Calcium Borate Research Articles

Highly saturated red-emitting novel europium doped yttrium calcium borate (Eu3+: Y2CaB10O19) phosphor materials for eco-friendly solid-state lighting applications

Optical parameters like low correlated color temperature (CCT), color rendering index (CRI), color purity, thermal stability and etc. are crucial parameters for the practical applications of white light emitting diode applications. High color purity around 100 % red emitting novel europium doped yttrium calcium borate (Eu3+: Y2CaB10O19) phosphors were harvested by conventional solid-state synthesis technique. The novel host material possesses monoclinic crystal structure with no observable shift in the diffraction lines with varying dopant concentrations. FTIR studies revealed the presence of BO3 and BO4 networks in the host lattice responsible for structural rigidity and good thermal stability. The phosphor materials synthesized xEu3+: Y2CaB10O19 (x = 0.01, 0.03, 0.05, 0.07 and 0.09), are sensitive to both 250 nm (UV) and 393 nm (Near UV/blue LED) for excitation that can produce deep orange (594 nm) emission along with red emission (612 nm). The optimum Eu3+ ion concentration was fixed at 5 mol% of dopant ions to prevent the concentration quenching. As prepared optimal phosphor material possesses high color purity around 100 %, CCT of 1214 K defines its applicability in WLED applications. The synthesized phosphor materials pertain excellent switching response, thermal stability and the fabricated P-i-G possesses desired photometric parameters for its practical applications.

Synthesis of nano calcium borate using sugarcane bagasse extract as a capping agent and its potential to promote germination in cowpea seeds

Boron and calcium are essential plant nutrient and their deficiency affects vegetative and reproductive growth of plants. Supplementing deficient nutrients by fertilizer application is essential but is accompanied by environmental pollution. Replacing conventional fertilizers with nanofertilizers may help in mitigating pollution as their nutrient use efficiency is higher. The synthesis of nanoparticles often utilizes chemicals that are detrimental to the environment. Thus use of greener alternative methods of synthesis of calcium borate nanoparticles is of special interest. In this study we synthesised nano calcium borate utilising the aqueous extract of sugarcane bagasse, a cheap, nontoxic, easily available agricultural waste, as a source of capping agent. The synthesized nanoparticles were characterized by powder XRD, FTIR and TEM. The calcium borate synthesized was amorphous in nature and of nanoscale. Priming cowpea seeds and misting them with synthesized calcium borate nanoparticle proved to be effective, resulting in enhanced seed germination, increased root length, and an improved vigour index compared to using bulk counterparts.

Investigation of flame-retardant characteristics of natural flax coated with hydrothermally synthesized calcium borate and organic PDA

Flame-retardant behavior of flax fabric coated by calcium borate powders with clove-like and elongated morphologies was investigated by thermal analysis and cone calorimeter. PDA was used to form strong and uniform adhesion of calcium borate onto fabric. Thermal analysis showed a 20% of decrease in mass loss, while detected exothermic/endothermic peaks as a result of the degradation of fabric and PDA. Significant reductions in HRR, p-HRR, EHC and CO2 amount were observed for fabric coated by PDA and elongated calcium borate powder. PDA was carbonized at low temperatures and formed a char layer that prevented flame propagation. At the same time, calcium borate powder dilutes the flammable gases in the environment with the release of water within its body. Among the calcium borate powders, rod-like morphology showed the best flame-retardant performance.

