Eu^(3+)掺杂石榴石型钒酸盐荧光粉研究进展

综述白色发光二极管的发光机理、发展历程,石榴石结构,Eu^(3+)单独掺杂、Eu^(3+)与其他稀土离子共同掺杂、Eu^(3+)与其他金属离子共同掺杂对石榴石型钒酸盐发光性能的影响等研究进展。提出白色发光二极管中红色荧光粉存在发光强度不足、稳定性低、寿命短等缺点,认为采用Eu^(3+)单独掺杂或者共同掺杂的方法能增强白色发光二极管中红色荧光粉的发光能力,对继续提高白色发光二极管中红色荧光粉的发光性能进行展望。

Endoscopic management of chronic radiation proctitis

Chronic radiation proctopathy occurs in 5%-20% of patients following pelvic radiotherapy. Although many cases resolve spontaneously,some lead to chronic symptoms including diarrhea,tenesmus,urgency and persistent rectal bleeding with iron deficiency anemia requiring blood transfusions. Treatments for chronic radiation proctitis remain unsatisfactory and the basis of evidence for various therapies is generally insuff icient. There are very few controlled or prospective trials,and comparisons between therapies are limited because of different evaluation methods. Medical treatments,including formalin,topical sucralfate,5-amino salicylic acid enemas,and short chain fatty acids have been used with limited success.Surgical management is associated with high morbidity and mortality. Endoscopic therapy using modalities such as the heater probe,neodymium:yttrium-aluminium-garnet laser,potassium titanyl phosphate laser and bipolar electrocoagulation has been reported to be of some benef it,but with frequent complications.Argon plasma coagulation is touted to be the preferred endoscopic therapy due to its eff icacy and safety profile.Newer methods of endoscopic ablation such as radiofrequency ablation and cryotherapy have been recently described which may afford broader areas of treatment per application,with lower rate of complications.This review will focus on endoscopic ablation therapies,including such newer modalities,for chronic radiation proctitis.

Empirical decay relationship between ionic conductivity and porosity of garnet type inorganic solid-state electrolytes

Ionic conductivity is one of the crucial parameters for inorganic solid-state electrolytes.To explore the relationship between porosity and ionic conductivity,a series of Li_(6.4)Ga_(0.2)La_(3)Zr_(2)O_(12) garnet type solid-state electrolytes with different porosities were prepared via solid-state reaction.Based on the quantified data,an empirical decay relationship was summarized and discussed by means of mathematical model and dimensional analysis method.It suggests that open porosity causes ionic conductivity to decrease exponentially.The pre-exponential factor obeys the Arrhenius Law quite well with the activation energy of 0.23 eV,and the decay constant is averaged to be 2.62%.While the closed porosity causes ionic conductivity to decrease linearly.The slope and intercept of this linear pattern also obey the Arrhenius Law and the activation energies are 0.24 and 0.27 eV,respectively.Moreover,the total porosity is linearly dependent on the open porosity,and different sintering conditions will lead to different linear patterns with different slopes and intercepts.

Non-isothermal decomposition kinetics of hydrogarnet in sodium carbonate solution

Carbonation decomposition of hydrogarnet is a significant reaction of the calcification-carbonation new method for alumina production by using low-grade bauxite.In this work,non-isothermal decomposition kinetics of hydrogarnet in sodium carbonate solution was studied by high-pressure differential scanning calorimetry(HPDSC) at different heating rates of 2,5,8,10,15 and 20 K·min^(-1),respectively.The activation energy(E_α) was calculated with the help of isoconversional method(model-free),and the reaction mechanism was determined by the differential equation method.The calculated activation energy of this reaction was 115.66 kJ·mol^(-1).Furthermore,the mechanism for decomposition reaction is Avrami-Erofeev(n=1.5),and the decomposition process is diffusion-controlled.

ORIGIN FOR IRRADIATION EFFECT OF 0.56 GeV C^(6+) ON CaVSn:YIG

This paper presents numerous physical characteristics of Ca, V, Sn doped yttrium iron garnet (CaVSn:YIG) irradiated with 0.56GeV carbon ions delivered by the Heavy Ion Research Facility of Lanzhou (HIRFL). The reason for change of the magnetic properties of the samples induced by energetic carbon ions bombardment is discussed. By comparison of this results with the irradiation effects of YIG induced by energetic argon, krypton and xenon obtained on the GANIL, Caen,France, it is concluded that the irradiation effect of 0.56 GeV C6+ on CaVSn.YIG arises from the electronic energy losses.

