Two new barium borate bromides: Ba2BO3Br and Ba3BO3Br3

Two new barium borate bromide crystals, Ba₂BO₃Br and Ba₃BO₃Br₃, have been obtained by spontaneous crystallization. Ba₂BO₃Br crystallizes in P−3m1 space group, with cell parameters of a = 5.5157(10) Å, c = 11.019(4) Å, and Z = 2, its structure is build up by alternately stacking along c-axis of [Ba₂(BO₃)₂]²⁻ layers and bromide [Ba₂Br₂]²⁺ layers. The solved structure is analog to Ba₂(BO₃)_1−x(CO₃)_xCl_1+x except the interstitial halogen atoms at (0, 0, 1/2) is missing and accordingly the partly CO₃ substitution for BO₃ has not been observed. Ba₃BO₃Br₃ crystallizes in a new structure type with P−1 space group and cell parameters of a = 9.280(4) Å, b = 9.349(7) Å, c = 13.025(9) Å, α = 92.71(3)°, β = 98.29(3)°, γ = 116.200(18)° and Z = 4. The basic structural unit in Ba₃BO₃Br₃ is the clusters composed of 4 BO₃ groups and 12 Ba atoms, which in turn are linked by eight Ba–O bonds with other four clusters to form sheets extend in the (001) plane.     

Nd6Li(BO3)3O4F2: A novel neodymium oxyborate fluoride containing two-dimensional Nd layers

Crystal of a new neodymium oxyborate fluoride Nd₆Li(BO₃)₃O₄F₂ was grown by the flux method. Its structure, determined by single crystal x-ray diffraction, belongs to the space group C2/c with cell parameters of a = 12.0629(2) Å, b = 6.94650(10) Å, c = 16.0528(3) Å, β = 104.5360(10)°. In the structure, Nd atoms coordinate to oxygen or fluorine atoms to yeild 7 or 8 coordinated Nd(O,F)n polyhedra. Those polyhedra are edge-shared to form a double layer of (Nd₁₂O₂₃F₄)^14? fluorite blocks. The blocks are linked by oxygen atoms of planar BO₃ groups in the c direction into a 3-dimensional network. Another novel element in the structure is that Li coordinates to 6 oxygen atoms from three BO₃ groups forming a propeller like arrangement, and theoretical calculation shows that such arrangement should give 3/4 that of BO₃ contribution to second harmonic effect. The crystal shows deep violet color with typical Nd³⁺ optical absorption and a UV transmission cut-off of 260 nm.     

Correlation between Luminescence and EPR Spectroscopy as Evidence of Ytterbium Pair Formation in Li6Ln(BO3)3:Yb3+ (Ln=Gd,Y) Borate Single Crystals

Synthesized powders and grown single crystals of nominal compositions Li₆Ln(BO₃)₃:Yb³⁺ (Ln=Y, Gd) were investigated by means of powder and single‐crystal X‐ray diffraction (XRD), as well as optical near‐IR spectroscopy in conjunction with electron paramagnetic resonance (EPR) spectroscopy. The appearance of two distinct zero‐phonon lines suggests the existence of two kinds of Yb³⁺ ions in the single crystals. The XRD results exclude the possibility of a phase transition occurring between room and low temperatures. EPR spectra of single crystals show the presence of both isolated ions and pairs of ytterbium ions substituted for Y³⁺. A strong temperature dependence of the intensity of Yb–Yb pairs resonance lines coincides with temperature dependence of emission peak at 978 nm, confirming a common origin of the defect giving rise to these spectra. Calculated from EPR spectra, the distance between pairs of Yb³⁺ is in good agreement with crystallographic ones: R=3.856 Å, R_cryst=3.849 Å.     

