Strontium Hydroxide Research Articles

Direct ceramic coating of calcium phosphate doped with strontium via reactive growing integration layer method on \u03b1-Ti alloy

A strontium (Sr)-doped hydroxyapatite-like coating was deposited on α-Ti alloy via the growing integration layer (GIL) method at various applied voltages. We added 0.03 M strontium hydroxide (Sr(OH)2·8H2O) to a solution containing calcium acetate and sodium dihydrogen phosphate to produce Sr-doped hydroxyapatite (Sr-HA) coatings. The scanning electron microscope (SEM) images of these coatings showed that all various features, such as average pore size, coating thickness, micro-hardness, and roughness, were similar to those of HA. As the voltage increased from 250 to 300 V, the amount of micro cracks decreased, and there were eliminated at 350 V. The SEM images also showed that the Sr-HA coatings were closely integrated with the alloy: without any gaps between the oxide layers and the alloy. In addition, energy-dispersive X-ray spectroscopy verified the Sr integration from the bottom up. X-ray diffraction patterns confirmed Sr-HA formation instead of calcium phosphate, even at the lowest voltage of 250 V. The value of Ecorr increased by 6.6% after raising the voltage from 250 to 350 V. The electrochemical impedance spectroscopy analysis confirmed that the adequate corrosion resistance of Sr-HA coatings, especially at the highest voltage of 350 V. In addition, the GIL treatment increased the layer resistance measured by Rp/Rc. Optimally, the GIL method used the highest voltage of 350 V to produce higher quality of Sr-HA-rich coatings.

Properties of fine Sr2+-substituted hydroxyapatite synthesized using ultrasonication

This study investigated the properties of fine Sr2+-substituted hydroxyapatite (SrHAp) synthesized using ultrasonication. SrHAp was synthesized by the addition of phosphoric acid solution to an ultrasonicated calcium hydroxide suspension containing strontium hydroxide. The X-ray diffraction peaks for SrHAp were shifted to low angle with increasing Sr/(Ca + Sr) atomic ratio. X-ray diffraction, energy dispersive X-ray spectroscopy and inductively coupled plasma spectroscopy measurements confirmed that HAp and strontium apatite (Sr10(PO4)6(OH)2;SrAp) formed a complete solid solution. When the Sr/(Ca + Sr) atomic ratio was 0.3 or less, the (Ca + Sr)/P atomic ratio was 1.67 or less, and the specific surface area was also large. The bending strength of a SrHAp sintered body was increased and the bending strength of the SrAp sintered body became 40 MPa when the Sr/(Ca + Sr) atomic ratio was above 0.3. The ethanol conversion rate using SrAp as catalyst was 7% for 1 hour and was 40% of HAp reagent. However, selectivity of SrAp from ethanol to butanol was 70%.

Solid-state symmetric supercapacitor based on Y doped Sr(OH)2 using SILAR method

Supercapacitor is one of the most promising and emerging type of energy storage devices having the merits of both conventional battery and traditional capacitor. In this regard, we have deposited Yttrium doped Strontium hydroxide thin films on stainless steel substrate with the help of a facile, cost-effective successive ionic layer adsorption and reaction technique at room temperature without using any binder. Doping of Yttrium into Strontium hydroxide enhances both electronic conductivity and electrochemical performance of the electrode for energy storage. Nanorods like structure with the tuberose morphology has been obtained with the help of field emission scanning electron microscopy. The cyclic voltammetry, galvanostatic charge-discharge and electrochemical impedance spectroscopy measurements show the pseudocapacitive battery like response. Among all the synthesised materials, 1.0 at. % Yttrium doped Strontium hydroxide shows a high specific capacity of 705.3 C g−1 at 0.4 mA current rate and stability of ∼82% at 2.5 mA current rate. The prototype light-weight solid-state symmetric supercapacitor device of Yttrium doped Strontium hydroxide electrodes has been fabricated by sandwiching PVA-Na2SO4 gel. Thus, we observe that this device has potential applications for the next-generation cost effective energy storage system.

