Synthesis and Characteristic Study on Complexes of Europium（Ⅲ） and Maleic Acid Doped with Non-Fluorescent Ions

Complex of europium （Ⅲ） with maleic acid, and binuclear complexes of europium（Ⅲ）with maleic acid doped with non-fluorescent ions gadolinium, lanthanum and yttrium, were synthesized. The compositions and structures of complexes were characterized with elemental analysis, single crystal X-ray diffraction, IR and DSC-TG. Fluorescent properties were studied with fluorescence spectrum. The results indicated that the strongest fluorescent complexes were obtained when the ratio of europium and non-fluorescent ion was 8：2. The order of Eu^3＋ fluorescence strengthened by three doped rare earths was Gd^3＋ 〉La^3＋ 〉Y^3＋     

Synthesis, crystal structure and characterization of one-dimension complex constructed by terbium（III） and 2-iodobenzoate

The complex of [Tb(2-IBA)₃(H₂O)₂]_n (2-IBA=2-iodobenzoate)was prepared by solvent method from TbCl₃·6H₂O and 2-iodobenzoic acid. The crystal structure was determined with X-ray single-crystal diffraction. The X-ray diffraction analysis indicated that the title complex crystallized in triclinic crystal system and Pī space group. The Tb³⁺ ion was coordinated by six oxygen atoms from five 2-IBA ligands and two oxygen atoms from two water molecules, giving a distorted square-antiprism polyhedral geometry. The carboxyl groups were bonded to the Tb³⁺ ions with bidentate-bridging and bidentate-chelating coordination modes. The adjacent Tb³⁺ ions were linked by two bidentate-bridging 2-IBA ligands, forming 1-D chain structure. The fluorescence spectrum of the complex showed four main peaks at 489, 543, 587, and 618 nm, corresponding to ⁵D₄→⁷F_J (J=6?3) transition emissions of the Tb³⁺ ion, respectively.     

Synthesis, characterization and fluorescence of N,N'-BIS (6-metyl-2-pyridine-carboxylamide-N-oxide)-1,2-ethane and corresponding rare earth (Ⅲ) complexes

A new ligand, N,N-BIS (6-metyl-2-pyridinecarboxylamide-N-oxide)-1,2-ethane (L) and six lanthanide(III) complexes (RE=La, Sm, Eu, Tb, Gd, Yb) were synthesized and characterized in detail. The results indicated that the composition of the binary complexes was determined as [REL(H₂O)(NO₃)₂]NO₃·nH₂O (n=0–2), and the Eu³⁺ complex had bright red fluorescence in solid state. Three complexes of Eu³⁺, Tb³⁺, and Gd³⁺ with 6-methylpicolinic acid N-oxide (L') were also synthesized. The relative intensity of sensitized luminescence for Eu³⁺ increased in the following order: L>L'. The phosphorescence spectra of the Gd³⁺ complexes at 77 K were measured. The energies of excited triplet state for the ligands were 20704 cm⁻¹ (L) and 20408 cm⁻¹ (L'). The facts that the ligands sensitized Eu³⁺ strongly and the order of the emission intensity for Eu³⁺ complexes were explained by ΔE(T-⁵D). This meant that the triplet energy level of the ligand was the main factor to influence RE³⁺ luminescence.     

Application of three Ln(Ⅲ)-coordination polymers in fields of luminescence,antibacteria and detection of Fe3+ and 4-nitrophenol

Three lanthanide-based coordination polymers(Ln-CPs) with layered structure,{[La₂(L)₃(DMF)(H₂O)₃]·H₂O}_n(1),{[Eu₂(L)₃(DMF)₂(H₂O)]·(H₂O)}_n(2){Tb₂(L)₃(DMF)₂(H₂O)]·H₂O}n(3) were successfully synthesized from H₂L(N,N’-bis(4-carbozylbenzyl)aniline).Remarkably,compound 3 has extremely high sensitivity to 4-n...     

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.     

