Hydroxide Fluoride Research Articles

Adsorption of titanium-aluminum layered hydroxides for removal of fluorine at low concentrations in water

Layered double hydroxides have good application prospects in the fields of water treatment and defluoridation. In this study, Ti-Al layered hydroxides (Ti-Al LDHs) were synthesized by the co-precipitation method at a Ti/Al molar ratio of 2/8 and a medium solution pH of 6.0. The SEM, XRD, and BET results showed that the Ti-Al LDHs showed a uniform stacking of lamellar structure and existed mainly in dispersed amorphous form, with a wide pore size and a larger specific surface area (108.34 m2/g). The results of adsorption experiments showed that the highest capacity could reach 116.2 mg/g, and the adsorption adsorption of Ti-Al LDHs on fluoride was more in line with the proposed second-order model, and the adsorption isotherm was more in line with the Langmuir model.In addition, Ti-Al LDHs can be applied in a wide pH range (4−10), have strong resistance to anionic competition, and have good regeneration performance after five adsorption-desorption cycles where the adsorption capacity is still equivalent to 73 % of the initial capacity. From the FTIR and XPS results, the adsorption process was mainly attributed to ion exchange, electrostatic attraction and surface complexation. Therefore, Ti-Al LDHs is a layered hydroxide fluoride removal adsorbent with good application prospects.

Recovery of aluminum oxide and iron oxide from aluminum electrolysis iron-rich cover material and preparation of aluminum fluoride.

In aluminum electrolysis, the iron-rich cover material is formed on the cover material and the steel rod connecting the carbon anode. Due to the high iron content in the iron-rich cover material, it differs from traditional cover material and thus requires harmless recycling and treatment. A process was proposed and used in this study to recovery F, Al, and Fe elements from the iron-rich cover material. This process involved aluminum sulfate solution leaching for fluorine recovery and alkali-acid synergistic leaching for α-Al2O3 and Fe2O3 recovery were obtained. The optimal leaching rates for F, Na, Ca, Fe, and Si were 93.92, 96.25, 94.53, 4.48, and 28.87%, respectively. The leaching solution and leaching residue were obtained. The leaching solution was neutralized to obtain the aluminum hydroxide fluoride hydrate (AHFH, AlF1.5(OH)1.5·(H2O)0.375). AHFH was calcined to form a mixture of AlF3 and Al2O3 with a purity of 96.14%. The overall recovery rate of F in the entire process was 92.36%. Additionally, the leaching residue was sequentially leached with alkali and acid to obtain the acid leach residue α-Al2O3. The pH of the acid-leached solution was adjusted to produce a black-brown precipitate, which was converted to Fe2O3 under a high-temperature calcination, and the recovery rate of Fe in the whole process was 94.54%. Therefore, this study provides a new method for recovering F, Al, and Fe in iron-rich cover material, enabling the utilization of aluminum hazardous waste sources.

Simultaneous Removal of Arsenate and Fluoride Using Magnesium-Based Adsorbents

In this study, arsenate, As(V), and fluoride (F) were simultaneously removed from contaminated water using MgO, Mg(OH)2, and MgCO3 as Mg-based adsorbents, as existing studies only focus on their individual removal. The removal performance of As(V) and F followed the order MgCO3 < Mg(OH)2 < MgO. Under the test conditions, MgO and Mg(OH)2 met the environmental standards for As and F (0.01 and 0.8 mg/L, respectively), but MgCO3 did not. The As(V) removal performance was not significantly affected by an increase in the initial F concentration. It was concluded that As(V) was adsorbed and removed more preferentially than F by Mg-based adsorbents because a considerable amount of F remained even when the majority of As(V) was removed. Most arsenic (As)-adsorption data for MgO fit the Langmuir and Freundlich models, whereas those for Mg(OH)2 did not fit either model well. Additionally, the As-adsorption data for MgCO3 fit the Freundlich model but not the Langmuir model. Most of the F-adsorption data for the Mg-based adsorbents fit the Langmuir and Freundlich models. The removal mechanisms of As(V) and F using Mg-based adsorbents were assumed to be predominantly caused by ion-exchange and chemical-adsorption reactions on the adsorbent surface because no magnesium arsenate, magnesium fluoride, or magnesium hydroxide fluoride species were observed in the X-ray diffraction analysis. This research advances the sustainable As–F simultaneous treatment method using inexpensive adsorbents.