Facile synthesis of ultrafine and high purity spherical strontium carbonate via gas-liquid reaction

In this work, a simple gas-liquid precipitation reaction was developed to fabricate spherical strontium carbonate (SrCO3) particles using strontium hydroxide (Sr(OH)2), carbon dioxide (CO2) and ethylene diaminetetraacetic acid strontium salt (EDTA-Sr) as raw materials. The effects of the concentration of EDTA-Sr and Sr(OH)2, airflow rate of CO2 and reaction temperature on the morphology of SrCO3 were investigated. The results showed that spherical SrCO3 particles can be formed when the concentration of EDTA-Sr reached 0.02 M as well as that of Sr(OH)2 was less than 0.1 M. The airflow rate of CO2 gas had little effect on the spherical morphology, and SrCO3 microsphere with good dispersion could be obtained when the reaction temperature reached 50 °C. Under the optimal conditions ([EDTA-Sr] = 0.02 M, [Sr(OH)2] = 0.1 M, 50 °C, [CO2] = 1 l min−1), high purity spherical SrCO3 particles with diameter of 200–800 nm can be easily obtained. Finally, the growth mechanism of spherical SrCO3 has been preliminarily presented, which indicated that EDTA-Sr is an excellent structure-directing agent for forming pherical SrCO3 particles. Our work offers an effective method for large-scale production of high purity spherical SrCO3.

Determination of Thermodynamic Parameters from the Dissolution of Strontium Hydroxide in Water and Mixed Solvent Systems by pH-Metric Method

In this study, saturated solutions of Sr(OH)2 in pure water and in mixed solvent systems (methanol - water, ethanol - water, 1-propanol - water, and 2-propanol - water) at two temperatures were prepared and titrated with standard HCl solution by using pH metry. Using these titration data, the molar solubility (s), solubilty product (Ksp) and Gibbs free energy (Go), entropy change (ΔSand#176;) and enthalpy change (ΔHand#176;) for dissolution of strontium hydroxide was determined. At room temperature (20and#176;C), the s, Ksp, ∆Go were found to be 4.28 x 10-2 mol L-1, 3.13 x 10-4 mol3L-3 and 19.70 kJ mol-1 respectively. The ΔHand#176; and ΔSand#176; of the reaction is 2.90 kJ mol-1 and – 60.80 J. mol-1 K-1. With increasing percentage content of organic solvent in mixed solvents, the molar solubility and Ksp decreased and ∆Go, ΔHand#176; and ΔSand#176; values increased. The results were correlated with the dielectric constant value of the solvents used in the study.

Determination of Thermodynamic Parameters from the Dissolution of Strontium Hydroxide in Water and Mixed Solvent Systems by pH-Metric Method

In this study, saturated solutions of Sr(OH)2 in pure water and in mixed solvent systems (methanol - water, ethanol - water, 1-propanol - water, and 2-propanol - water) at two temperatures were prepared and titrated with standard HCl solution by using pH metry. Using these titration data, the molar solubility (s), solubilty product (Ksp) and Gibbs free energy (Go), entropy change (ΔSand#176;) and enthalpy change (ΔHand#176;) for dissolution of strontium hydroxide was determined. At room temperature (20and#176;C), the s, Ksp, ∆Go were found to be 4.28 x 10-2 mol L-1, 3.13 x 10-4 mol3L-3 and 19.70 kJ mol-1 respectively. The ΔHand#176; and ΔSand#176; of the reaction is 2.90 kJ mol-1 and – 60.80 J. mol-1 K-1. With increasing percentage content of organic solvent in mixed solvents, the molar solubility and Ksp decreased and ∆Go, ΔHand#176; and ΔSand#176; values increased. The results were correlated with the dielectric constant value of the solvents used in the study.

