New lanthanide complexes of salicylaldehyde- Schiff bases with salicyloyl hydrazide and anthranilic acid, were synthesized by a novel method consisting of refluxing the mixtures of Schiff base ligands and lanthanide trichloroacetate in acetone. Solid complexes of formulae Ln(SHSASB)3·2H2O and Ln2(AASASB)3·2H2O where Ln = La---Yb and Y, were isolated. Pronto NMR and IR spectra for the complexes reveal the bidentate binding of both the Schiff base ligands to the lanthanide ion. Electronic spectra along with the conductance data for the complexes indicate a coordination number of six for the lanthanide ion in the complexes of both the Schiff bases. 相似文献
The synthesis of a number of lanthanide tetracyanometallate (TCM) compounds have been carried out by reaction of Ln3+ nitrate salts and potassium tetracyanometallates in solvent systems containing dimethylsulfoxide and water. These reactions result in the isolation of three distinct structure types: (1) monoclinic [Ln(DMSO)4(H2O)3M(CN)4](M(CN)4)0.5·2H2O (Ln = Eu, Tb and M = Pd, Pt), (2) orthorhombic {La(DMSO)3(H2O)2(NO3)M(CN)4}∞·H2O (M = Pd, Pt), and (3) orthorhombic {Ln(DMSO)3(H2O)(NO3)M(CN)4}∞ (Ln = Tb and M = Pd, Pt; Ln = Er, Yb and M = Pt) in the form of single crystals. Single-crystal X-ray diffraction has been used to investigate their structural features. Structure type 1 is a zero dimensional ionic compound with a M/Ln ratio of 1.5:1. It contains coordinated as well as uncoordinated [M(CN)4]2− (M = Pd, Pt) anions and features relatively long platinophilic interactions. Structure types 2 and 3 differ quite drastically from structure type 1, but they are very similar to each other. Both of the latter are one-dimensional in nature due to chains containing linkage of Ln3+ coordination spheres with trans-bridging [M(CN)4]2− anions. These coordination polymers both have a M/Ln ratio of 1:1, a lack of platinophilic interactions, and incorporation of a bidentate NO3− for charge balance. Photoluminescence properties for select Eu3+ and Tb3+ compounds have been investigated. They show characteristic absorption and emission for the Ln3+ ions, but no significant influence of the tetracyanometallate anions. 相似文献
The synthesis of a series of lanthanide tetracyanoplatinates containing the auxiliary ligands 1,10′-phenanthroline (phen) or 2,2′-bipyridine (bpy) have been carried out by reaction of Ln3+ nitrate salts with phen or bpy and potassium tetracyanoplatinate in solvent systems containing dimethylsulfoxide and dimethylformamide. The use of these solvents has lead to the isolation of [{Ln(DMSO)2(C12H8N2)(H2O)3}2Pt(CN)4](Pt(CN)4)2·2C12H8N2·4H2O (Ln = Eu (Eu-1), Tb (Tb-1), Yb(Yb-1)), [Ln(DMF)3(C12H8N2)(H2O)2NO3]Pt(CN)4 (Ln = La (La-2), Eu (Eu-2), Tb (Tb-2)), and [Ln(DMF)3(C10H8N2)(H2O)2NO3]Pt(CN)4 (Ln = La (La-3), Sm (Sm-3), Eu (Eu-3), Tb (Tb-3)) in the form of single crystals. Single-crystal X-ray diffraction has been used to investigate their structural features. The use of DMSO versus DMF as the solvent results in markedly different structural features. Eu-1 contains [{Eu(DMSO)2(C12H8N2)(H2O)3}2Pt(CN)4]2+ complex cations where the two Eu3+ centers are linked by a trans-bridging Pt(CN)42− anion to form a dimeric lanthanide complex cation. An additional uncoordinated Pt(CN)42− anion balances charge. Eu-2 and Eu-3 consist of zero-dimensional salts with [Eu(DMF)3(C12H8N2)(H2O)2(NO3)]2+ or [Eu(DMF)3(C10H8N2)(H2O)2(NO3)]2+ complex cations, respectively, and only non-coordinated Pt(CN)42− anions. Photoluminescence measurements illustrate that the Eu3+ and Tb3+ compounds for all three structure types display enhanced emission due to intramolecular energy transfer from the coordinated cyclic amines. 相似文献