Reactive Condensation of Cr Vapor on Aluminosilicates Containing Alkaline Oxides

The research presented herein is part of a larger project delving into the mechanisms and pathways for reactive condensation of Chromium (Cr) vapors in high-temperature (>500o C) environments. The overall goal of this research project is to improve fundamental understanding of reactive condensation pathways for chromium (Cr) vapors generated in high-temperature systems such as exhaust manifolds, steam turbines, boilers, or solid oxide fuel cells (SOFCs). Reactive evaporation of Cr from stainless steels commonly used in these systems is well-documented; however, the interactions between volatilized Cr species and surrounding interfaces during complex and dynamic system exposures is poorly understood. Understanding the interactions between volatilized Cr species and downstream components during operation is critical for improving system performance, environmental health, and safety as some condensed Cr forms toxic hexavalent Cr(VI) species. The focus of this study is on the effects of alkaline oxides present within the substrate material on reactive condensation mechanisms of Cr vapors. Studying the reaction mechanisms between Cr vapors and ceramic surfaces has direct application to SOFCs as these materials are widely used in the field. For example, alumina-silica glass-ceramics are used as sealants in SOFCs. These materials belong to the SiO2–Al2O3 system and contain different compositions of oxides including CaO, Na2O, MgO, K2O, B2O3, Y2O3, and BaO. Another sealing material used in SOFCs is mica, a class of silicate minerals that forms into distinct layers. Two types of mica commonly used in SOFC applications are muscovite (potassium aluminum silicate hydroxide fluoride, KAl2(AlSi3O10)(F,OH)2), and phlogopite (potassium magnesium aluminum silicate hydroxide, KMg3(AlSi3O10)(OH)2). The specific research objective is to explore the effects of alkaline oxide additives in aluminosilicates on Cr collection and speciation. To accomplish this objective, an experimental platform was designed to assess interactions between samples of high-temperature steel alloys or Cr oxide (Cr2O3) powder with ceramic insulating materials. The chemical composition of the insulating materials used in this study range from pure silica (SiO2) and alumina (Al2O3) to combinations thereof with and without inclusions of alkaline earth metals (e.g., Ca, Mg). Preliminary results show three- to four-fold increases in Cr(VI) formation on silica fibers with weight percentages of ~30 and ~40 percent alkaline oxides (CaO and MgO), respectively, after exposure to volatile Cr species, relative to low-alkaline silica. Figure 1 presents an overview of the experimental concept, Cr(VI) test kit, and preliminary results for dependency on alkaline oxide content. Figure 1

Research progress on hydroxide fluoride-based electrode materials for supercapacitors

Supercapacitors have attracted much attention due to their high-power density and long cycle life, making them a potential substitute for traditional batteries. Research on hydroxide fluorides as electrode materials for supercapacitors has been increasing. Hydroxide fluorides exhibit higher specific capacitance due to the redox reactions between transition metal elements in different oxidation states. However, their high resistance limits their rate performance and cycling stability, which hinders their large-scale application. This article summarizes the main synthesis methods of hydroxide fluorides, and by controlling the reaction conditions, hydroxide fluorides with different morphologies and structures can be obtained to meet various application requirements. In addition, considering the limitations of hydroxide fluorides, this article systematically introduces the main approaches to improving their electrode performance and summarizes the electrochemical characteristics and latest research progress of hydroxide fluorides.

