六偏磷酸钠与Ce(Ⅲ)及Ce(Ⅳ)的作用

本文通过溶解度、电导和沉降体积法研究了水溶液中硝酸铈(Ⅱ)和硝酸铈(Ⅳ)与六偏磷酸纳的反应,制得了相应的固态化合物:Na_3Ce(PO_3)_0·9H_2O,Ce_2(PO_3)_0·11H_2O,Na_2Ce(PO_3)_0·5H_2O和Na_3Ce[(PO_3)_0]_2·13H_2O。并对其热稳定性进行了研究。     

Preparation and Characterization of Red Emitting Phosphor Ba_xCa_(3-x)(PO_4)_2∶Ce, Mn

Preparation and Characterization of Red Emitting Phosphor Ba_xCa_(3-x)(PO_4)_2∶Ce, Mn     

Effect of Eu~(3+) contents on structure and luminescence properties of Na_3Bi_(2–x)(PO_4)_3:xEu~(3+) and Na_3Bi_(1–x)(PO_4)_2:xEu~(3+) phosphors

A series of Na_3Bi_(2–x)(PO_4)_3:xEu~(3+) and Na_3Bi_(1–x)(PO_4)_2:xEu~(3+) phosphors were successfully synthesized by solid-state method.The structure and luminescence properties were carefully investigated.The excitation spectra presented an obvious excitation band,and the peak was located at 396 nm,which matched well with the popular emissions from near-UV light-emitting diode chips.With the phase of Na_3Bi_(2–x)(PO_4)_3:xEu~(3+) changing to that of Na_3Bi_(1–x)(PO_4)_2:xEu~(3+),the intensity of magnetic dipole transition(~5D_0→F_1) at 598 nm became stronger than that of electric dipole transition(~5D_0→~7F_2) at 621 nm.Under 396 nm excitation,the chromaticity coordinates and the decay curves of the entitled phosphors were also investigated.Based on all experiments without concentration quenching,we could control the luminescence intensity of the material by adjusting the doping amount of the active ions.All results indicated that Na_3Bi_(2–x)(PO_4)_3:xEu~(3+) and Na_3Bi_(1–x)(PO_4)_2:xEu~(3+) phosphors have potential application as red phosphors in near UV chip-based white light emitting diodes.     

Bibliography of Science and Technology of Rare Earths Published in China(1991)

Solid State Physics,Solid State Chemistry and New Materials215 Spectroscopy of(La,Ce.Tb)(PO_4,BO_3),He Dawei et al.,Chinese Journal of Luminescence,1991,12(1),40.216 Growth and spectra of Ce_xGd_yTb_(1-x-y)P_5O_(14) Crystal,Hong Guangyan et al.,Chinese Journal of Luminescence,1991,12(1),71.217 Syntheses and luminescence properties of host luminescent material Na_5Eu(MoO_4)_4 and NaEu(MoO_4)_2,GuoChangxin et al.,Chinese Journal of Luminescence,1991,12(2),118.     

(NH_4)_2〔Ce(NO_3)_6〕的制备及其水溶性研究

着重讨论水溶性较大的(NH_4)_2 〔Ce(NO_3)_6〕络合物制备过程中酸度、硝酸铵量、温度等对其合成的影响,并用(NH_4)_2 〔Ce(NO_3)_6〕-NH_6NO_3-H_2O的罗什布相图说明硝酸高铈铵在硝酸铵的水溶液中的溶解度变化。     

LUMINESCENCE OF Ce~(3 ) IN STRONTIUM HALOPHOSPHATES

Fluorescence spectroscopic study unraveled that there exist two types of luminescent center incerium(3 )activated Sr_5(PO_4)_3Cl crystals.Luminescence properties of Ce~(3 ) in Sr_5(PO_4)_3X(X=F,Cl,Br)have been studied.Meanwhile crystalline Sr_5(PO_4)_3Br and the subsolidus phase relationship of binarystrontium halophosphate systems have been determined.     