[Na2[Ln2(sal)4(CF3SO3)2(H2O)4](CF3SO3)2]n Ln = Nd (1) and Eu (2) were synthesized from the reaction of salicylaldehyde, lanthanide(III) triflates, and sodium hydroxide. The compounds are iso-structural and possess a 2-D supramolecular network built up from discrete dinuclear Ln(III) units [Ln2(sal)4(CF3SO3)2(H2O)4] via exo-coordination of Na(CF3SO3). The sal ligands display μ2-O coordination modes involving both the phenolic and carbonyl oxygen atoms while the triflates function as both μ2 and μ3 bridges. Each Ln(III) in the network is eight coordinate and in bicapped trigonal prism coordination geometry. Luminescence from [Na2[Eu2(sal)4(CF3SO3)2(H2O)4](CF3SO3)2]n showed temperature dependent sensitized emission with significant quadrupolar contribution and decay dynamical studies followed single exponential kinetics. Together these results indicate that in the presence of Na+ ions, sal, and triflate are useful ligands in the construction of Ln(III) coordination polymers with unusual luminescence and structures. 相似文献
By reacting aquobis(1,2-naphthoquinone 1-oximato)copper(II) [Cu(nqo)2·H2O] with lanthanide chlorides, new heteropolynuclear complexes containing both CuII and LnIII (LnIII = LaIII, NdIII) were obtained. The compounds have been characterized by elemental and thermogravimetric analysis, electron microprobe analysis, and electronic and vibrational spectral data. A different CuII complex, containing nqo ligands and ionic perchlorate but no lanthanide ions, was obtained by reaction of Cu(nqo)2·H2O with lanthanide perchlorates. 相似文献
The mononuclear macrocyclic lanthanide(III) complexes, [Ln(H2L)(H2O)4]Cl3 (Ln = Y, La, Ce, Cu, Tb, Yb, Lu; H2L = H2LA, H2LB, H2LC) were prepared by condensation 3,3′-(3,6-dioxaoctane-1,8-diyldioxy)bis(2-hydroxybenzaldehyde) or 3,3′-(3-oxapentane-1,5-diyldioxy)bis(2-hydroxybenzaldehyde) with 1,5-diamino-3-azamethylpentane or 1,7-diamino-3-azamethylheptane in the presence of LnCl3 · nH2O as templating agent. The asymmetric [1+1] ligands H2LA, H2LB and H2LC contain one smaller or larger N3O2 Schiff base site and one crown-ether like O2O4 or O2O3 site. The preference of the lanthanide ion to reside into the Schiff base or the crown-ether like chamber was investigated in the solid state and in methanol or dimethylsulfoxide solution. It was found that in the solid state or in methanol the lanthanide(III) ion coordinates into the O2On site while in dimethylsulfoxide demetalation and partial metal ion migration from the O2On into the N3O2 chamber occur. The mononuclear lanthanide(III) complexes [Ln(H2L)(H2O)4]Cl3 with the Ln3+ ion in the O2On site have been used as ligands in the synthesis of the heterodinuclear complexes LnLn′(L)(Cl)4 · 4H2O by reaction with the appropriate Ln′(III) chloride in methanol and in the presence of base. The related homodinuclear complexes Ln2(L)(Cl)4 · 4H2O have been prepared by the one-pot condensation of the appropriate precursors in the presence of base and of the lanthanide(III) ion as templating agent.The single-crystal X-ray structure of [Eu(H2LA)(H2O)4]Cl3 · 5H2O has been determined. The europium ion is nine-coordinated in the O2O3 ligand site and bonded to four water molecules and the coordination polyhedron can be described as a square monocapped antiprism.The site occupancy of the different lanthanide(III) ions and the physico-chemical properties arising from the different dinuclear aggregation and/or from the variation of the crown-ether shape have been investigated by IR and NMR spectroscopy, MS spectrometry and SEM-EDS microscopy. In particular, site migration and/or transmetalation reactions, together with demetalation reactions, have been monitored by NMR studies in methanol and dimethylsulfoxide. It was found that these processes strongly depend on the shape of the two coordination chambers, the solvent used and the radius of the lanthanide(III) ions. Thus, these molecular movements can be tuned by changing appropriately these parameters. 相似文献
