Borate Compounds Research Articles

A new rapid synthesis of potassium borates by microwave irradiation

Potassium borates are one of the minor groups of boron minerals with its distinct non-linear optical properties. In this study, potassium borate compound of santite (KB5O8·4H2O) are synthesized using potassium carbonate (K2CO3) and boric acid (H3BO3) with a new and rapid method of microwave irradiation. The synthesized minerals are characterized by various analysis techniques of X-ray diffraction (XRD), Raman spectroscopy and scanning electron microscope (SEM). Three parameters of “microwave power level”, “reaction times” and “reaction stoichiometric constants (elemental potassium to boron ratios)” are determined for the optimum synthesis of potassium borate within the four step. At the end of the step 4, optimum products are obtained as santite type potassium borate. Synthesized potassium borates Raman bands are in mutual agreement with the boron compounds and the overall reaction yields to potassium borates are very high compared with the lower reaction times.

Zinc Borate Chemical Garden and Zinc Borate Powders from Tincal Mineral and Zinc Sulfate Heptahydrate

The formation of the first membrane, the swelling of the crystal by incoming water from the semipermeable membrane and the formation of irregular shaped branches were observed by optical microscopy, when zinc sulfate heptahydrate crystals were immersed in saturated borax solution. The powders obtained by mixing dilute aqueous borax and zinc sulfate solutions had B, O, Na, S and Zn elements. Presence of Na Zn 1/2B4O7.xH2O was indicated by EDX analysis. The molar ratio of B 2O3/ZnO in powders was around 2. FTIR analysis indicated the ratio of absorbance values of asymmetric stretching vibrations of B(3)-O at 1351 cm-1 to that of B (4)-O at 1026 cm-1 increased with their heating time at 90ºC during their preparation. X-ray diffraction patterns indicated the presence of Zn(OH)2 and Zn 4(OH)6(SO4)·4H2O. The zinc borate compounds in the powders were not crystalline since no sharp peaks related to zinc borates were present in x-ray diffraction diagram. There were two mass loss steps in TG curves of the powders. The first step at 150-350ºC and the second step at 700-950ºC were due to elimination of water and due to decomposition of sulfate ions respectively. The submicron powders were a mixture of zinc borate, Zn(OH)2, Zn4(OH)6(SO4)·4H2O and Na Zn 1/2B4O7.xH2O and they could be used as lubricant additive due to their small particle size of 600 nm.

Convenient Preparation and Structure Determination of Air- and Moisture-Tolerant Difluoromethylborates.

Convenient and reliable synthetic methods for difluoromethylborates have been established. The intermediary generated difluoromethylsilicate species from TMSCF2 H (TMS=trimethylsilyl) and potassium tert-butoxide were allowed to react with pinBPh (Me4 C2 O2 BPh) in the presence of 18-crown-6 to give the corresponding borate compound [pinB(Ph)CF2 H]- K+ (18-crown-6) as an air- and moisture-tolerant solid. The unambiguously determined crystal structure of [pinB(Ph)CF2 H]- K+ (18-crown-6) revealed that the difluoromethylborate unit partially coordinated on the potassium ion. Reaction of [pinB(Ph)CF2 H]- K+ (18-crown-6) with potassium difluoride (KHF2 ) in acetic acid enabled substitution of the pinacol unit and phenyl group with fluorides, and gave (difluoromethyl)trifluoroborate [F3 BCF2 H]- K+ (18-crown-6) in a good yield. The crystal structure of air- and moisture-tolerant [F3 BCF2 H]- K+ (18-crown-6), which would be a promising reagent for synthesis of various difluoromethylboron species, showed a polyrotaxane-like polymeric structure based on the K⋅⋅⋅F interactions between the K+ (18-crown-6), CF2 H, and BF3 units.

Lead-free transparent shields for diagnostic X-rays: Monte Carlo simulation and measurements.

