Structural and optical properties of pillared Eu3+-containing layered double hydroxides intercalated by 2- to 12-carbon aliphatic dicarboxylates

While the versatile composition of layered double hydroxides(LDHs)allows the introduction of almost any polyvalent cation in their structure,the exchangeable negatively charged ions intercalated between the plates increase their vast range of functionalities.Here we report on the preparation and optical properties of pillared Eu³⁺-substituted ZnAl LDHs intercalated by aliphatic dicarboxylates:-OOC-(CH₂)_n-2-COO-.The basal distance in these materials is dependent on the size and packing of the intercalated anions.By varying the number(n)of carbon atoms in the aliphatic chain from 2 to 12,the interlayer gallery of these ZnAlEu LDHs is considerably expanded from 0.9 to 2.1 nm.In the interlayer gallery,the aliphatic dicarboxylates form a monolayer,with the aliphatic chain inclined by an angleα≈63°with the hydroxide layers.The carbon atom in the COO-group is 0.43 nm far from the metal plane,showing that these carboxylates are not grafted in the brucite-like layers.These LDHs are thermally stable up to around 150℃,after which dehydroxylation of the hydroxide layers is observed.The Judd-Ofelt intensity parameters were obtained and compared to the Eu³⁺-containing complexes with the same ligand series indicating a more symmetrical and less polarizable chemical environment around the rare earth ion.     

A dual-stimuli-responsive intelligent layered lanthanide hydroxide for application in information security and latent fingerprint identification

With the rapid changes in the field of information, the research and development of optical storage materials with high security and large storage capacity are particularly important in the development of contemporary society. However, conventional memory materials with static fluorescent outputs have the disadvantages of easy simulation and forgery, which limits their practical application in the protection of confidential information. In this research, a dual-stimuli-responsive intelligent fluorescent material based on Tb³⁺ and Eu³⁺ ions doped layered lanthanide hydroxide (LYH:Eu_xTb_1–xDPA) was fabricated, which can realize reversible multi-color luminescence conversion (from green to red) by varying the pH and temperature. Combined with the Morse code and security pattern, the multiple encryption and decryption of confidential information and anti-counterfeiting can also be realized. Therefore, the obtained intelligent fluorescent material has a great application prospect for information security. In addition, due to the excellent color tunability, the material can provide the possibility to obtain potential fingerprints with high contrast and no background interference on different color substrates. The unique dual-stimuli-responsive behavior of this material provides more ingenious design inspiration for the design of multi-color intelligent fluorescent devices.     

低C、O含量氟化稀土的制备工艺研究

以氯化钇为原料,采用碳酸氢铵制备的碳酸盐,通过复合氟化剂转化生成氟化钇,经过烘干和粒子整合之后得到无水氟化钇。考察了碳酸盐晶体质量、复合氟化剂的配比和浓度、反应温度、稀土浓度、pH值等对稀土氟化物中C、O含量的影响。结果表明:在选定条件下,用复合氟化剂将碳酸钇晶体转化生成氟化稀土,可明显降低氟化稀土中C、O的含量。     

Ln3+ (Ln = Eu,Dy) - doped Sr2CeO4 fine phosphor particles: Wet chemical preparation,energy transfer and tunable luminescence

The Sr₂CeO₄:Ln³⁺ (Ln = Eu, Dy) fine phosphor particles were prepared by a facile wet chemical approach, in which the consecutive hydrothermal-combustion reaction was performed. The doping of Ln³⁺ into Sr₂CeO₄ has little influence on the structure of host, and the as-prepared samples display well-crystallized spherical or elliptical shape with an average particle size at about 100–200 nm. For Eu³⁺ ions-doped Sr₂CeO₄, with the increase of Eu³⁺-doping concentration, the blue light emission band with the maximum at 468 nm originating from a Ce⁴⁺ → O²⁻ charge transfer of the host decreases obviously and the characteristic red light emission of Eu³⁺ (⁵D₀→⁷F₂ transition at 618 nm) is enhanced gradually. Simultaneously, the fluorescent lifetime of the broadband emission of Sr₂CeO₄ decreases with the doping of Eu³⁺, indicating an efficient energy transfer from the host to the doping Eu³⁺ ions. The energy transfer efficiency from the host to Eu³⁺ was investigated in detail, and the emitting color of Sr₂CeO₄:Eu³⁺ can be easily tuned from blue to red by varying the doping concentration of Eu³⁺ ions. Moreover, the luminescence of Dy³⁺-doped Sr₂CeO₄ was also studied. Similar energy transfer phenomenon can be observed, and the incorporation of Dy³⁺ into Sr₂CeO₄ host leads to the characteristic emission of ⁴F_9/2 → ⁶H_15/2 (488 nm, blue light) and ⁴F_9/2 → ⁶H_13/2 (574 nm, yellow light) of Dy³⁺. The Sr₂CeO₄:Ln³⁺ fine particles with tunable luminescence are quite beneficial for its potential applications in the optoelectronic fields.     

