Search

Distribution of Mn2+ ions into lithium metaphosphate glass through modifier-site engineering is an effective approach to generate single-doped red phosphors for light emitting diodes (LED). This has been achieved through the systematic Li+-Mn2+ modifier mixing in xMnO‧(50-x)Li2O‧50P2O5 (0 ≤ x ≤ 50 mol%). In this regard, the mixed modifier effect on the structural and optical properties has been studied. While XRD demonstrates the amorphous structure of the prepared compositions, SAED reveals the formation of crystalline clusters in 50MnO‧50P2O5. XPS reveals that the ratio of BOs/NBOs (~0.5) is in agreement with that of theoretical stoichiometry. FTIR spectroscopy shows that the concentration of Q2 decreases, whereas Q1 increases. Also, it can be found that the density increases linearly with about 22% as the content of MnO increases. This is associated with a small decrease in molar volume (~3%). Overall, XPS, FTIR and density analyses indicate that Li+ and Mn2+ ions behave as network modifiers that resides in octahedral sites through the formation of LiO6 and MnO6, respectively. Indeed, there are strong absorption and excitation spectra due to the electronic transition in Mn2+. This results in an intensive orange-red emission around 608 nm (at x = 0.5) with a red-shift up to 684 nm (at x = 50) at excitation wavelength of 409 nm. This is ascribed to 4T1(G) → 6A1(S) electronic transition in the octahedrally coordinated Mn2+ ions with O2− anions. With increasing the MnO content, the emission is systematically intensified up to 10 mol% of MnO, and then quenched. This quenching is attributed to the increase in MnO6 groups, which cluster with each other. In these clusters, the electron transfer occurs between the neighboring Mn2+ ions. Furthermore, the independence of emission peak (shape and position) on the excitation wavelength demonstrates the presence of only high-dispersed Mn2+ activator center.

A series of (50 − x) P2O5–20B2O3–20CaO–10Na2O (x = 0–15 mol% MoO3) glass composition was prepared. Glass structure was analyzed using infrared absorption, UV–visible spectroscopy, electron spin resonance, density, and molar volume calculations. FTIR confirmed that Mo ions are contributed as MoO6 octahedral units in the glassy matrix, resulting in an increase in the pyrophosphate and BO3 groups at the expense of metaphosphate and BO4 units. UV–visible and ESR spectra detected Mo3+ and Mo5+ ions as species in the host glass due to the increase in MoO3 content. Broadband dielectric spectroscopy investigation on a broad range of frequencies and at different temperatures indicated that the enhancement of electrical conductivity of the prepared glasses due to molybdenum doping was prevented using confinement effect at the wells, causing demobilization of the charge carriers. Hence the dielectric spectra were caused by the mobility of charge carriers rather than the dynamics at the molecular scale. There is a clear correlation between the transport mechanism and dynamics at the interface of the charge carriers. Presently, the challenge is to understand if optimizing the accumulation of charges at the interfaces and electrodes is the origin of electrical storage energy.

Li–Cs metaphosphate glasses show one of the strongest mixed ion effects (MIE) known in d.c. conductivity. Previous studies had shown that the ions in these glasses are randomly distributed relative...

The atomic structure of a series of sodium iron phosphate glasses is studied using different experimental techniques: X‐ray and neutron diffraction (ND), infrared spectroscopy, extended X‐ray absorption fine structure (EXAFS), and X‐ray absorption near‐edge structure (XANES). Detailed information about the atomic pair correlations is obtained. The high resolution of ND in real space resolves two P–O distances at 1.48 Ǻ and 1.59 Ǻ as expected. All the glasses are found to consist of a phosphate tetrahedral network with metaphosphate chains and pyrophosphate units, and every phosphate unit is found to have two or three nonbridging oxygen (NBO) links available to coordinate with Na and Fe cations. The Fe–O coordination number in these glasses is found to decrease from 5.7 to 4.8 with increasing the Fe content, whereas the Na coordination number of approximately 5 is detected for all the samples.

The synthesis and characterization of polymeric and monomeric Zinc phosphinates are reported. Bis(hydroxymethyl)phosphinic acid is used as a ligand for the synthesis of both polymeric and monomeric phosphinates. A polymeric zinc phosphinate is synthesized by the reaction of bis(hydroxymethyl)phosphinic acid with zinc acetate dihydrate at room temperature. Each phosphinate ligand coordinates with two different zinc centers to generate polymeric zinc phosphinate. The above reaction is carried out with the addition of 1,10-phenanthroline to form monomeric zinc phosphinate compound. When the N-donor chelating ligand (1,10-phenanthroline) is introduced, the construction of polymeric zinc phosphinate is blocked by 1,10-phenanthroline which facilitates the formation of discrete monomeric zinc phosphinate. The synthesized zinc phosphinate compounds are characterized by FT-IR, 1H, 13C and 31P NMR, and also noticed thermal stability by thermogravimetric analysis (TGA). Both the polymeric and monomeric zinc phosphinate compounds are subjected for calcinations at 800 °C to produce zinc metaphosphate materials. Finally the crystalline phase of zinc metaphosphate materials is characterized by powder x-ray diffraction technique (PXRD).

The technology of synthesis of inorganic binder material based on sodium tripolyphosphate Na5P3O10 and orthophosphoric acid has been developed. The sequence of physicochemical transformations in this system, as well as the optimal mass ratio of orthophosphoric acid and sodium tripolyphosphate are established. The research uses methods of quantitative and qualitative X-ray phase analysis, differential thermal analysis, standard methods of testing samples for compressive strength. The ratios of the atomic radii of the cation (Na) and the anion (P2O7), as well as the presence of hydrogen bonds, provide a significant increase in the binding potential compared to other sodium phosphates. It was found that the strengthening of mixtures with 2…8 mass parts including sodium pyrophosphate, the filler of which is quartz-based sand, occurs as intensely as possible when heated to 150°C. A further increase in temperature above 250 °C leads to the conversion of sodium pyrophosphate to ordinary (non-polymeric) metaphosphate NaPO3, which exists without changes in chemical structure up to 1000°C. The developed binder material, given the global trends of decarbonization and resource conservation, is a competitive alternative to widely used synthetic resins and other organic materials. It does not contain harmful substances and does not emit dangerous products when heated.