In recent years, the preference for using lead-free radiation protection shields has increased because of concerns regarding lead poisoning and leakage. In medical and research laboratories, glass shields are preferred because of their transparency. In this study, various glass shields were examined and compared based on the international standards. One commercially available lead-based shield, four recently studied shields, and three new lead-free shields were considered, and their shielding factors were calculated. We presented three glasses based on borate, phosphate, and silicate compounds, which were named Ir1, Ir2, and Ir3, respectively. Based on the International Electrotechnical Commission standard (IEC 61331), the air-kerma ratios (attenuation ratios) and lead equivalent values were derived using Monte Carlo N-Particle eXtended (MCNPX) calculations, and mass attenuation coefficients and effective atomic numbers (Zeff) of all the shields were obtained from XCOM database, in the diagnostic X-ray energy range of 40-120keV. In addition, some measurements were performed for the reference (lead-based) glass to validate the simulations. The above-mentioned factors for silicate-bismuth-based (Ir3) and borosilicate-barium-based (Tu) glasses were found to be higher than the others and comparable to those of commercially available lead-based glass. In conclusion, Ir3 and Tu glasses were found to be the preferred lead-free transparent shields in the diagnostic X-ray energy range.

CsBaB3O6:Eu3+ red-emitting phosphors for white LED and FED: Crystal structure, electronic structure and luminescent properties

Recently, borate compounds have received much attention in the field of rare earth doped phosphors due to their excellent luminescent performance. In this work, to explore the potential in LED and FED applications, the CsBaB3O6:Eu3+ phosphor was investigated in detail by using Rietveld refinement, DFT calculations, photoluminescent and cathodoluminescent spectra. As a result, CsBaB3O6 has a planar stacked three-dimensional layered structure. Under the excitation of 395 nm n-UV light and electron beam, CsBaB3O6:Eu3+ phosphor exhibits a typical red emission of Eu3+. A good thermal stability and good resistance to saturation and degradation were observed in the CsBaB3O6:Eu3+ phosphor. The related photoluminescent and cathodoluminescent mechanisms were studied. The results indicate that CsBaB3O6:Eu3+ phosphor has potential in multifunctional applications.

Nanostructured Borate Halides for Optical Second Harmonic Generation at Surfaces

Optical second harmonic generation (SHG) at surfaces and interfaces is an exciting new technique. In order to achieve high surface specificity and sensitivity of the SHG technique, smaller particles of SHG materials are highly desired. Borate halides are regarded as a great source of SHG materials because of their outstanding nonlinear optical properties. Phase‐pure nanostructured samples of three borate halides of the type A2B5O9X were synthesized at low temperature in task‐specific ionic liquids (IL). Optimized reactions of acetates A(OAc)2 (A = Sr, Ba) and boric acid B(OH)3 with the mixed IL [P66614]X (X = Cl, Br) and LiNTf2 led to nano‐rods of Sr2B5O9Cl, nano‐needles of Sr2B5O9Br, and nano‐sheets of Ba2B5O9Cl. The reaction route presented here might trigger the synthesis of other borate compounds. Efficient second‐order nonlinear conversion by the nanostructured borate halides was confirmed using confocal SHG microscopy.

Photo-promoted Skeletal Rearrangement of Phosphine-Borane Frustrated Lewis Pairs Involving Cleavage of Unstrained C-C σ-Bonds.

An unprecedented photo-promoted skeletal rearrangement reaction of phosphine-borane frustrated Lewis pairs, o-(borylaryl)phosphines, involving cleavage of an unstrained sp2 C-sp3 C σ-bond is reported. The reaction realizes an efficient synthesis of cyclic phosphonium borate compounds. The reaction mechanism via a boranorcaradiene intermediate is proposed based on theoretical calculations. This work sheds light on the new photoreactivity of phosphine-borane FLPs.

Photo‐promoted Skeletal Rearrangement of Phosphine–Borane Frustrated Lewis Pairs Involving Cleavage of Unstrained C−C σ‐Bonds

AbstractAn unprecedented photo‐promoted skeletal rearrangement reaction of phosphine–borane frustrated Lewis pairs, o‐(borylaryl)phosphines, involving cleavage of an unstrained sp2C–sp3C σ‐bond is reported. The reaction realizes an efficient synthesis of cyclic phosphonium borate compounds. The reaction mechanism via a boranorcaradiene intermediate is proposed based on theoretical calculations. This work sheds light on the new photoreactivity of phosphine–borane FLPs.

