Pr Lu Research Articles

Synthesis and optical properties of novel red-emitting phosphors Ba3Lu1–xEuxB9O18 (x = 0–0.85)

The novel red-emitting phosphors Ba3Lu1–xEuxB9O18 (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.85) belonging to the Ba3REEB9O18 (REE – Y, Pr–Lu) family were successfully obtained by a multistep solid-phase synthesis. X-ray diffraction experiments revealed no phase transitions caused by the Eu3+ → Lu3+ isomorphic substitution in this series of solid solutions. An increase in the Eu3+ content leads to an expectable increase of hexagonal unit cell parameters and volume. Optical properties of the Ba3Lu1–xEuxB9O18 (x = 0–0.85) phosphors were investigated. The highest emission intensity was demonstrated by Ba3Lu0.6Eu0.4B9O18. The concentration quenching of luminescence was revealed for the x(Eu3+) > 0.4 samples. Concentration quenching, quantum yield and structural data were compared between three red-emitting Ba–Lu borates-phosphors (BLBO:Eu3+) containing independent crystallographic sites for the REE ions (n = 1–3) in crystal structure. It was revealed that the higher the number of nonequivalent cationic REE sites suitable for the Eu3+ → Lu3+ substitution, the higher the quantum yield taking into account practically equal amount of an optimal concentration of the activator-ion. Such an observation could be useful for a crystal chemical design of novel phosphors.

Thin Films and Glass–Ceramic Composites of Huntite Borates Family: A Brief Review

Rare-earth aluminum borates, RAl3(BO3)4 (where R = Y, Pr–Lu), are of great interest because of their attractive multifunctional properties, depending on their structure and composition. The combination of desirable physical and chemical characteristics makes them promising materials for lasers and nonlinear optics. Research focusing on RAl3(BO3)4 (RAB) compounds and their solids solutions has continued for more than five decades and has been reflected in numerous articles and several reviews. The last decade’s enhanced interest is being conducted towards epitaxial layers because of the availability of other possible applications, for instance, as scintillators, visible emitting phosphors or optical waveguides and waveguide lasers. On the other hand, the tendency of borate melts to form glasses makes them attractive for research of micro-crystallization processes in these systems and can be effortless towards finding relatively inexpensive optical glass–ceramic materials with similar composition as alternative components to laser systems. This article reviews the recent progress carried out hitherto on epitaxial layers and glass–ceramic composites of huntite-type rare-earth aluminum borates.

Heat Capacity of the R2Ge2O7 (R = Pr–Lu, Y) Rare-Earth Germanates

Heat Capacity of the R2Ge2O7 (R = Pr–Lu, Y) Rare-Earth Germanates

Heat capacity of rare-earth stannates in the range 350–1000 K

R2Sn2O7 (R = Pr–Lu) rare-earth stannates with the pyrochlore structure have been synthesized by solid-state reactions, by firing stoichiometric mixtures of SnO2 and R2O3 in air at 1473 K. The high-temperature heat capacity of the rare-earth stannates has been determined by differential scanning calorimetry in the temperature range 350 to 1000 K, and the Raman spectra of polycrystalline Tb2Sn2O7 and Dy2Sn2O7 samples have been measured.

Novel Two‐Step Topotactic Transformation Synthetic Route Towards Monodisperse LnOF:Re,3+ (Ln = Y, Pr–Lu) Nanocrystals with Down/Upconversion Luminescence Properties

A novel two‐step topotactic transformation (TT) synthetic route, Y2(OH)5NO3•nH2O (LYH)→Y(OH)2.02F0.98→YOF, is first developed for the monodisperse YOF:Re3+ (Re = Eu, Tb, Yb/Er, and Yb/Tm) nanostructure with bundle, tube, and atomically thick sheet morphologies. The intermediate Y(OH)2.02F0.98 precursor is synthesized from the starting point of the {0001} plane, which forms by a novel type of ion‐exchange from the brucite‐like LYH due to the structural similarity between the [Y2(OH)5(H2O)n]+ unit layer and the Y(OH)2.02F0.98 {0001} plane. Such ion‐exchange behavior is different from the traditional case for LYH exchanging the intercalated anions. The detailed structural characterization reveals that the formation of YOF is attributed to an in situ TT with the structural matching of [0001]Y(OH)2.02F0.98//[110]YOF. Moreover, this novel synthetic route can be also extended to other lanthanides oxyfluorides series (LnOF, Ln = Pr–Lu), and the as‐prepared YOF:Re3+ products exhibit intense characteristic down/upconversion luminescence. Our synthetic strategy dovetails well with the green concept in the current nanoscience and nanotechnology, which may bring new opportunity to LRHs and open a new avenue in the synthetic methodology for micro/nanomaterials.