Rational design and facile synthesis of highly active electrocatalysts with low cost for oxygen reduction reaction (ORR) are always of great challenge. Specifically, development of a new type of energy-saving materials with convenient method is regarded as the current bottleneck. Herein, an innovative strategy based on amino trimethylene phosphonic acid (ATMP) as chelating agent for cobalt-metaphosphate coordination polymer is reported to one-pot synthesis of a novel precursor in methanol for ORR electrocatalyst. Carbonization of the precursor at 900 °C at N2 atmosphere results in the feasible formation of cobalt metaphosphate based composite (Co(PO3)2/NC). A further step in the thermal cleavage at 650 °C at air for 4 h, Co(PO3)2/NC can be finally transformed into inorganic Co(PO3)2. Advanced spectroscopic techniques and density function theory (DFT) calculations are applied to confirm the main catalytically active center and the physical properties of Co(PO3)2/NC. This obtained Co(PO3)2/NC nanocomposite exhibits superior electrocatalysis to Co(PO3)2 with an enhanced onset potential (0.906 V vs. RHE) and diffusion limiting current (5.062 mA cm−2), which are roughly close to those of commercial 20% Pt/C (0.916 V, 5.200 mA cm−2).

Aluminum phosphates are known as inorganic hardening agents for the setting of alkali silicate solutions, but only few studies have been published on the setting mechanism of potassium water glass. The solution behavior of two aluminum metaphosphates in alkaline environments were investigated photometrically determining the dissolved aluminum content. The crystalline phase composition of the hardened potassium silicate systems was determined by X‐ray diffraction. New insights into the setting mechanism were obtained concerning the structure of the aluminum metaphosphate and the SiO2/K2O ratio of three different potassium silicate solutions. With increasing pH value aluminum tetrametaphosphate reacts rapidly and forms crystalline potassium tetrametaphosphate dihydrate by an ion‐exchange‐reaction. In parallel, a depolymerization of the cyclic metaphosphate structure occurs leading to potassium dihydrogen phosphate as final fragmentation product. With aluminum hexametaphosphate no ion‐exchange reaction product was observed. Only potassium dihydrogen phosphate could be found in higher quantities compared to the reaction with aluminum tetrametaphosphate., Insights on potassium silicates: Mechanism of the chemically initiated hardening of potassium silicate solutions with aluminum metaphosphates. Ion‐exchange reaction, depolymerization of the cyclic metaphosphate structures, and polycondensation of the amorphous alumosilicate binder matrix. Investigation of the dissolution behavior of aluminum metaphosphates in alkaline environment. Description of the crystalline phase composition.

Phosphate glasses of composition 48P2O5-30CaO-(22−x)Na2O-xTiO2 (with 0 °C ± 20°C. The chemical durability of these glasses shows an improvement when the TiO2 content varies from 0 to 2 mol%. The measurements of differential thermal analysis and density, both, indicate the increase of the glass transition temperature and the density. The increase of Tg leads to an improvement of glass rigidity. X-ray diffraction analysis of the glasses annealed at 650°C for 48 h, indicates the appearance of a mixture of metaphosphate and pyrophosphate phases when the TiO2 content varies from 0 to 2 mol%, the last become majority when the TiO2 content rich 2 mol%. Nevertheless, when the TiO2 content exceeds 2 mol%, the analysis, both, by infrared spectroscopy and X-ray diffraction, reveals a radical change of structure with the formation of majorities isolated orthophosphate groups. SEM micrographs illustrated that the number of crystallites increased in the glass network when the TiO2 content increased at the expense of the Na2O content. An increase in the TiO2 content beyond 2 mol% led to the formation of a larger number of crystallites of different sizes, dominated by small crystallite sizes assigned to majority isolated short orthophosphate groups. This phenomenon led to a decrease in chemical durability and seems to be the main cause promoting the bioactivity of glasses. The results of the bioactivity, after a test in an SBF physiological solution within 15 days, shows, both, the formation of hydroxyapatite and tricalcium phosphate layers, in addition to the layer Ca2P2O7, known by its bioactivity, in some samples. The results obtained on the glasses studied make them potential candidates for an application in tissue engineering.

The effect of phosphorus poisoning on the catalytic behavior of diesel oxidation catalysts was investigated over model and supplier monolith catalysts, i.e., Pd–Pt/Al2O3. The results of ICP and XPS from the vapor-phase poisoning over model catalysts suggested that the temperature of phosphorus poisoning affects both the overall content of phosphorus and the dispersion of phosphorus (i.e., inlet/outlet and surface/bulk). Phosphorus oxide (P2O5), metaphosphate (PO3−), and phosphate (PO43−) were identified in the poisoned model and supplier catalysts. The distribution of these species on poisoned model catalysts was highly dependent on the poisoning temperature, i.e., a higher temperature resulted in a higher concentration of PO43−. The outlets of the monoliths contained more PO43− and less P2O5 than the inlets. Both active sites and surface OH groups on model and supplier catalysts were contaminated upon phosphorus poisoning. It is found that PO43− had a stronger influence on the active sites than P2O5. One significant finding in this study is that the vapor-phase phosphorus poisoning could be a practical and cost efficient approach to simulate an accelerated aging/poisoning process.