Mixed Alkali Neodymium Orthoborates: K9Li3Nd3(BO3)7 and A2LiNd(BO3)2 (A = Rb,Cs)

Crystals of mixed alkali neodymium orthoborates, K₉Li₃Nd₃(BO₃)₇ and A₂LiNd(BO₃)₂ (A = Rb, Cs) were obtained by spontaneous crystallization. K₉Li₃Nd₃(BO₃)₇ crystallizes in space group P2/c with cell parameters of a = 11.4524(7) Å, b = 10.1266(6) Å, c = 12.3116 (10) Å, β = 122.0090(10)°. In the structure, NdO₈ polyhedra share corners and connect with planer BO₃ groups to form infinite [Nd₃B₃O₂₁]_n chains. These chains are linked by additional BO₃ groups to produce a double layer of [Nd₆B₆O₃₈]_n blocks in the ac plane with K and Li ions filled into the cavities. A₂LiNd(BO₃)₂ (A = Rb, Cs) crystallizes in space group Pbcm, with cell parameters of a = 7.113(2) Å, b = 9.691(3) Å and c = 10.135(3) Å for Rb₂LiNd(BO₃)₂, and a = 7.2113(3) Å, b = 9.9621(4) Å, and c = 10.3347(4) Å for Cs₂LiNd(BO₃)₂. In the structure, NdO₈ polyhedra are corner‐sharing with each other and further interlinked by BO₃ groups to comprise the infinite [Nd₄B₄O₂₄] sheets in the bc plane, with Rb/Cs and Li ions occupying the interlayered space. The compounds show effective near‐IR emission and their associated lifetimes are obtained by fluorescence spectra.     

Neue Thiophosphate: Die Verbindungen Li6Ln3(PS4)5 (Ln: Y,Gd, Dy,Yb, Lu) und Ag3Y(PS4)2

New Thiophosphates: The Compounds Li₆Ln₃(PS₄)₅ (Ln: Y, Gd, Dy, Yb, Lu) and Ag₃Y(PS₄)₂ The new thiophosphates Li₆Ln₃(PS₄)₅ (Ln: Y, Gd, Dy, Yb, Lu) were synthesized by heating mixtures of Ln, P, S, and Li₂S₄ at 900 °C (100 h) and they were investigated by single crystal X‐ray methods. The compounds with Ln = Y (a = 28.390(2), b = 10.068(1), c = 33.715(2) Å, β = 113.85(1)°), Gd (a = 28.327(2), b = 10.074(1), c = 33.822(2) Å, β = 114.297(7)°), Dy (a = 28.124(6), b = 10.003(2), c = 33.486(7) Å, β = 113.89(3)°), Yb (a = 28.178(3), b = 9.977(1), c = 33.392(4) Å, β = 113.65(1)°), and Lu (a = 28.169(6), b = 10.002(2), c = 33.432(7) Å, β = 113.54(3)°) are isotypic and crystallize in a new structure type (C2/c; Z = 12). Main feature are PS₄ tetrahedra isolated from each other surrounding the Ln and Li atoms via their S atoms. The coordination number of the five crystallographically independent Ln atoms is eight, but the polyhedra are quite different and they are interlinked to larger units extending in [010]. The environment of the Li atoms is irregular and formed by five to six S atoms. The crystal structure is compared with that of Li₉Ln₂(PS₄)₅ (Ln: Nd, Gd). For the synthesis of Ag₃Y(PS₄)₂ (a = 16.874(3), b = 9.190(2), c = 9.312(2) Å, β = 123.17(3)°) a mixture of Y, P, S, and Ag₂S was heated to 700 °C (50 h). The thiophosphate crystallizes in a new structure type (C2/c; Z = 4) composed of isolated PS₄ tetrahedra. The two crystallographically independent Ag atoms are surrounded by four S atoms in the shape of distorted tetrahedra. The Ag(1)S₄ polyhedra are cornershared to strands running along [001], which are linked together via Ag(2)S₄ tetrahedra. The environment of the Y atoms is composed of eight S atoms each building distorted square antiprisms. These polyhedra are connected with each other via common edges to a strand running along [001].     