Fluorescence and Judd-Ofelt analysis of rare earth complexes with maleic anhydride and acrylic acid

Two kinds of Eu-complexes, Eu(TTA)2(Phen)(AA) and Eu(TTA)2(Phen)(MA) (HTTA=2-Thenoyltrifluoroacetone, Phen=1,10- phenanthroline, AA=acrylic acid, MA=Maleic anhydride), which combined the excellent fluorescence properties of Eu(TTA)2(Phen)(H2O) and the reactivity of acrylic acid and maleic anhydride with radicals, were synthesized. The two complexes were characterized by elemental analysis, infrared (IR) spectra, and X-ray photoelectron spectroscopy (XPS). Based on the data shown from the fluorescent spectra of the Eu-MA and Eu-AA complexes, the ?λ (λ=2 and 4) experimental intensity parameters were calculated. The results demonstrated that the ?2 intensity parameters for the two complexes were smaller than those for the Eu(TTA)2(Phen)(H2O) complex, indicating that a less symmetri- cal chemical environment existed in the complexes. It implied that the radiative efficiency of the 5D0 of these two complexes could be en- hanced by ligand of MA and AA, respectively. The luminescent lifetime of the Eu-AA (τ=7.26×10–4 s) or Eu-MA complex (τ=8.12×10–4 s) was higher than that of the Eu(TTA)2(Phen)(H2O) complex, which was attributed to the substitution of the water molecule (H2O) in Eu(TTA)2(Phen)(H2O) by the MA or AA ligand.     

Synthesis and characterization of terbium(III)-pyromellitic acid (H4L)-1,10-phenanthroline (phen) luminescent complex

The terbium(III)-pyromellitic acid(H₄L)-1,10-phenanthroline(phen) luminescent complex was synthesized using a co-precipitation method. The chemical composition of the synthesized complex was speculated to be Tb₄L₃(phen)_0.075·10H₂O by elemental analysis, inductively coupled plasma-atomic emission spectroscopy (ICP-AES), and Fourier-transform infrared spectroscopy (FT-IR). The X-ray diffraction analytic results indicated that the synthesized complex is a new crystalline complex, whose structure was different from those of other two ligands. The scanning electron microscopy analytic results showed that the product was of spherical crystals with good dispersion property, and the mean diameter of the spheres was about 1-2 μm. The TG-DTA result showed that the complex had good stability below 489 °C. PL spectra showed that the complex emitted characteristic green fluorescence of Tb(III) ion under ultraviolet excitation.     

Photoluminescent properties of Eu3＋ and Tb3＋ codoped Gd2O3 nanowires and bulk materials

In this paper, the Gd2O3：Eu3＋,Tb3＋phosphors with different doping concentrations of Eu3＋and Tb3＋ions were prepared by a hydrothermal method for nanocrystals and the solid-phase method for microcrystals. The interaction of the doped ions with different concentrations and the luminescent properties of the nanocrystals and microcrystals were studied systematically. Their structure and morphology of Gd2O3：Eu3＋,Tb3＋phosphors were analyzed by means of X-ray powder diffraction （XRD）, transmission electron mi-croscopy （TEM） and scanning electron microscopy （SEM）. The photoluminescence （PL） properties of Gd2O3：Eu3＋,Tb3＋phosphors were also systematically investigated. The results indicated that when the concentration of doped Eu3＋was fixed at 1 mol.%, the emis-sion intensity of Eu3＋ions was degenerating with Tb3＋content increasing, while when the Tb3＋content was fixed at 1 mol.%, the emission intensity of Tb3＋ions reached a maximum when the concentration of Eu3＋was 2 mol.%, implying that the energy transfer from Eu3＋to Tb3＋took place. In addition, Tb3＋could inspire blue-green light and the Eu3＋could inspire red light. Therefore co-doping systems by controlling the doping concentration and the hosts are the potential white emission materials.     