Heteronuclear lanthanide-based coordination polymers exhibiting tunable multiple emission spectra

Reactions in water at room temperature between lanthanide ions and 5-hydroxy-1,3-benzene-di-carboxylic acid hereafter referred to as H2(hip) lead to a new family of lanthanide-based hetero-nuclear compounds with the general chemical formula [Ln2−2xLn2x′(hip)2(H2O)10,(hip),4H2O]∞ where Ln and Ln′ = Pr–Lu or Y and where 0 ≤ x ≤ 1. The physico-chemical properties of this family have been characterized by PXRD, TDXD, TG/TD, EDS, SEM, 89Y solid state NMR spectroscopy and optical spectroscopy. The luminescent properties of these compounds are studied in detail. This study reveals that the competition between intermetallic energy transfer and photo-induced electron transfer gives rise to complex multiple emission spectra. It is therefore possible, for some Ln/Ln′ compositions, to obtain green, yellow or red emission by tuning the excitation wavelength over a 50 nm range. From a global point of view, this study shows that this series of compounds could be of great interest as far as luminescent coordination polymers usable as taggants for the fight against counterfeiting are aimed.

Coordination Polymers Based on Heterohexanuclear Rare Earth Complexes: Toward Independent Luminescence Brightness and Color Tuning

Reactions in solvothermal conditions between hexanuclear rare earth complexes and H2bdc, where H2bdc symbolizes terephthalic acid, lead to a family of monodimensional coordination polymers in which hexanuclear complexes act as metallic nodes. The hexanuclear cores can be either homometallic with general chemical formula [Ln6O(OH)8(NO3)6](2+) (Ln = Pr-Lu plus Y) or heterometallic with general chemical formula [Ln(6x)Ln'(6-6x)O(OH)8(NO3)6](2+) (Ln and Ln' = Pr-Lu plus Y). Whatever the hexanuclear entity is, the resulting coordination polymer is iso-structural to [Y6O(OH)8(NO3)2(bdc)(Hbdc)2·2NO3·H2bdc]∞, a coordination polymer that we have previously reported. The random distribution of the lanthanide ions over the six metallic sites of the hexanuclear entities is demonstrated by (89)Y solid state NMR, X-ray diffraction (XRD), and luminescent measurements. The luminescent and colorimetric properties of selected compounds that belong to this family have been studied. These studies demonstrate that some of these compounds exhibit very promising optical properties and that there are two ways of modulating the luminescent properties: (i) playing with the composition of the heterohexanuclear entities or (ii) playing with the relative ratio between two different hexanuclear entities. This enables the independent tuning of luminescence intensity and color.

Vibrational spectroscopy of phthalocyanine and naphthalocyanine in sandwich-type (na)phthalocyaninato and porphyrinato rare earth complexes: Part 14. The infrared and Raman characteristics of phthalocyanine in “pinwheel-like” homoleptic bis[1,8,15,22-tetrakis(3-pentyloxy)phthalocyaninato] rare earth(III) double-decker complexes

The infrared (IR) spectroscopic data and Raman spectroscopic properties for a series of 13 “pinwheel-like” homoleptic bis(phthalocyaninato) rare earth complexes M[Pc(α-OC 5H 11) 4] 2 [M = Y and Pr–Lu except Pm; H 2Pc(α-OC 5H 11) 4 = 1,8,15,22-tetrakis(3-pentyloxy)phthalocyanine] have been collected and comparatively studied. Both the IR and Raman spectra for M[Pc(α-OC 5H 11) 4] 2 are more complicated than those of homoleptic bis(phthalocyaninato) rare earth analogues, namely M(Pc) 2 and M[Pc(OC 8H 17) 8] 2, but resemble (for IR) or are a bit more complicated (for Raman) than those of heteroleptic counterparts M(Pc)[Pc(α-OC 5H 11) 4], revealing the decreased molecular symmetry of these double-decker compounds, namely S 8. Except for the obvious splitting of the isoindole breathing band at 1110–1123 cm −1, the IR spectra of M[Pc(α-OC 5H 11) 4] 2 are quite similar to those of corresponding M(Pc)[Pc(α-OC 5H 11) 4] and therefore are similarly assigned. With laser excitation at 633 nm, Raman bands derived from isoindole ring and aza stretchings in the range of 1300–1600 cm −1 are selectively intensified. The IR spectra reveal that the frequencies of pyrrole stretching and pyrrole stretching coupled with the symmetrical C H bending of –CH 3 groups are sensitive to the rare earth ionic size, while the Raman technique shows that the bands due to the isoindole stretchings and the coupled pyrrole and aza stretchings are similarly affected. Nevertheless, the phthalocyanine monoanion radical Pc′ − IR marker band of bis(phthalocyaninato) complexes involving the same rare earth ion is found to shift to lower energy in the order M(Pc) 2 > M(Pc)[Pc(α-OC 5H 11) 4] > M[Pc(α-OC 5H 11) 4] 2, revealing the weakened π–π interaction between the two phthalocyanine rings in the same order.