An accelerated and effective synthesis of zinc borate from zinc sulfate using sonochemistry

Abstract Recently, sonochemistry has been used for the synthesis of inorganic compounds, such as zinc borates. In this study using zinc sulphate heptahydrate (ZnSO4·7H2O) and boric acid (H3BO3) as starting materials, a zinc borate compound in the form of Zn3B6O12·3.5H2O was synthesized using an ultrasonic probe. Product’s characterization was carried out with using X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FT-IR) and Raman spectroscopy. Zinc borate compound’s chemical bond structure was observed with Raman and FTIR. From the XRD results it was seen that Zn3B6O12·3.5H2O can be quickly synthesized upon heating at 80°C and 85°C (55 min) or 90°C (45 min) in very high yield (>90%). The minimum particle size obtained was ~143 μm from the SEM results. Zinc borate compound was synthesized at a lower temperature in less time than other synthesized zinc metal compound in literature.

Synthesis, crystal structure and topological features of microporous “anti-zeolite” Yb3(BO3)(OH)6∙2.1H2O, a new cubic borate with isolated BO3 groups

Abstract A new cubic borate, Yb3[BO3](OH)6⋅2.1H2O was synthesized in a multi-component hydrothermal system Yb2(CO3)3: B2O3: P2O5 = 5 : 2: 1 (T = 280 °C; P = 90–100 atm; pH = 3). The crystal structure was studied using single crystal X-ray analysis. The structure has been refined in the space group I432, possesses the unit cell parameter a = 12.2808(15) A. A microporous positively charged framework is formed by predominant Yb cations coordinated by O2−, OH− as a tetragonal antiprism, which are linked together via common edges and vertices. The extra framework BO3 triangles center narrow channels, directed along 3-fold axis, are perpendicular to them and clamped between large Yb polyhedra. The large cavities with the effective cavity width 7.7 A are filled by disordered water molecules. The crystal chemical formula could be written as (Z = 8): |(BO3)(H2O)2.1|[Yb3(OH)6]. A topological analysis was performed using the ToposPro software. The framework is characterized by the following tile sequence: [34]6[324.46.68]; the calculated structural complexity parameters are: v = 48 atoms, IG = 1.500 bits/atom, and IG,total = 72.000 bits/unit cell; the framework density is 12.96 Yb/1000 A3. The Yb-borate is similar to the tetragonal compounds with the general formula ABa12(BO3)7F4 (A = Li, Na) and LixNa1-xBa12(BO3)7F4, which are characterized by co-called “anti-zeolite” frameworks, formed by Ba2+ cations. The excess of water in the structure of the new borate compound Yb3[BO3](OH)6⋅2.1H2O is determined by its zeolitic nature and by hydrothermal growth conditions.

Structural, photo, optical and thermal luminescent properties of beta barium metaborate

Barium borate compounds (BaB4O7 – β-BaB2O4) were produced by different synthesis methods, which include solution assisted solid state synthesis method (SAS), microwave assisted solid state synthesis method (MAS) and high temperature solid state synthesis method (HTS). These different synthesis methods were carried out in air atmosphere (AA) and nitrogen atmosphere (NA). Luminescence emission spectra of barium borate compounds exhibited a broad band around 400 nm (∼310 nm excitation). X- ray induced luminescence measurements have shown a similar emission band, supporting the PL measurements. Photoluminescence decay curve of β-BaB2O4 compound (excited with 365 nm) is well fitted with a double exponential function with lifetimes τ1=3,69 ms and τ2=29,45 ms. At around 365 nm, Quantum Efficiency (QE) of the luminescence emission from β-BaB2B4 was calculated as 8 ± 1 percent. In order to test the possibility of using in radiation dosimetry, Optically Stimulated Luminescence (OSL) properties of β-BaB2O4 were investigated by determining radiation dose response, fading and repeatability of response. The OSL signal intensity was observed to increase linearly with increasing beta dose from 5 Gy to 1000 Gy. Thermoluminescence (TL) glow curve of β-BaB2O4 phosphor consist of broad glow peak with an apparent maximum at around 240 °C; which is also growing with radiation dose. The results presented here are of preliminary in nature and for a better understanding of the luminescence properties of β-BaB2O4 deserves more attention with possible applications as a phosphor and optical and dosimeter material.

