Structure Of SrO Research Articles

Catalytic and antimicrobial properties of Ag and polyacrylic acid doped SrO nanocomposites; molecular docking analysis

This study investigates the co-precipitation synthesis of (2 and 4 wt%) Ag and polyacrylic acid-doped SrO nanocomposites for bactericidal activities and catalytic Rhodamine B (RhB) decolorization. The objective of the investigation was to minimize the rate of electron-hole recombination of SrO to enhance charge transfer. The influence of Ag and PAA on the crystal structure, morphology, absorbance wavelength, and exciton recombination rate of SrO was studied using a systematic characterization. The binary dopants were added into SrO to reduce the crystallite size, which produces the new active sites (reduces the recombination rate) and may generate reactive oxygen species (ROS). In a neutral medium with sodium borohydride (NaBH4), the synthesized nanocomposites demonstrated reasonable results for catalytic reduction of RhB dye (74.3 %). The bactericidal efficiency (96.6 %) of prepared samples was measured for Escherichia coli (E. coli) at various concentrations. Molecular docking studies were performed to rationale the antibacterial activity of PAA-SrO and Ag/PAA-SrO nanocomposites against DHFRE. coli, DHPSE. coli, and FabIE.coli suggested their role as inhibitors.

Facile synthesis of novel SrO 0.5:MnO 0.5 bimetallic oxide nanostructure as a high-performance electrode material for supercapacitors

Perovskite bimetallic oxides as electrode material blends can be an appropriate method to enhance the supercapacitor properties. In the present research, SrO 0.5:MnO 0.5 nanostructures (NS) were synthesized by a facile co-precipitation method and calcinated at 750–800°C. Crystal structure of SrO 0.5:MnO 0.5 NS were characterized by X-ray diffraction, surface chemical composition and chemical bond analysis, and dispersion of SrO into MnO was confirmed by X-ray photoelectron spectral studies. Structural morphology was analyzed from scanning electron microscopy. Optical properties of SrO 0.5:MnO 0.5 NS were studied using UV-Visible spectrophotometer and SrO 0.5 and MnO 0.5 NS showed ∼75 nm grain, ∼ 64 nm grain boundary distance, with two maxima at 261 nm and 345 nm as intensity of absorption patterns, respectively. The synthesized SrO 0.5:MnO 0.5 NS exhibited high specific capacitance of 392.8 F/g at a current density of 0.1 A/g. Electrochemical impedance spectroscopy results indicated low resistance and very low time constant of 0.2 s ∼73% of the capacitance was retained after 1000 galvanostatic charge-discharge (GCD) cycles. These findings indicate that SrO 0.5:MnO 0.5 bimetallic oxide material could be a promising electrode material for electrochemical energy storage systems.

Structural phase transition and electronic structure of binary CaO and SrO under high pressure

We have investigated pressure-induced structural phase transition and electronic structure of binary alkaline-earth monoxides. From our static enthalpy calculations, CaO and SrO are found to undergo a common structural phase transition from B1 to B2 at 59.2 GPa and 32.4 GPa, respectively. B33 phase is found to be meta-stable for both investigated compounds. We have calculated electronic structure with Tran-Blaha modified Becke-Johnson potential (TB-mBJ) potential and the obtained band gaps are improved over standard PBE-GGA functional. CaO and SrO compounds are found to be indirect band gap insulators at ambient pressure. Interestingly, electronic structure calculations at high pressure suggest that B2 phase of CaO is an indirect band gap semiconductor while B2 phase of SrO is a direct band gap semiconductor, i.e., pressure-induced indirect → direct band gap transition is observed in SrO.

Thermoelectric properties of strontium oxide under pressure: First-principles study

We studied the electronic structure and thermoelectric properties of SrO under pressure via first-principle calculations. The obtained phase transition pressure of SrO from B1 phase to B2 phase is 37 GPa at room temperature. At Gamma point, the phonon largest peak frequencies of SrO are 14.6 THz (B1 phase) and 18.9 THz (B2 phase), in addition, the LO-TO splitting frequencies are 8.6 THz (B1 phase) and 8.21 THz (B2 phase) under 0 GPa for B1 phase and 64 GPa for B2 phase, respectively. The B1 phase of SrO has an indirect band gap (3.31 eV) at 0 GPa, while the B2 phase has a smaller direct band gap (2.27 eV) at 70 GPa. At 0 GPa, the born effective charges of SrO are 2.44 (B1 phase) and 2.60 (B2 phase), and the dielectric constants are 3.80 (B1 phase) and 4.47 (B2 phase). When the temperature reaches 700 K and the carrier density reaches 1.2×1021 cm−3, the ZT value of B1 phase reaches 0.61 at 0 GPa. By comparison, we found that the thermoelectric properties of the B1 phase behave better than those of the B2 phase at zero pressure.