Synthesizing Alkaline Earth Metal Hydroxides Nanoparticles through an Innovative, Single-Step and Eco-Friendly Method

The objective of this paper is to introduce a patented and eco-friendly method to synthesize aqueous suspension of all types of alkaline-earth metal hydroxides nanoparticles (NPs). This method is based on an ion exchange process; the exchange takes place at ambient temperature/pressure, starts from cheap or renewable reagents and, in one single step, results in the creation of the crystalline desired nanoparticles in only a few minutes. In terms of structural and morphological features, the synthesized nanoparticles are characterized by means of XRD-Rietveld refinement, FTIR, and TEM. In particular, we obtained pure and crystalline magnesium and calcium hydroxide suspensions, showing the typical brucite crystal structure with a hexagonal lamellar morphology and dimensions generally <100 nm. With respect to the strontium and barium hydroxide suspensions, we observed different kinds of hydroxides (either anhydrous and hydrate forms), characterized by orthorhombic or monoclinic crystal lattices with rod-like nanostructured morphologies. Despite the different morphologies, all synthesized nanoparticles appear constituted by a superimposition of primary nanoparticles, of dimensions ranging from a few to 15 nm, correlated to the increase in the atomic number of the alkaline earth metal.

Influence of Cu on the Performance of Tuberose Architecture of Strontium Hydroxide Thin Film as a Supercapacitor Electrode

AbstractA simple, economical successive ionic layer adsorption and reaction (SILAR) method has been used for synthesizing 1, 2 and 3 at.% copper‐doped strontium hydroxide over a stainless‐steel (SS) substrate. X‐ray diffraction reveals the orthorhombic crystal structure of polycrystalline Cu‐doped Sr(OH)2. FTIR and Raman analyses explore the chemical bond analysis of the active material. The morphology of the Cu‐doped Sr(OH)2 was analyzed by using SEM. This shows novel hierarchical‐branched tuberose with flakes. The energy‐dispersive X‐ray spectroscopy (EDAX) also confirms the doping of Cu into Sr(OH)2. The electrochemical properties have been investigated by using cyclic voltammetry (CV) and galvanostatic charge−discharge measurements. It has been perceived that doping clearly affects the supercapacitive behavior. The specific capacity of the 3 at.% Cu‐doped Sr(OH)2 film electrode exhibits a maximum specific capacity of 817 C g−1 at 0.4 mA cm−1 in 1 M Na2SO4 electrolyte, but has a low cycle stability. The 2 at.% Cu‐doped sample shows high cycle stability by retrieving 71 % of its capacity after 5000 cycles. The relationship between the doping concentration and supercapacitive behavior has also been discussed. The good capacitive behavior and cycle stability of the Cu‐doped Sr(OH)2 gives the new perspective for the flexible electrode material, which can be used in the near future as an energy storage material.

Fluorescence branching ratios and magnetic tuning of the visible spectrum of SrOH

The magnetic tuning of the low rotational levels in the X̃2Σ+ (0,0,0), Ã2Πr (0,0,0), and B̃2Σ+ (0,0,0) electronic states of strontium hydroxide, SrOH, have been experimentally investigated using high resolution optical field-free and Zeeman spectroscopy of a cold molecular beam sample. The observed Zeeman shifts and splittings are successfully modeled using a traditional effective Hamiltonian approach to account for the interaction between the Ã2Πr and B̃2Σ+ states. The determined magnetic g-factors for the X̃2Σ+, Ã2Πr, and B̃2Σ+ states are compared to those predicted by perturbation theory. The dispersed fluorescence resulting from laser excitation of rotationally resolved branch features of the 000B̃2Σ+←X̃2Σ+, 000Ã2Π3/2←X̃2Σ+ and 000Ã2Π1/2←X̃2Σ+ transitions have been recorded and analyzed. The measured fluorescence branching ratios are compared with Franck-Condon calculations. The required bending motion wave functions are derived using a discrete variable representation (DVR) method. Implications for laser slowing and magneto-optical trapping experiments for SrOH are described.

