Metal Borate Research Articles

Preparation, characterization and spectral studies of Cr 1− xEu xBO 3 ( x = 0, 0.01 and 0.05)

Rare earth (Eu 3+)-doped transition metal borate of compositions Cr 1− x Eu x BO 3 ( x = 0, 0.01 and 0.05) have been prepared by B 2O 3 flux method in ultra pure form. All compositions are characterized by powder XRD and crystallized in hexagonal lattice with space group R 3 ¯ c . IR spectra show characteristic planar BO 3 vibrational bands. The diffuse reflectance spectra (DRS) are consistent with ligand to metal ion charge transfer and octahedral symmetry around Cr 3+ ion. From the observed band positions, the crystal field parameter Dq and Racah interelectronic repulsion parameters B and C are calculated. From the excitation spectrum of Cr 0.95Eu 0.05BO 3, the phonon energy and electron–phonon-coupling strength are obtained. Its emission spectrum has two intense transitions corresponding to 5D 0 → 7F 2 at 614 nm in the red and 5D 0 → 7F 1 at 592 nm in orange regions.

Synthesis and crystal structure of dicobalt nickel orthoborate, Co 2Ni(BO 3) 2

A new binary metal borate compound, dicobalt nickel orthoborate, Co 2Ni(BO 3) 2 has been successfully synthesized by thermally-induced solid-state chemical reaction at 900 °C between the initial reactants of Co(NO 3) 2·6H 2O, Ni(NO 3) 2·6H 2O and H 3BO 3 (mol ratio 2:1:2). The product was structurally characterized by powder X-ray diffraction technique. Co 2Ni(BO 3) 2 crystallizes in the kotoite type and isostructural with the chemical formula M 3(BO 3) 2 where M = Mg, Co and Ni. Co 2Ni(BO 3) 2 belongs to the orthorhombic crystal system with the refined unit cell parameters of a = 5.444(8), b = 8.404(0), c = 4.504(1) Å, Z = 2 and space group was determined as Pnmn. FTIR, elemental analysis and thermal analysis were also discussed in the article.

Low-Temperature, Phosphate-Free Conversion Coatings: A cost-effective, high-performance, environmentally friendly alternative to iron phosphate.

Transition metal borates, attracting researchers to investigate whether they can exhibit Li cycling similar to the metal oxides, were criticized for their poor electrochemical reversibility. Herein, citric acid assisted sol-gel technique had been used to synthesize high-performance VBO3 anode for Li-ion batteries. High-purity and well-crystallized VBO3 particles covered with amorphous carbon layer (VBO3/carbon) were applied as electrodes for both rechargeable Li and Na batteries. In the Li system, the VBO3/carbon composite delivered a high reversible capacity of 859.5 mA h g−1 in the first cycle, and showed an outstanding rate ability of ∼720 mA h g−1 even at a current density of 200 mA g−1, which suggests both V and B in VBO3 had participated in the electrochemical redox reaction during the Li intercalation and extraction. However, the Na storage of VBO3/carbon after conversion reaction exhibited typical capacitance behavior but poor electrochemical reversibility.

Promoting gold nanocatalysts in solvent-free selective aerobic oxidation of alcohols

A trace amount of metal carbonate, acetate or borate significantly boosts gold nanocatalysts in selective aerobic oxidation of alcohols under mild solvent-free conditions.

FTIR SPECTRAL ANALYSIS ON HEAVY METAL BORATE GLASSES

Inorganic heavy metal borate glasses were prepared through the melt quenching technique. Two sets of glasses were prepared, the compositions are (wt.%) 35 Bi 2 O 3+(50-x) B 2 O 3+15 Na 2 O +x PbO , where x=0, 10, 20, 30 and 35 MO +30 Na 2 O +35 B 2 O 3 ( MO = Bi 2 O 3, PbO , ZnO ). The FTIR structural analysis was made. These glasses have different borate groups and it mainly depends on the modifier/metal ion concentration. The influence of heavy metal and transition metal ion on the borate network were also identified.