Facile Synthesis of Microsphere-like Co0.85Se Structures on Nickel Foam for a Highly Efficient Hydrogen Evolution Reaction.

Microsphere-shaped cobalt selenide (Co0.85Se) structures were efficiently synthesized via a two-step hydrothermal process. Initially, cobalt hydroxide fluoride (Co(OH)F) microcrystals were prepared using a hydrothermal method. Subsequently, Co0.85Se microsphere-like structures were obtained through selenization. Compared to Co(OH)F, the microsphere-like Co0.85Se structure exhibited outstanding catalytic activity for the hydrogen evolution reaction (HER) in a 1.0 M KOH solution. Electrocatalytic experiments demonstrated an exceptional HER performance by the Co0.85Se microspheres, characterized by a low overpotential of 148 mV and a Tafel slope of 55.7 mV dec-1. Furthermore, the Co0.85Se electrocatalyst displayed remarkable long-term stability, maintaining its activity for over 24 h. This remarkable performance is attributed to the excellent electrical conductivity of selenides and the highly electroactive sites present in the Co0.85Se structure compared to Co(OH)F, emphasizing its promise for advanced electrocatalytic applications.

Interface Engineering by Hydrophilic and Zincophilic Aluminum Hydroxide Fluoride for Anode‐Free Zinc Metal Batteries at Low Temperature

AbstractAnode‐free batteriesgreatly promote overall energy density, but they require an extremely high Coulombic efficiency (CE, >99.7%) to function normally. It becomes very challenging in aqueous batteries, because of water‐related parasitic reactions and dendrite growth on Zn anodes. Herein, aluminum hydroxide fluoride coated on Cu foils (Cu@AOF) is used to realize the anode‐free aqueous batteries. AOF exhibits a high adsorption affinity to H2O and a low diffusion energy barrier for Zn adatoms, promoting the desolvation process and surface migration. Meanwhile, the strong interaction between AOF and Zn2+ enables it to regulate the Zn2+ flux and benefit lateral growth. Then, the anode‐free full cells of Cu@AOF||Zn0.5VO2 exhibit a record‐high cycle life of 2000 cycles at 1 A g−1 with an ultra‐high average CE of 99.95%. More impressively, the full cell shows a long cycle life of 400 cycles with a high CE of 99.94% at −20 °C. This work provides sheds light on the rational engineering of the electrode interfaces to obtain excellent performance at low temperatures.

Detection of major VOCs in exhaled breath under ppb level using porous ZnO nanobelts

AbstractAtomic defects can enhance catalytic efficiency by providing coordinatively unsaturated sites in the crystal structure of metal oxides. It allows facile chemical reactions because the sites can react with other molecules with relatively lower energy. Therefore, atomic defect engineering can be a cost‐effective strategy to replace novel metal catalysts for the development of ultrasensitive gas sensors. Herein, we fabricated porous ZnO nanobelts with atomic step structures for acetone, ethanol, and isoprene gas sensing under the parts‐per‐billion (ppb) level. Numerous atomic step structures could be formed by removing H and F atoms during the conversion process of ZnOHF at 500°C. The synthesis method of metal oxide nanomaterial by conversion from metal hydroxide fluoride will provide the atomic defects and it will be useful to prepare ultrasensitive sensing material. Furthermore, the gas selectivity of the porous ZnO nanobelt was investigated based on the appearance energy associated with the separation of the methyl group.