Multicationic Sr4Mn3O10 mesostructures: molten salt synthesis, analytical electron microscopy study and reactivity

Molten salt synthesis of anisotropic Sr4Mn3O10 particles.

Tuberose surface architecture of Sr(OH)2 film as supercapacitive electrode

The first report, on tuberose surface morphology of strontium hydroxide (Sr(OH)2) has been achieved on stainless-steel (SS) substrate in the form of thin film by easy, economical efficient and less time consuming successive ionic layer adsorption and reaction (SILAR) technique at room temperature. X-ray diffraction analysis reveals polycrystalline nature of film with orthorhombic crystal structure. Fourier Transmission Infrared Spectroscopy (FTIR), Energy-dispersive X-ray spectroscopy (EDS) and Raman analyses reveal the composition and phase purity of the active material. The morphology of the prepared sample was characterized by Field Emission Scanning Electron Microscopy (FE-SEM), Higher Resolution Transmission Emission Microscopy (HR-TEM) which confirms the tuberose morphology of the Sr(OH)2 thin film. Furthermore, tuberose surface architecture has been successfully utilized as supercapacitive electrode with high specific capacity of 413Cg−1 in 1M NaOH aqueous electrolyte at 2Ag−1 current density. Also, the electrode has emerged with 45.95Whkg−1 of energy density and 2.6kWkg−1 as power density at 2Ag−1 current density.

Energy and exergy analysis of a heat storage tank with a novel eutectic phase change material layer of a solar heater system

ABSTRACTSolar energy is one of the most important renewable energy sources, but it is not available every time and every season. Thus, storing of solar energy is important. One of the popular methods of heat storage is use of phase change materials (PCMs) which have large thermal energy storage capacity. In this study, the heat storage tank in a domestic solar water heating system was chosen as control volume. The experiments were performed in the province of Elazıg, Turkey, in November when solar radiation was weak due to cloudy sky. The heat storage tank of the system was modified to fill PCM between insulation and hot water part. A few PCMs which are Potassium Fluoride, Lithium Metaborate Dihydrate, Strontium Hydroxide Octahydrate, Barium Hydroxide Octahydrate, Aluminum Ammonium Sulfate, and Sodium Hydrogen Phosphate were analyzed to proper operating conditions using a Differential Scanning Calorimeter (DSC) and the best PCM was obtained with the Aluminum Ammonium Sulfate and Sodium Hydrogen Phosphate mixture. Thus, eutectic PCM was obtained and used in a heat storage tank of the solar water heating system. Energy and exergy analysis of heat storage tank was performed with and without the PCM. Energy and exergy analysis has shown that the heat storage tank with the PCM is more efficient than without the PCM and the maximum exergy efficiency was obtained as 22% with the heat storage tank with the PCM.

Carbonate biomineralization and heavy metal remediation by calcifying fungi isolated from karstic caves

Microbially induced calcium carbonate precipitation (MICP) is a potential technology for creation of durable calcitic minerals. In the current study, we for the first time explored the potential of calcifying ureolytic fungi isolated from Moondyne cave of Western Australia for their biomineralization, metal and radionuclide remediation potential. Two ureolytic isolates Aspergillus sp. UF3 and Fusarium oxysporum UF8 showed significant production of calcite along with co-precipitation of heavy metal Lead and radionuclide Strontium as carbonates. Carbonic anhydrase production in synergism with urease is also reported. Micrographic results demonstrated association of fungal mycelium with biominerals. The biominerals precipitated by calcifying fungi were found to be calcite, vaterite, aragonite along with carbonates and hydroxides of Lead and Strontium. Effective biomineralization with calcium oxalate, a cheap calcium source is also reported. The results of current study suggest that ureolytic fungi from karstic environments bear immense potential for biomineralization, bioremediation and biorecovery of important metals.

