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4D printing is the next step in additive manufacturing. Magnetoresponsive materials facilitate the creation of gripping tools through 4D printing, allowing for structural changes in response to external stimuli. In this study, the structural change is manifested as motion, triggered by an external magnetic field. This technology offers significant advantages in medical and industrial applications, including the printing of life-like moving organ models for medical training and the development of actuators for use in explosive environments. Magnetoresponsive materials are programmed with a magnetic profile and actuated by an external magnetic field. A compound of strontium ferrite microparticles S r F e 12 O 19 ( ≤ 20 μ m ) and an elastic polymer (thermoplastic copolyester) with a Hardness of Shore D 40 was produced. A star-shaped body was programmed and actuated by two permanent magnets, each of B r = 1.29 - 1.32 T . As there is no analytical approach for calculating the required actuation flux density, one has been developed. The approach is verified experimentally by using a Hall probe. It is appropriate to set the field with a Helmholtz coil, despite the utilization of two permanent magnets. The use of a commercial fused filament fabrication printer for the processing of magnetoresponsive materials has been realized here for the first time. The main contributions are the short time constant (around t a = 0.1 s ) for actuation and the repeatability (around n = 200 actuation cycles) of the motion. The feasibility of multiple diverse reprogramming is a step forward in 4D printing. Hence, the post-print programming and the inhomogeneity of the field limit the ease of the presented method. [ABSTRACT FROM AUTHOR]

Multipolar bonded magnets based on a thermoset matrix provide the opportunity to expand the applications of bonded magnets, especially within the drive technology industry, in terms of the high thermal and chemical resistance, along with a higher utilisation of the magnetic potential. To realize the application of polymer bonded magnets based on thermosets within the drive technology industry, general design parameters in terms of the material, the process parameters, and the tool concept are needed. These allow for a fundamental realization of multipolar bonded magnets with complex geometries in drive technologies, based on thermosets as the matrix material. This paper investigates the impact of the material (matrix material and filler grade), the process conditions (holding pressure (ph) and heating time (th)), and the tool concept (gating position and system, sleeve material, pole division, and sample thickness) on the magnetic properties in terms of the remanence (BR) and the deviation (Δs) of the pole division, as well as the orientation of the fillers in the middle of the pole and at the pole pitch. For each parameter, an optimised value is derived. In the majority of the cases, this value is equal in terms of the magnetic properties and the orientation. In terms of the sleeve material and the sample thickness, the ideal value differs between the two criteria. Therefore, an optimised value for each criterion, as well as an overall value, is defined. In terms of the material, PF, along with a high filler grade; in terms of the process conditions, a high holding pressure (ph) and a low heating time (th); and in terms of the tool concept, a two-pinpoint gating system, located in the middle of the pole, a Ferro-Titanit-Cromoni sleeve material, a high pole division, as well as small sample thickness, should be selected to improve the properties of polymer bonded magnets based on thermosets. [ABSTRACT FROM AUTHOR]

Divalent cations have captured the interest of researchers in biomedical and dental fields due to their beneficial effects on bone formation. These metallic elements are similar to trace elements found in human bone. Strontium is a divalent cation commonly found in various biomaterials. Since strontium has a radius similar to calcium, it has been used to replace calcium in many calcium-containing biomaterials. Strontium has the ability to inhibit bone resorption and increase bone deposition, making it useful in the treatment of osteoporosis. Strontium has also been used as a radiopacifier in dentistry and has been incorporated into a variety of dental materials to improve their radiopacity. Furthermore, strontium has been shown to improve the antimicrobial and mechanical properties of dental materials, promote enamel remineralization, alleviate dentin hypersensitivity, and enhance dentin regeneration. The objective of this review is to provide a comprehensive review of the applications of strontium in dentistry. [ABSTRACT FROM AUTHOR]