Nonlinear optical crystal BiAlGa2(BO3)4

The new nonlinear optical crystals BiAlGa₂(BO₃)₄ have been grown by spontaneous crystallization with molten flux based on a Bi₂O₃–B₂O₃ solvent. From single crystal X-ray diffraction measurement, BiAlGa₂(BO₃)₄ has been found to crystallize in the trigonal huntite structure type, space group R32, with cell dimensions a = 9.4433(9) and c = 7.4130(10) Å. The diffuse reflectance spectrum on a powder sample indicated that the short-wavelength absorption edge of BiAlGa₂(BO₃)₄ extends to approximately 271 nm. Second-harmonic generation (SHG) on powder samples has been measured using Kurtz and Perry technique, which indicated that BiAlGa₂(BO₃)₄ is a phase-matchable material, and its SHG coefficient is measured to be four times as large as that of KDP.     

Thermochemistry of rare earth complexes [Ln(Ala)2(Im)(H2O)](ClO4)3 (Ln=Pr, Gd)

The two complexes, [Ln(Ala)₂(Im)(H₂O)](ClO₄)₃ (Ln=Pr, Gd), were synthesized and characterized. Using a solution-reaction isoperibol calorimeter, standard enthalpies of reaction of two reactions: LnCl₃⋅6H₂O(s)+2Ala(s)+Im(s)+3NaClO₄(s)=[Ln(Ala)₂(Im)(H₂O)](ClO₄)₃(s)+3NaCl(s)+5H₂O(l) (Ln=Pr, Gd), at T=298.15 K, were determined to be (39.26±0.10) and (5.33±0.12) kJ mol^–1 , respectively. Standard enthalpies of formation of the two complexes at T=298.15 K, Δ_fH^Θ_m {[Ln(Ala)₂(Im)(H₂O)](ClO₄)₃(s)} (Ln=Pr, Gd), were calculated as –(2424.2±3.3) and –(2443.4±3.3) kJ mol^–1 , respectively.     

Synthesis,crystal structure and optical properties of a new beryllium borate,CsBe4(BO3)3

A novel beryllium borate CsBe₄(BO₃)₃ has been grown in crystals by high-temperature flux method using spontaneous nucleation technique for the first time. The crystal structure of this compound was determined by single crystal X-ray diffraction analysis. It crystallizes in the orthorhombic space group Pnma with lattice parameters a = 8.3914(5) Å, b = 13.3674(7) Å, c = 6.4391(3) Å, Z = 4, V = 722.28(7) Å³. The crystal takes the same structure type as Rb analog based on the units of BO₃ triangles and BeO₄ tetrahedrons, displaying a three-dimensional tunnel structure with Cs atoms filling in the cages. The IR spectrum confirms the presence of BO₃ groups and the UV–vis–IR diffuse reflectance spectrum exhibits this compound has a short UV cut-off edge below 200 nm. Band structures and density of states were calculated.     

A new potassium rare earth oxyborate K2La2(BO3)2O

A series of potassium rare earth oxyborates, K₂RE₂(BO₃)₂O (RE = La, Nd, Sm and Eu), have been synthesized. Single crystal of the first member of the series, K₂La₂(BO₃)₂O, has been grown by the flux method. Its structure, determined by single crystal X-ray diffraction, shows that it belongs to the monoclinic system, space group P2₁/c with unit cell parameters of a = 11.422(2) Å, b = 6.6803(13) Å, c = 10.813(2) Å, β = 17.23(3)° and Z = 4. Optical transmission spectrum shows that the K₂La₂(BO₃)₂O crystal is highly transparent from 215 nm to 2750 nm.     