Effect of molar concentration on the crystallite structures and electrochemical properties of cobalt fluoride hydroxide for hybrid supercapacitors

Cobalt fluoride hydroxide (Co(OH)F) crystallite structures with various cobalt concentrations (20, 40, 60, and 80 mM) were grown on nickel foam (NF) substrate using a traditional hydrothermal method and potentially applied as an electrode material for battery-type supercapacitors. Physicochemical analyses showed that the optimal Co(OH)F–60/NF electrode had orthorhombic crystalline phase and comprised of several rhombohedral, octahedral, and decahedral crystallite structures. The electrochemical double-layer capacitance and impedance spectroscopy analyses confirmed that the Co(OH)F–60/NF sample had high active sites and lower equivalent series resistance, respectively. Owing to the more electroactive sites, the Co(OH)F–60/NF electrode delivered a high specific capacity (389.9 C g−1 at 1 A g−1), and remarkable long-term stability (90.02% capacity retention after 10000 cycles) compared to the other Co(OH)F/NF electrodes assessed. A hybrid supercapacitor device (HSC) was designed using the optimized Co(OH)F–60/NF as a positive electrode and activated carbon (AC) as a negative electrode, which delivered a reasonable specific capacity of 130.0 C g−1 and an outstanding stability (92.74% capacitance retention after 8000 continuous cycles). The Co(OH)F–60/NF//AC HSC device provided a maximum energy density of 28.89 Wh kg−1 at a power density of 800.0 W kg−1.

Formation of fringed carnation-like cobalt manganese fluoride hydroxide assisted by ammonium fluoride for supercapacitor applications

The binary transition metal oxides or hydroxides have received significant attention as potential materials in supercapacitor applications owing to their unique characteristics. In this study, a binary cobalt-manganese fluoride hydroxide-CoMn(OH)F is assembled successfully through the crucial assistance of an ammonium fluoride agent in an alkali source of hexamethylenetetramine (HMTA). At a rational design, the CoMn(OH)F with fringed carnation-like morphology obtains a specific capacitance of 541 F g −1 (at a current density of 1 A g −1 ) in a three-electrode system and cycling stability of 84% after 15,000 cycles. Furthermore, an asymmetric device CoMn(OH)F//activated carbon in a two-electrode system not only exhibits a remarkable specific capacitance of 135 F g −1 (at 0.4 A g −1 ), a high energy density of 39 Wh kg −1 , and a power density of 3.65 kW kg −1 but also maintains 91% of the initial capacitance after 10,000 cycling tests. These electrochemical performances demonstrate the considerable potential of the fluoride hydroxide CoMn(OH)F for supercapacitor applications. • CoMn(OH)F was formed via the key role of NH 4 F and the optimal precursor ratio. • CoMn(OH)F had a fringed carnation-like morphology. • Sample obtained synergistic effects of diffusion and capacitive-controlled process. • CoMn(OH)F//AC exhibited energy density 39 Wh kg −1 and power density 3.65 kW kg −1 .

Nickel-foam supported cobalt fluoride hydroxide crystallites as an efficient and durable electrocatalyst for oxygen evolution reaction

This paper reports the facile hydrothermal synthesis of Co(OH)F crystallites on a nickel-foam (NF) substrate for the oxygen evolution reaction (OER). Scanning and transmission electron microscopy showed that the as-synthesized Co(OH)F crystallites consisted of different rhombohedral, octahedral, and decahedral shapes, 0.3–0.5 μm in size. The desired Co(OH)F catalyst synthesized in this study delivered a lower overpotential of 273 mV at a current density of 10 mA cm−2, with a smaller Tafel slope of only 45 mV dec−1, compared to other fluoride-containing catalysts because of their unique structural features, higher double-layer capacitance, and rapid charge transfer. Furthermore, a stable potential was maintained for more than 20 h during the chronopotentiometry test at a constant current density of 10 mA cm−2.