The corrosion of carbon steel in nitrate hydrates used as phase change materials

Corrosion behaviour of mild carbon steel was studied in five assumed phase change materials: magnesium nitrate hexahydrate, magnesium nitrate hexahydrate with the addition of magnesium hydroxide (0.5 wt%) and strontium hydroxide (0.5 wt%), respectively, at 90 °C; calcium nitrate tetrahydrate at 50 °C and a mixture of magnesium nitrate hexahydrate and calcium nitrate tetrahydrate (1:1) at 72 °C. Corrosion rate was studied via mass loss and the steel specimens were analysed after the study. The corrosion rate of steel specimens is over recommended limit except of the mixture Mg(NO3)2 · 6 H2O − Ca(NO3)2 · 4 H2O (1:1). Steel can be used for the long‐term service in this mixture while in the other cases it can be used only with caution based on the specific application.

Measurement of Strontium Monoxide in Methane-Air Flames.

The spectroscopy of alkaline earth metal compounds is stimulated by the use of these compounds in practical areas ranging from technology to medicine. Applications in the field of pyrotechnics were the motivation for a series of flame emission spectroscopy experiments with strontium-containing compounds. Specifically, strontium monoxide (SrO) was studied as a candidate radiator for the diagnosis of methane-air flames. Strontium monoxide emissions have been observed in flames with temperatures in the range 1200 K to 1600 K for two compounds: strontium hydroxide and strontium chloride. Comparisons are made of the measured SrO spectra to simulated spectra in the near-infrared region of 700 nm to 900 nm.

Synthesis and structural properties of (Y, Sr)(Ti, Fe, Nb)O3−δ perovskite nanoparticles fabricated by modified polymer precursor method

The yttrium, iron and niobium doped-SrTiO3 powders have been successfully fabricated by a modified low–temperature synthesis method from a polymer complex. The usage of strontium hydroxide precursor instead of conventional strontium nitrate or strontium carbonate provides to the possibility of significant decrease of annealing temperature. It allows to prepare a material with sphere-shape grains of nanometric size (15–70 nm). The results of thermal analysis indicate that the crystallization of precursor takes place at different stages. The product after heat treatment at 600 °C for 3 h in air was also characterized by X-Ray diffraction method (XRD) and Fourier transform – infrared spectroscopy (FT-IR). After the crystallization and the impurity removal process, a single-phase material was obtained in case of all analyzed samples. The morphology of obtained nano-powders was also studied by a scanning electron microscopy (SEM). It can be concluded, that this method allows obtaining a perovskite phase of a metal doped SrTiO3 with nanometric particles.

Strontium doped poly-ε-caprolactone composite scaffolds made by reactive foaming

In the reconstruction and regeneration of bone tissue, a primary goal is to initiate bone growth and to stabilize the surrounding bone. In this regard, a potentially useful component in biomaterials for bone tissue engineering is strontium, which acts as cationic active agent, triggering certain intracellular pathways and acting as so called dual action bone agent which inhibits bone resorption while stimulating bone regeneration. In this study we established a novel processing for the foaming of a polymer (poly-ε-caprolactone) and simultaneous chemical reaction of a mixture of calcium and strontium hydroxides to the respective carbonates using supercritical carbon dioxide. The resultant porous composite scaffold was optimized in composition and strontium content and was characterized via different spectroscopic (infrared and Raman spectroscopy, energy dispersive X-ray spectroscopy), imaging (SEM, μCT), mechanical testing and in vitro methods (fluorescence vital staining, MTT-assay). As a result, the composite scaffold showed good in vitro biocompatibility with partly open pore structure and the expected chemistry. First mechanical testing results indicate sufficient mechanical stability to support future in vivo applications.