Development of new calibrating material for luminescence spectrometer from Eu3+ doped aluminum sodium calcium borate glass

The calibration standards are formulated to correct emissions spectra and systematically monitor sensitivity fluctuations in luminescence spectrometers. This study outlines the development of luminescence calibration standards utilizing glass doped with lanthanide ions, specifically focusing on Eu3+ ions chosen for their robust emission properties. Glasses composed of aluminum calcium sodium borate doped with Eu3+ ions were prepared using the melt-quenching technique, with varying compositions of 20Al2O3–20CaO–20Na2O–(40–x)B2O3–xEu2O3 (where x = 0.0, 0.5, 1.0, 3.0, 5.0, and 7.0 mol%). The intense red emission around 615 nm through the 5D0 to 7F2 transition of Eu3+ was detected. To ensure measurement reliability, this study conducted measurements under four different stimulations: ultraviolet–visible light (photoluminescence), X–ray (radioluminescence), proton (protonluminescence), and electron (cathodoluminescence), verifying consistent peak positions. The findings from this study validate the potential of aluminum sodium calcium borate glasses doped with Eu3+, particularly those containing 3.0 mol% of Eu2O3, as effective calibration materials for luminescence spectrometers. This highlights their capability for accurate and consistent calibration, emphasizing their importance in maintaining measurement precision in the luminescence spectrometer.

Fabrication of energy efficient P-i-G structure with novel dysprosium-doped yttrium calcium borate (Dy: Y2CaB10O19) phosphors: Highly efficient materials for cool white light emission conducive to green technology

Novel polycrystalline phosphor-yttrium calcium borate doped with dysprosium ions (Dy3+: Y2CaB10O19) was synthesized for the first time by solid-state reaction technique. The crystal structure was found to be monoclinic having C2 space group. SEM was performed to analyze the surface morphology of the phosphor materials and to assess the distribution of phosphor particles in the glass matrix. Fourier transform infrared (FTIR) spectroscopy of the samples was studied to know the molecules present. The emission spectra by 350 nm excitation possessed characteristic peaks at 480 nm (blue) and 577 nm (yellow). The CIE chromaticity co-ordinate and correlated color temperature (CCT) were deduced to be (x = 0.3384, y = 0.3823) and 5297 K respectively. Luminescence decay time for the optimized phosphor was determined to be 0.70 ms. The prepared phosphors were embedded in the glass matrix at an elevated temperature of 1000 °C. The transmittance spectra of the prepared glass materials were recorded to analyze its transparency in the visible region. The internal quantum yield was deduced to be 53.91 %.

Scalable Dual In Situ Synthesis of Polyester Nanocomposites for High-Energy Storage.

Incorporating ultralow loading of nanoparticles into polymers has realized increases in dielectric constant and breakdown strength for excellent energy storage. However, there are still a series of tough issues to be dealt with, such as organic solvent uses, which face enormous challenges in scalable preparation. Here, a new strategy of dual in situ synthesis is proposed, namely polymerization of polyethylene terephthalate (PET) synchronizes with growth of calcium borate nanoparticles, making polyester nanocomposites from monomers directly. Importantly, this route is free of organic solvents and surface modification of nanoparticles, which is readily accessible to scalable synthesis of polyester nanocomposites. Meanwhile, uniform dispersion of as ultralow as 0.1 wt% nanoparticles and intense bonding at interfaces have been observed. Furthermore, the PET-based nanocomposite displays obvious increases in both dielectric constant and breakdown strength as compared to the neat PET. Its maximum discharged energy density reaches 15 J cm-3 at 690 MV m-1 and power density attains 218 MW cm-3 under 150 Ω resistance at 300 MV m-1, which is far superior to the current dielectric polymers that can be produced at large scales. This work presents a scalable, safe, low-cost, and environment-friendly route toward polymer nanocomposites with superior capacitive performance.