Hierarchical Cobalt Fluoride Hydroxide Nanomaterials for Highly Sensitive Acetone Gas Sensor

Introduction The needs of simple diagnosis on diabetes from exhaled human breath alarms us to develop highly sensitive low concentration acetone gas sensor [1]. with Co-based materials have been recognized as promising candidates for catalysts [2]. However, the usage of Co-based materials was mostly limited to cobalt oxides for application in gas sensor [3-4]. In this study, for the first time, we examined the suitability of novel 2-d hierarchical cobalt fluoride hydroxide (Co(OH)F) nanomaterial for gas sensor application. The fluorine in Co(OH)F as an additional catalyst could enable to enhance sensing ability. Moreover, we used SiO2 sphere template to fabricate nanosheets-based unique morphology which has high surface-to-volume ratio, resulting in improvement of sensing ability. The sensor-based on the Co(OH)F nanomaterials exhibited good sensitivity and selectivity toward acetone gas. We also suggested mechanisms behind the good sensing performances. Method Silicon dioxide (SiO2) spheres were used as templates for synthesizing Co(OH)F on surfaces of them. Cobalt(II) chloride (CoCl2), ammonium fluoride (NH4F), and urea(CO(NH2)2) were added as precursors to form Co(OH)F nanostructures in hydrothermal reactor and heated at 120 °C for 10 h to get rid of SiO2 sphere template. To fabricate interdigitated electrodes, platinum was sputtered and patterned using photolithography method on Si/SiO2 substrate with 10 μm distance. Dispersed Co(OH)F powders in water were drop-coated on the interdigitated electrodes and dried at 100 °C. Additional post-annealing at 350 °C for 2 h could transform the Co(OH)F to Co3O4 with some amount of fluorine inside. We tested sensing performances in our homemade sensing system equipped with mass flow controllers (MFCs), cylinders of various gases, a multimeter, and a power supply. Responses were determined by Rg/Ra, where Rg is resistance with gas input, and Ra is resistance in air, respectively. Results and Conclusions Figure 1 (a) demonstrates a SEM image of the hierarchical 2-d Co(OH)F nanostructures with super thin sheets (~10 nm thick). With the high surface-to-volume ratio owing to the thickness of sheets and abundant voids inside, and abundant fluorine acting as a catalyst, a sensor based on this material could show high response of 3.13 toward 1.6 ppm of acetone gas as shown in Figure 1 (b). We also tested the gas responses as functions of operating temperature in the range of 25 °C through 250 °C to acetone gas concentration of 13 ppb to 1.6 ppm, gas species such as acetone, toluene, carbon monoxide, hydrogen, and nitrogen dioxide to figure out the selectivity, and time elapse for around a month. The fabricated gas sensor exhibited good sensitivity and selectivity. We also could obtain fluorine-doped cobalt oxide-based gas sensor with good long-term stability through post-annealing process. In addition, investigating the effects of fluorine amounts on sensor performances, we could figure out the reason of high response of the sensors. We could expect this pioneering work on this adoption of novel 2-d hierarchical Co(OH)F nanostructures for the acetone gas sensor could offer more chances for developing high performance exhaled gas sensor applications for the near future. Acknowledgement J.-S. Park was partially supported by the Project (No. P0006858) of KIAT and MOTIE in Korea.

Lithium ion battery research and development: the Nigerian potential

Lithium-ion batteries (LiBs) are growing in popularity as energy storage devices. Handheld, portable electronic devices use LiBs based on Lithium Cobalt Oxide (LiCoO2) which in spite of its attendant safety risks offers high energy density. Other types of LiBsbased on Lithium iron phosphate (LiFePO4), Lithium-ion manganese oxide (LiMn2O4, Li2MnO3, or LMO), and Lithium nickel manganese cobalt oxide (LiNiMnCoO2 or NMC) have better safety issues with lower energy density. These batteries which are rechargeable are used in cell phones, laptops and tablets, electric and hybrid cars (EV), grid storage, cordless power tools, medical equipment, and other high-tech devices. Nigeria, with a population above two hundred million, is a big market for lithium-ion batteries. The mineral ore for the cathode of lithium-ion batteries is available in Kogi, Nasarawa, Ekiti, Kwara, Cross River, Oyo, and the Plateau States. These include amblygonite(Li,Na)AlPO4(F,OH), Lithium Sodium Aluminum Phosphate Fluoride Hydroxide and lepidolite (K(Li,Al)3(Al,Si, Rb)4O10(F,OH)2, Potassium lithium aluminum silicate hydroxide fluoride, spodumene: (LiAl(SiO3)2 Lithium Aluminum Silicate, petalite: (LiAl(Si2O5)2 aluminum hydroxy-[hydroxy(oxo)silyl]oxy- oxosilane; lithium), and graphite which is used as the anode material is available in Kaduna and the Adamawa States. In view of these available resources, the Projects Development Institute (PRODA) Enugu, a Science and Engineering based Research Institute under the supervision of the Federal Ministry of Science and Technology has pioneered battery research and development with a particular focus on Lithium-ion batteries. It is expected in the long run that lithium-ion batteries would be produced locally for rechargeable lanterns in view of the country’s energy deficit. This would spring up small and medium enterprises that would drive the economy by the beneficiation and refining of the content of the raw material which is available in the country and thus creating wealth for our citizenry.

