Traditional High Temperature Solid State Research Articles

Enhancement of the photoluminescence and long afterglow properties of Ca2MgSi2O7:Eu2+ phosphor by Dy3+ co-doping

The Ca2MgSi2O7:Eu2+ and Ca2MgSi2O7:Eu2+, Dy3+ long afterglow phosphors were synthesized under a weak reducing atmosphere by the traditional high temperature solid state reaction method. The synthesized phosphors were characterized by powder X-ray diffraction (XRD) and energy dispersive X-ray spectroscopy (EDX) techniques. The luminescence properties were investigated using thermoluminescence (TL), photoluminescence (PL), long afterglow, mechanoluminescence (ML), and ML spectra techniques. The crystal structure of sintered phosphors was an akermanite type structure, which belongs to the tetragonal crystallography. TL properties of these phosphors were investigated, and the results were also compared. Under the ultraviolet excitation, the emission spectra of both prepared phosphors were composed of a broad band peaking at 535 nm, belonging to the broad emission band. When the Ca2MgSi2O7:Eu2+ phosphor is co-doped with Dy3+, the PL, afterglow and ML intensity is strongly enhanced. The decay graph indicates that both the sintered phosphors contain fast decay and slow decay process. The ML intensities of Ca2MgSi2O7:Eu2+ and Ca2MgSi2O7:Eu2+, Dy3+ phosphors were proportionally increased with the increase of impact velocity, which suggests that this phosphor can be used as sensors to detect the stress of an object.

Enhancement of the photoluminescence and long afterglow properties of Sr2MgSi2O7:Eu(2+) phosphor by Dy(3+) co-doping.

Sr2MgSi2O7:Eu(2+) and Sr2MgSi2O7:Eu(2+),Dy(3+) long afterglow phosphors were synthesized under a weak reducing atmosphere by the traditional high temperature solid state reaction method. The synthesized phosphors were characterized by powder X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), and photo-, thermo- and mechanoluminescence spectroscopic techniques. The phase structure of the sintered phosphor was an akermanite type structure, which belongs to tetragonal crystallography. The thermoluminescence properties of these phosphors were investigated and compared. Under ultraviolet light excitation, the emission spectra of both prepared phosphors were composed of a broad emission band peaking at 470 nm. When the Sr2MgSi2O7:Eu(2+) phosphor was co-doped with Dy(3+), the photoluminescence (PL), afterglow and mechanoluminescence (ML) intensity were strongly enhanced. The decay graph indicated that both the sintered phosphors contained fast decay and slow decay processes. The ML intensities of Sr2MgSi2O7:Eu(2+) and Sr2MgSi2O7:Eu(2+),Dy(3+) phosphors were increased proportionally with increasing impact velocity, a finding that suggests that these phosphors could be used as sensors to detect the stress of an object.

Europium doped di-calcium magnesium di-silicate orange–red emitting phosphor by solid state reaction method

A new orange–red europium doped di-calcium magnesium di-silicate (Ca2MgSi2O7:Eu3+) phosphor was prepared by the traditional high temperature solid state reaction method. The prepared Ca2MgSi2O7:Eu3+ 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 P4¯21m, this structure is a member of the melilite group and forms a layered compound. The chemical composition of the sintered Ca2MgSi2O7:Eu3+ phosphor was confirmed by EDX spectra. The PL spectra indicate that Ca2MgSi2O7:Eu3+ can be excited effectively by near ultraviolet (NUV) light and exhibit bright orange–red emission with excellent color stability. The fluorescence lifetime of Ca2MgSi2O7:Eu3+ phosphor was found to be 28.47 ms. CIE color coordinates of Ca2MgSi2O7:Eu3+ phosphor is suitable as orange-red light emitting phosphor with a CIE value of (X = 0.5554, Y = 0.4397). Therefore, it is considered to be a new promising orange–red emitting phosphor for white light emitting diode (LED) application.

Photoluminescence properties of europium doped di-strontium magnesium di-silicate phosphor by solid state reaction method

Europium doped di-strontium magnesium di-silicate phosphor namely (Sr2MgSi2O7:Eu3+) was prepared by the traditional high temperature solid state reaction method. The phase structure of sintered phosphor was akermanite type structure which belongs to the tetragonal crystallography with space group P42¯1m, this structure is a member of the melilite group and forms a layered compound. The EDX and FTIR spectra confirm the present elements in Sr2MgSi2O7:Eu3+ phosphor. Photoluminescence measurements showed that the phosphor exhibited strong emission peak with good intensity, corresponding to 5D0 → 7F2 (613 nm) red emission and weak 5D0 → 7F1 (590 nm) orange emission. The excitation spectra monitored at 613 nm show broad band from 220 to 300 nm ascribed to O–Eu charge-transfer band (CTB) centered at about 269 nm, and the other peaks in the range of 300–400 nm originated from f–f transitions of Eu3+ ions. The strongest band at 395 nm can be assigned to 7F0 / 5L6 transition of Eu3+ ions due to the typical f–f transitions within Eu3+ of 4f6 configuration.