In order to provide a short-term oxidation protection system for graphite at high temperature, an aluminum metaphosphate coating was prepared on the surface of graphite by cathodic electrochemical treatment, and its oxidation protective ability was investigated using an isothermal oxidation test. The microstructure, chemical composition, and phase components of the aluminum metaphosphate coating were respectively analyzed through scanning electron microscope, dispersive X-ray analysis, and X-ray diffraction. The results showed that aluminum metaphosphate coating with a thickness of about 24 μm provides good oxidation resistance for graphite at 1250 °C, and it reduces the oxidation rate of graphite in a 5-h period by a factor of two. The good oxidation protective ability of the as-prepared coating at 1250 °C is related to the formation of a layer consisting of aluminum metaphosphate and aluminum orthophosphate phases.

In the present work, phosphate-bonded porous silicon carbide (SiC) ceramics were prepared by using aluminum dihydrogen phosphate as binder. The morphologies, phase composition, microstructures, mechanical strength, porosity and bulk density of the porous ceramics were investigated. It was found that the aluminum dihygrogen phosphate binder bonding method was a novel and low cost process to prepare near net-shape and high strength porous SiC ceramics at low temperature. The bonding mechanism was A type and B type aluminum metaphosphate which formed from aluminum dihygrogen phosphate during heat treatment bonded the SiC particles together to form porous ceramics. With temperature increasing, the phase of B type gradually transformed into A type aluminum metaphosphate, and the transformation was completed at 900 °C. The A type aluminum metaphosphate began to decompose into AlPO4 and P2O5 when the sintered temperature higher than 908 °C. The flexural strength of the porous SiC ceramics reached the maximum at 900 °C and decreased sharply with temperature increasing. The decomposition of A type aluminum metaphosphate made the strength reduce. The bulk density increased with aluminum dihydrogen phosphate content and decreased with temperature, in contrast, the porosity decreased with increasing binder content and temperature.

[EN] The glass forming ability of inorganic substances has traditionally been evaluated in kinetic terms related to the rate of spontaneous crystallization of their melts, which is related to viscosity from the macroscopic point of view. However, differences or similarities between the local structures of glasses and crystals of the same composition could have an additional influence on the kinetic ability to form a stable glass or a crystal from a melt. In this work, the local structure of alkali metaphosphate glasses and crystals has been analyzed by means of P MAS-NMR to demonstrate that the ability to form a glass is directly related to the differences between the atomic organization in the glassy states and the structure of the stable crystals at lower temperatures. This implies that chemical compositions having a similar atomic order in their glass and crystal structures will not easily develop the disordered long-range structure of glass., Agencia Estatal de Investigación/FEDER) MAT2017-87035-C2-1-P. The authors are thankful to G. Tricot from the University of Lille (France) for the acquisition of part of the NMR spectra.

Phosphofructokinases (Pfks) catalyze the ATP-dependent phosphorylation of fructose-6-phosphate (F6P) and they are regulated in a wide variety of organisms. Although numerous aspects of the kinetics and regulation have been characterized for Pfks, the knowledge about the mechanism of the phosphoryl transfer reaction and the transition state lags behind. In this work, we describe the X-ray crystal structure of the homodimeric Pfk-2 from E. coli, which contains products in one site and reactants in the other, as well as an additional ATP molecule in the inhibitory allosteric site adjacent to the reactants. This complex was previously predicted when studying the kinetic mechanism of ATP inhibition. After removing the allosteric ATP, molecular dynamic (MD) simulations revealed conformational changes related to domain packing, as well as stable interactions of Lys27 and Asp256 with donor (ATP) and acceptor (fructose-6-) groups, and of Asp166 with Mg2+. The phosphoryl transfer reaction mechanism catalyzed by Pfk-2 was investigated through Quantum Mechanics/Molecular Mechanics (QM/MM) simulations using a combination of the string method and a path-collective variable for the exploration of its free energy surface. The calculated activation free energies showed that a dissociative mechanism, occurring with a metaphosphate intermediate formation followed by a proton transfer to Asp256, is more favorable than an associative one. The structural analysis reveals the role of Asp256 acting as a catalytic base and Lys27 stabilizing the transition state of the dissociative mechanism.

Calcium phosphate glasses have a high potential for use as biomaterials because their composition is similar to that of the mineral phase of bone. Phosphate glasses can dissolve completely in aqueous solution and can contain various elements owing to their acidity. Thus, the glass can be a candidate for therapeutic ion carriers. Recently, we focused on the effect of strontium ions for bone formation, which exhibited dual effects of stimulating bone formation and inhibiting bone resorption. However, large amounts of strontium ions may induce a cytotoxic effect, and there is a need to control their releasing amount. This work reports fundamental data for designing quaternary CaO-SrO-P2O5-TiO2 glasses with pyro- and meta-phosphate compositions to control strontium ion-releasing behavior. The glasses were prepared by substituting CaO by SrO using the melt-quenching method. The SrO/CaO mixed composition exhibited a mixed cation effect on the glassification degree and ion-releasing behavior, which showed non-linear properties with mixed cation compositions of the glasses. Sr2+ ions have smaller field strength than Ca2+ ions, and the glass network structure may be weakened by the substitution of CaO by SrO. However, glassification degree and chemical durability of pyro- and meta-phosphate glasses increased with substituted all CaO by SrO. This is because titanium groups in the glasses are closely related to their glass network structure by SrO substitution. The P-O-Ti bonds in pyrophosphate glass series and TiO4 tetrahedra in metaphosphate glass series increased with substitution by SrO. The titanium groups in the glasses were crosslink and/or coordinate phosphate groups to improve glassification degree and chemical durability. Sr2+ ion releasing amount of pyrophosphate glasses with &gt, 83% SrO substitution was larger than 0.1 mM at day seven, an amount that reported enhanced bone formation by stimulation of osteogenic markers.

