Aluminum Borate Research Articles

Lightweight porous Al2O3‐based ceramics with highly controllable performance via binder jetting

AbstractThis study introduces a feasible approach for preparing Al2O3‐based ceramics with highly controllable performance via binder jetting. The Al2O3‐based ceramics were prepared using Al2O3 and H3BO3 as raw materials. The results showed that the samples prepared with 0.24 mol H3BO3 exhibited high apparent porosity (64%–66.67%), well‐bending strength (3.46–8.53 MPa), and low thermal conductivity (0.113–0.329 W·m−1·k−1 at 200–800°C). It was observed by an electron microscope that the increase of boric acid content led to the in‐situ formation of more aluminum borate grains in the sample. Meanwhile, the remaining Al2O3 reacts with silicon oxide in the impregnation solution to form mullite whiskers. The whiskers ensured that the sample had superior mechanical properties and lower thermal conductivities. Based on the above properties, the possibility of Al2O3‐based ceramics application in the aerospace field can be speculated.

Enhanced Epoxy Composites Reinforced by 3D-Aligned Aluminum Borate Nanowhiskers.

Recently, the durability of high-performance and multifunctional portable electronic devices such as smartphones and tablets, has become an important issue. Electronic device housing, which protects internal components from external stimuli, such as vibration, shock, and electrical hazards, is essential for resolving durability issues. Therefore, the materials used for electronic device housing must possess good mechanical and electrical insulating properties. Herein, we propose a novel high-strength polymer nanocomposite based on 3D-aligned aluminum borate nanowhisker (ABOw) structures. ABOw was synthesized using a facile hydrothermal method, and 3D-aligned ABOw structures were fabricated using a freeze-casting process. The 3D-aligned ABOw/epoxy composites consist of repetitively layered structures, and the microstructures of these composites are controlled by the filler content. The developed 3D-aligned ABOw/epoxy composite had a compressive strength 56.72% higher than that of pure epoxy, indicating that it can provide high durability when applied as a protective material for portable electronic devices.

Concentration Dependence Orange Light Generation Through Sm3+‐Doped Soda Lime Alumino Borate Glasses for Orange Laser Medium Material

The melt‐quenching technique is used to fabricate calcium sodium aluminum borate glasses (Sm: ANCB) doped with varying concentrations of Sm3+ ions. Characteristics of ANCBSm glasses, including density, molar volume, refractive index, absorption, emission (via visible light, X‐ray, and proton excitation), decay time, and CIE color coordinates, are analyzed. The density, molar volume, and refractive index of ANCBSm glass increased with Sm2O3 concentration. Sm3+ ions enabled photon absorption in both visible and NIR regions, with a strong reddish‐orange emission at 600 nm due to the 6H5/2 → 6P3/2 transition under various excitations. X‐ray excitation is also compared with BGO scintillation crystals. The J–O theory predicted the radiative properties of Sm3+ ion emission levels. Decay curves of the 6H5/2 levels showed a single exponential nature with a millisecond‐order lifetime. CIE chromaticity of ANCBSm glasses is in the reddish‐orange region. ANCBSm glasses have potential applications in orange laser medium material.

STUDY OF THE EFFECT OF FLUXING MATERIALS ON THE DEPOSITION OF METAL BEADS FROM HIGH CARBON FERROCHROME SLAG

The study of the effect of the properties of high-carbon ferrochrome slags on the creation of favorable conditions for the deposition of metal beads with the introduction of the following fluxing additives in an amount of 3-10%: slag produced by refined ferrochrome (stale and stabilized), cryolite, fluorite, feldspar, colemanite, fused borate ore, aluminum slag of aluminum production. The influence of the type and quantity of fluxing materials on the viscosity and crystallization temperature of high-carbon ferrochrome slags has been studied. It is noted that the use of all types of fluxing materials under study leads to a decrease in the crystallization temperatures of the processed slag. It can be seen from the results of metallographic and phase analyses that the best values for the degree of coagulation and deposition of metal crowns were achieved with the introduction of aluminum slag, colemanite and borate ore.