The magnetic and luminescence characteristics of trimorphic homodinuclear macrocyclic complexes of lanthanides and a 2:2 phenolate Schiff's base L, derived from 2,6-diformyl-p-cresol and triethylenetetramine were determined. The complexes of Pr3+ exhibit non-Curie-Weiss temperature dependent magnetic susceptibilities for which satisfactory fits to an axial relationship depends on crystal field splitting and a weak binuclear Pr3+Pr3+ antiferromagnetic interaction. The exchange interaction parameters are zJ′ = −2.2, −4.4 and −7.0 cm −1 for ‘off-white’ Pr2L(NO3)4·2H2O, ‘yellow’ Pr2L(NO3)4, and ‘orange’ Pr2L(NO3)2(OH)2, respectively. In contrast, magnetic susceptibilities of the Ln2L(NO3)3(OH) complexes (Ln = Dy, Ho) follow Curie-Weiss behavior over the entire temperature range (6 K to 300 K). The complexes of closed shell ions La3+, Lu3+, Y3+ and those of the half filled shell ion Gd3+ exhibit a strong ligand fluorescence in the 450 nm to 650 nm range with decay times at 77 K of 5–8 ns for Ln≠Gd or 2–4 ns for Ln = Gd. The complexes of Gd3+ also exhibit a phosphorescence at 600 nm (decay time ∼ 200 μs). The complexes containing Ce3+, Eu3+, Tb3+ and Er3+ show very weak ligand luminescence indicative of effective quenching processes. Sensitized emission from the lanthanide ion is observed only with the Eu3+ complexes (5Do → 7Fj transitions). The emission lifetimes are on the order of 250 μs in the pure Eu3+ complexes. The emission decay curves from dilute samples of Eu3+ in ‘off-white’ La2L(NO3)4nH2O show a noticeable rise time as well as a biphasic decay (fast component ∼ 400 μs; slow component ∼ 2500 μs). The luminescing states of L and Eu3+ have a common excitation spectrum which is similar to the electronic absorption spectrum of L indicating that ligand-to-metal ion energy transfer processes are dominant. Overall the result if this study suggest that the spectral properties of the complexes are determined by the coordination mode of the lanthanide ions to the Schiff base portion of macrocyclic ligand. 相似文献
The reactions of 2,2′-bipyridyl-3,3′-dicarboxylic acid (H2bpdc) and 1,10-phenanthroline (phen) with lanthanide (III) salts in different concentrations under hydrothermal conditions formed two series of supramolecular isomers of 1D zigzag chains of [Ln(bpdc)1.5(phen)(H2O)]n·3nH2O (1Ln·3H2O), and 2D frameworks of [Ln(bpdc)1.5(phen)(H2O)]n (2Ln), (Ln = Ho, Er, Tm, and Yb). At lower concentrations, the supramolecular isomers of 1Ln were formed, in which each isomer has a dinuclear centrosymmetric dimeric unit of [Ln2(phen)2(H2O)2(μ2-bpdc)2]2+, and the dimeric units are alternately connected by μ2-bpdc2− to form a 1D zigzag chain of 1Ln. At higher concentrations, the supramolecular isomers of 2Ln were formed. All the compounds of 2Ln are isomorphous, in which two μ3-bpdc2− bridge two [Ln(phen)(H2O)]3+ units to yield a 1D double-chains of [Ln2(phen)2(H2O)2(bpdc)2]n2n+, and [Ln2(phen)2(H2O)2(bpdc)2]n2n+ chains are further connected by μ4-bpdc2− to form a 2D network of [Ln(bpdc)1.5(phen)(H2O)]n. The 2D sheets are combined through the intersheet π-π interactions between the adjacent phen molecules to form a 3D structure of 2Ln. The compounds of Er(III), and Yb(III) exhibit corresponding characteristic photoluminescence in the near-infrared (NIR) region, in which 1Ln and 2Ln show obviously different emission intensity due to their different structures. 相似文献
The luminescence and absorption spectra of the lanthanide ions in solids and coordination compounds are characterized by sharp pure electronic lines, which are accompanied by much weaker lines of vibronic transitions. The vibronic spectroscopy is a good probing tool for investigations of the properties of surrounding ion ligands. The lanthanides formates are efficient luminescent crystals and can be viewed as the elementary type in the whole class of the oxygen-containing lanthanide coordination compounds. The intensity of vibronic transitions in spectra of luminescence and excitation europium (5D0→7F2, 7F0→5D2), terbium (7F6→5D4), gadolinium (6P7/2→8S7/2) in anhydrous formates of the type Ln(HCOO)3 (Ln = Eu, Tb, Gd) and Y(HCOO)3.2H2O doped with Eu3+ and Tb3+ (C ~1 mol%) are reported. Also, the infrared and Raman spectra were obtained for the same compounds. Related integral intensity vibronic sidebands depend on the type of electronic transition of the same ion and varies for the same electronic transitions in different crystals. The obtained experimental data referring to the rate constants of vibronic transitions and intensity distribution in vibronic spectra on normal vibrations of the formate groups are in agreement with the predictions based on the Stavola–Dexter theory of cooperative vibronic transitions. 相似文献