Four different phosphate glass formulations (F0, F1, F2, and F3) were developed according o wheat nutrient requirements to be used as controlled-release fertilizers. These glasses contain macro-elements (P2O5-K2O-CaO-MgO), with the addition of microelements (Fe-Mn-Zn-B-Cu-Mo) in each formulation. The effects of these elements’ addition on thermal properties, glass structure, and dissolution behaviors were investigated. Results showed that these glasses are composed essentially of metaphosphate chains and that the addition of micronutrients could change the chemical durability of phosphate glasses. A greenhouse experiment was performed using wheat (Triticum durum L.) to evaluate the efficiency of the four glasses, with or without application of chemical nitrogen (N) (N + VF and VF, respectively). The different formulas were tested using two rates of 0.3 and 1 g per plant. In addition to the vitreous fertilizer formulations, two other treatments were applied: control treatment with no amendment and Nitrogen-Phosphorus-Potassium treatment with the application of the conventional fertilizers on the base of optimal rates. After four months of cultivation, vitreous fertilizers application significantly improved growth (7% to 88%), photosynthetic (8% to 49%) parameters, and yield (29% to 33%) compared to NPK treatment and to the control. It has been found that formulas F1, F2, and F3 may constitute a potential alternative to conventional fertilization due to their positive impact on wheat production and can be used in practice as an environmentally controlled-release fertilizer.

Phosphate-based glasses (PBGs) offer significant therapeutic potential due to their bioactivity, controllable compositions, and degradation rates. Several PBGs have already demonstrated their ability to support direct cell growth and in vivo cytocompatibility for bone repair applications. This study investigated development of PBG formulations with pyro- and orthophosphate species within the glass system (40 &minus, x)P2O5&middot, (16 + x)CaO&middot, 20Na2O&middot, 24MgO (x = 0, 5, 10 mol%) and their effect on stem cell adhesion properties. Substitution of phosphate for calcium revealed a gradual transition within the glass structure from Q2 to Q0 phosphate species. Human mesenchymal stem cells were cultured directly onto discs made from three PBG compositions. Analysis of cells seeded onto the discs revealed that PBG with higher concentration of pyro- and orthophosphate content (61% Q1 and 39% Q0) supported a 4.3-fold increase in adhered cells compared to glasses with metaphosphate connectivity (49% Q2 and 51% Q1). This study highlights that tuning the composition of PBGs to possess pyro- and orthophosphate species only, enables the possibility to control cell adhesion performance. PBGs with superior cell adhesion profiles represent ideal candidates for biomedical applications, where cell recruitment and support for tissue ingrowth are of critical importance for orthopaedic interventions.

In the present work, we studied Er-doped KPO3-Ca(PO3)2 metaphosphate glass and its devitrification behavior. It is shown that two concurrent crystallization processes (surface and bulk crystallization) are observed in this glass with the precipitation of two different phases of KCa(PO3)3: the hexagonal phase is mostly formed at the surface, whereas the orthorhombic isomorph is found in the bulk. The possibility of synthetizing a transparent glass-ceramic is demonstrated. From the changes in the spectroscopic properties of the obtained glass-ceramic materials, Er3+ ions are suspected to enter into the lattice of the KCa(PO3)3 crystal. acceptedVersion

We report a novel negative conversion electrode material, manganese (II) metaphosphate Mn(PO3)2. This compound can be synthesized by a facile solid-state method, and after carbon-coating delivers an attractively high reversible capacity of 477 mAh/g at 0.1C and 385 mAh/g at 1C. We investigated the reaction mechanism with a combination of ex situ X-ray absorption spectroscopy, in situ X-ray diffraction, and high-resolution transmission electron microscopy. We observed a direct conversion process by monitoring the first discharge in operando, in which Mn(PO3)2 reacts with Li to give fusiform Mn nanograins a few Ångstroms in width, embedded in a matrix of lithium conducting LiPO3 glass. Due to the fine nanostructures of the conversion products, this conversion reaction is completely reversible.

The development of efficient, inexpensive, and stable hydrogen evolution reaction (HER) electrocatalysts is the key to large-scale water electrolysis technologies for hydrogen production. Constructing heterojunction electrocatalysts has become one of the effective strategies for designing high-performance HER electrocatalysts due to their unique heterogeneous interfaces. Herein, a new strategy of PH3 assisted synthesis of metaphosphate is reported, which is used to construct Co(PO3)2@NPC/MoS2 heterostructures (where NPC is N-doped porous carbon). The results show that the formation of Co(PO3)2@NPC/MoS2 heterogeneous interfaces can optimize the electronic structure of the electrocatalyst and greatly improve its HER performance. As a result, a lower overpotential of 119 mV at 10 mA cm-2 is obtained in alkaline electrolyte. This work provides a new perspective for the design of high-performance electrocatalysts for electrocatalytic water splitting.

The calcination of phosphogypsum (PG) was employed to produce gypsum plaster to achieve its recovery and utilization. Although previous studies have indicated the possibility of producing hemihydrate and anhydrous gypsum, the influence mechanism of the impurities in calcined PG (CPG) on the properties of plaster is unclear. Herein, the paper aims to investigate the effect of the impurities on the properties of gypsum plaster at elevating calcination temperatures. The phase transformation of PG and impurities were characterized by X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM), and the hydration properties of gypsum plaster were investigated, including water requirement for normal consistency (WR), setting time, compressive and flexural strength, hydration products and degree, and microstructure. The results show that the increase in calcination temperature resulted in higher anhydrite content, and CPG showed similar chemical and mineral compositions at high temperatures (500°C–800 °C). Additionally, harmful impurities barely changed at low calcination temperatures (150°C–400 °C), resulting in the reduced mechanical properties despite its higher hydration degree; however, the calcination at high temperatures converted harmful impurities into inert insoluble calcium pyrophosphate (Ca 2P2O7), calcium metaphosphate (Ca(PO3)2 ), calcium fluoride (CaF 2 ) and sodium sulfate (Na 2SO4). With the best calcination temperature of 800 °C, gypsum plaster showed a relatively quick setting and maximum strength with a compact microstructure and low hydration degree due to the large formation of Na2SO4 and nucleation sites . Recycling PG to prepare anhydrite is recommended because of its excellent performance and lower energy consumption than traditional building materials.