Crystal Structure, Vibrational Spectroscopy, and Thermal Behavior of K2Mg [B6O7(OH)6] 2×4H2O.

AbstractFor Abstract see ChemInform Abstract in Full Text.

Matrix isolation infrared spectroscopic and density functional theoretical study of the aluminum, gallium and indium borates

The aluminum, gallium and indium borates have been produced by co-deposition of metal and boron atoms with oxygen molecules in excess argon at low temperature. The metal borate molecules were identified on the basis of the experimentally observed vibrations with isotopic effects ( 16O/ 18O substitutions, and 10B/ 11B and 69Ga/ 71Ga in natural abundance) as well as density functional calculations. The aluminum, gallium and indium borates were predicted to have linear geometries with a highly ionic electronic structure.

Crystal structure, vibrational spectroscopy, and thermal behavior of K 2Mg[B 6O 7(OH) 6] 2·4H 2O

A crystal of the double metal borate K 2Mg[B 6O 7(OH) 6] 2·4H 2O was synthesized in K 2B 4O 7·5H 2O and MgCl 2·6H 2O solution at pH 7.5. Its crystal structure was determined from single crystal X-ray diffraction data. It belongs to the pī triclinic space group, with the following unit cell parameters: a = 7.495(6) Å, b = 7.795(6) Å, c = 10.877(9) Å, α = 108.067(11)°, β = 95.323(10)°, γ = 90.837(11)°, Z = 2, V = 600.9(8) Å 3, D c = 2.024 g/cm 3. The crystal structure of K 2Mg[B 6O 7(OH) 6] 2·4H 2O consists of K O polyhedra, Mg O octahedra and [B 6O 7(OH) 6] 2− polyborate anions. The assignments of the recorded FT-IR absorption frequencies and Raman shift of this compound were given. Dehydration of this compound occurs in two steps and leads to an amorphous phase which undergoes crystallization.

Optical and non-linear optical properties of Nd3+-doped heavy metal borate glasses

Inorganic glasses are suitable materials for fabricating active and passive photonic devices. In this work, glasses of composition 35MO–30Na2O–(35−x)B2O3–xNd2O3 (MO=Bi2O3, PbO and x=0, 1) have been prepared through the melt quenching method. In order to characterize the linear and non-linear optical properties, the Fourier Transform Infrared, optical absorption, photoluminescence and open aperture z-scan measurements have been performed. FTIR results show that the glasses have BO3, BO4 and non-bridging oxygens (NBO) as local structures, in addition to the [BiO3] units. Using the Judd–Ofelt theory the theoretical oscillator strengths have been calculated. Radiative properties indicate that these glasses are potential laser materials. Z-scan measurements reveal the occurrence of non-linear optical absorption, which is attributed to the presence of Bi3+ and Pb2+ ions in the glasses. It is found that in the transparency region, the non-linearity exhibited is that of the fifth order.

An insight into the phenomena involved in a multiple-function stationary phase for the capillary electrochromatographic separation of 2'-, 3'-, and 5'-monophosphorylated nucleoside isomers.

The electrochromatographic separations of 2'-, 3'- and 5'-monophosphates of adenosine, guanosine, cytidine, and uridine were carried out with an open-tubular capillary column which was wall-coated with a highly selective reagent, 28-membered macrocyclic polyamine, 4, 8, 12, 18, 22, 26-hexaaza-1,15-dioxacyclooctaeicosane ([28]ane-N6O2). The effects of pH, composition and concentration of background electrolyte (BGE), applied voltage, column length, and the additive of the BGE, such as metal ions, borate, beta-cyclodextrin and organic solvent on the separation of these monophosphorylated nucleotide isomers were investigated. The results suggested that the interactions between analytes and the bonded groups on the wall predominantly comprise anion coordination and anion exchange in addition to the electrophoresis. A well-resolved electrochromatogram was obtained with the capillary column of 100 cm (75 cm effective length) x 75 microm inside diameter (ID), citrate buffer (20 mM, pH 3.99), applied voltage of -22 kV and detection at 254 nm. Column efficiency was found with the average theoretical plate numbers of 119,500/m and a low detection limit of 0.01 microM level could be achieved for the separation of these isomers.