A new type of orthoborates: ASr4La3(BO3)6 (A = Li,Na)

Two new rare earth containing orthoborate crystals ASr₄La₃(BO₃)₆ (A = Li, Na) have been obtained by spontaneous nucleation from high-temperature melts of A₂O–SrO–La₂O₃–B₂O₃–AF. X-ray diffraction analyses show that they both crystallize in the rhombohedral space group R-3 with cell parameters of a = 12.309(7) Å, c = 9.316(7) Å and a = 12.4049(13) Å, c = 9.348(2) Å for the Li and Na compounds respectively. Similar to the large A′₆MM′(BO₃)₆ family, these compounds are all related to the structure of Sr₃Y(BO₃)₃ with La and Sr statistically occupy the Sr site, and the alkaline elements and remaining Sr enter the ordered Y1 and Y2 sites, which can be approximately represented as (La_2.91Sr_3.09)(La_0.09Sr_0.91)Li[B₆O₁₈] and (La_2.85Sr_3.15)(La_0.15Sr_0.85)Na[B₆O₁₈]. The characteristic of the structure is that the La/Sr and isolated BO₃ groups form a network with tunnels along the c-axis where the alkaline A and Sr ions alternatively reside. The optical transmission spectrum shows that the ultraviolet absorption edge of NaSr₄La₃(BO₃)₆ crystal is about 193 nm and Raman spectra reveal that both crystals possess sharp peaks at 930 cm⁻¹.     

High-pressure synthesis, crystal structure, and structural relationship of the first ytterbium fluoride borate Yb5(BO3)2F9

Yb₅(BO₃)₂F₉ was synthesized under high-pressure/high-temperature conditions in a Walker-type multianvil apparatus at 7.5 GPa and 1100 °C, representing the first known ytterbium fluoride borate. The compound exhibits isolated BO₃-groups next to ytterbium cations and fluoride anions, showing a structure closely related to the other known rare-earth fluoride borates RE₃(BO₃)₂F₃ (RE=Sm, Eu, Gd) and Gd₂(BO₃)F₃. Monoclinic Yb₅(BO₃)₂F₉ crystallizes in space group C2/c with the lattice parameters a=2028.2(4) pm, b=602.5(2) pm, c=820.4(2) pm, and β=100.63(3)° (Z=4). Three different ytterbium cations can be identified in the crystal structure, each coordinated by nine fluoride and oxygen anions. None of the five crystallographically independent fluoride ions is coordinated by boron atoms, solely by trigonally-planar arranged ytterbium cations. In close proximity to the above mentioned compounds RE₃(BO₃)₂F₃ (RE=Sm, Eu, Gd) and Gd₂(BO₃)F₃, Yb₅(BO₃)₂F₉ can be described via alternating layers with the formal compositions “YbBO₃” and “YbF₃” in the bc-plane.     

Crystal structure of neodymium and gadolinium dihydroxy-nitrate,Ln(OH)2NO3

The crystal structures of Nd(OH)₂NO₃ and Gd(OH)₂NO₃ have been determined from single-crystal X-ray diffraction techniques. Crystallization occurs in monoclinic space group P2₁ (No. 4) with a = 6.420(1), b = 3.838(1), c = 7.746(2) Å, and β = 98.18(2)° for Nd(OH)₂NO₃ and a = 6.340(2), b = 3.715(1), c = 7.728(2) Å, and β = 96.95(2)° for Gd(OH)₂NO₃. The structures were refined to residual indices of 0.025 and 0.048, respectively, using 372 and 360 unique reflections. The lanthanoid metal atoms are nine-coordinated, having a tricapped trigonal prismatic geometry. The nitrate counter ion acts as a bidentate ligand, while the two hydroxide oxygen atoms link symmetry-related lanthanoid atoms, forming two-dimensional layers.     