Hydrothermal synthesis and structural studies of a new coordination polymer of lanthanum（III） with benzene-1,2,4,5-tetracarboxylic acid and 4,4＇-bipyridine

A new lanthanum complex formulated as {(bpyH₂)[La(btc)(H₂O)₄(NO₃)]·2H₂O}_n (1) (btcH₄=benzene-1,2,4,5-tetracarboxylic acid; bpy=4,4′-bipyridine) was hydrothermally synthesized. The complex was characterized by FT-IR spectroscopy, elemental analysis and X-ray diffraction. X-ray crystal structural analysis revealed that the compound belonged to the monoclinic space group C2/c with cell parameters a= 1.42806(7) nm, b=1.10258(5) nm, c=1.60333(8) nm and β=101.9400(10)°. The complex was polymeric with La^III atoms linked by four O atoms from two carboxylate groups of one benzene-1,2,4,5-tetracarboxylate. The La^III atom was ten coordinated in a distorted tetracapped trigonal prism. In the crystal structure, a wide range of noncovalent interactions consisting of hydrogen bonding (of the types of O—H…O, N—H…O and C—H…O) and ion pairing interactions connected the various components into a supramolecular structure.     

Specific features of Eu^3＋ and Tb^3＋ magnetooptics in gadolinium-gallium garnet （Gd3Ga5O12）

We reported magnetooptical properties of Eu3+(4f(6)) and Tb3+(4f(8)) in single crystals of Gd3Ga5O12 (GGG), Y3Ga5O12 (YGG), and Eu3+(4f(6)) in Eu3Ga5O12 (EuGG) for both ions occupying sites of D2 symmetry in the garnet structure. Absorption, luminescence, and magnetic circular polarization of luminescence (MCPL) spectra of Tb3+ in GGG and YGG and absorption and magnetic circular dichroism (MCD) of Eu3+ in EuGG were studied. The data were obtained at 85 K and room temperature (RT). Magnetic susceptibility of Eu3+ in EuGG was also measured between 85 K and RT. The magnetooptical and magnetic susceptibility data were modeled using the wavefunctions of the crystal-field split energy (Stark) levels of Eu3+ and Tb3+ occupying D2 sites in the same garnets. The results reported gave a precise determination of these Stark level assignments and confirmed the symmetry labels (irreducible representations) of the closely-spaced Stark levels (quasi-doublets) found in the 5D1 (Eu3+) and 5D4 (Tb3+) multiplets. Ultraviolet (UV) excitation (<300 nm) of the 6PJ and 6IJ states of Gd3+ in the doped GGG crystals led to emission from 5D4 (Tb3+) and 5D1 and 5D0 (Eu3+) through radiationless energy transfer to the 4f(n-1)5d band of Tb3+ and to UV quintet states of Eu3+. The temperature-dependent emission line shapes and line shifts of the magnetooptical transitions excited by UV radiation suggested a novel way to explore energy transfer mechanisms in this rare-earth doped garnet system.     

Substituent effects on novel lanthanide(III) hydrazides complexes

New lanthanide (Eu³⁺ and Gd³⁺) complexes were successfully synthesized and the effect of the p-phenyl substituent on the Eu³⁺ luminescent properties was evaluated. In this sense, benzhydrazide, p-toluic hydrazide, 4-hydroxybenzhydrazide and 4-aminobenzoic hydrazide were used as ligands and the complexes were obtained by mixing the lanthanide salts with hydrazides in ethanol at room temperature and keeping the reaction for 2 h under mechanical stirring. Crystal of Gd-amino was obtained and its structure was elucidated by single-crystal X-ray diffraction, revealing that Gd³⁺ centered in a distorted tricapped trigonal-prismatic molecular geometry. IR spectroscopy and the elucidated structure confirm hydrazides acting as bidentate ligands binding to Ln³⁺ ions through the oxygen of carbonyl group and the nitrogen of terminal amine, forming a five-membered ring. CHN analyses confirm the molecular formulas [Gd(amino)₄(H₂O)](NO₃)₃·(C₂H₅OH) and [Eu(toluic)₃(H₂O)₃](NO₃)₃. Lower T₁ state energies are observed for ligands p-substituted with higher electron donating capacity groups, such as p-NH₂ and p-OH. In contrast, higher lifetimes and quantum efficiencies are obtained for Eu³⁺ complexes with ligands p-H and p-CH₃ substituted, which are not deactivator groups.     