Influence of praseodymium oxide on the structural, mechanical and photon, charged particles, and neutron shielding properties of alumina borate glass

The structural, mechanical and radiation shielding properties of (69-x)B2O3-20TeO2-10Al2O3-1HfO2-xPr6O11 (where x = 0, 0.25, 0.5, 0.75, 1 mol %) glass system were investigated. This study introduces a novel approach by incorporating Pr6O11 into glass composition, highlighting its unique contributions to enhancing elastic properties, fracture toughness, hardness, and radiation shielding abilities. Experimental measurements were conducted within the energy range of 59.54–661.62 keV and theoretical calculations are made for MAC values. The presence of Pr6O11 was noted to positively influence the gamma shielding capabilities. At 59.54 keV, the addition of 0.25 mol% Pr6O11 increased the mass attenuation coefficient of the glass by 2.9 %, and the addition of 1 mol% Pr6O11 increased it by 29.8 %. The addition of 0.25 mol% Pr6O11 increased the fast neutron removal cross section of the glass by 4.4 %. Also, it is observed that the glass with 1 mol% Pr6O11 is the best shielding material against alpha and proton particles. A significant enhancement of 24.36 % in the fracture toughness value was observed, increasing from 1.059 to 1.317 MPa m1/2 at 1 mol% Pr6O11. Experimental hardness values increased from 3.374 to 3.985 GPa, resulting in an improvement of 18.11 % at 1 mol% Pr6O11. The thermal stability (ΔT, °C) value demonstrated a notable increase from 85 to 106, indicating a significant 24.7 % improvement at 0.25 mol% Pr6O11.

In-situ synthesis of BN/Al18B4O33 heterogeneous core-shell nanowires with different BN shell thicknesses and the microstructure evolution mechanism

A simple method was developed for the controllable synthesis of novel BN-coated aluminum borate (Al18B4O33) heterogeneous core-shell nanowires using Al4B2O9 nanowhiskers as rigid templates. This method allows the fabrication of Al18B4O33 nanowires with BN coatings of different thicknesses. The phases, microstructures, and chemical compositions of the samples were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FT-IR), transmission electron microscopy (TEM), and other characterization techniques. The heterogeneous core-shell nanowires of BN/Al18B4O33 had diameters and tube lengths of 35–60 nm and 400–600 nm, respectively, and the thickness of the BN cladding shell was between 2 and 7 nm. The concentration of B* volatilized on the whisker surface could be controlled by varying the ammonia flow rate, which in turn regulated the thickness of the BN cladding layer. The thickness of the BN cladding changed more significantly when the ammonia flow rate was varied at the Al4B2O9 nanowhisker's decomposition temperature. The experimental results show that the BN on the BN/Al18B4O33 heterogeneous core-shell structured nanowires conforms to the vapor–solid (VS) growth mechanism.

Magnetic field effect on the electric permittivity of rare-earth aluminium borates

The renormalization of the electric permittivity of rare-earth aluminium borates is studied theoretically from the first principles. It is shown how the electric permittivity depends on the external magnetic field and temperature for several compounds of rare-earth ions of that class.

Structural, optical, and the effect of beta source (90Sr/90y) radiation on the thermoluminescence properties of the transition metal activated on lithium aluminum borate phosphor (Li3Al3(BO3)4:Mn)

The activation of Lithium aluminum borate material with varying concentrations of transition metal of manganese was studied. The synthesis of the phosphor samples was achieved by employing the solid-state sintering technique. The study aimed to determine the structural property, optical property, and the effect of beta source (90Sr/90y) radiation on the thermoluminescence properties of the phosphor material. The analyzed structure of both doped and undoped samples was obtained to be from 52.17 to 67.13 nm as the crystallite size and 67.00–120.00 nm as the particle size respectively. The optical studies showed an increase in mole concentration of the doped samples resulted in an increase in absorbance and a decrease in the energy band gap from 4.45 to 4.00 eV. The thermoluminescence report measured showed that the Mn-doped sample on lithium aluminum borate has the most prominent peak at 78 °C (major peak) and 294 °C (minor peak) when exposed to radiation dose (90Sr/90y beta source) of 50 Gy. The acquired activation energy was resolved using some of the models which include the initial rise, deconvolution, and the heat rate techniques. The dose response was determined to be linear from the Mn-doped lithium aluminum borate.