Hydrated lanthanides picrate complexes with cis-1,3-dithiane-1,3-dioxide ( cis-DTSO 2). Structure of the Ho compound

Compounds with composition [Ln( cis-DTSO 2) 4(H 2O) 2](pic) 3 (pic=picrate, Ln=Pr–Lu and Y) were obtained by reaction of hydrated lanthanide picrate with cis-DTSO 2 in absolute ethanol. The adducts were characterized by elemental analyses and IR spectra. The parameters obtained from the absorption spectrum of the solid Nd compound indicate that the metal–ligand bonds present weak covalent character. The low intensity emission spectrum obtained at 77 K for the Eu compound indicates the existence of dimeric species. X-ray powder patterns show only one isomorphous series. X-ray single-crystal data of the holmium compound showed that the crystal system is triclinic, space group P 1 ̄ , a=13.387(1) Å, b=14.243(1) Å, c=14.965(1) Å, α=99.879(8)°, β=102.063(9)°, γ=101.620(1). The Ho ion achieves a coordination number of eight by the bonding of two oxygens of one bidentate cis-DTSO 2, four oxygens of four monodentate cis-DTSO 2, one of which acts as a bridge between two neighboring Ho ions, and two water molecules, giving rise to a distorted square antiprism polyhedron. The picrate anions are not bonded to the Ho(III) ion. The crystal packing is governed by an intricate net of hydrogen bonds.

Determination of trace rare earth impurities in high-purity cerium oxide by using electrothermal vaporization ICP-AES after HPLC separation with 2-ethylhexyl hydrogen 2-ethylhexylphosphonate resin as the stationary phase

A method is proposed to determine trace rare earth impurities in high-purity CeO2 by HPLC combined with electrothermal vaporization inductively coupled plasma atomic emission spectrometry (ETV-ICP-AES). The chromatographic retention behaviours of the matrix (Ce) and rare earth impurities were studied using 2-ethylhexyl hydrogen 2-ethylhexylphosphonate (P507) resin as the stationary phase and dilute nitric acid as the mobile phase. It was found that the matrix (Ce) can be separated quantitatively with dilute nitric acid as the mobile phase, and the rare earth impurities (Pr–Lu) can be eluted effectively by use of EDTA as an eluent. The experimental results show that a favorable separation between the matrix (Ce) and rare earth impurities (Pr–Lu) can be obtained within 60 min. The method proposed has been applied to determine 14 rare earth impurities in high-purity CeO2 with satisfactory results.

Spectroscopic and Thermal Studies of Y(III) and Lanthanide(III) Complexes with 3,4-Dichlorobenzoic Acid

The tris(3,4-dichlorobenzoate) complexes of Y(III) and (La-Lu)(III) were prepared. Their solubilities in water at 293 K were determined (6.57×10−4–3.04×10−4 molċdm−3). The IR spectra suggest that the carboxylate ligand is bidentate. The dihydrated complexes (Y, Ce–Lu) are dehydrated in one step, the tetrahydrated La complex in two steps. The anhydrous compounds decompose to oxides Ln 2O3, Pr6O11, and Tb4O7 (Y, La, Pr–Lu) with intermediate formation of LnOCl or directly to the oxide in the case of Ce (CeO2)

Preparation, properties and thermal decomposition of Y(III) and lanthanide(III) pyridine-2, 5-dicarboxylates

Abstract The conditions of the formation of Y(III) and lanthanide (III) (LaLu) isocinchomeronates were studied, and their quantitative compositions and solubilities in water at 293 K were determined. The IR spectra of the hydrated complexes were recorded and their thermal decomposition in static air were determined. During heating the hydrated isocinchomeronates Ln2(C7H3NO4)3·nH2O (n = 6−20) lose some (Ce, Pr, DyTm) or all (Y, La, NdTm, Dy, Lu) of their crystallization water molecules in one (Y, La, PrDy, Er, Yb, Lu) or two (Ce, Ho, Tm) steps then the hydrated complexes decompose directly to the oxides (Y, Ce, PrLu) or with intermediate formation of oxocarbonates Ln2O2CO3 (La).