Microwave-hydrothermal synthesis of calcium borate whiskers: Influencing factors and formation mechanism

The synthesis of whiskers is an important means of high-value utilization of calcium resources. Calcium borate (Ca2B2O5·H2O) whiskers were synthesized by microwave hydrothermal method using CaCl2, Na2B4O7·10H2O and NaOH as raw materials at 140 °C for 2 h. A series of characterizations were conducted on the obtained calcium borate whiskers, including phase identification (XRD and FT-IR), crystal morphology (SEM), crystal structure (TEM and SAED), and thermal stability (TG). Through batch experiments under the control of influencing factors, the effects on product phase and morphology were systematically studied, such as raw material concentration (Ca2+ concentration and the molar ratio of boron/calcium), reaction temperature, holding time and pH value. For the prepared calcium borate whiskers, SAED demonstrated that the whiskers have a single crystal structure, characterized by a sarciniform shape with diameter ranging from 1.2 to 3.1 μm and a length of 50 to 120 μm. And thermal analysis revealed that the calcium borate whiskers remained stable without losing crystalline water at a synthesis temperature of 140 °C, while releasing crystalline water at a temperature range of 383.6 °C to 430.9 °C. The optimal conditions for Microwave-Hydrothermal synthesis were identified based on experimental phenomena, and the solution-liquid–solid (SLS) process of whisker formation was proposed and analyzed. The possible chemical reactions and growth mechanisms of calcium borate whiskers under microwave hydrothermal synthesis were briefly proposed by adjusting the reaction conditions and observing the process of morphological changes.

Solid–Liquid Phase Equilibria of the Aqueous Ternary System Containing Lithium Borate and Calcium Borate at T = (298.2, 323.2, and 348.2 K)

Solid–Liquid Phase Equilibria of the Aqueous Ternary System Containing Lithium Borate and Calcium Borate at <i>T</i> = (298.2, 323.2, and 348.2 K)

Synthesis and Investigation of the Hydration Degree of CA2 Phase Modified with Boron and Fluorine Compounds.

This study investigated the effect of fluoride and boron compound additives on the synthesis and hydration process of calcium aluminate (CA2). The analysis showed that the temperature of the full synthesis of CA2 without mineralizing additives was 1500 °C. However, the addition of fluorine and boron compounds at 1% and 3% significantly reduced the synthesis temperature to a range of 1100-1300 °C. The addition of fluoride compounds did not result in the formation of fluoride compounds from CaO and Al2O3, except for the calcium borate phase (Ca3(BO3)2) under certain conditions. In addition, the cellular parameters of the synthesized calcium aluminate phases were not affected by the use of these additives. Hydration studies showed that fluoride additives accelerate the hydration process, potentially improving mechanical properties, while boron additives slow down the reaction with water. These results highlight the relevance of fluoride and boron additives to the synthesis process and hydration kinetics of calcium aluminate, suggesting the need for further research to optimize their application in practice. TG studies confirmed the presence of convergence with respect to X-ray determinations made. SEM, EDS and elemental concentration maps confirmed the presence of a higher Al/Ca ratio in the samples and also showed the presence of hexagonal and regular hydration products.

Optical and Structural Properties of TiO2 doped Calcium Borate Glasses

The novel glasses were created using the melt quenching technique and the glass composition xTiO2-(50-x) CaO-50B2O3, where x=0, 1, 3, 5, 7, 9 in mol%, which was characterized by XRD spectra and confirmed the glass samples’ amorphous nature. Using the Archimedes principle, the density of the glasses was determined, and the associated molar volume was estimated. Density increases with increasing mol% TiO2, whereas molar volume decreases, as anticipated. The absorption spectra from the wavelength region of 200nm–1100nm were obtained using a UV-visible spectrometer. Tauc’s plot was used to evaluate the direct and indirect energy band gap, and the fluctuation of the energy band gap with mol% TiO2 has been discussed. The refractive index has also been estimated using energy band gap data. In the 400-4000 cm-1 range, the FT-IR functional groups were confirmed.