Interaction of Np(v) with borate in alkaline, dilute-to-concentrated, NaCl and MgCl2 solutions.

The interaction of Np(v) with borate was investigated in 0.1-5.0 M NaCl and 0.25-4.5 M MgCl2 solutions with 7.2 ≤ pHm ≤ 10.0 (pHm = -log[H+]) and 0.004 M ≤ [B]tot ≤ 0.16 M. Experiments were performed under an Ar-atmosphere at T = (22 ± 2) °C using a combination of under- and oversaturation solubility experiments, NIR spectroscopy, and extensive solid phase characterization. A bathochromic shift (≈5 nm) in the Np(v) band at λ = 980 nm indicates the formation of weak Np(v)-borate complexes under mildly alkaline pHm-conditions. The identification of an isosbestic point supports the formation of a single Np(v)-borate species in dilute MgCl2 systems, whereas a more complex aqueous speciation (eventually involving the formation of several Np(v)-borate species) is observed in concentrated MgCl2 solutions. The solubility of freshly prepared NpO2OH(am) remained largely unaltered in NaCl and MgCl2 solutions with [B]tot = 0.04 M within the timeframe of this study (t ≤ 300 days). At [B]tot = 0.16 M, a kinetically hindered but very significant drop in the solubility of Np(v) (3-4 log10-units, compared to borate-free systems) was observed in NaCl and dilute MgCl2 solutions with pHm ≤ 9. The drop in the solubility was accompanied by a clear change in the colour of the solid phase (from green to white-greyish). XRD and TEM analyses showed that the amorphous NpO2OH(am) "starting material" transformed into crystalline solid phases with similar XRD patterns in NaCl and MgCl2 systems. XPS, SEM-EDS and EXAFS further indicated that borate and Na/Mg participate stoichiometrically in the formation of such solid phases. Additional undersaturation solubility experiments using the newly formed Na-Np(v)-borate(cr) and Mg-Np(v)-borate(cr) compounds further confirmed the low solubility ([Np(v)]aq ≈ 10-6-10-7 M) of such solid phases in mildly alkaline pHm-conditions. The formation of these solid phases represents a previously unreported retention mechanism for the highly mobile Np(v) under boundary conditions (pHm, [B]tot, ionic strength) of relevance to certain repository concepts for nuclear waste disposal.

A novel synthesis of nanoflower-like zinc borate from zinc oxide at room temperature

For the first time, the nanoflower-like zinc borate compound was obtained by precipitation at room temperature using zinc oxide nanoparticles as a precursor. The obtained zinc borates were characterized by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), x-ray diffraction (XRD), thermal gravimetric analysis (TGA), and Raman spectroscopy analysis. Monoclinic of zinc borate 2ZnO. 3B2O3.3.5H2O was achieved under the XRD pattern and the elemental chemical analysis. The particle size of the obtained materials is approximately 5 nm using TEM analysis. The TGA shows that the achieved zinc borate is outstanding stable at high temperatures. The result of this work provides a new route for the fabrication of zinc borate nanoparticle, which could be widely used in many applications.