Synthesis of Strontium Substituted Hydroxyapatite through Different Precipitation Routes

The aim of this work was to evaluate the effect of precursor materials used in the synthesis on the Sr incorporation levels into the hydroxyapatite (HAp) lattice and to characterize the synthesis products. HAp powders containing various amounts of Sr were synthesized through three different precipitation routes. In all cases, the as-synthesized products were found to be pure HAp. However, atomic absorption spectrometry analysis showed that by reacting orthophosphoric acid with calcium hydroxide and strontium hydroxide, as well as by reacting diammonium hydrogen phosphate with calcium nitrate tetrahydrate and strontium nitrate a significant proportion of the Sr added, did not substitute into the HAp lattice. X-ray diffraction analysis revealed that the effect of substituting relatively high amounts (up to 3.69 ± 0.37 wt.%) of Sr into the HAp lattice was to decrease the cristallinity. Brunauer-Emmett-Teller (nitrogen absorption) analysis showed that the incorporation of Sr reduced particle sizes of the precipitated HAp products. Contrary, scanning electron microscopy revealed that the incorporation of Sr increased length of the precipitated needle-like particles.

Uranium(VI) hybrid materials with [(UO2)3(µ3‐O)(µ2‐OH)3]+as the sub–building unit via uranyl–cation interactions

AbstractThe hydrothermal reaction of uranyl nitrate with 1,4‐benzenedicarboxylic acid (H2bdc) in the presence of strontium or potassium hydroxides and nitrates afford the formation of two new uranyl hybrid materials featuring extensive uranyl‐strontium or uranyl‐potassium interactions with [(UO2)3(µ3‐O)(µ2‐OH)3]+as the sub‐building unit. Sr1.5[(UO2)12(O)3(OH)13(bdc)4]⋅6H2O (1) contains one‐dimensional (1D) uranyl oxohydroxyl ribbons made of trinuclear pentagonal bipyramidal uranyl units. The ribbons are linked together via uranyl‐strontium interactions to form 2D inorganic domains which are further connected throughµ4‐bdc anions forming a 3D hybrid structure. This is the first reported uranyl‐strontium interaction in extended hybrid solid with the shortest Sr‐O−ylbond length of 2.596 (8) Å. K3[(UO2)12(O)3(OH)13(bdc)4]⋅8H2O (2) has a similar 3D hybrid structure built up through extensive K‐O−ylinteractions with the shortest K‐O−ylbond length of 2.620 (6) Å. Raman spectroscopy has confirmed the presence of oxo‐bridging (U−O−U) vibrations. Thermal stabilities and photoluminescent properties are reported.

A single-step direct hydrothermal synthesis of SrTiO3 nanoparticles from crystalline P25 TiO2 powders

In the study, strontium titanium (SrTiO3) nanoparticles were successfully synthesized by a single-step direct hydrothermal process under alkaline condition from crystalline P25 titanium dioxide (TiO2) powders and strontium hydroxide octahydrate (Sr(OH)(2)center dot 8H(2)O) at 220A degrees C. The samples obtained were characterized by X-ray diffraction (XRD), indicating that the products were highly crystalline cubic SrTiO3 nanoparticles. The lattice parameter, unit cell volume, and atomic position were refined by Highscore Plus and Maud program to determine the crystal structure parameters. The thermal field emission scanning electron microscope and energy-dispersive spectrometer (FE-SEM-EDS) showed the samples prepared were cubic SrTiO3 nanoparticles with regular morphology. The fine morphologies and structures of SrTiO3 were investigated by field emission high-resolution transmission electron microscope (HR-TEM). The specific surface areas of samples were investigated by the BET method. As a comparison, SrTiO3 nanoparticles also were synthesized by solid-state reaction. The samples synthesized by hydrothermal method have bigger specific surface areas and smaller grain sizes than the sample synthesized by solid-state method. Big mole ratio Sr/Ti and short reaction time are helpful to produce small particles with large specific surface area. The reaction mechanism of the hydrothermal process was illustrated finally.