Microwave-assisted combustion synthesis and characterization studies of novel dysprosium doped yttrium calcium borate (Dy3+: Y2CaB10O19) phosphor materials for efficient white light applications

Micro-wave assisted combustion synthesis technique was adopted to synthesize the dysprosium-doped yttrium calcium borate xDy3+: Y(2-x) CaB10O19 (Dy:YCB) polycrystalline phosphor materials with varying concentrations (x = 1, 3, 5, 7 and 9 mol %) for the first time. The formation of phase, crystal structure was analyzed by x-ray diffraction study and was affirmed to be formed pertaining to the monoclinic crystal structure (a = 11.475 Å, b = 6.345 Å, c = 9.223 Å and α = γ = 90°, β = 91.83°) with C2 space group. The absorption capability of the prepared samples was investigated by UV-DRS spectroscopy and the optical band gap was found to be 5.28 eV. FTIR study validated the presence of functional groups and their molecular vibrations. The excitation wavelength of the synthesized samples was found to be 350 nm from photoluminescence excitation (PLE) spectra. The PL emission spectra were recorded to authenticate the emission wavelengths and found to possess two emission peaks at 480 nm (blue) and 577 nm (yellow) contributed by the Dy3+ ions. The optimized dopant concentration of dysprosium ion was fixed at x = 0.07 to avoid the concentration quenching effect. The chromaticity co-ordinate of optimized sample was determined to be x = 0.3188, y = 0.3233 which are closer to ideal white light co-ordinate. The color temperature was determined to be 6209 K, which occurs in the cool white light region. Luminous efficacy of radiation (LER) was determined to be 269.31 l m/Wopt for the optimal phosphor. The luminous efficiency for the optimal phosphor was determined to be 40%. Color rendering index (CRI) of the optimal sample was evaluated to be 77. Internal quantum yield (IQE) of the optimal sample was determined to be 50.58 %. The phosphor materials have excellent thermal stability as validated from the temperature dependent PL measurements.

A novel Ti3SiC2-CaB6 modified Al-coated carbon fiber/boron phenolic resin ceramizable composite (ACF/BPRC) with excellent long-term oxidative corrosion resistance and high temperature load-bearing capacity

Carbon fiber/phenolic composites (CF/Ph) are susceptible to oxidation failure. In this work, Ti3SiC2-CaB6 modified ACF/BPRC was prepared, and its long-term (20min) oxidation resistance in a broad temperature range (600-1400 ℃) was investigated. The mass residual rate at 1400 ℃ and flexural strength post static ablation at 1400 ℃ for 20min was 90.9% and 41.8MPa, respectively. The ceramizable composite underwent ceramization reactions and was converted to ceramized composite, and a thermal protection barrier composed of TiO2, TiC, TiB2, SiC, Al2O3, and molten Al and calcium borate was constructed. Thus, the long-term oxidation resistance and high-temperature load-bearing capacity was enhanced notably.

Dissolution behavior and kinetic investigation of 〖Ca〗^(2+) in the dissolution of colemanite in propionic acid presence saturated with synthetic flue gas

Colemanite (〖2CaO.3B〗_2 O_3.5H_2 O) is a calcium borate mineral and can be expressed as the primary material of industrial production of boric acid. Boric acid is one of the most essential raw materials obtained by solving colemanite ore in acidic solutions and gases. The dissolution behavior and kinetics of 〖Ca〗^(2+) in a solution of colemanite in a propionic acid solution saturated with synthetic flue gas were examined. In this context; the effects of particle size, reaction temperature, acid concentration, solid-liquid ratio and synthetic flue gas flow rate parameters were investigated. According to the experimental data, it was observed that the amount of 〖Ca〗^(2+) passing to the solution increased with the increase of the reaction temperature, acid concentration and gas flow rate, and with the decrease in solid-liquid ratio and grain size. Experimental results were analyzed by homogeneous and heterogeneous models using the Statistica package program, and it was determined that the dissolution of 〖Ca〗^(2+) in solution complies with the “Avrami” model. The activation energy (E) was found as 〖26.83 kJ.mol〗^(-1) and the Arrhenius constant (A) was found as 〖8.9*10〗^3.