Prediction of half-metallicity in strontium oxide doped with hafnium: A GGA+U perspective

Abstract Based on GGA+U (generalized gradient approximation plus Hubbard potential) study, the electronic and magnetic properties of SrO doped with hafnium were investigated using FP-LAPW (full potential linearised augmented plane wave) method. Hafnium is doped in cubic rock salk structure of SrO. In ferromagnetic phase, the doped compound is stable because it contains least energy in this phase. The half-metallic characteristic is predicted in Hf0.125Sr0.875O compound with energy spin band gap in spin down channel. Doping of Hf in SrO creates magnetism in the doped Hf0.125Sr0.875O compound. The compound owing half-metallic ferromagnetism could be suitable for spintronics applications.

ПРИМЕНЕНИЕ СИСТЕМЫ ЭКОЛОГИЧЕСКОГО МЕНЕДЖМЕНТА ISO 14000 В ЖИВОТНОВОДЧЕСКИХ ОРГАНИЗАЦИЯХ

An important component of the image of a modern enterprise is the quality and environmental friendliness of products. International standard ISO 14001:2015 specifies requirements for an environmental management system that an organization can use to improve the environmental performance of its activities. The spread of the application of ISO 14000 standards in Russian enterprises is hampered by a number of problems: improper planning of the development and implementation of the quality management system, low involvement of the company's management and personnel in the development and implementation of the quality management system. The implementation of ISO 14000 standards in livestock organizations is possible if the criteria are met: the land plot is removed from large cities and industrial zones, the livestock of farm animals meets the standards, the size of the land plot meets the standards for keeping farm animals. It is advisable to organize a quality management system department in the organizational structure of the SRO "Association of Peasant (Farm) Farms and Agricultural Cooperatives of the Perm Territory" for comprehensive support and coordination of the activities of agricultural organizations in the region.

Luminescence properties and cathodoluminescence degradation of Bi doped SrO powder

Bi3+ doped strontium oxide (SrO:Bi) phosphor powders were synthesized by the solgel combustion method using metal nitrates as precursors and citric acid as fuel. The optimum Bi3+ doping concentration was found to be 0.2 mol. %, and the optimum annealing temperature was found to be 1100 °C (2 h). The x-ray diffraction patterns corresponded with the known face-centered-cubic structure of SrO. Williamson–Hall plots showed that the crystallite size was in the range of ∼180 nm. Diffuse reflectance measurements of the pure host material showed that it was strongly reflecting (∼100%) down to a wavelength of about 230 nm, but when doped with Bi, an absorption band at 275 nm was observed that increased with Bi concentration. Scanning electron microscopy revealed a cubic morphology, and the grain size increased with annealing temperature. Photoluminescence measurements indicated that the phosphor exhibited efficient blue emission around 445 nm under UV excitation, which also occurred for electron irradiation, but slightly shifted about 5 nm to a longer wavelength. Auger electron spectroscopy (AES) was employed to analyze the surface chemical composition of the powder after pumping to a vacuum pressure of 2.6 × 10−8 Torr and back-filling the vacuum system with O2 to a pressure of 1.0 × 10−7 Torr. By simultaneous monitoring of the cathodoluminescence (CL) and AES peak-to-peak heights over time for 22 h, the CL degradation of the phosphor was investigated. SrO was found to be stable under electron irradiation. The phosphor may have potential applications in the fields of lighting and displays due to its broad blue emission.