Tm3+浓度对Y2(MoO4)3∶Tm3+,Yb3+荧光粉上转换发光性质的影响

采用传统的高温固相反应法合成了Tm3+/Yb3+共掺杂Y2(MoO4)3系列荧光粉。XRD结果表明合成的样品为相纯度好的Y2(MoO4)3。在980 nm光激发下,样品具有较强的位于487 nm和800 nm的蓝色和近红外发射,同时伴有较弱的位于649 nm的红光发射。它们分别来自于Tm3+的1G4→3H6、3H4→3H16和G4→3F4跃迁。根据功率相关的上转换发射和能级图分析了Tm3+的上转换发光机制。结果表明,1G4和3H4能级的布居分别来自于三光子和两光子的能量传递上转换。此外,随着Tm3+浓度的增加,蓝色、红色和近红外发射带均呈先增加后降低的趋势,即发生了浓度猝灭。同时,蓝光发射和近红外发射的强度比随Tm3+掺杂浓度的增加而减小。

The effect of sintering temperature on prepared and properties of calcium hexaluminate/gehlenite composites

In this paper, the calcium-hexaluminate/gehlenite (CA6/C2AS) composites have been synthesized by traditional high temperature solid state method using magnesium slag as a source of calcium and silicon. The phases, micromorphology and physical properties of the samples were characterized and analysized. The results show that the CA6 and C2AS grains formation starts at 1300oC, the main reaction has completed above 1450oC. The granular particles of C2AS are distributed in CA6 grain boundaries. With the sintering temperature increased, the amount and the grains of CA6 grow up gradually, while the amount of C2AS reduces. The CA6 grains don?t growth excessively for the space hindrance function. With the sintering temperature increased the body density, linear shrinkage and flexural strength increases, while the apparent porosity decreases.

A novel emitting color tunable phosphor Ba3Gd(PO4)3: Ce3+, Tb3+ based on energy transfer

A novel emitting color tunable phosphor Ba3Gd(PO4)3: Ce3+, Tb3+ was synthesized by the traditional high temperature solid state reaction method. The photoluminescence (PL) and energy transfer (ET) properties of Ce3+ and Tb3+ doped Ba3Gd(PO4)3 host were studied in detail. The obtained phosphors show both a blue emission from Ce3+ and a yellowish-green emission from Tb3+ with considerable intensity under ultraviolet (UV) excitation (~310nm). When the content of Ce3+ was fixed at 0.05, the emission chromaticity coordinates could be adjusted from blue to green region by tuning the contents of Tb3+ ions from 0.01 to 0.5 through an ET process. The critical distance between Ce3+ and Tb3+ is 16.16Å. The ET mechanism from Ce3+ to Tb3+ ions was proved to be dipole–dipole interaction. The developed phosphor exhibits a strong excitation in UV spectral region and high efficient ET from Ce3+ to Tb3+ ions. It may find applications as a green light-emitting UV-convertible phosphor in white LED devices. Furthermore, a white light emission phosphor Ba3Gd(PO4)3: Ce3+, Tb3+, Mn2+ was also investigated.

Cyan emission of phosphor Sr6BP5O20:Eu2+ under low-voltage cathode ray excitation

A series of Eu2+ doped Sr6BP5O20 phosphors were prepared by a traditional high temperature solid state reaction method. Their photoluminescence under ultraviolet (UV) light and low-voltage electron beam excitation were investigated. Cyan emission band with a maximum wavelength at about 480nm can be observed. The chromaticity coordinates reveal the phosphor can evidently enlarge the gamut compared with tricolor phosphors. The results show that Sr6BP5O20:Eu2+ may be a potential candidate for field emission displays (FEDs).

Host absorption sensitizing and energy transfer to Eu3+ by Gd3+ in Ba6Gd2−xNa2Eux(PO4)6F2

Eu3+ activated fiuoro-apatite phosphors Ba6Gd2-xNa2Eux(PO4)(6)F-2 were synthesized using the traditional high temperature solid state reaction method, and their VUV-vis spectroscopic properties of Eu3+ were studied. The results show that phosphor Ba6Gd1.90Na2Eu0.10(PO4)(6)F-2 has intense absorption in the VUV range because of Gd3+ ions as sensitizers. The energy transfer process from Gd3+ to Eu3+ in Ba6Gd2-xNa2Eux(PO4)(6)F-2 were investigated and discussed in terms of luminescence spectra and decay curves, showing that the energy transfer of Gd3+ -> Eu3+ is efficient. (C) 2013 Elsevier Inc. All rights reserved.