The triboluminescence of Eu2(SO4)3·8H2O and Tb2(SO4)3·8H2O crystals in an atmosphere of sulfur dioxide (SO2) or sulfur hexafluoride (SF6) was studied. Quenching of the gaseous (emitter N2) and solid‐state (emitter Ln3+) components of the triboluminescence (TL) emission spectrum was seen when compared with the TL spectra of the crystals in air. One reason for the quenching is a reduction in the effective charge both on the crystal surface and in micro‐cracks under an SO2 or SF6 atmosphere, leading to a decrease in the probability of electrical breakdown and a reduction in electric field strength responsible for the electroluminescence excitation of lanthanide ions in TL. In an SO2 atmosphere, there is an additional mode of quenching, as confirmed by quenching of the crystal photoluminescence (emitter Ln3+). It is supposed that this quenching is due to an exchange of energy on electronic excitation of the lanthanide ions to the vibrational sublevels of the SO2 molecules adsorbed on the crystal surface. Another additional channel of TL quenching originates from non‐radiative transfer of excitation energy during collisions between the *N2 and SO2 molecules in the gaseous phase. 相似文献
Two lanthanide coordination polymers, {[La2(bpdc)3(H2O)4]·(H2O)4}n (1) and {[Sm2(bpdc)3(H2O)2]·(H2O)5}n (2) (H2bpdc = 2,2′-bipyridine-3,3′-dicarboxylic acid) have been obtained by hydrothermal synthesis. Single-crystal X-ray diffraction shows that 1 and 2 are two-dimensional network structures based on the zigzag chains which are linked by bpdc ligands, forming the first examples of binary lanthanide polymers with bpdc. It is unprecedented that the adjacent zigzag chains are symmetrical in mirror images with the arraying form of ?ABAB?. In 1 and 2, lanthanide ion are all nine-coordinate and bpdc ligands exhibit different kinds of coordination modes. The 1-D infinite water chain in 1 and pentameric water ring in 2 have been found between lattice water molecules. Thermo-gravimetric analyses of 1 and 2 display considerable thermal stability. Photoluminescent properties of 1 and 2 are discussed. 相似文献
New first examples of complexes with the general formula {[Ln2Sr(C4H3OCOO)8(H2O)4]}n, where Ln = La3+ (1), Pr3+ (2), Nd3+ (3), Sm3+ (4), Eu3+ (5), Gd3+ (6), Tb3+ (7), Ho3+ (8), Yb3+ (9) and Er3+ (10) have been prepared and investigated by photoluminescence spectroscopy and magnetic susceptibility measurements. The X-ray crystal structure has been determined for the {[Er2Sr(C4H3OCOO)8(H2O)4]}n (10) complex, indicating that this complex is built from two crystallographic independent coordination polymers {[Er2Sr(C4H3OCOO)8(H2O)4]}n in the triclinic crystal system and P1 space group. The X-ray diffraction (XRD) pattern of the samples shows that all lanthanide compounds are isostructural to 10. The luminescence spectrum of a microcrystalline sample of “2Eu-Sr” compound displays the characteristic Eu3+ (5D0 → 7FJ (J = 0-4)) metal centred transitions; also “2Nd-Sr” proved to be luminescent in the near IR. Measurements of the magnetic susceptibility for 2, 3, 5 and 10 were described using Crystal Field approach. 相似文献
Successful syntheses of the first examples of homodinuclear macrocyclic lanthanide complexes are reported. The complexes were obtained as compounds of the 2:2 Schiff base formed by condensing 2,6-diformyl-p-cresol and triethylenetetramine (L7) by a template procedure using lanthanide nitrates and perchlorates. When reactant methanolic solutions were concentrated the complexes were deposited as yellow or orange microcrystalline precipitates, Ln2L7(NO3)4sigma; nH2O or Ln2L7(NO3)4tau; x(OH)x, x = 1 or 2, whereas solutions diluted three times deposited complexes as flaky off-white crystalline precipitates of light lanthanides. The orange Ln2L7(NO3)2(OH)2 complexes can be converted in quantitative yield to the off-white flaky form of Ln2L7(NO3)4sigma; nH2O by refluxing them in methanolic solution containing triethylenetetramine and a three-fold excess of Ln(NO3)3. The complexes were characterized by elemental analysis, fast atom bombardment mass spectrometry, UV-Vis and infrared spectroscopy and thermogravimetry. Interesting and mostly new polyatomic oxo clusters, e.g. Ln2O3+, Ln3O4+, Ln4O6+, Ln5O7+, were dominant in the mass spectra but are treated in detail elsewhere. 相似文献