Synthesis of Ce-doped yttrium aluminum garnet phosphor by impinging streams co-precipitation

Phosphor yttrium aluminum garnet Y3A15O12 （YAG）, activated with trivalent cerium （Ce^3＋）, was synthesized by T-tube impinging streams, T-type vortex impinging streams co-precipitation method （IS-CP） and direct co-precipitation method （D-CP）, respectively. The crystallization, morphologies, particle size and particle size distribution of the phosphors obtained under different experimental conditions were studied. The influence of various factors on the luminescence intensity of the phosphor was also investigated, such as feeding methods, volume flow rate, contents of Ce and initial reactant concentration. The results show that the precursors synthesized by T-tube impinging streams co-precipitation reaction transform to Y3A15O12 （YAG） phosphor at about 1 000 ℃. The particles are far smaller and narrower than those prepared by D-CP. In the impinging streams co-precipitation system, the luminescent intensity of YAG：Ce phosphor increases with the increase of liquid flow rate. The intensity firstly increases then decreases with the increasing Ce^3＋ doping content, and the maximum intensity is shown at 1.67% （molar fraction） Ce. Luminescent intensity gradually decreases with the increase of initial concentration of reactants. At the same operational condition, the luminescent intensity of the phosphors prepared by T-tube impinging streams reactor is higher than that by D-CP, and the luminescent intensity of the phosphors prepared by T-type vortex impinging streams is higher than that by T-tube impinging streams reactor.

Synthesis and ionic conductivity of Li_6La_3BiSnO_(12) with cubic garnet-type structure via solid-state reaction

The synthesis and transport properties of the Li6La3BiSnO1212 solid electrolyte by a solid-state reaction were reported. The condition to synthesize the Li6La3BiSnO1212 is 785 °C for 36 h in air. The refined lattice constant of Li6La3 BiSnO1212 is 13.007A. Qualitative phase analysis by X-ray powder diffraction patterns combined with the Rietveld method reveals garnet type compounds as major phases. The Li-ion conductivity of the prepared Li6La3BiSnO12 is 0.85×10^-4 S/cm at 22 °C, which is comparable with that of the Li5La3Bi2O12. The Li6La3BiSnO1212 compounds are chemically stable against Li CoO2 which is widely used as cathode material up to 700 °C but not against the Li Mn2O4 if the temperature is higher than 550 °C. The Li6La3 BiSnO1212 exhibits higher chemical stability than Li5La3Bi2O12, which is due to Sn substitution for Bi.

Garnet of the Pyrope-Majorite Series from Coorara Meteorite and Lamprophyres of Central Timan

In kersantite and spessartite dikes of Chetlas Kamen＇ in Central Timan among accessory garnets, that are rather rare in lamprophyres, there was discovered few and for the first time high-majorite pyrope garnet with majorite minal Mg3Fe2[SiO4]3 （26-42%）, similar to majorite garnet originating from a meteorite. Majorite discovered in Coorara meteorite is very rare in the terrestrial rocks. As it is shown, there is 18% pyroxene admixture in original analysis of maj orite that is why a surplus of S i appeared in its formula. In rocks, where majorite garnet was found, there are also revealed microcrystalline diamonds.

Transmission electron microscopic study of the fine-grained vein matrix in the Suizhou L6 meteorite

The mineralogy of shock vein matrix in the Suizhou meteorite has been investigated by optical and transmission electron microscopy. It was revealed that the vein matrix is composed of majorite-pyrope garnet, mag- aesiowtistite, and ringwoodite, with FeNi-FeS inter- growths. The observation and character of ring-like selected electron diffraction （SAED） patterns indicate that Lhe idiomorphic garnet crystals in the vein matrix have different orientations. The polycrystalline nature of magnesiowtistite is also confirmed by a ring-like SAED pattern. Both garnet and magnesiowtistite crystals showed sharp Jiffraction spots, signifying the good crystallinity of these ：wo minerals. The SAED pattern of cryptocrystalline 5ngwoodite shows only diffuse concentric diffraction tings. FeNi metal and troilite （FeS）, which were molten during the shock event, occur in the matrix as fine eutectic FeNi-FeS intergrowths filling the interstices between garaet and magnesiowiistite grains. Based on the phase dia- gram of the Allende chondrite and the results of this TEM study, it is inferred that majorite-pyrope garnet first crystallized from the Suizhou chondritic melt at 22-26 GPa, Followed by crystallization of magnesiowtistite at 20-24 GPa, and then ringwoodite at 18-20 GPa. The eutectic intergrowths of FeNi-metal and troilite are proposed to have crystallized during meteorite cooling and solidified at the last stage of vein formation.