Study on Preparation and Property of Poly－Aminosilicone－Rare Earth Composite

The poly-aminosilicone-rare earth composite was prepared by poly-aminosilicone cross-linked with rare earth and active silanol. The thermal stability of the composites was studied by thermogravimetric analysis (TG). Force condition of the composites in electric field was analyzed and relative polarizability was derived. It is found that the composites containing different rare earth ions have different relative polarizability. The experiment results reveal that organosilicon materials with different electrical performance can be obtained by this way. Meanwhile, the absorption and flourescene spectrum of composites were also investigated. Compared to rare earth chloride, the spectrum properties of the composite are changed obviously. The possible reasons for these phenomena were discussed.     

Synthesis, Characterization and Fluorescence of Rare earth Nitrate Complexes with Triaza-crown Ether Derivative

Sinceaza crownethershowsspecialcoordinationpropertiestotransitionmetalandheavymetalions[1,2 ] ,therearemanyreportsofthecomplexesinhost guestchemistry ,molecularrecognition[3 ,4] andionophoreinmembranetransportation[5] ,butthereislittlereportontheirrareearthscomplexesandthefluorescenceaboutthecomplexes[6] ,andthefluorescenceintensityoftheircomplexesarenotverystrong .Weinsetbenzoylgroupintothemacrocycle ,expectingthatitsrareearthscomplexeshavebetterfluorescenceproperties .Inthispaperthesynthesis…     

Synthesis, Characterization of α-Oxopentanedioic Acid-Isonicotinoyl Hydrazone Rare Earth-Complexes and Relaxivity of Gd-complex

Themagneticresonanceimaging (MRI)tech niqueforthemedicineisveryusefultodiagnosepre tumorandbloodvesseldiseaseinheartandbrainandothermalignantpre diseases .Therefore ,specialatten tionhasbeenalsopaidtoMRIcontrastagents ,whichareindispensablediagnosingdrugsforthemagneticresonanceimagingtechnique[1,2 ] .Gadolinium (Ⅲ)complexwithsomepolycarboxylicandpolyaminelig ands ,suchasGd(DTPA)·nH2 O ,waswidelyusedincliniclongago .OurpreviousworkshowsthatsomepolycarboxylicSchiffbasecomplexeswithrareea…     

Synthesis,Characterization and Luminescent Properties of Complexes of Rare Earth Nitrates with Tris{2-[N-(pyridine-methanoyl)amino]ethyl} amine

Duringthelastdecade ,thedesignandsynthesisoftripodalligandsandtheirmetalcomplexeshaveattractedconsiderableattentionduetotheirpotentialusesaslumi nescentprobesinmedicineandbiochemistry[1～ 7] ,ascatalysts[8] andelectrochemicalmaterials[9] .However ,thecomplexesofrareearthmetalwithtripodalligandshavefewreported[10 ] .Asanextensionofourstudiesoncomplexesofmetalwithtripodalligands ,anewtripodalligand (tris { 2 [N (pyridine methanoyl)amino]ethyl}amine ,L)anditscomplexeswithrareearthnitratesweresyn…     

Spectroscopic investigations and luminescence spectra of Sm3+ doped soda lime silicate glasses

Sm3+ doped soda lime silicate glasses co-doped with As2O3 were prepared and characterised by measuring their absorption spectra in UV-VIS/NIR regions and luminescence spectra in the visible region. Judd-Ofelt intensity parameters, Ωλ, were evaluated from the measured intensifies of the various absorption bands. Ωλ parameters of these glasses were compared with the Ωλ parameters of other reported Sm3+ glasses to study the bonding environment surrounding the Sm3+ in the present glasses. Presence of [AsO4]3- tetrahedra in the second coordination sphere around the central Sm3+ ion made these glasses less covalent as compared to other oxide glasses but the ratio Ω4/Ω6 of the～1.83 indicated them to be fairly stable. With the help of Ωλ parameters and luminescence data for various emission lines, radiative properties for different emission lines were calculated. The values of radiative properties indicated that 4G5/2→6H7/2 and 4G5/2→6H9/2 transitions responsible for orange luminescence might be used in the development of materials for LED's and other optical devices in the visible region.     