Ultrasonic-Assisted Synthesis of Zinc Borates: Effect of Boron Sources

Sonochemistry meaning ultrasound-assisted chemistry plays an important role in the synthesis of inorganic compounds. Among these inorganic compounds, zinc borates are used for the flame-retarding agent. In this study using zinc chloride (ZnCl2), boric acid (H3BO3), Na2B4O7and#183;10H2O, Na2B4O7and#183;5H2O and NaOH as raw materials, a zinc borate compound in the formulae of Zn3B6O12and#183;3.5H2O was obtained using an ultrasonic probe. Crystal structures of samples were identified using X-ray diffraction (XRD). The symmetric and asymmetric stretching between boron and oxygen atoms were searched by Fourier-transform infrared (FT-IR) and Raman spectroscopies. The effects of boron sources on sample morphology were examined by scanning electron microscopy (SEM). From the results, it was seen that Zn3B6O12and#183;3.5H2O can easily be produced from these raw materials with the synthesis parameters of 80-90and#176;C and 40-55 min. From the SEM results, it was seen that the minimum particle size obtained was 172 nm. Reaction efficiencies were calculated between 79.6 and 94.0 and#177; 0.5%. Thermal feature of the obtained pure phase, investigated with the thermogravimetric analyses. The dehydration of the synthesized Zn3B6O12and#183;3.5H2O was seen between 262 and 413and#176;C with a total mass loss of 13.25%.

Ultrasonic-Assisted Synthesis of Zinc Borates: Effect of Boron Sources

Sonochemistry meaning ultrasound-assisted chemistry plays an important role in the synthesis of inorganic compounds. Among these inorganic compounds, zinc borates are used for the flame-retarding agent. In this study using zinc chloride (ZnCl2), boric acid (H3BO3), Na2B4O7and#183;10H2O, Na2B4O7and#183;5H2O and NaOH as raw materials, a zinc borate compound in the formulae of Zn3B6O12and#183;3.5H2O was obtained using an ultrasonic probe. Crystal structures of samples were identified using X-ray diffraction (XRD). The symmetric and asymmetric stretching between boron and oxygen atoms were searched by Fourier-transform infrared (FT-IR) and Raman spectroscopies. The effects of boron sources on sample morphology were examined by scanning electron microscopy (SEM). From the results, it was seen that Zn3B6O12and#183;3.5H2O can easily be produced from these raw materials with the synthesis parameters of 80-90and#176;C and 40-55 min. From the SEM results, it was seen that the minimum particle size obtained was 172 nm. Reaction efficiencies were calculated between 79.6 and 94.0 and#177; 0.5%. Thermal feature of the obtained pure phase, investigated with the thermogravimetric analyses. The dehydration of the synthesized Zn3B6O12and#183;3.5H2O was seen between 262 and 413and#176;C with a total mass loss of 13.25%.

Nonlinear Optical Crystals for Second Harmonic Generation

Some important nonlinear optical crystal families in three spectral regions (DUV-FIR) have been discussed with reference to their anionic groups. In the M–F–IR region iodides and chalcopyrite-type compound, in the Vis-NIR region sillenites, perovskites and KTP families and in the DUV region borate compound have been investigated. Their important optical and structural factors have been presented. As moderate birefringence increases phase matching wavelength range, the birefringence measurement has been described in more detail. Recent research has focused on optimizing the structure for obtaining high-LDT crystals in the M–F–IR region and removing the layering structure to achieve large-sized crystals in the DUV region. The entry of small ions in the first case and the replacement of stronger interlayer ions such as Ba and Sr, which have a stronger bond with double layer in the second case, are the solutions presented. Combination of two polarized structure units in such a way to make constructive superposition is followed to rise SHG efficiency. The crystals with 3D network are promising for large size growth.

Growth and crystal structure of Li3Ba4Sc3B8O22 borate and its Tb3+ doped green-emitting phosphor

A new lithium barium scandium borate (Li3Ba4Sc3B8O22) was obtained by solid-state synthesis and grown by spontaneous crystallization. Single-crystal X-ray diffraction analysis showed that it crystallizes in the centrosymmetric space group P-1 with the cell dimensions a = 5.2230(4) Å, b = 8.5609(6) Å, c = 11.4157(8) Å, α = 73.3750(6)°, β = 78.5020(6)°, γ = 87.0520(6)°, and V = 479.28(6) Å3 and a structure that consists of two layers formed by single [BO3] and double [B2O5] triangles, [ScO6] octahedra, [BaO9] polyhedra, and disordered [LiO4] tetrahedra or squares. The diffuse optical reflection spectrum indicates that Li3Ba4Sc3B8O22 is transparent in the range of 250–800 nm. Furthermore, an effective green emission centred at 545 nm was observed for the as-prepared Tb3+-doped Li3Ba4Sc3B8O22, making this borate compound a promising host material for engineering light-emitting phosphors.