Structural Characterization and Chemistry of the Industrially Important Zinc Borate, Zn[B3O4(OH)3

AbstractFor Abstract see ChemInform Abstract in Full Text.

Self-adjusted synthesis of ordered stable mesoporous minerals by acid-base pairs.

Although the chemical diversity of ordered composite mesoporous materials has been expanding during the past decade, progress has been limited by the need for a general synthetic approach that is predictive and makes use of well developed fundamental chemical principles. Researchers have previously used the interaction of organic-inorganic (OI) species that are present during the nucleation of the composite phase, and several synthesis pathways, such as direct surfactant-inorganic interaction (S+I-, S-I+, S0I0) and mediated interaction (S+X-I+, S-X+I-), have been proposed. Here we describe a new perspective in which the self-adjusted inorganic-inorganic (II) interplay between two or more inorganic precursors is guided by acid-base chemistry considerations, and in this simple way we produce an overall 'framework' for the sophisticated combination of synergic inorganic acid-base precursor pairs. We propose several new routes and demonstrate their versatility and validity through the successful syntheses of a wide variety of highly ordered, large-pore, homogeneous, stable and multicomponent mesostructured minerals, including metal phosphates and metal borates, as well as various metal oxides and mixed metal oxides. We show that the highly ordered mesostructured metal phosphates can be moulded into morphologies of choice, and that they show interesting physicochemical properties.

Structural Characterization and Chemistry of the Industrially Important Zinc Borate, Zn[B3O4(OH)3

Several unique crystalline zinc borates are known, a few of which find industrial use in significant tonnages. Although the most important of these has been a commercial product for more than 3 decades, it was never before structurally characterized. The structure of Zn[B3O4(OH)3] (1) was determined for the first time by single-crystal X-ray diffraction, revealing it to be a complex network consisting of infinite polytriborate chains cross-linked by coordination with zinc and further integrated by hydrogen bonding. The structure of 1 bears similarities to certain borate minerals, most notably, studenitsite (Ca[B3O4(OH)3]) and colemanite (Ca[B3O4(OH)3]·H2O); however, significant differences are described. Hydrolytic and thermochemical properties of 1 are discussed. This compound illustrates the important role played by metal cations in directing the spatial arrangement of anionic polyborate structural units in metal borates. This new structural information leads to a revision in the chemical formula, 2ZnO·...

Nanowires of metal borates

Nanowires of metal borates Al18B9O33 and MgB4O7 were synthesized by thermal evaporation of mixed powders containing metal oxide (Al2O3 or MgO) and boron oxide. Typical widths of these nanowires are in the range of 10 to ∼100 nm and lengths are in the range of several to several tens of micrometers. The nanowires were studied using a high-resolution transmission electron microscope equipped with electron energy loss spectrometer and energy dispersive x-ray spectrometer. The metal borate nanowires fabricated in this way are single crystals. It is proposed that these metal borate nanowires are grown in a vapor–solid process, in which both the metal oxide and boron oxide vapors were simultaneously involved.

Synthesis and X-ray crystal structures of two new alkaline-earth metal borates: SrBO2(OH) and Ba3B6O9(OH)6

Using hydrothermal techniques, two new compounds—strontium borate SrBO2(OH) and barium polyborate Ba3B6O9(OH)6—have been prepared. The structures of the title compounds were solved by single-crystal X-ray diffraction analysis. In the structure of SrBO2(OH), the Sr2+ ion is surrounded by eight oxygen atoms and the borate ion is identified as an individual [BO2(OH)]2− group. The structure of Ba3B6O9(OH)6 can be regarded as constructed from anionic borate chains, the negative charges of which are compensated for by the Ba2+ cations residing between the adjacent chains. The unusual feature of this compound can also be described in terms of infinite chains of B3O3 six-membered rings sharing B atoms, which are all tetrahedrally coordinated by oxygen atoms. The materials have also been characterized by infrared and energy dispersive spectroscopies, thermal analysis, and second harmonic generation powder measurement.