Synthesis, Structure and Ionic Conductivity of La2／3-x Li3x MoO4

AlargenumberofM0 .5A0 .5M′O4 (M :rareearthion ,Bi3+,Fe3+,Cr3+,etc .A :alkaliion ,Cu+,Ag+,etc .M′ :Mo ,W )withtetragonalscheelite typestructurehavegoodcatalyticproperties .Aslumines centsubstrates ,theyhaveexcellentsensitizationtolu minescenceofrareearthion .Manyresearchesontheirstructure ,catalytic ,magneticandluminescentproper tieshavebeenmadesince 196 0s[1～ 10 ] .Thegeneralformulaforcompoundswiththetetragonalscheelite typestructureisAM′O4 wherethecationM′istetrahe drallycoordinat…     

Preparation and luminescence properties of the red-emitting phosphor（Sr1-xCax）2Si5N8：Eu^2＋ with different Sr/Ca ratios

A series of Eu2+-doped ternary nitride phosphors, with a formula of (Sr1-xCax)2Si5N8: Eu2+, were synthesized by high-temperature solid-state method. The structure and luminescence properties were characterized, indicating the potential application as a red phosphor in the phosphor-converted white light-emitting diodes. The X-ray diffraction patterns showed that the Sr2Si5N8 and Ca2Si5N8 phases were generated at each end of (Sr1-xCax)2Si5N8: Eu2+ and coexisted in the range of 0.5≤x≤0.75. The emission spectra showed broad emission bands originating from the 4f65d1→4f7 transition of Eu2+ ions. The emission peak changed with the variations in Ca2+ concentration.     

Combustion synthesis and luminescence properties of LaPO4： Eu （5%）

Rare earth doped materials are an important type of phosphors due to their excellent performance such as stability at high tem-perature and light emission covering the entire visible domain. The combustion synthesis at acid pH of the monoclinic LaPO4: Eu(5%) pow-sis was followed by structure, morphology characterisation and luminescent properties of the obtained compound. The room temperature emission measurements under ultraviolet excitation at 254 nm were made for the emission transition 5D0→7FJ of this phosphor. The CIE (Commission Internationale de L'Eclairage) chromatic coordinates, dominant wavelength and colour purity were determined and compared to other luminescent materials obtained by other methods.     

Preparation of cerium and yttrium doped ZnO nanoparticles and tracking their structural,optical, and photocatalytic performances

Yttrium(Y) and cerium(Ce) co-doped ZnO nanoparticles(NPs) were synthesized via the simple sol-gel auto-combustion route.The effect of Ce and Y doping on the structure,morphology,optical,Zeta potential,and photocatalytic activities of ZnO NPs was examined by Fourier transform infrared(FTIR)spectrometer,X-ray diffraction(XRD),transmission electron microscope(TEM),UV-vis spectrophotometer,and Zetasizer instrument.XRD data show that the fabricated samples crystallize into a hexagonal wurtzite struct...     

新型三元合金Nd(Y)-Fe-B吸波材料的制备及其性能研究

通过真空熔炼、行星球磨和适当退火处理后制得一种新型吸波材料NdxYFe92.56-xB6.5(x=4,5,6,7).对其性能进行测试后表明,退火前后各样品对微波的吸收量在所测频率范围内整体较高波动较小,其中,未退火处理的样品在频率为12.41GHz处最大吸收量达38.084dB,在下退火15min后样品吸波性有显著提高,在频率为12.04GHz处最大吸收量达94.573dB.     

锌与稀土分离及碱式碳酸锌的制备

在稀土湿法冶金生产工艺中实现了锌与稀土的萃取分离,制备出优于国标的碱式碳酸锌产品,对该产品进行了X射线衍射分析和经过原子吸收光谱对产品进行碳含量的分析,确定合成的碱式碳酸锌主要是以Zn5(CO3)2(OH)6形式存在。     

耐高温深棕色稀土陶瓷颜料的制备和表征

本试验合成了廉价的稀土深棕色陶瓷颜料。对颜料进行了物相鉴定及元素分析，绘制了吸收光谱。结果表明，颜料的析出结晶为Ｍｎ１．５Ｃｒ１．５Ｏ４和ＳｉＯ２。少量稀土元素进入晶格，它有加深颜色、提高鲜艳度和改进高温稳定性的特点。对发色机理进行了初步探讨。     

稀土合金的金相样品制备及组织分析

以Ｌａ－Ｃｏ－Ｎｉ三元系和Ｎｄ－Ｃｕ、Ｇｄ－ＣＵ二元系为例,介绍了稀土合金相试样的制备步骤和原则,给出了用该方法制作的５Ｌａ－７３Ｃｏ－２２Ｎｉ、５Ｌａ－８９Ｃｏ－６Ｎｉ、２５．６Ｌａ－３４Ｃｏ－４０．４Ｎｉ、Ｎｄ－６９Ｃｕ、Ｇｄ－１２Ｃｕ等成分合金的金相照片,并进行了适当的分析。     

掺杂稀土BaTiO3的制备及镍基催化剂的活性

采用柠檬酸盐法和溶胶-凝胶法合成出稀土掺杂的BaTiO3,并考察了稀土离子掺杂对BaTiO3颗粒粒径的影响。测定了掺杂BaTiO3的比表面积、晶相、粒度等粉体性能,指出稀土离子有抑制BaTiO3晶粒长大的作用。稀土掺杂的BaTiO3作镍基催化剂载体,以CO2/CH4重整制合成气为探针反应,评价了这些催化剂的催化活性,实验表明掺杂稀土有助于提高催化活性。