Structural transformation and property improvement of Fe78Si9B13 amorphous ribbon by pulsed laser processing

The effects of pulsed laser processing (PLP) with different laser power (PL = 10, 20 and 30 W) on the surface morphology, structure and properties of Fe78Si9B13 amorphous ribbon were investigated. It was found that the circular blobs, convex in perimeter and sunk in middle, distributed regularly on the surface of ribbon after PLP with PL = 10 W. As PL increased to 20 and 30 W, obvious splashes occurred around the laser blobs. On the surface of ribbons after PLP, fresh amorphous structures were generated, which were confirmed by small angle X-ray scattering and transmission electron microscope data. Meanwhile, a small number of nanocrystallines formed at heat affected zone. The X-ray diffraction results indicated that the transformation from fcc to bcc SRO structure units occurred during PLP, resulting in a lower characteristic distance δC. The pitting resistance, soft magnetic property and thermal stability of ribbons were enhanced after PLP. Especially, the properties had a significant improvement with increasing PL from 10 to 20 W, but had a slight deterioration as PL increased further from 20 to 30 W. Overall, an optimal laser power of 20 W was obtained for PLP of Fe78Si9B13 amorphous ribbon in this work.

Investigation of electronic structure and half-metallic ferromagnetic behavior with large half-metallic gap in $$\hbox {Sr}_{1-x}\hbox {V}_{x}\hbox {O}$$ Sr 1 - x V x O

In this study, we investigate the electronic structure and magnetic properties of V-doped rock-salt SrO as a $$\hbox {Sr}_{1-x}\hbox {V}_{x}\hbox {O}$$ ternary compound at concentration $$x = 0.25$$ by the use of first-principle calculations of density functional theory using the full potential linearized augmented plane wave method. The electronic structures of $$\hbox {Sr}_{0.75}\hbox {V}_{0.25}\hbox {O}$$ have a half-metallic character due to the metallic nature of majority-spin states and semiconducting features of minority-spin states. From results of the magnetic properties, we have found that the $$\hbox {Sr}_{0.75}\hbox {V}_{0.25}\hbox {O}$$ has a total magnetic moment of $$3\,\mu _{\mathrm{B}}$$ and the p–d exchange coupling is ferromagnetic between V magnetic impurity and the host carriers of O atoms. The $$\hbox {Sr}_{0.75}\hbox {V}_{0.25}\hbox {O}$$ compound exhibits a wide half-metallic gap of 1.00 eV; this factor is a fundamental characteristic of half-metallic ferromagnetic materials for spintronics applications.

Structure of the system SrO—SiO2—TiO2 and its importance in the technology of technical ceramics

Coexisting phases in the system SrO—SiO2—TiO2 are established. The elementary triangles, their relative area and asymmetry degree of the system SrO—SiO2—TiO2 are given. Geometrical-topological characteristics of the phases of the system are given. The areas of composition of the system, the most promising in technology of technical ceramics, are determined.

Hydration Structures of MgO, CaO, and SrO (001) Surfaces

Using density functional theory (PBE functional), we show that the degree of surface hydroxylation increases in the MgO, CaO, SrO series, accompanied by an increase in water adsorption energy. Already for water coverage of two monolayers, structures with dissolved M2+ ions are considerably more stable than the intact, nondissolved surface. The dissolved ions above the surface form different patterns including ordered ones (e.g., an infinite stripe) that are preferred for MgO(001) and CaO(001) and disordered ones that are favored for SrO(001). Contrary to previous assignments, an analysis of calculated X-ray photoelectron spectra shows that O(1s) signals arising from OH and H2O groups might coincide in the experimental spectrum.

Influence of composition on the structure and properties of SrO–Sb2O3–P2O5 low-melting sealing glasses

AbstractSrO–Sb2O3–P2O5 glass system was prepared by high temperature melting method. The effects of Sb2O3 and P2O5 content on the structure, thermal behavior and chemical durability of the glasses were studied by infrared spectrometer, thermal dilatometer, differential thermal analyzer and constant temperature water bath heating. It can be concluded that the characteristic temperatures of the glasses increased firstly and then decreased with the increasing of Sb2O3 content, whereas the tendency of the coefficient of thermal expansion (CTE) varied inversely. The crystallization ability of the glasses was significantly increased and the water resistance was reduced for Sb2O3 content of 35 mol % and 40 mol %. The glasses with 20 mol %, 25 mol % and 30 mol % Sb2O3 showed better performance in every respect than the others and the glasses containing 25 mol % Sb2O3, characterized by the best performance, can be chosen as host glasses for further research.