Novel Tb³⁺-Doped LaAl₂B₄O₁₀ phosphors: Structural analysis, luminescent properties, and energy transfer mechanism

This study explores the structural and luminescent properties of terbium (Tb³⁺)-doped lanthanum aluminium borate (LaAl₂B₄O₁₀, abbreviated as LAB) phosphors, a novel host lattice for Tb³⁺ doping. LAB:Tb³⁺ phosphors, with varying dopant concentrations, were synthesized using a microwave-assisted combustion synthesis approach and characterized using X-ray diffraction (XRD), Rietveld refinement, and photoluminescence spectroscopy at both room and low temperatures. The structural analysis confirmed the hexagonal crystal structure of LAB and revealed successful incorporation of Tb³⁺ ions without altering the fundamental lattice. Luminescence studies demonstrated that the LAB:Tb³⁺ phosphors show strong green emission primarily attributed to the 5D4→7F5 transition of Tb³⁺. The optimal doping concentration was determined to be 5 wt% Tb³⁺, which provided maximum luminescence efficiency. This concentration also allowed for a critical study of energy transfer mechanisms within the phosphor, revealing dipole-dipole interactions with a critical distance of 9.80 Å between Tb³⁺ ions. Additionally, the CIE chromaticity coordinates of LAB:0.05 Tb³⁺ were precisely determined to be (0.289, 0.4460), indicating the potential for high-quality green emission suitable for solid-state lighting and display technologies. This work not only demonstrates the potential of LAB:Tb3+ as a highly efficient green luminescent material, but also sheds light on the mechanisms responsible for energy transfer and concentration quenching.

Microstructure, mechanical and neutron shielding properties of aluminum borate ceramics obtained from alumina and boric acid

Microstructure, mechanical and neutron shielding properties of aluminum borate ceramics obtained from alumina and boric acid

Transparent aluminoborosilicate glass-ceramics containing Al4B2O9 nanorods

Transparent glass-ceramics containing nanorods are attractive for many applications. In this work, transparent aluminoborosilicate glass-ceramics containing aluminum borate nanorods are reported. Effects of Al2O3 and SiO2 concentrations on the thermal properties and crystallization of aluminoborosilicate glasses are studied. It is found that lithium aluminosilicate nanocrystals and Al4B2O9 nanorods are co-precipitated in glasses with Al2O3/SiO2 molar ratios of 0.29 and 0.33, and only Al4B2O9 nanorods are precipitated in glasses with Al2O3/SiO2 molar ratios of 0.375 and 0.42. Precipitation of these nanocrystalline phases leads to the enhancement in Vickers hardness. Glass-ceramics with Al2O3/SiO2 molar ratios of 0.375 and 0.42 are highly transparent in the visible region due to the small size of the Al4B2O9 nanorods precipitated inside.

Rare-Earth-Ion (RE3+)-Doped Aluminum and Lanthanum Borates for Mobile-Phone-Interrogated Luminescent Markers

In this paper, we present the synthesis and luminescent spectra of rare-earth (RE)-doped aluminum and lanthanum borates intended to serve as narrow excitation–emission band fluorescent markers. We perform a detailed 3D excitation–emission matrix (EEM) analysis of their spectra, compare the measurements from both standard and mobile phone spectrometers, and outline the basic differences and advantages of each method. While smartphones have a different and non-uniform spectral response compared to standard spectrometers, it is shown that they offer a number of advantages such as contactless interrogation, efficient suppression of the UV excitation light, and simultaneous spectral analysis of spatially arranged arrays of fluorescent markers. The basic emission peaks have been observed and their corresponding electronic transitions identified. The obtained results show that the rare-earth-doped La and Al borates feature excitation–emission bandwidths as low 15 nm/12 nm, which makes them particularly appropriate for use as luminescent markers with UV LED excitation and smartphone interrogation.