Synthesis and luminescence of β-SrGe(PO_4)_2:RE(RE=Eu~(2+),Eu~(3+),Tb~(3+)) phosphors for UV light-emitting diodes

A new series of β-Sr Ge(PO_4)_2:RE(RE=Eu~(2+),Eu~(3+),Tb~(3+)) phosphors were synthesized and characterized by using X-ray powder diffraction as well as excitation, and emission spectroscopy. The results exhibited that the singly doping Eu2+, Tb~(3+) and Eu~(3+) of β-Sr Ge(PO_4)_2 emit strong blue, green and red light under UV irradiation, respectively. Based on the charge transfer transitions of O~(2–)→RE~(3+), an overlapping excitation band of the as-obtained phosphors could be found in UV region, which made β-Sr Ge(PO_4)_2:RE(RE=Eu~(2+),Eu~(3+),Tb~(3+)) serve as a new series of RGB phosphors. Meanwhile, these phosphors could also be excited by 380 nm excitation simultaneously, and hence the three phosphors mixed physically could achieve the tunable hues from blue to white region by adjusting the mixed ratios.     

Luminescence properties of phosphate phosphors Ba3Gd1−x(PO4)3:xSm3+

A series of reddish orange phosphors Ba_3Gd_(1-x)(PO_4)_3:xSm~(3+)(x = 0.02.0.04,...,0.12) were prepared by the high-temperature solid-state reaction. X-ray powder diffraction(XRD) and diffuse reflectance and photoluminescence spectra were utilized to characterize the structure and spectral properties of the phosphors. The phosphors have strong absorption in the near-UV region. CIE chromaticity coordinates of the phosphors are located in the reddish orange region since the strongest emission band is around 598 nm and related to the ~4 G_(5/2)→~6 H_(7/2) transition of Sm~(3+). Optimal concentration of Sm~(3+) in the phosphors is about 6.0 at%. The quantum yield of the Ba_3Gd_(0.94)(PO_4)_3:0,06 Sm~(3+) under excitation at 403 nm is about 52.07%. Temperature dependent photoluminescence spectra of the Ba_3Gd_(0.94)(PO_4)_3:0.06 Sm~(3+) were measured and the phosphor exhibits high thermal stability of emission. All the results show that the Ba_3Gd(PO_4)_3:Sm~(3+) phosphor may be a potential red phosphor for near-UV based white LEDs.     

Luminescent properties of SrSi2N2O2:Ce3+,Tb3+-a potential phosphor for white light emitting diodes

Ce3+ and Tb3+ co-doped SrSi2N2O2 phosphors were prepared by solid-state reaction. The X-ray diffraction pattern exhibited that the phosphor consisted mainly of oxygen-rich SrSi2N2O2. The optical properties of SrSi2N2O2:Ce3+, SrSi2N2O2:Tb3+ and SrSi2N2O2:Ce3+,Tb3+ were studied, respectively. The emission intensity of Tb3+ at 541 nm was remarkably enhanced by Ce3+ in SrSi2N2O2:Ce3+,Tb3+ phosphor, which was attributed to the energy transfer from Ce3+ to Tb3+. The chromaticity coordinates of phosphors were investigated as a function of Tb3+ concentration. When the Ce3+ and Tb3+ concentrations were 0.02 and 0.18 mol per formula unit, respectively, the chromaticity coordinate was (0.257, 0.337) in the CIE 1931 chromaticity diagram. SrSi2N2O2Ce3+,Tb3+ phosphors could be used for white light emitting diodes.     

磷酸铵在(NH_4)_3PO_4-(NH_4)_2WO_4-NH_4OH-H_2O系中溶解度研究

采用等温结晶法研究了磷酸铵在(NH_4)_3PO_4-(NH_4)_2WO_4-NH_4OH-H_2O系中的溶解度。结果表明:低温、高氨浓度下(NH_4)_3PO_4-(NH_4)_2WO_4-NH_4OH-H_2O系中磷酸铵的溶解度非常小,易溶的磷酸铵表现出难溶的特征。温度10℃、氨含量15.6%(质量分数)时,磷酸铵的溶解度可低至0.02%(质量分数,P_2O_5);钨酸铵浓度对磷酸铵溶解度的影响很小;白钨矿磷酸铵分解液氨盐析-冷却结晶回收磷酸铵过程钨基本不结晶析出。研究结果为白钨矿磷酸铵分解液高效回收磷酸铵和初步脱磷奠定了理论基础。     