Influence of different nucleating agent additives on phase structure and ferroelectric properties of SrO–BaO–Nb2O5–CaO–SiO2–B2O3 glass-ceramics

Ferroelectric glass-ceramics of the SrO–BaO–Nb2O5–CaO–SiO2–B2O3 system with different nucleating agents Cr2O3, BaF2, ZrO2, CaF2 and CeO2, have been prepared by conventional melt casting followed by controlled crystallization processing. The effect of different nucleating agent additions on crystallization mechanism, crystallization behaviors, microstructures and dielectric properties of the glass-ceramics are studied using DTA, XRD techniques, SEM and LCR analyzer. The results show that the addition of different nucleating to the glass-ceramics decreases the crystallization temperatures, accelerates the secondary phase elimination and promotes the uniform distribution of grain size. The well development of microstructure promoted by the nucleating agents can result in the improvement of the dielectric constant as well as energy storage density remarkably. The sample with CeO2 as the optimum nucleating agent achieves the dielectric constant of 301, breakdown strength of 622 kV/cm and the highest energy storage density of 5.15 J/cm3.

Stoichiometric, nonstoichiometric, and locally nonstoichiometric SrTiO3 films grown by molecular beam epitaxy

SrTiO 3 films were grown by reactive molecular beam epitaxy to have varying degrees of both global and local cationic nonstoichiometries (with stoichiometry defined as a 1:1 ratio of Sr:Ti). Slight global excesses of Sr and Ti resulted in two-fold reconstructions in the reflection high-energy electron diffraction patterns along the [110] and [100] azimuths, respectively. Larger global nonstoichiometries (2:1 and 1:2 ratios) were also accommodated into the film’s crystalline structure and affected the long-range crystalline order as observed in the x-ray diffraction patterns, both of which were related to the parent perovskite pattern. Local nonstoichiometries were introduced by depositing multiple monolayers (MLs) (from 2 to 33) of SrO and TiO2 in an alternating fashion, while maintaining the global SrTiO3 stoichiometry. These layered structures of SrO and TiO2 blocks inter-reacted during growth to form highly crystalline epitaxial SrTiO3. Films grown in this manner with blocks thicker than 8 MLs were fully relaxed and, when the block thicknesses ranged between 8 and 10 MLs, the full widths at half maxima of 2θ peaks were narrower than the standard SrTiO3 films having blocks 1 ML thick.

The role of Sr2+ on the structure and reactivity of SrO–CaO–ZnO–SiO2 ionomer glasses

The suitability of Glass Polyalkenoate Cements (GPCs) for use in orthopaedics is retarded by the presence in the glass phase of aluminium, a neurotoxin. Unfortunately, the aluminium ion plays an integral role in the setting process of GPCs and its absence is likely to hinder cement formation. However, the authors have previously shown that aluminium free GPCs may be formulated based on calcium zinc silicate glasses and these novel materials exhibit significant potential as hard tissue biomaterials. To further improve their potential, and given that Strontium (Sr) based drugs have had success in the treatment of osteoporosis, the authors have substituted Calcium (Ca) with Sr in the glass phase of a series of aluminium free GPCs. However to date little data exists on the effect SrO has on the structure and reactivity of SrO-CaO-ZnO-SiO(2) glasses. The objective of this work was to characterise the effect of the Ca/Sr substitution on the structure of such glasses, and evaluate the subsequent reactivity of these glasses with an aqueous solution of Polyacrylic acid (PAA). To this end (29)Si MAS-NMR, differential scanning calorimetry (DSC), X-ray diffraction, and network connectivity calculations, were used to characterize the structure of four strontium calcium zinc silicate glasses. Following glass characterization, GPCs were produced from each glass using a 40 wt% solution of PAA (powder:liquid = 2:1.5). The working times and setting times of the GPCs were recorded as per International standard ISO9917. The results acquired as part of this research indicate that the substitution of Ca for Sr in the glasses examined did not appear to significantly affect the structure of the glasses investigated. However it was noted that increasing the amount of Ca substituted for Sr did result in a concomitant increase in setting times, a feature that may be attributable to the higher basicity of SrO over CaO.

A first principle investigation of the polarized evanescent d states inCo/SrTiO3 magnetic junctions

The band structure of SrO terminatedCo/SrTiO3 superlattices is investigated within the first principle augmented spherical wave methodallowing us to discuss the oxide induced polarization and to examine the decay of theevanescent states into the oxide layer which is essential for the understanding oftunnelling phenomena through the insulator. The calculated d polarization ofthe Co electrode at the interface confirms qualitatively the interpretation of themeasurements and presents a crossover from positive to negative values aroundEF−0.9 eV. It is also shown that, due to the high d character of the band structure of Sr and Ti, dstates do not decay more rapidly into the oxide layer than s or p states, and they have apreserved polarization.