Effect of rare earth ions doping on properties of LiFePO4/C cathode material

LiFe0.99RE0.01PO4/C cathode material was synthesized by solid-state reaction method using FeC2O4·2H2O, Li2CO3, NH4H2PO4, RE(NO3)3·nH2O as raw materials and glucose as a carbon source. The doping effects of rare earth ions, such as La3+, Ce3+, Nd3+, on the structure and electrochemical properties of LiFePO4/C cathode material were systematically investigated. The as-prepared samples were characterized by means of X-ray diffraction(XRD), scanning electron microscopy(SEM) and particle size analysis. The electrochemical properties were investigated in terms of constant-current charge/discharge cycling tests. The XRD results showed that the rare earth ions doping did not change the olivine structure of LiFePO4, and all the doped samples were of single-phase with high crystallinity. SEM and particle size analysis results showed that the doping of La3+, Ce3+ and Nd3+led to the decrease of particle size. The electrochemical results exhibited that the doping of La3+ and Ce3+ could improve the high-rate capability of LiFePO4/C cathode material, among which, the material doped with 1% Ce3+ exhibited the optimal electrochemical properties, whose specific discharge capacities could reach 128.9, 119.5 and 104.4 mAh/g at 1C, 2C and 5C rates, respectively.     

Homogenization heat treatment of Mg-7.68Gd-4.88Y-1.32Nd-0.63Al-0.05Zr alloy

The microstructures and mechanical properties of the Mg-7.68Gd-4.88Y-1.32Nd-0.63A1-0.05Zr magnesium alloy were investigated both in the as-cast condition and after homogenization heat treatment from 535 to 555 ℃ in the time range 0-48 h by op- tical microscopy, scanning electron microscopy and hardness measurement. The as-cast alloy consisted of ct-Mg matrix, Mgs（Y0.5Gd0.5） phase which is a eutectic phase, strip of Al2（Y0.6Gd0.4） phase, little A13Zr and Mg（Y3Gd） phase. With the increasing of homogenization temperature and time, the Mgs（Y0.5Gd0.5） phase was completely dissolved into the matrix. The Al2（Y0.6Gd0.4） phase was almost not dissolved which impeded grain boundaries motion making the grain size almost not changed in the process of ho- mogenization. The optimum homogenization condition was 545 ℃/16 h. The tensile strength increased, yield strength decreased and the plasticity improved obviously after 545 ℃/16 h homogenization treatment.     

Rare-earth-doped oxysulfides for GaAs-pumped luminescent devices

There has been much recent interest in phosphors that emit visible radiation when excited with infrared light from a semiconductor injection diode source. Various fluoride hosts-LaF₃, YF₃, and BaYF₅—have been reported to give efficient green emission when doubledoped with ytterbium and erbium. We have found that rare-earth oxysulfides—La₂O₂S, Gd₂O₂S, and Y₂O₂S—are also efficient phosphors for this application when properly prepared. Green emission is obtained from phosphors doped with ytterbium and erbium, the green emission arising from erbium ions in the²H_11/2 and⁴S_3/2 excited states. The emission is accompanied by red emission from the lower⁴F_9/2 states, but this is sufficiently weak that the apparent color of the emitted light is only slightly altered by the red emission. The green emission is in a group of lines near 5500Å, near the peak of the eye sensitivity. By using thulium doping instead of erbium, blue emission is obtained from the¹G₄ states of thulium. This is accompanied by red emission, also from the¹G₄ states. The comparative performance of La₂O₂S, Gd₂O₂S, and Y₂O₂S is presented.     