Cool white light generation of Dy3+ activated aluminum sodium calcium borate glass for W-LED application

The Dy3+-activated aluminum sodium calcium borate glass with white light emission might have been created through the melt-quenching process. This research explores the optical and luminescence characteristics of borate glasses. Dy3+-activated glasses exhibit absorption in the visible (VIS) and near-infrared spectrums. The absorption starts from the 6H15/2 ground state to the higher state concerning optical characteristics. The emission spectra of dysprosium-doped glasses' photoluminescence show greater intensity at 483 nm (blue light) and 575 nm (yellow light), which are critical wavelengths for white light-generating materials. The luminescence intensity of Dy3+ ions increased up to a 0.50 mol% concentration, while the decay time decreased with an increasing dysprosium ion concentration. The emission spectra were used to estimate the CIE 1931 chromaticity and corresponding color temperature, revealing a shift towards the cold white light location at that temperature. The stimulated emission cross-section is calculated via the Judd-Ofelt theory. All characteristic outcomes suggest that the existing dysprosium-enabled glasses are excellent materials for generating cool white light in W-LED applications.

Comparative study of Eu3+ doped calcium borate glasses and crystalline calcium hexaborate phosphors

Comparative study of Eu3+ doped calcium borate glasses and crystalline calcium hexaborate phosphors

An efficient attenuator for gamma rays and slow neutrons of elastic and transparent lead sodium zinc calcium borate glass

An efficient attenuator for gamma rays and slow neutrons of elastic and transparent lead sodium zinc calcium borate glass

Unveiling the structure of calcium borate glass by neutron diffraction, MAS-NMR, Raman and first-principles calculations

Calcium borate glass is a challenging system, due to the rich variety of borate units and alterable boron coordination number, and hence they are also of particular interest for academic study. In this study, neutron diffraction, solid-state magic angle spinning nuclear magnetic resonance (MAS-NMR) and Raman spectroscopy were combined with first-principles calculations, experience potential structure refinement (EPSR) simulations to investigate the structure of xCaO·(1-x)11B2O3 glass. Property data such as density and glass transition temperature were also measured to study the impact of structural changes on the properties of glasses. The structure of calcium borate glass was analyzed using various methods including structural unit, atomic pair bond length, coordination number, ring structure, chain structure and cavity distribution. Most notably, the atomic labeling method plays a key role in the structural analysis process. Through this method some new conclusions were obtained. For example, the increase of CaO content mainly leads to the conversion of BO to NBO in the glass structure, and has little effect on the content of BO3 and BØ4-. This result further leads to an increase in Ca-NBO interactions. Interestingly, the bond length distribution of Ca-NBO and B-NBO is shorter than that of Ca-BO and B-BO, so the glass structure becomes denser. The structural reason why the density of calcium borate glass is less than the crystal density was also revealed. This study contributes to unveiling the structure of calcium borate glass and exploring the correlation between the structure and properties of calcium borate glass, which provides a valuable reference for developing more valuable amorphous materials.

Molluscicidal activity of calcium borate nanoparticles with kodom ball-flower structure on hematological, histological and biochemical parameters of Eobania vermiculata snails

Land snails are the most harmful pests in agricultural fields. Eobania vermiculata is a widespread snail species that causes massive damage to all agricultural crops. Thus, the molluscicidal activity of calcium borate nanoparticles (CB-NPs) against Eobania vermiculata was evaluated and compared with metaldehyde (Gastrotox® E 5% G). The amorphous phase of CB-NPs was obtained after thermal treatment at a low temperature (500 °C) which conformed by X-ray diffraction (XRD) analysis. CB-NPs are composed of aggregated nano-sheets with an average thickness of 54 nm which enhanced their molluscicidal activity. These nano-sheets displayed meso-porous network architecture with pore diameters of 13.65 nm, and a 9.46 m2/g specific surface area. CB-NPs and metaldehyde (Gastrotox® E 5% G) exhibited molluscicidal effects on Eobania vermiculata snails with median lethal concentrations LC50 of 175.3 and 60.5 mg/l, respectively, after 72 h of exposure. The results also showed significant reductions of Eobania vermiculata snails hemocytes' mean total number, the levels of Testosterone (T) and Estrogen (E), alkaline phosphatase, acid phosphatase, albumin, and protein concentrations, succinate dehydrogenase, glucose, triglycerides and phospholipids levels, while significant increases in the phagocytic index and mortality index, both transaminases (ALT and AST) and glycogen phosphorylase concentration were observed after the exposure to LC50 of CB-NPs or metaldehyde (Gastrotox® E 5% G) compared to the control group. Therefore, CB-NPs could be used as an alternative molluscicide for controlling Eobania vermiculata, but further studies are needed to assess their effects on non-target organisms.