Serendipitous syntheses of the series Cs3Ln7Te12 (Ln = Sm,Gd, Tb): Compounds with large tunnels

Single crystals of Cs₃Ln₇Te₁₂ (Ln = Sm, Gd, Tb) have been grown accidentally through the reaction of Ln and Te with a CsCl or Cs₂Te₃ flux at elevated temperatures. The crystal structures have been determined from single crystal X-ray diffraction data. These compounds, which are isostructural with Rb₃Yb₇Se₁₂, crystallize in space group Pnnm of the orthorhombic system with two molecules in the following cells: Cs₃Sm₇Te₁₂, a=13.750(6), b=28.332(7), c=4.473(3) Å, T=293 K; Cs₃Gd₇Te₁₂, a=13.6064(13), b=28.209(3), c=4.4324(4) Å, T=153 K; Cs₃Tb₇Te₁₂, a=13.5708(16), b=28.116(3), c=4.4147(5) Å, T=153 K.     

Synthesis of Er5(BO3)2F9 and Properties of RE5(BO3)2F9 (RE = Er,Yb)

Er₅(BO₃)₂F₉ was synthesised under conditions of 3 GPa and 800 °C in a Walker‐type multianvil apparatus. The crystal structure was determined on the basis of single‐crystal X‐ray diffraction data, collected at room temperature. Er₅(BO₃)₂F₉ is isotypic to the recently synthesised Yb₅(BO₃)₂F₉ and crystallises in C2/c with the lattice parameters a = 2031.2(4) pm, b = 609.5(2) pm, c = 824.6(2) pm, and β = 100.29(3)°. The physical properties of RE₅(BO₃)₂F₉ (RE = Er, Yb) including high temperature behaviour and single crystal IR‐ / Raman spectroscopy were investigated.     

Synthesis,structure and optical properties of new lanthanide-based derivatives Ln2SbS5Br (Ln=La,Ce)

The first bromothioantimonates of cerium and lanthanum, Ce₂SbS₅Br (I), CeLaSbS₅Br (II) and La₂SbS₅Br (III), have been synthesized and characterized. I and III crystallize in the Pnma (n°62) space group while the structure of II was refined in the P2₁2₁2₁ (n°19) space group probably due to an ordering between Ce and La. The cell parameters are: a=8.847(2) Å, b=5.492(1) Å, c=17.697(6) Å, V=859.9(6) ų for I; a=8.9023(9) Å, b=5.5113(6) Å, c=17.809(2) Å, V=873.8(3) ų for II and a=8.905(2) Å, b=5.526(1) Å, c=17.883(3) Å, V=880.0(5) ų for III. These three materials exhibit the same novel structural arrangement with lanthanides surrounded by sulfur and bromine anions in two different LnS₇Br₃ and LnS₈Br units. Some sulfur atoms are engaged in SS bonding dimers while antimony exhibits a SbS₄E coordination (E=lone pair), the characteristics of which hint at a stereo-active 5s² electron pair. The charge balance in the materials is written as Ln^III₂Sb^III(S₂)^–IIS^–II₃Br. The same red color of the three materials rules out the occurrence of the Ce-4f¹→Ce-5d¹ electronic transition usually observed in Ce containing sulfides. In contrast, band structure calculations (TB-LMTO-ASA) assigned the observed absorption threshold around 2.08 eV for the three phases to the existence of a VB→CB electronic transition, i.e. an unpaired S or Br→Sb or paired S charge transfer.     

Triangulation in the Li2O-Ln2O3-B2O3 (Ln = Nd, Eu, Dy, Yb, and Y) systems and the melting character of ternary compounds

Li₂O-Ln₂O₃-B₂O₃ (Ln = Nd, Eu, Dy, Yb, and Y) ternary systems were studied along their inner sections. Two types of ternary compounds were found: Li₃Ln₂(BO₃)₃ (Ln = Nd, Eu, Dy, and Yb) and Li₆Ln(BO₃)₃ (Ln = Dy and Yb). The systems were triangulated. Melts were chosen for growing single crystals of ternary compounds in multinary systems. Original Russian Text ? Sh.A. Gamidova, 2009, published in Zhurnal Neorganicheskoi Khimii, 2009, Vol. 54, No. 1, pp. 142–145.     