Zur Synthese und Struktur ternärer Chalcogenide der Seltenen Erden AlnX 2 mit A ≙ alkalimetall und X ≙ Schwefel, Selen oder Tellur

The sulfides RbLnS 2 and CsLnS 2 were synthesized by heating alkali carbonate and the respective rare earth oxides under an H 2S atmosphere at 1000 °C. The ternary sulfides form thin, mostly coloured plate-like crystals. The structures of the cesium compounds and RbCeS 2 were characterized by X-ray investigations on single crystals. All the compounds crystallize with the α-NaFeO 2 structure type; for CsLnS 2 compounds with Ln ≙ PrLu the βRbScO 2 structure type was found as a second modification. This was proven by a single crystal X-ray investigation on CsPrS 2. The samarium compounds NaSmSe 2, KSmSe 2, NaSmTe 2, KSmTe 2, and RbSmTe 2 were prepared as examples for the corresponding selenides and tellurides. Syntheses were done by reacting the elements in a closed system. These chalcogenides also crystallize with the α-NaFeO 2 structure type. NaSmSe 2 shows an additional low temperature modification with a statistical distribution of the cations. For KSmTe 2 the structural determination was carried out on a single crystal. The sequence of the lattice constants and the ζ-parameters of the sulfur atoms will be discussed in accordance to their dependence on the lanthanide contraction.

Synthesis and characterization of lanthanide 3-ferrocenyl-5-(2-furyl)-pyrazoline-1-dithiocarbaminate complexes

Sodium 3-ferrocenyl-5-(2-furyl)-pyrazoline-1-dithiocarbaminate (FFPD) reacts with anhydrous lanthanide chlorides in absolute ethanol to give the complexes Ln(FFPD) 3· nH 2O (Ln La, Pr Lu and Y; n=3). The ligand and its complexes were characterized by elemental analyses, IR, UV and NMR spectra, molar conductance and TG-DTA analyses. In all the complexes the dithio ligands show bidentate behaviour.

Complexes of lanthanide nitrates with a schiff base derived from o-vanillin and p-toluidine

New complexes of lanthanide nitrates with a Schiff base derived from o-vanillin (2-hydroxy-3-methoxy-benzaldehyde) and p-toluidine having the general formula [LnL 2(NO 3) 2]NO 3 (where Ln = PrLu except Pm, L = Schiff base) have been prepared and characterized. Molar conductance studies indicate 1 : 1 electrolyte behaviour for these complexes. The IR spectra show that two Schiff base ligands and two nitrate groups are bound to the lanthanide ion in a bidentate fashion. Another nitrate group is in the outer coordination sphere. TG and DTA studies indicate that these complexes are stable up to 235°C and do not contain water or alcohol molecules.

Phase diagrams of thE CaF 2- (Y, Ln) F 3 svstems I. Experimental

The phase diagrams of the CaF 2- (Y, Ln) F 3 systems, where Ln is any one of the lanthanides except Pm and Eu, were studied by thermal and X-ray phase analysis methods. The investigations were made from 800 (600)°C up to the melting temperature. The oxygen concentration of the specimens was checked after thermal treatment. For the systems with Ln = Ce, Pr, Tb, Ho, Tm and Lu the fusibility data have been obtained for the first time. Phases with the following structure types are present in the systems investigated: (a) solid solutions Ca 1− x (Y, Ln) x F 2+ x with the fluorite structure type, which undergo ordering in the systems with Ln = HoLu, Y; (b) non-stoichiometric phases (Y, Ln) 1− y Ca y F 3− y with the tysonite (LaF 3) structure type, which undergo ordering in the systems with Ln = TbLu, Y; (c) solid solutions with the α-UO 3 structure type, based on α modifications (Y, Ln) F 3 (Ln = ErLu); and (d) modifications (Y, Ln) F 3 (Ln = GdLu) of the β-YF 3 type. Successive transitions, from solid solutions of the components of the system to the berthollide phases and the stoichiometric compound, were found for phases with the tysonite structure type. The maxima on fusion curves of non-stoichiometric phases were noticed in Sm, Gd, Tb, Ho and Er for Ca 1− x - (Y, Ln) x F 2− x and for Ln = PrLu in (Y, Ln) 1− y Ca y F 3− y . The coordinates of non-variant points for equilibria of the liquid-solid type and also the equations describing the dependence of the lattice parameters of nonstoichiometric phases on the composition are given for the systems investigated.