白钨矿添加磷酸盐和苛性碱浸取的生成物

有资料报导白钨矿添加磷酸盐苛性碱浸取的反应式为: 10CaWO_4+6PO_4~(3-)+20H~-=Ca_(10)(PO_4)_6(OH)_2↓+10WO_4~(2-)…………………………………………(1) 其生成物是否为Ca_(10)(PO_4)_6(OH)_2,我们没有条件去测定它。现仅就我们的试验结果来探讨其生成物是Ca_(10)(PO_4)_6(OH)_2还是Ca_(10)(PO_4)_n(OH)_(20-3n)。欢迎大家一道来研究这个问题。     

Flotation performance and adsorption mechanism of styrene phosphonic acid as a collector to synthetic(Ce,La)_2O_3

The flotation performances of styrene phosphonic acid(SPA) to synthetic(Ce,La)_2O_3(REO), calcium fluorite(CaF_2) and fluorapatite(Ca_5F(PO_4)_3) were investigated by flotation tests, flotation of synthetic mixed mineral, the surface adsorption capacity and the polarizing microscopy to solve the flotation separation problem of rare earth oxides from roasted concentrate. The flotation test results indicated that compared with CaF_2 and Ca_5F(PO_4)_3, SPA exhibited superior collecting performance to direct flotation recovery of REO and floated out above 90% REO at pH 3–6. However, the collecting ability of SPA to CaF_2 and Ca_5F(PO_4)_3 was extremely weak and the highest recovery was only 20% at pH 2–11. The flotation of synthetic mixed mineral showed that SPA was a good collector reagent for flotation of synthetic REO at pH 5, so REO, CaF_2 and Ca_5F(PO_4)_3 could be separated from roasted concentrate by using SPA as a collector. The surface adsorption capacity tests and polarizing microscopy results confirmed that SPA was adsorbed on REO surface, while CaF_2 and Ca_5F(PO_4)_3 were not. The adsorption mechanism of SPA to synthetic REO was studied by solution chemistry analysis of collector, the ζ-potential tests, infrared spectroscopy and X-ray photoelectron spectroscopy(XPS) analyses. The results indicated that SPA was physically adsorbed onto REO surface, which exhibited excellent flotation selectivity to REO against CaF_2 and Ca_5F(PO_4)_3.     

(NH_4)_2[Ce(NO_3)_6]水溶性的研究

硝酸高铈铵(NH_4)_2[Ce(NO_3)_6]是一种水溶性很大,又具有很强氧化性的桔红色络合物晶体。它主要被应用于集成电路板的腐蚀剂和聚丙烯(月先)胺的聚合剂或引发剂。制备的方法采用高浓度硝酸溶解Ce(OH)_4,再用NH_4NO_3合成,经离心机甩干而被制成。     

Synthesis,photoluminescence properties and thermal investigation by TG-MS of RE(DAS)_3·xH_2O(RE=Eu~(3+),Tb~(3+))

Rare earth(Ⅲ) diphenyl-4-amine sulfonates(RE(DAS)_3·xH_2O,RE=Eu~(3+),Tb~(3+))phosphors were synthesized by precursor method from barium diphenyl-4-amine sulfonate and rare earth sulfates.FTIR,TG/DSC coupled to mass spectrometry(TG/DSC/MS),X-ray powder diffraction(XPD),scanning electron microscopy(SEM) and photo luminesce nce(PL) spectroscopy were utilized to structurally and morphologically characterize the samples.Thermal decomposition of Eu(DAS)_3·7H_2O and Tb(DAS)_3·2H_2O at 973 K under dynamic air atmosphere results in crystalline Eu_2O_2SO_4 and Tb_2O_2SO_4 materials,respectively.Accordingly,MS spectra reveal the liberation of thermal decomposition products of precursors,largely as CO_2,NO_2 and SO_2 gases.The diphenyl-4-amine sulfonate(DAS) ligand demonstrats a good stabilizing property for Eu~(3+) and Tb~(3+) ions.The Eu(DAS)_3·7H_2O and Tb(DAS)_3·2H_2O compounds display efficient red and green emissions,under UV excitation,arising from the ~5D_0→~7F_J(J=0-4) and ~5D_4→~7F_J(J=0-6) transitions of the Eu~(3+) and Tb~(3+) ions,respectively.     