The selectivity of phosphoryl P(O)R3, sulfoxide S(O)R2, and carbonyl C(O)R2 (R?=?NH2, CH3, OH, and F) derivatives with lanthanide cations (La3+, Eu3+, Lu3+) was studied by density functional theory calculations. Theoretical approaches were also used to investigate energy and the nature of metal–ligand interaction in the model complexes. Atoms in molecules and natural bond orbital (NBO) analyses were accomplished to understand the electronic structure of ligands, L, and the related complexes, L–Ln3+. NBO analysis demonstrated that the negative charge on phosphoryl, carbonyl, and sulfoxide oxygen (OP, OC, and OS) has maximum and minimum values when the connected –R groups are –NH2 and –F. The metal–ligand distance declines as, –F?>?–OH?>?–CH3?>?–NH2. Charge density at the bond critical point and on the lanthanide cation in the L–Ln3+ complexes varies in the order –F?<?–OH?<?–CH3?<?–NH2, due to greater ligand to metal charge transfer, which is well explained by energy decomposition analysis. It was also illustrated that E(2) values of Lp(N)?→?σ*(Y–N) vary in the order P=O ? S=O ? C=O and the related values of Lp(N)?→?σ*(Y=O) change as C=O ? S=O ? P=O in (NH2)nYO ligands (Y?=?P, C, and S). Trends in the L–Ln3+ CP–corrected bond energies are in good accordance with the optimized OY?Ln distances. It seems that, comparing the three types of ligands studied, NH2–substituted are the better coordination ligands.
Graphical Abstract Density functional theory (B3LYP) calculations were used to compare structural, electronic and energy aspects of lanthanide (La, Eu, Lu) complexes of phosphine derivatives with those of carbonyls and sulfoxides in which the R– groups connected to the P=O, C=O and S=O are –NH2, –CH3, –OH and –F.
This contribution describes the synthesis and complete characterization of dinuclear (Ln2(SB)3) and rigorously dimeric ([(SB)Ln(N(TMS)2)]2) lanthanide complexes bearing “saturated” tetradentate Schiff bases (SB). The molecular connectivities, nuclearity, and metal ion coordination geometries in these compounds are governed by the interplay of Schiff-base steric requirements, metal ion radius, and reaction conditions (i.e., solvent choice, concentration, and temperature); the impact of these factors will be discussed and emphasized in the context of structural similarities and notable intramolecular interactions within these related compounds. Also presented is a tetranuclear Nd3+ complex exhibiting a ladder arrangement of metal ions and μ-oxo bridges; its formation occurs by the destruction of THF at elevated temperatures. All the compounds presented can be reproducibly synthesized in high yields and analytical purity. 相似文献
New complexes with the general formula [RE(TPC)3 · (H2O)2], where RE=Eu3+, Sm3+, Gd3+, Tb3+ and TPC=2-thiophenecarboxylate, have been prepared and investigated by photoluminescence spectroscopy. These compounds were characterized by complexometric titration, elemental analyses and infrared spectroscopy. The X-ray crystal structure has been determined for the [Eu(TPC)3 · (H2O)2] compound, indicating that this complex is in dimeric form bridged by two carboxylate ions with monoclinic crystal system and space group P21/n. The coordination polyhedron can be described as a distorted square antiprism, where six oxygen atoms belong to the TPC ligand and two oxygen atoms belong to the water molecules, with site symmetry close to C2v. The theoretical value of the intensity parameter , which is in agreement with the experimental one, indicates that the Eu3+ ion is in a highly polarizable chemical environment. Based on the luminescence spectra, the energy transfer from the ligand triplet state (T) of TPC to the excited levels of the Eu3+ ion is discussed. The emission quantum efficiency of the 5D0 emitting level of the Eu3+ ion was also determined. In the case of the Tb3+ ion, the photoluminescence data show the high emission intensity of the characteristic transitions 5D4 → 7FJ (J=0-6), indicating that the TPC ligand is a good sensitizer. It is also noticed that the complexes with the Eu3+ and Tb3+ ions are more luminescent than the complex with the Sm3+ ion. 相似文献