RbLi2Ga2(BO3)3

The structure of rubidium dilithium digallium tris­(borate), RbLi₂Ga₂(BO₃)₃, contains two‐dimensional sheets of open‐branched rings of GaO₄ tetrahedra and planar BO₃ triangles that are joined by LiO₄ tetrahedra to form a three‐dimensional framework. Ten‐coordinate Rb atoms lie on twofold axes and occupy channels within the framework that extend along the b axis.     

DFT study of 1‐D Li6Gd(BO3)3

Solid‐state calculations were performed with the program CASTEP to analyze some electronic structure features of the crystal compound Li₆Gd(BO₃)₃ (LIGDBO), which is known to be an efficient gamma radiation detector, in particular when doped with rare‐earth ions. The structure of this material displays a clear 1‐D preference, where chains of atoms are formed along one of the crystalline axes. These quasilinear chains are responsible for the energy transfer occurring in the system prior to the actual detection. To elucidate on some aspects of the former process, calculations based on a few cluster models were also carried out by means of the molecular program JAGUAR. One of our results corresponds to a theoretical absorption energy value close to that experimentally obtained. In our calculation, the absorption process seems to be associated with the formation of an excitonic magnon state. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2003     

Structures of nonlinear hexagonal boratotungstates Ln3BWO9 (Ln = La, Pr, Nd, Sm, Gd, Tb, Dy)

Polycrystalline boratotungstates of composition Ln₃BWO₉ (Ln = Pr, Nd, Sm, Gd, Tb, Dy) are prepared by solid-phase synthesis and structurally studied. The structures are refined using the Rietveld method for hexagonal space group P6₃ (Z = 2). The boratotungstate structures are frameworks. The rare-earth cations in the structure are coordinated by an array of nine oxygen atoms (three oxygen atoms from borato groups BO₃ and six from WO₆ polyhedra). The nature of the optical nonlinearity in the hexagonal boratotungstates Ln₃BWO₉ is a direct consequence of the acentricity of both the tungstate and the rare-earth polyhedra in the structure. Dimorphism is discovered in polycrystalline La₃BWO₉.     

Ln3UO6Cl3 (Ln=La,Pr, Nd) -. Die ersten Oxochlorouranate der Seltenen Erden

Ln₃UO₆Cl₃ (Ln=La, Pr, Nd) — The First Oxochlorouranates of the Rare Earths . The new compounds Ln₃UO₆Cl₃ (Ln=La, Pr, Nd) were prepared by heating stoichiometric amounts of LnOCl/Ln₂O₃/U₃O₈ (7 : 1 : 1) (Ln=La, Nd) and PrOCl/Pr₆O₁₁/U₃O₈ (12 : 1 : 2) in silica ampoules (5 d, 1000°C, Ln=La; 9 d 800°C, Ln=Pr, Nd) in the presence of an excess of chlorine [p(Cl₂, 25°C)=1 atm]. Single crystals were obtained by chemical transport reactions using chlorine [p(Cl₂, 25°C)=1 atm] as transport agent [T₂=1000°C→T₁=900°C (Ln=La); T₂=840°C→T₁=780°C (Ln=Pr, Nd)]. Crystals of Ln₃UO₆Cl₃ (Ln=La, Pr, Nd) were investigated by X-ray diffraction methods and La₃UO₆Cl₃ additionally by high resolution electron microscopy. The compounds Ln₃UO₆Cl₃ crystallize in the hexagonal spacegroup P6₃/m (No. 176) with Z=2 formula units per unit cell. Isotypical structure refinements resulted in R=3.04% respectively R_w=1.91% (Ln=La), R=4.72% respectively R_w=3.80% (Ln=Pr) and R=3.99% respectively R_w=2.49% (Ln=Nd). Uranium is coordinated with six oxygen atoms forming a trigonal prism. Lanthanide ions are 10-coordinated (6 oxygen atoms, 4 chlorine atoms).