Structural investigation of sodium borate glasses and melts by Raman spectroscopy. II. Conversion between BO 4 and BO 2O − units at high temperature

Raman scattering spectra were recorded for pure boron oxide and sodium borate glasses and their melts at the temperature ranging from room temperature to 1200 °C to investigate the structural changes occurring in the melts. The amounts of short-range order structures (SRO), BO 2O − and BO 3, were estimated from the high frequency bands at 1100–1600 cm −1. The ratio of 4-fold coordinated boron oxide BO 4, N 4, at high temperature could be derived for the glass melts as a function of Na 2O concentration. In Na 2O ⩽20 mol% region, N 4 showed a slight decrease while the remarkable decrease of N 4 was found in the region of Na 2O ⩾25 mol% with increasing temperature. The enthalpy of the equilibrium reaction, BO 4↔ BO 3+ NBO monotonously increased from 20 to 80 kJ/mol with an increase in Na 2O. A characteristic temperature T X SRO was found to exist, which defines the temperature sensitive–nonsensitive transition point of the above conversion of the structures of SRO, and did not necessarily coincide with the glass transition temperature. T X SRO plots were located between the liquidus line and the immiscibility dome in the phase diagram. Using this temperature and composition relationship, anomalous behavior of isothermal viscosity and strong-fragile characteristics of melts could be explained quantitatively.

Medium-range order clusters in metal melts

Structures of molten metals Cu and Al, alloys Cu Al, Al-Ni, Al-Fe and, Al-Si were investigated by using high temperature X-ray diffractometer. It has beenfound that there are not only short-range order structures (SRO) but also medium range order structures (MRO) in Cu-Al, Al-Ni, Al-Fe alloy melts. There are only short-range order structures in the pure metals Cu and Al and Al-Si alloy melts at different temperatures. It has also been found that the presence and the disappearance of the MRO structures in molten metals are a function of temperature. Moreover, the pre-peak in the structure factor is an indication of MRO in molten metals. There is a pre-peak in each structure factor S ( Q ) of Al-Fe alloy melt containing 14 wt% Fe, 16 wt% Fe and 19 wt% Fe at 1550℃, showing that there are the medium range order structures in these alloy melts. For Al-35wt%Ni alloy, the pre-peak exists in S ( Q ) when the temperature is lower than1300℃, and it is weakened drastically when the temperature surpasses 1300℃. The pre-peak occurs at values of scattering vector Q =18.5 nm -1 in the structural factor of Cu-12 wt %Al alloy melts at 1250℃. The height of the pre-peak in the melt decreases with increasing temperature. These results show that there exist not only the SRO structure but also MRO structurein the Al-M melts, and the MRO is correspondent to the tendency of formation of chemical compound. The formation mechanism of the MRO is also studied in this work. Based on the measured results of Cu-Al alloy, a model of the MRO is pre-sented.

Local structure and dynamics of high temperature SrO–Al 2O 3 liquids studied by 27Al NMR and Sr K-edge XAS spectroscopy

In situ spectroscopic studies of liquid oxides at temperatures greater than 2000 °C remain challenging experiments but provide a unique opportunity to better understand their physical properties. Aerodynamic levitation, combined with laser heating, has been conducted with NMR or XAS spectroscopy to obtain the characterisation of local structure and dynamics of very high temperature liquids of the SrO–Al 2O 3 binary system. We present and discuss results obtained using time resolved 27Al NMR in the range 1800–2300 °C for seven different compositions and the first results obtained by Sr K-edge XAS for the SrO–Al 2O 3 binary system.

The influence of O 2 on oxidative coupling of methane over oxide catalysts using N 2O as oxidant

The study of the influence of molecular oxygen on N 2O decomposition under conditions of oxidative coupling of methane (OCM) and on the simple reaction of N 2O decomposition (without methane) was carried out over SrO and Li/Bi 2O 3 . It was found that molecular oxygen caused the decrease in the rate of N 2O decomposition over all the catalysts studied under conditions of OCM. However, the overall catalytic activity over Bi-containing catalysts are significantly lower than that for SrO. Poisoning by molecular oxygen was established over Li/Bi 2O 3 for N 2O decomposition without methane. Over SrO molecular oxygen was not shown to inhibit the decomposition of nitrous oxide in the absence of methane. It was established that the defect structure of SrO was changed under catalytic conditions. The participation of structural defects for N 2O decomposition and CO 2 formation was proposed.