Nanomagnetism variation with fluorine content in Co(OH)F

Magnetic behaviors of cobalt hydroxide fluoride, Co(OH)F2-x Fx (x = 1.09 and 1.26), which are consisted with nanorods of ∼5 μm length and diameter ∼100 nm, obtained by a facile hydrothermal method, have been researched with the variation of fluorine content as a result of the different amount of reactant NH4F addition. Magnetic coupling performance are characterized based on the observation and analysis of magnetic susceptibility, X-ray Absorption Fine Structure (XAFS) and specific heat. Co(OH)F2-x is found to undergo an antiferromagnetic transition at 40 K. The peak temperature (T) on the transition curves shifts to lower temperature according with the increased magnetic field (H) following the rule of H2/3∞ (-T) because of the surface spin-glass behavior. The paramagnetic susceptibility can be fitted with the modified Curie–Weiss law between 100 K and 320 K. The negative Curie-Weiss temperature indicates that the antiferromagnetic coupling becomes stronger with the fluorine content. In addition, at temperatures below 5 K, the magnetic reordering was observed as spin-glass. Exchange bias behavior in Co(OH)F2-x was found after field cooling process demonstrating an exotic surface magnetic behavior generated with high fluorine contents due to the deformation of CoO6 octahedral induced large spin-glass behavior.

Layered Double Hydroxide Fluoride Release in Dental Applications: A Systematic Review.

This systematic review appraises studies conducted with layered double hydroxides (LDHs) for fluoride release in dentistry. LDH has been used as antacids, water purification in removing excess fluoride in drinking water and drug delivery. It has great potential for controlled fluoride release in dentistry, e.g., varnishes, fissure sealants and muco-adhesive strips, etc. The Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Statement was followed with two reviewers performing a literature search using four databases: PubMed, Web of Science, Science Direct and Ovid Medline with no date restrictions. Studies including any LDH for ion/drug release in dentistry were included, while assessing the application of LDH and the value of the methodology, e.g., ion release protocol and the LDH production process. Results: A total of 258 articles were identified and four met the inclusion criteria. Based on two in vitro studies and one clinical study, LDH was previously studied in dental materials, such as dental composites and buccal muco-adhesive strips for fluoride release, with the latter studied in a clinical environment. The fourth study analysed LDH powder alone (without being incorporated into dental materials). It demonstrated fluoride release and the uptake of volatile sulphur compounds (VSC), which may reduce halitosis (malodour). Conclusion: LDHs incorporated in dental materials have been previously evaluated for fluoride release and proven to be clinically safe. LDHs have the potential to sustain a controlled release of fluoride (or other cariostatic ions) in the oral environment to prevent caries. However, further analyses of LDH compositions, and clinical research investigating any other cariostatic effects, are required.

Hydrolysis of Zn Ions: Controllable Synthesis of ZnxCo1–x(OH)F Nanostructures with Their Electrochemical and Optical Properties

Recently, the synthesis and properties of metal hydroxide fluorides have attracted more attention. In this paper, a series of bimetallic hydroxyl fluorides, ZnxCo1–x(OH)F, were grown on a functiona...