One-dimensional electrospun alumina borate ceramics: transformation from fiber-like structure to ribbon-like structure at the increased concentrations of precursor sol

One-dimensional electrospun alumina borate ceramics: transformation from fiber-like structure to ribbon-like structure at the increased concentrations of precursor sol

Structural, Physical and Optical studies of Sc3+ doped Lithium Aluminum Borate glasses

Optically transparent lithium aluminum borate containing scandium glasses with composition 70B2O3 – 20Li2O – (10 – x) Al2O3 – xSc2O3 (where x= 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6 and 0.7 in mol %) were fabricated by conventional melt quenching technique. The non-crystalline nature of the samples was monitored by X-ray diffraction and it confirms non-crystalline nature. Structure of the fabricated glasses are assessed using the Fourier transform infrared spectra. The absorption spectra of these glasses have been recorded in the wavelength range 200 nm – 1100 nm. Direct and indirect optical energy band gaps were calculated from Tauc’s plots. The physical parameters such as refractive index (RI), optical basicity and interaction parameters were determined using proper formulas to know the characteristics of fabricated glass matrix. The results obtained indicate that 0.3 mol% Sc2O3-containing BLASc glass is more suitable for w-LEDs and lasers applications.

Novel ceramic supports for catalyst with hierarchical pore structures fabricated via additive manufacturing-direct ink writing

The use of direct ink writing technology, combined with in-situ grown whiskers, has facilitated the development of 3D-printed ceramic catalyst supports-aluminum borate porous ceramics (ABPCs) with hierarchical pore structures. The optimal slurry consists of 0.2 wt% polycarboxylate, 19 wt% water addition, and 1.2 wt% sodium alginate. The most effective printing parameters are determined to be a 1.0 mm nozzle diameter, 10 mm/s printing speed, 4.0 kPa air pressure, and 0.4 mm layer height. After sintering at 1100 ℃, pure-phase aluminum borate (Al18B4O33) ceramics are achieved, leading to the formation of needle-like aluminum borate whiskers. The aspect ratio of whiskers, flexural strength, BET-specific surface area, and photocatalytic activity of ABPCs increase initially and then decrease with increasing sintering temperature. The ABPCs coated with a titanium oxide layer display a photocatalytic degradation rate of 83.92% for methyl orange solution. These results underscore the immense potential of ABPCs in high-temperature catalyst support applications.

Combustion features of dispersed aluminum and boron in high-energy composition

Combustion of dispersed metals in an oxidizing environment is of practical interest, which is related to the prediction of characteristics of high-energy compositions (HECs) containing metal powders, as well as the characteristics of various propulsion systems and gas generators. The research studies peculiarities of ignition and combustion of dispersed systems of Al, B and Al-B mixture in gas products formed during thermal decomposition and combustion of HEC components. In the study of the characteristics of ignition and combustion, the development of flame processes, a continuous CO2 laser (high-speed radiant heating) and a continuous-pressure flow bomb (stationary combustion), including the filter system for the capture of condensed combustion products (CCPs) were applied. It was found that the high reactivity of dispersed Al reduces the ignition time and increases the burning rate of HECs, and increases the volume fraction of fine condensed particles. The use of amorphous B or Al-B mixture (17.2/82.8 mass ratio) increases the ignition time (up to 62%) and significantly reduces the burning rate of HECs, at the same time, the volume share of large CCPs increases due to the melting of the oxide layer on the surface of B particles and their increased cohesion. Analysis of CCPs showed that fine and large agglomerate particles were formed on the surface of the reactive HEC layer, which contain oxides of the metals used. When Al particles are burned together with B particles, complex oxides (aluminum borates) can be formed.

The impact of heat treatment on the luminescence properties of Dy/Ag co-doped sodium alumina borate glasses

The sodium alumina borate glasses were synthesized by conventional melt-quenching method and heat treated with different durations to ensure the formation and growth of Ag nanoparticles. Transmission electron microscope measurements revealed that the average nanoparticle size increases with the heat treatment duration. The bonding nature between Dy3+ ions and surrounding ligands was getting more covalent with HT. Judd-Ofelt intensity parameters proved the asymmetric nature around Dy3+. The most intense emission and excitation bands of Dy3+ ions were observed for 6 h heat-treated glass (HT-6h). Intense blue (483 nm) and yellow (572 nm) emissions were obtained in which the yellow one has the highest radiative parameters approving the suitability of glasses for yellow laser applications. Based on colorimetric results emission closest to white light can be generated by HT-6h under 426 nm excitation. The decay time of 4F9/2 → 6H13/2 transition increases with heat treatment attributed to the combined effect of the enhanced local electric field induced by the Ag nanoparticles and energy transfer from Ag species to Dy3+ ions. The findings show that Dy3+/Ag+ co-doped sodium alumina borate glasses are potential materials for photonic applications.