Samarium doped apatite-type orange-red emitting phosphor Ca_5(PO_4)_2SiO_4 with satisfactory thermal properties for n-UV w-LEDs

A novel single-phase Sm~(3+) activated Ca_5(PO_4)_2SiO_4 phosphor was successfully fabricated via a conventional solid-state method, which can be e fficie ntly excited by near ultraviolet(n-UV) light-emitting chips.The crystal structure and luminescence properties were characterized and analyzed systematically by using relevant instruments. The Ca_5(PO_4)_2SiO_4:Sm~(3+) phosphor shows an orange-red emission peaking at600 nm under the excitation of 403 nm and the optimal doping concentration of Sm~(3+) is determined to be 0.08, The critical distance of Ca_5(PO_4)_2SiO_4:0.08 Sm~(3+) is calculated to be 1.849 nm and concentration quenching mechanism of the Sm~(3+) in Ca_5(PO_4)_2SiO_4 host is ascribed to energy transfer between nearestneighbor activators. The decay time of Ca_5(PO_4)_2 SiO_4: 0,08 Sm~(3+) is determined to be 1.1957 ms. In addition, the effect of temperature on the emission intensity was also studied, 72.4% of the initial intensity is still preserved at 250 ℃, better thermal stability compared to commercial phosphor YAG:Ce~(3+) indicates that Ca_5(PO_4)_2SiO_4:0.08 Sm3+ has excellent thermal stability and active energy is deduced to be 0.130 eV.All the results demonstrate that orange-red emitting Ca_5(PO_4)_2SiO_4:0.08 Sm~(3+) phosphor exhibits good luminescent properties. Owing to the excellent thermal quenching luminescence property,Ca_5(PO4)_2SiO_4:0.08 Sm~(3+) phosphor can be applied in n-UV white light emitting diodes and serve as the warm part of white light.     

硼磷酸钇基质中Ce3+、Tb3+、Gd3+的发光及能量传递

用 BPO4 和稀土氧化物为原料 ,首次合成了铈、铽、钆共激活的硼磷酸钇绿色荧光粉 ,研究了基质中Ce3 、Tb3 、Gd3 的发光以及它们之间的相互作用。该基质中存在 Ce3 → Tb3 、Gd3 → Tb3 的能量传递 ,以及 Ce3 和 Gd3 之间的竞争吸收和独自发射。在铈、铽共激活的硼磷酸钇体系中掺入钆后 ,Ce3 的发射以及 Tb3 的 5D4 → 7FJ和 5D3→ 7FJ的发射均增强 ,但总的效果是 Gd3 阻碍了 Ce3 → Tb3 的能量传递。基质中钇全部被钆代替后 ,荧光粉的发光亮度增加 ,光纯度也较好 ,发光色坐标 X值稍变小。     

LiZnPO4：Tb^3＋,Ce^3＋ green phosphors with high efficiency

Tb3+ and Ce3+ co-activated LiZnPO4 phosphors with high luminescence efficiency were synthesized by a high temperature solid-state reaction at 1000 oC for 3 h. The XRD patterns, photoluminescence spectra and SEM were recorded and the effects of Tb3+ and Ce3+ concentration, sintering condition on the luminescent properties of as-synthesized phosphors were investigated. The emission spectra under ultraviolet (200-300 nm) radiation showed a dominant peak at 543 nm attributed to the 5D4→7F5 transition of Tb3+, which was greatly en-hanced by the co-doping of Ce3+, indicating that there occurred an efficient non-radiative energy transfer from Ce3+ to Tb3+. The optimal dop-ing concentrations of Tb3+ and Ce3+ were determined to be 9% and 10%, respectively.     