© 2018, The Society for Mining, Metallurgy & Exploration. Complete isolation of chromium (III) from the reference material (SARM 131), Upper Group 2 (UG2) chromite ore, and Merensky Reef mineral ore was achieved using ammonium phosphate salt as flux. Optimum pH (3.2–3.8) conditions and sample to flux ratios (1:25) were some of the factors that were critical for the complete isolation of chromium. Increasing the sample to flux ratio (1:50 excess) however resulted in the conversion of all the elements in the melt into a green solution (pH, 5.8–6.7). A different chromium compound was subsequently isolated from the green solution by allowing this solution to stand in an open vessel in a cupboard for a month during which time the pH decreased to pH 3.5–4.2. Quantitative analyses of chromium from the isolated precipitates of SARM 131, UG2 chromite ore, and Merensky Reef mineral ore indicated chromium contents of 41.87, 60.41, and 23.93% respectively which were very close to the chromium content in the original samples. Analysis of the chromium precipitates using IR indicated the presence of phosphates (1100–1200 cm−1) while SEM-EDX analysis showed the presence of microscopic crystalline particles with Cr, P, and O as the major elements. Further characterization of the chromium precipitates using XRD and Raman successfully identified the product as chromium (III) metaphosphate C-type (Cr(PO3)3, JCPDS no. 01-077-0672), in the isolated chromium precipitates.

Microbial fuel cells (MFCs) as renewable electricity-generation devices are often confronted with the poor long-term durability and high cost of cathodic catalysts. In this study, iron (III) metaphosphate/iron phosphide/partly-graphitized carbon ((Fe(PO3)3)/FeP/PGC) catalysts obtained at 750–950 °C are used as air–cathode catalysts for oxygen reduction reaction (ORR) in single-chamber MFCs. As temperature increases, graphitization degree of carbon skeleton in (Fe(PO3)3)/FeP/PGCs gradually increases to obtain a higher electrical conductivity. At 900 and 950 °C, monoclinic structured Fe(PO3)3 is formed in PGC structure to constitute the Fe(PO3)3/FeP heterojunctions, which should originate from the partial oxidation of FeP. The maximum power density (1.162 ± 0.022 W m−2) of MFCs is obtained by Fe(PO3)3/FeP/PGC (900 °C) cathode, which is higher than that of commercial Pt/C (1.052 ± 0.015 W m−2) and only has a decline of 4.56% after 1900 h operation (excellent durability). Well-dispersed Fe(PO3)3/FeP heterojunctions and abundant oxygen-containing groups (C–O–C, C–O–H and C–OH) play the important roles in achieving the high charge transfer efficiency (8.7 ± 0.2 Ω) and long-term durability in bio-electricity generation. Fe(PO3)3/FeP/PGC (900 °C) primarily proceeds the efficient four-electron ORR pathway by exploiting the synergistic effects between the active components (Fe(PO3)3/FeP) and porous structure (533.77 m2 g–1). This study provides the promising non-precious-metal ORR electro-catalysts for replacing Pt/C in renewable energy-generation systems.

The flash-vacuum thermolysis (FVT) of trimethylsilyl tert-butylhalogenophosphonates is performed in an attempt to generate tert-butyldioxophosphorane. The FVT proceeds with elimination of halogenotrimethylsilane to give unstable tert-butyldioxophosphorane readily transforming into a trimer. Tert-butylhalogenophoshonic acids form rather stable salts with trimethylamine, which eliminate triethytamine hydrohalohenide on the heating to afford a trimer. У результаті флеш-вакуумного термолізу (ФВT) триметилсиліл-трет-бутилгалогенфосфонатів утворюється трет-бутилдіоксофосфоран. ФВТ відбувається з відщепленням галогентриметилсилану і утворенням нестабільного трет-бутилдіоксифосфорану, який легко перетворюється в тример. Трет-бутилгалогенофосфонові кислоти з триетиламіном дають стійкі солі триетиламіну, які при нагріванні відщеплюють триетиламін галогенгідрат, перетворюючись у діоксофосфорани, які легко тримеризуються вже під час утворення. В результате флеш-вакуумного термолиза (ФВT) триметилсилил-трет-бутилгалогенфосфонатов образуется трет-бутилдиоксофосфоран. ФВТ проходит с отщеплением галогентриметилсилана и образованием нестабильного трет-бутилдиоксифосфорана, легко превращающегося в тример. Трет-бутилгалогенофосфоновые кислоты с триэтиламином дают устойчивые соли триэтиламина, которые при нагревании отщепляют триэтиламин галогенгидрат, превращаясь в диоксафосфораны, легко тримеризующиеся уже в момент образования.

New magneto-optical vitreous materials were obtained by melting-quenching technique comprising wet route raw materials preparation. The glass has the following composition in oxide mol. %: 10 Li 2 O, 9 Al 2 O 3 , 5 ZnO, (35; 20; 50) B 2 O 3 , (35; 50; 20) P 2 O 5 , 3 Bi 2 O 3 , 3 PbO, phosphorus and boron oxide being the vitreous network formers. It was also prepared a similar reference glass composition but without Bi 2 O 3 and PbO. Optical and structural characterization by ultraviolet-visible (UV–Vis), Fourier Transform Infrared (FTIR) and Raman Spectroscopy of the bulk glasses showed a transmission over 90%, metaphosphate structure of glass together with Q 2 boron oxide units and P–O‒B bonds. The mechanical parameters, hardness ( H ), Young's modulus ( E ) and fracture toughness ( K IC ) of boron phosphate glasses, evaluated by micro- and nanoindentation techniques, demonstrated mostly higher values in comparison with those for alumino-phosphate glasses due to mixed boro-phosphate network. Thermal behavior was investigated by Differential Scanning Calorimetry (DSC) putting in evidence the vitreous transition temperature which decreases with about 45 °C when Bi and Pb oxides were added and two crystallization effects. The diamagnetic character of a highly transparent Bi and Pb oxide co-doped boron phosphate glass was confirmed by ellipsometry, and the glass presented high magneto-optical properties at the top of the commercial bulk products.