Luminescence and time-resolved spectroscopy properties of (Gd1−xEux)(BO2)3 multicrystals

(Gd1−xEux)(BO2)3 (0≤x≤1) phosphors are synthesized by traditional high temperature solid state reaction. The photoluminescence (PL) properties of Gd(BO2)3 and Gd(BO2)3 activated with Eu3+ are investigated. The PL spectra exhibit the typical characteristic emission and excitation of Gd3+ and Eu3+ ions, and support the energy transfer taking place from Gd3+ to Eu3+ ions. The relationship between Eu3+ doping concentration and emission intensity is also studied. Even if all of the Gd3+ ions are substituted by Eu3+ ions, the concentration quenching between Eu3+ happens. However, the quenching is not complete. The luminescence decay curves are measured, and the lifetimes become short with the Eu3+ content increasing. The decreasing Gd3+ lifetimes also indicates that there exists efficient energy transfer between Gd3+ and Eu3+ ions.

Crystal structure and photoluminescence properties of Eu 2+-activated Ba 2LiB 5O 10 phosphors

A novel orange-yellow-emitting Ba 2LiB 5O 10:Eu 2+ phosphor has been synthesized by traditional high temperature solid state reaction. A monoclinic crystal structure of Barium lithiumborates Ba 2LiB 5O 10 was verified by the investigation of X-ray diffraction (XRD). The compound crystallizes in the space group of P121/m1(11) (Z = 2) with the unit cell parameters a = 4.414(1) Å, b = 14.576(2) Å, c = 6.697(2) Å and β = 104.26(2)°. Barium and lithium atoms are located in distorted octahedral and tetrahedral oxygen coordinations, respectively. Upon around 365 nm excitation, the Eu 2+-activated Ba 2LiB 5O 10 phosphors exhibit a single broad emission band with the maximum at about 587 nm, due to the 4f 65d → 4f 7(8S 7/2) transition of Eu 2+. This work investigates the relationship between luminescence properties and structural characterization of the Ba 2LiB 5O 10: Eu 2+. This newly developed phosphor shows high potential as a phosphor conversion for white LED applications.

Bright green-emitting, energy transfer and quantum cutting of Ba_3Ln(PO_4)_3: Tb^3+ (Ln = La, Gd) under VUV-UV excitation

Tb3+ doped Ba3Gd(PO4)3 and Ba3La(PO4)3 phosphors were synthesized using the traditional high temperature solid state reaction method. The excitation, emission, and decay spectra were measured at room temperature. Efficient energy transfer (ET) from Gd3+ to Tb3+ exists in Tb3+ doped Ba3Gd(PO4)3, and the ET efficiency increases with the increase of Tb3+ concentration. The visible quantum cutting (QC) via cross relaxation was observed upon exciting low-spin (7D(J)) 5d levels of Tb3+ ions. Ba3Tb(PO4)3 sample shows relatively strong emission intensity in comparison with Zn2SiO4: Mn2+ (ZSM) upon 172 nm excitation, and with a decay time τ(1/10) about 6.4 ms under 351 nm excitation, indicating the potential application of this phosphor for plasma display panels (PDPs) and Hg-free lamps.

Luminesce properties of the single white emitting phosphor Eu2+, Mn2+ co-doped Ca2SiO3Cl2

The intense white emitting phosphors Ca2SiO3Cl2:Eu2+, Mn2+ were synthesized by traditional high temperature solid state reaction，and their luminesce properties were studied. The results indicate that the emission band consists of three peaks located at 425 nm，498 nm and 578 nm, respectively. The emission peaks at 425 and 498 nm originate from the transition 5d→4f of Eu2+ ions that occupy the two Ca2+ sites in the crystal of Ca2SiO3Cl2, while the 578 nm emission is attributed to the energy transfer from Eu2+ ions to Mn2+ ions. The white light can be obtained by mixing the three emission colors of blue (425 nm), green(498 nm) and red(578 nm) in the single host. The excitation spectra of the three emission colors all extend from 250 nm to 420 nm, and their peaks positioned around 370 nm, 385 nm, 396 nm and 412 nm, respectively. The phosphor can be excited effectively by InGaN chip in the range of 350—410 nm. The experiment results show that the Ca2SiO3Cl2: xEu2+, yMn2+ is a single host phosphor with superior properties for use in white light emitting diode (w-LED).