F → f transition luminescence of Eu2+ in barium–aluminum–borate oxyfluoride glass ceramics

A new type of transparent luminescent glass ceramics with the ability to generate the line emission of Eu2+ ions were prepared. EPR was used to explore the mechanism of transformation of the optical transition of Eu2+ from 4f65d1→4f7 to 4f7→4f7.

Synthesis and luminescence characteristics of yttrium, aluminum and lanthanum borates doped with europium ions (Eu 3+)

Inorganic materials doped with rare earth (RE) ions are an object of intense research due to their optical and electrical properties. These materials have the potential for various applications, such as solid-state lasers, active planar waveguides, optical fiber amplifiers, light-emitting diodes (LEDs), displays, ink fillers, security features, etc. RE trivalent ions can emit light from the ultraviolet (UV) to the near-infrared (NIR) regions due to electronic transitions of the 4f-5d levels. Yttrium borate doped with europium ions was prepared by solid-state synthesis in a muffle furnace at 900oC for 4 hours, while lanthanum and aluminum borates doped with europium ions were prepared at 1000oC for 6 hours again in a muffle furnace. The resulting materials are fine white powders. Among the rare earth ions, europium is one of the most commonly used activators because the ions of Eu3+ and Eu2+ can be used as emission sites in the host lattices. Eu3+ ions can produce effective sharp emission peaks in different matrix compositions. Photoluminescence analysis of the samples was performed, based on which the luminescence intensity of the Eu3+ ion was determined through a comparative characteristic. YBO3:Eu3+ phosphor is optically active and chemically stable. It is characterized by a strong orange-red emission at ≈ 591 nm, ≈ 612 and ≈ 696 nm due to the 5D0→7F1 and 5D0→7F2 electronic transitions, respectively. Red emission is also observed for LaBO3:Eu3+ at ≈ 592 and ≈ 615 nm, characterizing the 5D0→7F1 and 5D0→7Fj (j=0, 1, 2, 3, 4) transitions. While aluminum borate doped with europium ion shows intense emission at ≈ 612 nm, making this material suitable for lighting devices. The technique of Fourier transform infrared spectroscopy (FTIR) was used to study the structure of the obtained materials.

Fabrication of high-strength magnetocaloric Fe2AlB2 MAB phase ceramics via combustion synthesis and hot pressing

The work focuses on the study of the structure, phase composition, mechanical, electrical, and thermophysical properties, as well as the heat resistance and magnetocaloric effect of Fe2AlB2 MAB phase obtained by combining the self-propagating high-temperature synthesis and hot pressing. An investigation of the phase composition and structure of a consolidated sample disclosed that the main component of the ceramic is plate-like Fe2AlB2 grains with a thickness of 170–200 nm and a length of 2–5 μm. The resulting single-phase hot-pressed ceramics exhibited hardness values up to 12.8 GPa, fracture toughness up to 5.2 MPa∙m1/2, bending strength up to 429 MPa, and a thermal conductivity coefficient up to 7.47 W/(m∙K). A differential scanning calorimetry analysis revealed that at a temperature of 1284 °C the complete decomposition of Fe2AlB2 occurred. The magnetocaloric effect measured by the direct method was 0.92 K at a Curie temperature of 291 K. The heat resistance of Fe2AlB2 was studied at 1000 °C. It has been established that the oxidation process is governed by a linear law, whereby a multilayer structure of a heterogeneous oxide film is formed on the surface of the sample. The surface layer of the oxide film consisted of hematite α-Fe2O3, while the inner layer comprised boron-containing oxides in the form of iron warwickite Fe2BO4 and a porous layer of aluminum borate Al4B2O9, formed as needle/wire-shaped crystals. The formation of a FeB-based sublayer at the interface with the substrate has been established. The calculated oxidation rate after 30 h of testing was 5.55∙10−4 mg/(cm2∙s).