Iron impurity in raw material remains a major challenge in producing colourless glass. In this investigation, we report microwave (MW) heating capable of altering Fe-redox ratio (Fe2+/∑Fe) enabling preparation of colourless phosphate glass. The effect of Sn concentration in retention of Fe[II] in glass melted in MW was compared with conventional glasses. Colourimetric study developing Fe2+-ferrozine colour complex reveals Fe-redox ratio ≥0.49 required to obtain colourless phosphate glass. In microwave heating, addition of 1 wt.% Sn metal powder can impart the desired effect whereas addition of 1.9 wt.% Sn metal powder is required in conventional heating. The correlation equation of Fe-redox ratio with concentration of Sn metal is found to be different in microwave and conventional heating. Thus, exploiting this different redox changes in MW heating optical properties can be tailored. Preservation of higher Fe[II] in MW melted glass is also confirmed by XPS and TGA. 31P MAS NMR spectra suggest that transition from cross linked ultra phosphate to linear polymer metaphosphate network in incorporation of Sn is found different in glass prepared adopting microwave irradiation. 27A1 MAS NMR spectra suggest higher relative content of Al6+ in glass obtained from MW heating. Energy consumption analysis revels 3.4 kWh in MW heating while 14 kWh in conventional glass melting using resistance heating. Further, glass melting in MW can be completed within 2 h unlike ~5 h needed in conventional. MW heating plays a significant role in improving properties to make colourless phosphate glass in addition to significant energy and time saving.

Modifier-mixing provides a useful tool for tailoring the structural dynamics of oxide glasses. Its physical basis, however, remains subject to intense discussion. Here, we extend our previous consideration of Ca-Mg mixing in alkaline earth metaphosphate glasses [J. Non-Cryst. Solids 468, 74–81 (2017)] across the broader range of alkaline earth species. We report on the effects of divalent modifier mixing for pairs selected from the group of Mg, Ca, Sr and Ba. For this, short-range structural features as obtained from nuclear magnetic resonance, Raman and far-infrared spectroscopy are related to various physical properties, including ionic mobility. Depending primarily on the difference in ion size and bond localization among the modifier cation species, we find different extents of the mixed-modifier effect. This agrees with the dynamic structure model in which the mismatch of cation sites governs non-linear mixing effects.

Glasses in the ternary system Cr2O3-PbO-P2O5 were prepared by direct melting of the mixture with stoichiometric proportions of the reagents Cr2O3, PbO and (NH4)2HPO4 at 1080℃. The glasses obtained are transparent in colour and have a non-hygroscopic appearance. The study of the dissolution rate was carried out on ternary glasses xCr2O3-(45-x)PbO-55P2O5 with (1 ≤ x ≤ 4; mol%), immersed in distilled water at 90℃ for 24 days, indicating a maximum of chemical durability when the level of chromium oxide passed through 2 mol%. Both, IR spectra and X-ray diffraction have indicated the predominance of metaphosphate or cyclic metaphosphate groups with some traces of isolated orthophosphate groups when the Cr2O3 content is equal to x = 2. Analysis of the density values also, has showed a maximum density for x = 2 mol%. The covalent radius values of oxygen have indicated that the minimum value rcal (O2–) is observed for x = 2 mol% and therefore a relatively high reinforcement of the metal-oxygen-phosphorus (Cr-O-P) bonds. SEM Micrographs have exhibited two phases, a vitreous phase and a crystalline phase. The radical change in the structure from ultraphosphate Q3 groups to ring metaphosphate Q2 and orthophosphate groups Q0 seems to be the cause of the formation of crystallites. Beyond 2 mol% of Cr2O3, the structure of the glass changed relatively and the orthophosphate phases increased to the detriment of the metaphosphate phases. We observed a decrease in chemical durability. However, it was confirmed that the dissolution rate (DR) of the S2 analysed compound is comparable to the values of borosilicate glasses which are used as alternative materials for the immobilisation of nuclear waste substances.

The effect of calcium ion on the separation of rhodochrosite and calcite was systematically investigated based on flotation tests, zeta potential measurements, and scanning electron microscopy analysis. The flotation results showed that the separation of rhodochrosite and calcite was inefficient due to rhodochrosite and calcite being similar in many physical and chemical properties, which could make the separation of rhodochrosite from calcite inefficient. The separation of rhodochrosite and calcite can be significantly improved by adding sodium hexa metaphosphate (SH) because SH could depress calcite flotation while it did not bring an impact on rhodochrosite flotation. However, when calcium ion was added into this flotation system, the separation of rhodochrosite and calcite deteriorated as SH also depressed rhodochrosite flotation under this condition. The solution chemical calculation and scanning electron microscopy analysis illustrated that the formation of calcite precipitation coated on the rhodochrosite surface was the main reason because calcium ion increased the depression effect of SH on rhodochrosite. Keywords: Rhodochrosite, Calcite, Calcium ion, Flotation, Separation