Fabrication and characterization of Ce:YIG thin film

Yttrium iron garnet （YIG） is widely used for microwave ferrite devices, especially for optical isolators. In this paper, ferrite ceramic target using cerium （Ce）-substituted YIG was made using ferric oxide （Fe203）, cerium oxide （CeO2） and yttrium oxide （Y2O3） powders as raw material. Ce： YIG thin films were fabricated by radio frequency （RF） magnetron sputtering. The experimental result showed that the polycrystalline YIG was obtained after sintering at 1 350 ℃ for 6 h, and the polycrystalline Ce： YIG thin films were achieved annealing up to 700 ℃ in the air.

Geochronology,geochemistry and geodynamics implications of Middle Triassic garnet-bearing muscovite monzogranite in central Jilin Province

Zircon LA-ICP-MS U-Pb geochronology and geochemical analyses are undertaken for the garnet-bear-ing muscovite monzogranite in Yitong area, central Jilin Province. The formation age and petrogenesis of the granite are determined, and the regional tectonic background is discussed. Zircons from the granite are euhe-dral-subhedral in shape, and display fine-scale oscillatory growth zoning, indicating a magmatie origin. LA- ICP-MS zircon U-Pb dating result indicates that the garnet-bearing muscovite monzogranites formed in the mid-dle Triassic （243 Ma ）. The garnet-bearing muscovite monzogranites have high SiO2 （SiO2 = 74.1%- 76.49% ）, rich aluminum （A1203 = 14.47%-14.68% ） and alkali （ NazO ＋ K20 = 4.31%-7.9% ）, low Fe203T and MgO （MgO =0.1%-0. 13% , Fe203T =0.46%-1.02% ）. The ratio of CaO/Na20 is between 0.17--0. 21. The garnet-bearing muscovite monzogranites in Yitong region are relatively enriched in light rare earth elements （LREEs） and large ion lithophile elements （LILEs） , and depleted of heavy rare earth elements （HREEs） and high field strength elements （HFSEs）. They are characterized by high Sr and Ba, poor Rb and Y, and negative Eu abnormally （δEu =0.48-0.62） , with Rb/Sr 〈 1. The εHf（t） values and TDM2 of zircons range from ＋ 6. 10 to ＋ 8.00 and from 725 Ma to 814 Ma, respectively. The above features indicate that gar- net-bearing muscovite monzogranites in Yitong area were derived from partial melting of metasedimentary rock. These granites have high Sr/Y ratios, which suggest they formed in a thickened continental crust. Combined with the coeval granitic rocks in central Jilin Province, we suggested that a significant eollisional and thickening event took place during the Middle Triassic.

Effects of Ti-and Mg-bearing minerals on hydrothermal formation of hydroandradite

The effects of Ti-and Mg-bearing minerals on the crystal structure,morphology,particle size distribution,and formation mechanism of efficient desilication product of hydroandradite(HA)during hydrothermal conversion in a synthetic sodium aluminate solution were investigated via X-ray diffractometer,scanning electron microscope and particle size analyzer.During HA formation,anatase,rutile,and periclase dissolved in sodium aluminate solution engage in ion substitution reactions between Ti4+and Si4+,and between Mg^(2+)and Ca^(2+),respectively.However,dissolved hydromagnesite cannot enter into the HA.The content of HA after the hydrothermal reactions changes slightly with the increase of anatase and periclase contents,but it notably decreases with increased quantities of rutile and hydromagnesite.Ti-bearing minerals reduce the particle size and enhance the specific surface area of HA,whereas Mg-bearing minerals exert the opposite effect.The morphology of HA with Ti-and Mg-bearing minerals changes from spherical particles to flocculent structure and hexagonal plate-like particles.