Measurement of heat flow through cast slabs of calcium sulfate dihydrate

SummarySlabs of cast calcium sulfate dihydrate have been used for decades as a heat transfer barrier in commercial and residential construction and are assessed in accordance with the parameters defined by ASTM C1396. The study described herein hypothesizes that minor impurities have significant effects on the high‐temperature performance of these casts. Five thermocouples are cast into a 20‐mm‐thick slab at approximately 4‐mm intervals are measured between ambient and approximately 1000°C in a furnace. Thermal diffusivity and inertia are estimated from this temperature profile. This study compares natural, flue gas desulfurized (FGD) and reagent grade hemihydrates that have been converted into the dihydrate form with distilled water; the common additives kaolin and borax are used to modify the cast. The thermocouple data allow an effective thermal diffusivity (α′) and an effective thermal inertia (I′) to be calculated. The hemihydrate source and kaolin content are found to affect the high‐temperature performance; the FGD source increases the thermal inertia, and kaolin inhibits the formation of other borate compounds through intercalation.

Bis(oxalato)borate and difluoro(oxalato)borate-based ionic liquids as electrolyte additives to improve the capacity retention in high voltage lithium batteries

Two ionic liquids (ILs), which are functionalized with bis(oxalato)borate (BOB) and difluoro(oxalato)borate (DFOB) as the anion, have been synthesized and applied as additives for the battery grade electrolyte 1 M LiPF6 in an equivolume mixture of EC-DEC-DMC (LP71). When 0.3 M IL was added to LP71, peaks attributed to the formation of solid electrolyte interface (SEI) were observed during cyclic voltammetry for both cathodic and anodic sides. The presence of peaks during anodic scans suggests that the ILs possess the ability to form SEI on cathode surfaces. The high voltage Li | LiNi0.5Mn1.5O4 (LNMO) cells, employing the integrated electrolytes, exhibited a discharge capacity of around 120 mAh g−1. The retention rates of discharge capacity after 100 cycles were found to be 99.2% and 98.1% for the solution with 0.3 M of BOB-IL and DFOB-IL, respectively. By means of impedance analysis during the galvanostatic cycling, the growth of SEI was confirmed when BOB-IL was used as the additive. In this case, in the infrared spectra of the cycled LNMO electrodes, peaks related to borate compounds and polycarbonate were observed. This confirms that the BOB-IL promotes the formation of stable interfaces between the electrolyte and LNMO.

Biomimetic nanochannel membrane for cascade response of borate and cis-hydroxyl compounds: An IMP logic gate device

Biomimetic nanodevice is an important branch to expand the potential applications of artificial nanochannels. Here, we constructed nanochannels for cascade response of borate and cis-hydroxyl compounds by modifying the nanochannels of track-etched polycarbonate (TEPC) membranes with polyvinyl alcohol (PVA). Firstly, borate bound to PVA and increased the negative charge density on the surface of the nanochannels, which obstructed the transport of 1,5-naphthalene disulfonate (NDS2−). Subsequently, the addition of cis-hydroxyl compounds induced leaving of borate due to the stronger binding affinities between borate and cis-hydroxyl compounds, which reduced the negative charge density on nanochannels and then enhanced the transport of NDS2−. The cascade response of the nanochannels also accord with the properties of IMP (implication) logic gate. In addition, such nanochannels showed good reproducibility and reversibility. Therefore, this cascade response model based on nanochannels has the potential to be used as switches in area of actuators and biosensors, and is also expected to be used to understand the interaction of substances in nanoscale and simulate the physiological functions of boron.