We report the use of H3PO4 as a reactant in atomic layer deposition (ALD) of lithium metaphosphate. The ALD growth cycle starts by injection of the lithium tetramethyl heptadionate ( LiTMHD) precursor followed by injection of the H3PO4 reactant. Both the reactant and the precursor are injected into the ALD chamber via direct liquid injection, which allows us to achieve ALD without plasma or high temperatures. The liquid H3PO4 solution, injected 10 s after the precursor, evaporates and decomposes into the gaseous mixture of H3PO4, P4O10, and H2O. The H3PO4 and P4O10 molecules finally react with the LiTMHD molecules adsorbed at the sample substrate, which results in the film growth. The obtained films are amorphous, and the x-ray photoelectron spectroscopy measurements reveal the LiPO3 composition. The growth process exhibits the features of the ALD, namely, the saturation of the growth rate with cycle duration and the maximum growth rate when the number of the injected precursor/reactant molecules reaches a critical value. We show theoretically that the growth rate is governed by the gas-phase equilibrium between H3PO4 and P4O10, both of which are reactive but to different degrees. Depending on the temperature and other conditions, we obtain a reactive gas adjustable at will between pure H3PO4 and pure P4O10. Our theory explains essential features of the observed ALD growth. It determines which of the two reactants ( H3PO4 or P4O10) causes the growth and which of them provides a faster growth.

This work reports on obtaining iron phosphate-supported from activated carbon derived from the acai fruit (Euterpe oleracea Mart.) waste, with H3PO4 and Fe(NO3)2 as precursors. The samples were well-prepared by thermal decomposition at 400 °C (CP-400) and 500 °C (CP-500) with biomass, phosphoric acid, and iron nitrate ratio of 1:1:1 (wt/wt/wt). We characterized the products by X-ray diffraction, confirming the phase mixture of Fe(PO3)3 metaphosphate (P21/n), Fe2P4O12 tetrametaphosphate (C2/c), and amorphous carbon. All active modes were identified for biomass and iron phosphates in infrared spectroscopy. SEM images showed several irregular agglomerates formed by iron phosphate in both samples, where carbon (C), oxygen (O), iron (Fe), and phosphorus (P) were detected in the EDX analysis. The resulting N2 adsorption/desorption obtained isotherms were classified as type I (CP-400) and II (CP-500), with a surface area of 303 m2 g−1 and 206 m2 g−1, respectively. The adsorption of methylene blue dye (MB) in the aqueous solutions of composites CP-400 and CP-500 were 40 mg g−1 and 50 mg g−1, respectively. The photo-Fenton reaction using these composites as solid catalysts showed 99.6% of discoloration for CP-400 and 97.5% for CP-500, at 240 min under UV-light.

The influence of molybdenum on the actual chemical composition of phosphate glasses prepared in the range of the batch compositions from ultraphosphate to pyrophosphate was studied. An analysis of the glasses by XRF, ESR and 31P MAS NMR, supplemented by Raman spectroscopy, showed that the chemical composition of the ultraphosphate glass shifted significantly to the metaphosphate region of divalent cations, leading to very stable glass. The chemical composition of the remaining glasses also shifted towards a lower phosphorus content, i.e., to pyrophosphates, but their chemical composition remained in the area between metaphosphates and pyrophosphates of divalent cation. A chemical model was designed for all the glasses, the main glass-forming compounds were determined and the result was successfully confronted with the compositional dependences of both the glass transition temperature and the coefficient of thermal expansion.

We have reconfirmed the anomalistic reversible strain (shrinkage) after tensile creep in the specific metaphosphate glass melts with entropic elasticity in a wide range of applied stresses. We attempted to elucidate the origin of the anomalistic shrinkage by focusing on the relaxation modes. The fast mode was identified for all glasses by two different measurements, i.e., the dynamic viscoelasticity in the linear range and the creep recovery in the non-linear range. In contrast, the slow mode in addition to the fast mode was confirmed only for the glasses showing the anomalistic shrinkage. The slow mode induced the essential shrinkage at whole tensile stresses, whereas the fast mode, especially at higher tensile stresses, contributed to the moderate shrinkage. As the most likely mechanism in the linear range, the local segmental motion with mobile cation motion and the large-scale relaxation of the connected molecules through scission and renewal of the bond between alkali cations and the oxygen anion were assigned to the fast and the slow modes, respectively. In the non-linear range, the dimensionless strain-rate dependence of the reversible strains for both modes had a similar characteristic to that of the viscosity.

Despite considerable advances in biomaterials-based bone tissue engineering technologies, autografts remain the gold standard for rehabilitating critical-sized bone defects in the oral and maxillofacial (OMF) region. A majority of advanced synthetic bone substitutes (SBS’s) have not transcended the pre-clinical stage due to inferior clinical performance and translational barriers, which include low scalability, high cost, regulatory restrictions, limited advanced facilities and human resources. The aim of this study is to develop clinically viable alternatives to address the challenges of bone tissue regeneration in the OMF region by developing ‘dual network composites’ (DNC’s) of calcium metaphosphate (CMP)—poly(vinyl alcohol) (PVA)/alginate with osteogenic ions: calcium, zinc and strontium. To fabricate DNC’s, single network composites of PVA/CMP with 10% (w/v) gelatine particles as porogen were developed using two freeze–thawing cycles and subsequently interpenetrated by guluronate-dominant sodium alginate and chelated with calcium, zinc or strontium ions. Physicochemical, compressive, water uptake, thermal, morphological and in vitro biological properties of DNC’s were characterised. The results demonstrated elastic 3D porous scaffolds resembling a ‘spongy bone’ with fluid absorbing capacity, easily sculptable to fit anatomically complex bone defects, biocompatible and osteoconductive in vitro, thus yielding potentially clinically viable for SBS alternatives in OMF surgery.