The thermal capacity and enthalpy of gadolinium sesquiselenide over a wide temperature range

Measurements have been made on the thermal capacity of γ-Gd₂Se₃ at 58.88–298.34 K. Values have been obtained for the thermal capacity, entropy, reduced Gibbs energy, and enthalpy under standard conditions: C°_p = 125.87 ± 0.5 J· mole⁻¹ · K⁻¹; S°(298.15 K) = 196.5 · 1.6 J · mole⁻¹ · K⁻¹; Φ°(298.15 K) = 103.6 ± 1.6 J · mole⁻¹ · K⁻¹; H°(298.15 K)-H°(0) = 27681 ± 138 J · mole⁻¹. The enthalpy of Gd₂Se₃ has been measured and the major thermodynamic functions have been calculated for the solid and liquid states over the temperature range 450–2300 K. The temperature dependence of the enthalpy in the ranges 300–1800 K and 2000–2300 K are represented: H°(T)-H°(298.15 K) = = 1.1949 · 10⁻² · T² + 122.38 · T + 347402 · T⁻¹ − 38716 and H°(T)-H°(298.15 K) = 262.81 · T-− 196047, respectively. The calculated temperature, enthalpy, and entropy of melting for Gd₂Se₃ are: T_m = 1925 ± 40 K, Δ_mH° (Gd₂Se₃) = 68.5 kJ · mole^-1, Δ_mS°(Gd₂Se₃) = 35.6 J · mole⁻¹ · K⁻¹. __________ Translated from Poroshkovaya Metallurgiya, Nos. 3–4(448), pp. 56–61, March–April, 2006.     

Synthesis,fluorescence properties of Tb(III) complexes with novel mono-substituted β-diketone ligands

Two novel pyridine-2,6-dicarboxylic acid derivatives of mono-β-diketone named methyl 6-biphenylacetyl-2-pyridinecarboxylate (MBP) and 6-biphenylacetyl-2-pyridinecarboxylic acid (BAA) and their corresponding binary complexes Tb(MBP)₃.6H₂O and Tb(BAA)₃·6H₂O were synthesized. The ligands were characterized by elemental analysis, FT-IR and ¹H-NMR, and the complexes were characterized with elemental analysis, FT-IR, ¹H-NMR and thermogravimetric and differential thermal analysis(TG-DTA). The investigation of fluorescence properties of the complexes Tb(MBP)₃·6H₂O and Tb(BAA)₃·6H₂O showed that the introduction of the biphenyl enlarged the π-conjugated system of the ligands and enhanced the luminescent intensity of the complexes. The Tb(III) ion could be sensitized more efficiently by the ligands, in particular, the fluorescence intensity of the complex Tb(BAA)₃·6H₂O was about 20% higher than that of Tb(MBP)₃·6H₂O and 30% higher than that of Tb(III) complexes with bis-β-diketone-type ligands that we have previously reported.     

Synthesis, characterization and luminescent properties of needle-like lanthanide-doped orthorhombic Y5O4F7

Thermal annealing of YOH1.1F1.9 and YOH1.1F1.9:Ln3+(Ln3+=Eu3+,Tb3+ and Gd3+) precursors in air gave access to synthesize yttrium oxyfluoride phosphors with well-preserved needle-like morphologies. The phase purities of samples strongly depended on the thermal annealing temperature. At 600 °C, pure Y5O4F7 with orthorhombic structure were obtained, as evidenced by powder X-ray diffraction measurement and chemical analysis. The interesting microstructure evolution of the annealed sample from well-organized nanoparticles on curly slices to microrod-bundle structure had been aroused by raising annealing temperature. The multicolor fluorescent emissions of Y5O4F7:Ln3+ phosphors were observed, e.g. ultraviolet emission for Gd3+ , green emission for Tb3+ and red emission for Eu3+ , which resulted from characteristic transitions of different lanthanide ions.     

EXAFS investigation and luminescent properties of nanosized Tb: Lu2O3 phosphors

Nanosized terbium doped Lu2O3 phosphors were synthesized via a modified co-precipitation processing.The as-prepared Tb:Lu2O3 phosphors was consisted of well crystallized nanosized sphere particles with a diameter of about 30 nnx Local structure of Tb ions in Lu2O3 lattice was investigated by an analytical approach based on Fourier transformation of the extended X-ray absorption fine structure(EXAFS) data.X-ray near edge structure (XANES) spectra suggested that all Tb ions doped were tervalonce.EXAFS results indicated that Tb ions have entered the Lu2O3 cubic lattice by means of solid solution.The coordination number and first shell Tb-O distance dropped with the increasing of Tb concentration.Emission spectra of the phosphors was shown to be typical for Tb3+ with main components at 542,550 and 490 nm,derived from irradiative relaxation of 5D4 level.The emission intensity decreased severely with the increasing of Tb concentration from 1 mol.% to 15 tool.%,suggesting a significant concentration quenching above 1 mol.% Tb.The reduction of emission intensity was interpreted by higher distortion derived relaxation among the surface state resident Tb3+ ions.     