Suppression Mechanism for Dissolution of Conversion-Type CuCl2 Electrode in LiPF6/methyl Difluoroacetate Electrolyte

As the cathode materials in conversion-type lithium ion batteries, transition-metal chlorides are well-known to easily dissolve in many organic solvents. However, the LiPF6/methyl difluoroacetate (MFA; CHF2COOCH3) electrolyte is effective in suppressing the dissolution of the CuCl2 electrode, as reported for a Li/CuCl2 battery. This effect did not arise in the MFA solvent without LiPF6, but did on slightly dissolving LiPF6 in the MFA solvent. This was because a very small amount of film was formed on the surface of the CuCl2 electrode due to the addition of the small amount of LiPF6, and the film was composed of copper fluoride hydroxide, partial release of Cl from CuCl2, and CuCl.

Interfacial Scaffolding Preparation of Hierarchical PBA‐Based Derivative Electrocatalysts for Efficient Water Splitting

AbstractThe development of highly efficient and durable electrocatalysts is crucial for overall water splitting. Herein, the in situ scaffolding formation of 3D Prussian blue analogues (PBAs) on a variety of 2D or 1D metal hydroxides/oxides to fabricate hierarchical nanostructures is first demonstrated. Typically, cobalt hydroxide or oxide nanoarrays are used as the precursor and structural oriented template for the subsequent growth of 3D PBA nanocubes. The mechanism study reveals that the interfacial scaffolding process can be reversibly controlled via the in situ ion exchange process with adjusting coordination ions. Thus, the facile, versatile strategy can extend to successfully fabricate a variety of hierarchical PBA‐based nanostructures including on cobalt fluoride hydroxide, copper hydroxide, monometal or bimetal nickel–cobalt hydroxides, cobalt oxide, and manganese oxide nanosheets with structural tailor‐ability and chemical diversity. More interestingly, the metal nitride derivatives obtained via controlled calcination process exhibit good electrocatalytic activity for water splitting with low overpotentials, and remarkable durability for 1200 h, thanks to the superior intrinsic activity of bimetal nature and the scrupulous hierarchical structure. This versatile strategy provides a paradigm for rational design of PBA‐based functional nanomaterials, which is highly promising in energy conversion, storage, and electrocatalytic fields.

A novel synthetic route towards monodisperse yttrium hydroxide fluoride by anion exchange and luminescence properties

In this study, pure and rare earth ions-doped yttrium hydroxide fluoride (Y(OH)2.02F0.98 denoted as YHF) were fabricated via an ion exchange route employing anion exchangeable lanthanide hydroxyanion as a sacrificial template. And the anion exchange materials Y2(OH)5Cl·1.5H2O (YHCl) are synthesized during the preparation of YHF samples. The structure, morphology, formation process, and luminescence properties were well investigated by using XRD, SEM, and PL spectra. Under ultraviolet light excitation, the YHF:Ln3+ (Ln = Eu, Tb, Dy, Sm) phosphors show strong light emissions with different colors for different doping ions. These features manifest the ion exchange route might open a new avenue in synthetic methodology for luminescent materials.

On the influence of water on the mechanochemical synthesis of low F-doped Al-hydroxide fluorides

The significant role played by water in the mechanochemical synthesis of highly distorted aluminum hydroxide fluorides is on the main focus of this research paper. The importance of water in the synthesis was evaluated considering separately combinations of O/OH sources (Al(OH)3, Al2O3) and fluorine sources with or without structural water (β-AlF3.3H2O, α-AlF3). Each system was studied by typical bulk and surface characterization techniques (XRD, MAS NMR, DTA-TG, NH3-TPD) and compared to each other in order to gain a more comprehensive insight of the importance of including water in the synthesis of amorphous aluminum hydroxide fluorides.