Technological greases based on polyphosphates of alkali metals have great prospects for application at high-temperature machining of steel. An important task is to study the anti-corrosive effect of polyphosphates on steel at elevated temperatures. Temperature ranges, in which phase transformations of metaphosphate and sodium tripolyphosphate, as well as interaction with iron oxide, occur, were established using a thermogravimetric method. Composition of products of interaction between metaphosphate and sodium tripolyphosphate and scale is determined employing an X-ray phase analysis. It was established that in the region of temperatures of hot steel deformation the iron oxides, contained in scale, are dissolved in molten metaphosphate and sodium tripolyphosphate. As a result of interaction between sodium metaphosphate and iron oxide, the mixed polyphosphates Na 3 Fe 2 (PO 4 ) 3 and Na 9 Fe 2 (P 3 O 10 ) 3 are formed. It is shown that sodium tripolyphosphate almost does not participate in the interaction with the iron oxide of scale. Comparison of the results of corrosion test of the steel surface, treated in the presence of a polyphosphate lubrication and sodium chloride, testifies to the high anti-corrosive effect of polyphosphates. Thus, the time before the emergence of first signs of corrosion in the presence of polyphosphates increased fourfold, while the degree of corrosion damage was reduced by 40 times. It was established that at the deformation treatment of steel at a temperature of 800 °C in the presence of a polyphosphate lubricant, corrosion resistance is due to the formation of a barrier film at the steel surface, consisting of mixed polymer phosphates.

Ceramic-like residues were obtained by firing silicone rubber (SiR)/ammonium polyphosphate (APP) composites both with and without magnesium hydroxide (MH) composites at different temperatures. To evaluate the self-supporting property, the bending angles of the residues were tested. The effect of MH and firing temperatures on the self-supporting property was investigated. Results show that the addition of MH reduces the bending angles of the residues and improves their densification. Furthermore, as temperature increases, the bending angles of the residues containing magnesium decrease and their flexural strength is improved. Infrared spectroscopy (IR), X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) analyses demonstrate that formation of crystalline magnesium pyrophosphate within the residues is due to interaction between MH and APP, and the relative content of the crystalline phase increases with increasing temperatures. Solid-state nuclear magnetic resonance (SNMR) further confirms the phosphates, but the above crystalline phase also amorphous magnesium orthophosphate and magnesium metaphosphate. Moreover, as temperatures increase, the relative content of the crystalline phase is improved, which agrees well with the XRD analysis. Therefore, the crystalline phase formed at high temperatures plays a main role in the improvement of the self-supporting property.

The method validation is prelimnary step in a research when researcher has not familier yet with the instruments, procedures and different sample matrices. The aim is obtaining suitable analytical method. Spectrophotometry is an instrumental method which is simpler, faster and cheaper than other instrumental methods. This study optimized and validated Spectrophotometry method for the determination of ascorbic acid in Jeruk Bali Fruit (Citrus maxima). Ascorbic acid in acidic condition gives blue color when was reacted with ammonium molybdate, then the absorbance was observed in visible wavelength area. Optimization to determine ascorbic acid (250.0 µg) required the addition of 4.0 ml of 5% sulphuric acid, 1.5 ml of 3% metaphosphate acid, 1.5 ml of 5% ammonium molybdate and the resulting color was stabil within 20-30 minutes. Furthermore, optimized condition was applied to validate Spectrophotometry method for the determination of ascorbic acid in Jeruk Bali Fruit. Selectivity test obtained 701 nm as wavelength of choice, linierity test resulted Y=0.0019x+0.071 and r=0.9998 (p=0.000; p0.01), Coeffisien of Variation (C.V)=0.3512%, recovery was (%) = 100.2128±1.7039. Using optimized and validated condition, the determination of ascorbic acid in Jeruk Bali Fruit from Indonesia =0.0208±0.0129 (%; w/w).

Yb3+/Er3+ co-doped phosphate glass and glass ceramics were prepared by high-temperature melting method. The X-ray diffraction, transmission electron micrographs, up-conversion and infrared emissions, photothermal conversion properties of the samples have been measured. The results showed the annealing time had a great impact on the microstructure and luminous performance of the phosphate glass. At the beginning of annealing, the metaphosphate crystals were firstly dissolved out. The metaphosphate crystals gradually turned into the orthophosphate with the increasing of annealing time. The emission intensity of the sample was obviously improved after the precursor glass was annealed. The up-conversion and infrared emissions of the sample annealed at 600 °C for 24 h, reached the maximum intensity. Compared with the photothermal properties of glass, the lower photothermal conversion efficiency of the glass ceramics testified the strong emission. Keywords: Yb3+/Er3+ co-doped, Up-conversion emission, Phosphate glass ceramics

Various characterization techniques were used to study the composition of the glass series xAl2O3-(40 - x)CaO-10Na2O-50P2O5 (with 0 ≤ x ≤ 10) in terms of chemical durability, X-ray diffraction, IR spectroscopy and scanning electron microscopy (SEM). The improved chemical durability was attributed to the replacement of easily hydrated P-O-P bonds by covalent and resistant Ca-O-P and Al-O-P bonds. However, the change in the dissolution rate (DR) versus time showed a marked decrease in chemical durability with increasing the Al2O3 content to the detriment of the CaO content. The X-ray diffraction analysis of glasses annealed at 550°C and 660°C for 48 hours indicated the presence of pyrophosphate phases and predominant metaphosphates or cyclic metaphosphate phases when the Al2O3 content was ≤7.5 mol%. Nevertheless, both, X-ray diffraction and IR spectroscopy confirmed the structural tendency change from metaphosphate (Q2) and pyrophosphate structural units (Q1). Toward short isolated orthophosphate units (Q0) when the Al2O3 content above 7.5 mol%. SEM micrographs illustrated that the number of crystallites increased in the glass network when the Al2O3 content increased at the expense of the CaO content. An increase in the Al2O3 content to 10 mol% led to the formation of a larger number of crystallites of different sizes, dominated by small crystallite sizes assigned to short isolated orthophosphate groups. This phenomenon led to a decrease in chemical durability and seems to be a favorable factor for the formation of the apatite layers which enclose the glass, in a SBF solution test, able of regenerating bone tissue in biomedical application.