A New Methodology to Evaluate the Sealing Process Based on Pressure Drop and Fluid Loss in Fractures during the Drilling Operation

Summary Natural or artificial fractures are common in the wellbore during drilling operations. These fractures allow the flow of drilling fluid into the rock formation. The loss of circulation increases the operation’s cost and nonproductive time, which may threaten the well’s structural integrity. To overcome this problem, it is necessary to understand the flow of fluids through fractures and develop methods to mitigate the loss of circulation. This work’s main contributions are expanding the knowledge on the flow of drilling fluids through fractured channels, conducting an experimental study on the flow of suspensions of lost circulation materials (LCM) in fractures, and performing a theoretical analysis to obtain mathematical models describing fractured channels’ sealing. This work proposes a correlation between the pressure drop and the volumetric flow rate of fluid through fractures. To validate the model, a physical simulator collected fluid flow data and pressure drop in fractures with 2-mm, 5-mm, and 10-mm apertures and 1.02-m length. A blend of polymers and calcium borate was used in suspension in water viscosified with xanthan gum (XG). Density and rheological behavior tests were performed to characterize the studied fluids. The LCM had a bimodal particle-size distribution, and the formulated fluids had a Herschel-Bulkley rheological behavior. Pressure drop, flow rate, and rheological data were used to propose a correlation between pressure drop and volumetric flow rate through the fracture. The proposed correlation was used to monitor the sealing of fractures by calculating their hydraulic diameter throughout the sealing process. The LCM suspensions underwent filtration tests to observe the effects of sealing particles on the mudcake and filtrate volume. The proposed correlation fitted the experimental data with less than 10% deviation. The fracture hydraulic diameter was estimated using experimental data of volumetric flow rate and pressure drop, which made it possible to monitor the sealing process of fractures through time. The sealing and filtration tests showed that the borate and polymer blends are effective as filtration control agents and LCM.

High resistivity free-standing crosslinked graphene oxide substrates: hopping conduction mechanism and application to recyclable electronics

Graphene oxide (GO) is an oxidized derivative of graphene that can be formed into free-standing wafers by aqueous processing methods. We propose GO as a potential alternative printed electronic substrate material to mitigate the waste electronic and electrical equipment problem. By dissolving these substrates in water, GO permits the mechanical separation and recovery of discrete components from defunct circuits, thus closing the life cycle of printed circuits. In this work we measure the anisotropic, frequency dependent resistivity of free-standing GO wafers under DC and AC (f = 0.1 Hz–500 kHz) excitation and in varying relative humidity (RH) conditions. Unmodified GO and GO crosslinked with calcium ions, borate ions, and glutaraldehyde were characterized. AC resistivity measurements reveal charge transport in free-standing GO occurs by several distinct hopping conduction mechanisms that are sensitive to the crosslinking formulation. GO crosslinked with calcium ions exhibits the highest DC resistivity, 4.6 × 105 Ωm and 2.6 × 104 Ωm, for out-of-plane and in-plane directions, respectively, at 17% RH. Both AC and DC resistivities decrease with increasing RH. We demonstrate that GO wafers can be used as dielectric substrates in the construction of simple electronic circuits with discrete electronic components. Finally, we present a proof-of-concept for electrical trace and component recovery via disassembly of GO wafers in water.