Physicochemical properties of Li3Ba2La3(MoO4)8:Eu,Tb red-emitting phosphor for solid state white lamps

In this work,combustion synthesis was used for the first time to fabricate a phosphor material with red emission for applications in solid-state white-light lamps.We synthesized a material with emission wavelength at λ_em=617 nm,excited under long UV-blue wavelength based on Eu³⁺,Tb³⁺-activated molybdates Li₃Ba₂(La_1-x-yEu_xTb_y)₃(MoO₄)₈ with 0 ≤ x ≤1 and 0 ≤ y ≤ 1.A series of pow...     

Kinetic investigation of dissolution of CaWO4 in oxalic acid solution

Abstract

In this study, the effects of stirring speed, temperature, H₂C₂O₄ concentration and particle size on the dissolution rate of CaWO₄ in H₂C₂O₄ solutions were investigated. CaWO₄ was dissolved in H₂C₂O₄ solutions as series parallel type reaction. In the first step which took place according to Langmuir-Hinshelwood Mechanism, H₂C₂O₄ was adsorbed as a mobile adsorption layer on the surface of CaWO₄, reacted to form adsorbed calcium aqua oxalato tungstate (Ca[WO₃(C₂O₄)H₂O]) intermediate product and the adsorbed Ca[WO₃(C₂O₄)H₂O] was desorbed into the solution. In the second step, Ca[WO₃(C₂O₄)H₂O] hydrolysed and formed H₂WO₄ which reacted with H₂C₂O₄ to form hydrogen aqua oxalato tungstate (H₂[WO₃(C₂O₄)H₂O]) as end product together with solid CaC₂O₄H₂O. Model kinetic equations were derived which showed the relationships of the fractional conversion of CaWO₄, the concentration of Ca[WO₃(C₂O₄)H₂O] and the concentration of H₂[WO₃(C₂O₄)H₂O] with time. The diagrams drawn according to the model kinetic equations were in good agreement with the experimentally obtained diagrams (R²>0·99).

Dans cette étude, on a examiné les effets de la vitesse d’agitation, de la température, de la concentration d’H₂C₂O₄ et de la taille de particule sur la vitesse de dissolution de CaWO₄ dans des solutions d’H₂C₂O₄. On a dissous le CaWO₄ dans des solutions d’H₂C₂O₄ en une réaction de type série-parallèle. Dans la première étape, qui avait lieu d’après le Mécanisme de Langmuir-Hinshelwood, l’H₂C₂O₄ était adsorbé en une couche mobile d’adsorption à la surface du CaWO₄, réagissait pour former le produit intermédiaire adsorbé, aqua oxalato tungstate de calcium (Ca[WO₃(C₂O₄)H₂O]), et ce Ca[WO₃(C₂O₄)H₂O] adsorbé était désorbé dans la solution. Dans la seconde étape, le Ca[WO₃(C₂O₄)H₂O] était hydrolysé et formait l’H₂WO₄ qui réagissait avec l’H₂C₂O₄ pour former de l’aqua oxalato tungstate d’hydrogène (H₂[WO₃(C₂O₄)H₂O]) comme produit final avec le CaC₂O₄H₂O solide. On a dérivé les équations cinétiques du modèle, lesquelles montraient les relations de la conversion fractionnelle du CaWO₄, de la concentration de Ca[WO₃(C₂O₄)H₂O] et de la concentration d’H₂[WO₃(C₂O₄)H₂O] en fonction du temps. Les diagrammes dessinés d’après les équations cinétiques du modèle étaient en bon accord avec les diagrammes obtenus expérimentalement (R²>0·99).