Metamorphism and zircon U–Pb dating of garnet amphibolite in the Baoyintu Group, Inner Mongolia

Garnet amphibolite in the Baoyintu Group, Inner Mongolia, is mainly composed of garnet, hornblende, plagioclase, quartz and minor rutile/ilmenite. Garnet occurs as porphyroblasts surrounded by plagioclase, forming typical ＂white-eye socket＂ texture. Garnet shows grossular content of 0.26-0.28 and pyrope of 0.11-0.13, without significant zoning. Plagioclase is generally zoned with anorthite （An） increasing from core to rim. The P-T pseu- dosection calculated using THERMOCALC in the system MnNCKFMASHTO shows that the garnet amphibolite experienced a clockwise P-T path with a peak at 1.3 GPa/725 ℃ defined from the minimum An content in plagioclase and maximum pyrope content in garnet, followed by an isothermal decompression. LA-ICP-MS zircon dating for the garnet amphibolite indicates metamorphic ages of 399 ± 6 Ma. The peak P-T condition corresponds to a thermal gradient of ～ 18 ℃/km, indi- cating typical medium-pressure type that commonly occurs in orogenic process with crustal thickening. We prefer to interpret this orogenic event to be a result of collision, following the closure of the Paleo-Asian Ocean before the early Devonian although there is a popular view that the Paleo-Asian Ocean may have lasted to the early Mesozoic.

The Dabie-Sulu orogenic peridotites:Progress and key issues

Orogenic peridotites in the Dabie-Sulu orogenic belt are commonly subdivided into‘crustal’type and‘mantle’type.They exhibit distinct mineral textures,metamorphic evolution,and whole-rock and mineral compositions.Most‘mantle’type peridotites originated from the subcontinental lithospheric mantle(SCLM)of the North China Craton and thus provide direct evidence of crust-mantle interactions in the continental subduction channel.In garnet peridotites,both garnet and Cr-spinel can be equilibrated at peak pressure conditions.Their stabilities are mainly controlled by the refertilized degree of whole-rock;therefore,spinel composition cannot be used to discriminate the partial melting degree of orogenic peridotites.Refractory mantle-derived dunites contain the textures of low Mg and high Ca olivine veins that crosscut orthopyroxene porphyroblasts,which is considered as evidence for silica-undersaturated melt-rock reactions.Such reactions occurring before subduction may potentially affect Re-Os isotopic compositions.Rutile,Ti-clinohumite and zircon in mantle-derived peridotites or pyroxenites provide direct mineralogical evidence for the transport of high field strength elements(HFSEs)from the subducted crust into the mantle wedge.Based on detailed in situ element and isotope analyses,we can constrain the source of metasomatic agents,the metasomatic time and the process of mass transfer.The mantle wedge above continental subduction zones has a wide range of oxygen fugacity values(FMQ=?5.50–1.75),showing a roughly negative correlation with the subducted depths.However,the calculated results of oxygen fugacity are significantly affected by mineral assemblages,P-T conditions and dehydrogenation-oxidation of nominally anhydrous mantle olivine during exhumation.Although significant progress has been made in the study of orogenic peridotites in the Dabie-Sulu orogenic belt,many critical questions remain.With new approaches and advanced technologic applications,additional knowledge of the phase relation in the peridotite-pyroxenite complex system,the mantle geodynamic process before continental subduction,the effects of crustal metasomatism on chemical composition,the oxygen fugacity,and the physical properties of the mantle wedge is anticipated.

P-T-t path of metamorphism for the Julin Group and its geodynamical implications in Yuanmou,Yunnan

The metamorphic complex of the Julin Group occurs in the Yuanmou area of Yunnan Province on the western margin of the Yangtze Platform, and connects with the Kangdian metamorphic complex to the north. Based on the detailed petrographic observations and studies of garnet growth zoning, a P-T-t path has been reconstructed for the staurolite-kyanite zone in the Julin Group. This path is characterized by (1) a counter-clockwise evolutional trend, (2) a quicker increase of temperature than that of pressure in the initial prograde metamorphism, but slower near the peak, then temperature and pressure simultaneously reaching the peak metamorphic conditions, and (3) a slow near-isobaric cooling during the retrograde process. The P-T-t path for prograde metamorphism is closely related to magmatic accretion in the arc setting. The magmatic accretion model, metamorphism type and tectonic setting may be compared with the global Grenville tectono-metamorphic events, and related to the assembly of the Rodinia at the late Meso-proterozoic-early Neoproterozoic (~1.0 Ga). The retrograde P-T-t path shows a slow near-isobaric cooling, indicating sustained heat supplies from the upper mantle and no rapid erosion. This heat source may be originated from the Neoproterozoic (~0.82 Ga) breakup of the Rodinia.