Thermally stimulated luminescence and lattice defects in crystals of alkali metal borate LiB 3O 5 (LBO)

The recombination processes and lattice defects in crystals of alkali metal borate LiB 3O 5 (LBO) were studied by the means of the thermally stimulated luminescence (TL) and electron spin resonance (ESR) techniques. The glow curves, the spectra of the LBO recombination luminescence, and the angular variations of ESR-spectra of the O − center in three different planes were measured in the temperature range from 80 to 400 K . The luminescence bands were assigned to the electron ( E m =4.0 eV ) and hole ( E m =4.2 eV ) recombination processes. The model of the trapped hole center O − was proposed. The processes responsible for the formation of localised electronic excitations in LBO were discussed and compared with those taking place in other wide-gap oxides.

A new class of materials for lithium-ion batteries: iron(III) borates

The first electrochemical investigation of transition metal borate structures are reported, focusing on FeBO 3 and Fe 3BO 6. In Fe 3BO 6, uptake of lithium initiates a two-phase process that results in framework disintegration, as expected from structural considerations and formation of an amorphous material that reversibly cycles lithium with a specific capacity of 450 mhA/g at an average potential of 1.6 V, in the regime of anode applications. Substitution of Fe(III) with other metals in the Fe 3BO 6 lattice is found to be detrimental to cycling behavior. Reduction of the particle size results in a reversible capacity up to 700 mAh/g, albeit with some fading on cycling.

Role of boron species in the hydrogenation of o-chloronitrobenzene over polymer-stabilized ruthenium colloidal catalysts

The role of boron species in selective hydrogenation of o-chloronitrobenzene ( o-CNB) over polymer-stabilized ruthenium colloids has been studied. Of the two kinds of boron species (boride and borate) present in ruthenium colloids prepared by NaBH 4 reduction, it was verified that only borate had a significant effect on the hydrogenation of o-CNB, while boride performed as a spectator. When metal cations were added into ruthenium colloidal catalyst system as modifiers, respectively, we observed that the synergetic effect between borate and metal cations occurred in these systems. It is suggested that metal complex ions were formed between the metal cations and borate ions.

Nature of the boson peak in Raman spectra of sodium borate glass systems: influence of structural and chemical fluctuations and intermolecular interactions

The nature of the boson peak in the low-wavenumber Raman spectra of (Na2O)x–(B2O3)1−x glasses is analyzed to be a manifestation of intermolecular interactions within regions of inhomogeneity, which are inherent to all glasses. The wavenumber of the boson peak satisfies the modified Szigeti and Odelevskii equation, previously successfully applied to studies of intermolecular vibrations in organic liquids and their mixtures. This allows one to conclude that the boson peak is connected with intermolecular interactions of structural groups, which are not bound in a glass-forming network, but form regions of structural and chemical inhomogeneities. The existence of such regions in alkali metal borate glasses and their high concentration were previously confirmed by small-angle x-ray scattering data. Thus intermolecular interactions can be described by a soft potential. It has been also found that the absolute intensity of the boson peak substantially decreases with an increase in the modifier concentration in accordance with the specific heat and the thermal phonon conductivity behavior as well as the theoretical expectations for glasses with increasing fragility. However, this decrease does not have a monotonic character but exhibits a slight bump at x = 0.2. Such a concentration behavior is connected with a decrease in the free volume in the vicinity of this concentration and a suppression of the relaxation processes in favor of vibrational modes, which begin to contribute to the boson peak. Copyright © 2000 John Wiley & Sons, Ltd.

Synthesis, crystal chemistry, and optical properties of metal borates

Crystalline inorganic borates comprise a structurally intriguing, technologically important class of solid-state oxides. During the past 18 months, new and unique examples have been synthesized; enhanced performance characteristics have been realized; and improved descriptions of physical properties have been developed. Combined, these advances will likely increase the overall scope of applicability for these materials.