor was prepared by the traditional high temperature solid state reaction method. The prepared Ca 2 MgSi 2 O 7 :Eu 3þ phosphor was characterized by X-ray diffractometer (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM) with energy dispersive x-ray spectroscopy (EDX), fourier transform infrared spectra (FTIR), photoluminescence (PL) and decay characteristics. The phase structure of sintered phosphor was akermanite type structure which belongs to the tetragonal crystallography with space group P42 1 m, this structure is a member of the melilite group and forms a layered compound. The chemical composition of the sintered Ca 2 MgSi 2 O 7 :Eu 3þ phosphor was confirmed by EDX spectra. The PL spectra indicate that Ca 2 MgSi 2 O 7 :Eu 3þ can be excited effectively by near ultraviolet (NUV) light and exhibit bright orangeered emission with excellent color stability. The fluorescence lifetime of Ca 2 MgSi 2 O 7 :Eu 3þ phosphor was found to be 28.47 ms. CIE color coordinates of Ca 2 MgSi 2 O 7 :Eu 3þ phosphor is suitable as orange-red light emitting phosphor with a CIE value of (X ¼ 0.5554, Y ¼ 0.4397). Therefore, it is considered to be a new promising orangeered emitting phosphor for white light emitting diode (LED) application.
Investigation of MAl2−xSixO4−xNx:Eu 2+ phosphor for improving luminescence properties of white LEDs
Indonesian Journal of Electrical Engineering and Computer Science, 2022
We implement a solid-state reaction technique to MAl2−xSixO4−xNx (M = Ca, Sr, Ba) as well as its variant doped with Eu at 1300-1400 °C in a nitrogen hydrogen environment. Then, we measure the solubility of (SiN) + in MAl2O4. By replacing (AlO) + with (SiN) + , whose solubility is dependent on M cations, nitrogen may be integrated into MAl2O4. (SiN) + has poor solubility in CaAl2O4 (x ≈ 0.025) and SrAl2O4 lattices (x ≈ 0.045) but a considerable integrated quantity of (SiN) + against BaAl2O4 (x ≈ 0.6). Because of the low solubility of (SiN) + , incorporation of (SiN) + barely affects the luminescence characteristics of MAl2O4 when doped with Eu 2+ (M = Ca, Sr), resulting in discharges in green as well as blue at nearly constant wavelengths measured at 440 as well as 515 nm, respectively. With certain concentrations of (SiN) + as well as Eu 2+ , Eu 2+-doped BaAl2−xSixO4−xNx emits one wide green discharge line under a maximum within the region 500-526 nm. Furthermore, once we add nitrogen, both the excitation as well as discharge lines for Eu 2+ exhibit one substantial redshift. BaAl2−xSixO4−xNx: Eu 2+ is a compelling transmuting phosphor that can be utilized for white light-emitted diodes (WLED) devices because of its efficient stimulation in the range of 390-440 nm radiation.
Acs Applied Materials & Interfaces, 2010
A series of single-composition emission-tunable Ca 9 Y(PO 4 ) 7 :Eu 2+ ,Mn 2+ phosphors were synthesized by solid-state reaction. The energy transfer from Eu 2+ to Mn 2+ in Ca 9 Y(PO 4 ) 7 host matrix was studied and demonstrated to be a resonant type via a dipole-quadrupole mechanism with the critical distance of ∼ 11 Å. The wavelength-tunable white light can be realized by coupling the emission bands centered at 486 and 638 nm ascribed to the contribution from Eu 2+ and Mn 2+ , respectively. By properly tuning the relative composition of Eu 2+ /Mn 2+ , chromaticity coordinates of (0.31, 0.33) can be achieved under excitation at 250-440 nm. Moreover, white-light-emitting diodes were fabricated through the integration of 365 nm chips and single composition white-lightemitting phosphors (Ca 0.975 Eu 0.01 Mn 0.015 ) 9 Y(PO 4 ) 7 into a single package shows a cool white light of 7200 K, color rendering index of 76, and color coordinates of (0.30, 0.31) close to that of ideal white light can be achieved.
Eu^2+ and Mn^2+ codoped Ba_2Mg(BO_3)_2—new red phosphor for white LEDs
Optics Letters, 2008
A new red phosphor, Ba 2 Mg͑BO 3 ͒ 2 :Eu,Mn, was synthesized by the solid-state reaction method and its photoluminescence properties were investigated by excitation and emission spectra and decay curves. Its excitation band is extending from 250-450 nm, which is adaptable to the emission band of near-ultraviolet LED chips ͑350-420 nm͒. Upon the excitation of 365 nm light, the phosphor exhibits strong red emission centered at 615 nm. The relationship between Eu 2+ and Mn 2+ dopants was studied from the viewpoint of a crystal structure and by photoluminescence spectra and decay curves. The results show that the characteristic Eu 2+ emission predominate in the emission band and Mn 2+ promote the redistribution of Eu 2+ at the cation sites of the host crystal.
Journal of Solid State Chemistry, 2015
Red phosphors with narrow emission around 615 nm (with FWHM $ 5-10 nm) having chemical compositions of A 0.6 Ca 2.16 Mo 0.2 W 0.8 O 6 : Eu 0.12 3 þ /Na 0.12 þ (A¼ Mg, Sr) have been found to exhibit the highest luminescence amongst the molybdate-tungstate family when excited by sources in the 380-420 nm wavelength range. Thus they are most suitable for enhancing color rendering index and lowering color temperature in phosphor converted white LEDs (pc-WLEDs) with near-UV/blue LED excitation sources. The excitation band edge in the near UV/blue wavelength in the reported phosphor has been attributed to the coordination environment of the transition metal ion (Mo 6 þ , W 6 þ) and host crystal structure. Furthermore the quantum efficiency of the phosphors has been enhanced by adjusting activator concentration, suitable compositional alloying using substitutional alkaline earth metal cations and charge compensation mechanisms.