A variety of novel gaseous polyatomic binary and ternary oxides were observed at ambient temperature arising from lanthanide (Ln) nitrate Schiff base complexes, simple salts and sesquioxides, in an FAB mass spectrometer. The new binary oxides (as singly positive ions) detected are Ln2O3, Ln3O3, Ln3O4, Ln4O4, Ln4O5, Ln4O6, Ln5O6, Ln5O7, Ln5O8, Ln6O8, Ln6O9, Ln7O10, Ln8O11, Ln8O12 and Ln9O13; the ternary gaseous oxides are CeEuO2, CeEu2O3 and Ce2EuO4, LaYbO2, La2YbO4 and LaYb2O4; NdHoO3, Nd2HoO4, and NdHo2O4; YTmO3; YxTm3−xO4, x=1−2; YxTm4−xO6, x=1−3; YxTm5−xO7, x=1−4; YxTm6−xO9, x=1−5. Some of these oxides show the lanthanide cations in unusual oxidation states. Gadolinium-gallium ternary oxides, GdGaO2, GdGaO3 and Gd2GaO4 were also detected. The FAB MS environment is significantly reducing, yielding a homologous series EunOn where Eu2+ is dominant (E°(Eu3+/Eu2+)=−0.35 V) and no gallium or indium oxides (E°(M3+/M°=−0.34 V (In), −0.53 V (Ga)) were formed. The stoichiometry of the polylanthanide ternary oxides formed is determined largely by the chemistry of the major metallic component. The gaseous polyatomic oxides are probably formed through a reductive condensation process involving primary species Ln+ and LnO+ formed when the rare earth compounds are struck by fast Xe atoms. The demonstrated possibility of double component oxide formation broadens the number and types of gaseous lanthanide oxides which are accessible. 相似文献
Five new supramolecular lanthanide coordination polymers with three different structures, {[La2(IA)3(phen)2] · 2H2O}n (1), {[Ln(IA)1.5(phen)] · xH2O}n [x = 1, Ln = Eu (2); x = 0.25, Ln = Dy (3)], and [Ln(IA)1.5(phen)]n [Ln = Er (4); Yb (5)], were prepared by hydro- and solvothermal reactions of lanthanide chlorides with itaconic acid (H2IA) and 1,10-phenanthroline (phen), and structurally characterized by single crystal X-ray diffraction. 1 Comprises 1-D double-chains that are further assembled to a 3-D supramolecular structure via hydrogen bonds and π-π stacks between phen molecules. 2 and 3 have 2-D infinite networks which are further constructed to form 3-D supramolecular architectures with 1-D channels by π-π aromatic interactions. 4 and 5 have 2-D layer structures consisting of three types of rings which are further architectured to form 3-D supramolecular structures by C-H?O hydrogen bonds. The H2IA ligands are all completely deprotonated and exhibit tetra-, penta-, and hexadentate coordination modes in the titled complexes. The high-resolution emission spectrum of 2 shows only one Eu3+ ion site in 2, which is in agreement with the result of X-ray diffraction. And the magnetic property and the thermal stability of 2 were also investigated. 相似文献
Novel Ca2B2O5·H2O:Eu3+ nanotubes, constructed with nanobelts, were prepared using a hydrothermal method. The Ca3(BO3)2:Eu3+ nanobelts with a thickness of about 100 nm were made for the first time using a two‐step hydrothermal process with Ca2B2O5·H2O:Eu3+ as the precursor. The samples were characterized by energy dispersive X‐ray spectroscopy, X‐ray diffraction, Fourier transform infra‐red spectroscopy, thermogravimetry differential thermal analysis and scanning electron microscopy. The relationship between Ca3(BO3)2:Eu3+ and Ca2B2O5·H2O:Eu3+ was also studied. Possible reaction and growth mechanisms for Ca2B2O5·H2O:Eu3+ and Ca3(BO3)2:Eu3+ were proposed. Ca3(BO3)2:Eu3+ preserved the basic microstructure unit of Ca2B2O5·H2O:Eu3+. Both Ca2B2O5·H2O:Eu3+ and Ca3(BO3)2:Eu3+ exhibited red emissions centred at 614 nm, but the maximum excitation peaks for Ca2B2O5·H2O:Eu3+ and Ca3(BO3)2:Eu3+ differed. Ca3(BO3)2:Eu3+ exhibited higher photoluminescence intensity but a lower R/O value than Ca2B2O5·H2O:Eu3+. 相似文献
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