Photoluminescence properties of Tb3+ and Ce3+ co-doped Sr2MgSi2O7 phosphors for solid-state lighting

Sr2Mg Si2O7:Tb3+,Ce3+ phosphors were synthesized by solid-state reaction and placed in a muffle furnace in a reducing atmosphere at 1300 oC for 3 h. Photoluminescence properties and energy transfer were investigated. The Ce3+/Tb3+ energy transfer was thoroughly investigated by their emission/excitation spectra and photoluminescence lifetime, there was shortened lifetime of Ce3+(from 51.31 to 50.06 ns) which could support evidence of energy transfer from Ce3+ to Tb3+ in the host. The varied emitted color of Sr1.97–yMg Si2O7:0.03Tb3+,y Ce3+ phosphors could be achieved by altering the concentration of Ce3+, the chromaticity coordinates(x, y) varied from(0.225, 0.376) to(0.172, 0.231). In Sr1.96 Mg Si2O7:0.03Tb3+,0.01 Ce3+ phosphors, the results indicated that Sr2 Mg Si2O7:Tb3+,Ce3+ might be useful as tunable phosphors for ultraviolet white-light-emitting diodes.     

Tunable emission properties of tri-doped Ca_9LiY_(2/3)(PO_4)_7:Ce~(3+),Tb~(3+),Mn~(2+) phosphors with warm white emitting based on energy transfer

Tri-doped Ca_9 LiY_(2/3)(PO_4)_7:Ce~(3+),Tb~(3+),Mn~(2+)phosphors were prepared by a high-temperature solid state method.Under UV light excitation,Ca_9 LiY_(2/3)(PO_4)_7:Ce~(3+)samples exhibit a broad band ranging from 320 to 500 nm.At 77 K,the emission spectra of Ca_9 LiY_(2/3)(PO_4)7:Ce~(3+)samples present two obvious emission peaks,indicating that Ce~(3+)ions occupy two different kinds of lattice sites(Ca(1/2) and Ca(3)),As a good sensitizer for Tb~(3+),Ce~(3+)ions in Ca_9 LiY_(2/3)(PO_4)_7 lattice can effectively transfer part of energy to Tb~(3+),and the energy trans fer mechanism is determined to be dipole-dipole interaction.Consequently,the emitting color for Ce~(3+) and Tb~(3+) co-doped Ca_9 LiY_(2/3)(PO_4)_7 samples can be tuned from bluish violet to green.In order to further enlarge the emission gamut,Mn~(2+)ions as red emission components were added,forming tri-doped single-phase Ca_9 LiY_(2/3)(PO_4)_7:Ce~(3+),Tb~(3+),Mn~(2+)phosphors.The Ca_9 LiY_(2/3)(PO_4)_7:Ce~(3+),Tb~(3+),Mn~(2+)phosphors exhibit tunable emission properties through controlling the relative doping concentration of Ce~(3+),Tb~(3+)and Mn~(2+).Especially,Ca_9 LiY_(2/3)(PO_4)_7:0.09 Ce~(3+),0.12 Tb~(3+),0.30 Mn~(2+)can emit warm white light.The sample shows good thermal stability.At 150℃,the emission intensity for Ce~(3+)(360 nm),Tb~(3+)(545 nm) and Mn~(2+)(655 nm) decreases to 63%,69%,and 72% of its initial intensity,respectively.Moreover,the sample obtains good stability after 10 cycles between room temperature and150℃.     

Tb(Ⅳ)碱式碳酸盐的制备和一些性质的研究

本文报导了在[OH~-]=0.400～0.500M,[CO~(2-)_3]=2.000～2.200M条件下,Tb(Ⅲ)可被K_2S_2O_3氧化生成红棕色的Tb(Ⅲ)、Tb(Ⅳ)碱式碳酸盐固体混合物,Tb(1V)碱式碳酸盐含量约占80％。Tb(1V)碱式碳酸盐在PH=4的NaAc-HAc溶液中生成较稳定的橙红色络合物,它在370～380nm处有宽带吸收峰。