In this work, strontium hexaferrite (SrFe 12 O 19) with partial substitutions of aluminum and calcium (Sr 0·67 Ca 0·33 Fe 8 Al 4 O 19) and hexaferrite with partial substitutions of manganese (SrMnFe 11 O 19) were synthesized by the polymeric complex method (Pechini). The samples were calcined at a temperature of 1000 °C for 4 h. The crystalline phases, structure, and morphology of the samples were determined by X-ray diffraction, scanning electron microscope, and transmission electron microscopy. The magnetic properties were measured at room temperature using a vibrating sample magnetometer with an applied field of up to 20 kOe. The point of zero charge was determined by measuring the zeta potential. Finally, for adsorption experiments, the concentration of Pb (II) in the samples was determined by Inductively Coupled Plasma Optical Emission Spectroscopy (ICP-OES). The results show that the sample with partial manganese substitutions (SrMnFe 11 O 19) exhibits the highest removal of pollutants (Pb2+) with a maximum adsorption capacity of 24.23 mg/g. [ABSTRACT FROM AUTHOR]

The reaction of the trivalent lanthanoide triflates Ln(OTf)3 (Ln=Sm, Eu; OTf=CF3SO3−) with the respective metals in acetonitrile leads to the Ln(II)‐triflates Eu(OTf)2(CH3CN) (monoclinic, P21/n, Z=4, a=1053.54(1), b=610.28(5), c=1946.92(2) pm, β =98.611(4)) and Sm(OTf)2(CH3CN) (monoclinic, P21/n, Z=4, a=1054.41(4), b=612.16(2), c=1952.65(7) pm, β =98.524(2)). The isotypic strontium compound Sr(OTf)2(CH3CN) (monoclinic, P21/n, Z=4, a=1056.39(5), b=610.05(3), c=1950.1(1) pm, β =98.900(2)°) has been obtained from SrCO3 and triflic acid. The compounds have been investigated by X‐ray diffraction, vibrational spectroscopy, luminescence spectroscopy, cyclic voltammetry, thermal analysis, and magnetic measurements. [ABSTRACT FROM AUTHOR]

In the crystals of alkaline earth metal compounds strontium and barium with the non-steroidal anti-inflammatory drug nimesulide, the strontium cation is nine-coordinated with a distorted tricapped trigonal prismatic geometry TCTPR-9, whereas the ten-coordinated barium ion exhibits a distorted tetracapped trigonal prismatic geometry TCTPR-10. [ABSTRACT FROM AUTHOR]

Polycrystalline compounds of lanthanum strontium manganite (La1-xSrxMnO3, LSMO) are widely used in electronic storage devices due to their minimal losses and electronic charge transport properties. In this study, we investigated how varying substitutions of Sr2+ for values of x = 0.0, 0.1, and 0.2 affected the tuning of the optical band gap and dielectric losses in La1-xSrxMnO3 nanoparticles. Synthesized samples were structurally analyzed via X-ray diffraction. A rhombohedral R 3ccrystal structure was confirmed for all prepared samples; crystallite size ranging from 15 nm to 20 nm was estimated along with other lattice parameters. Polygonal or hexagonal-like morphology was revealed by field emission scanning electron microscopy, with a moderate size distribution of nanoparticles affected by thinner grain boundaries in doped LSMO. Energy dispersive spectroscopy was employed to confirm the elemental composition of each compound, and the infrared spectrum indicated bonding in the fingerprint region It was observed that there was a significant reduction in the optical band gap, which was measured using ultraviolet spectrometer absorption data. The band gap decreased from 4.34 eV to 4.11 eV. This reduction was found to be related to the difference in refractive index, which was calculated using both Moss and Herve–Vandamme relations. In parallel, frequency-dependent dielectric analysis revealed that frequency was proportional to the increase in Sr content, inversely affecting dielectric loss. Moreover, the AC conductivity of the prepared samples increased with the rise in Sr content, as described by Johnscher’s universal power law in the region of high frequency. [ABSTRACT FROM AUTHOR]

[Display omitted] The catalytic activity improvement of Fe-based active sites derived from metal organic frameworks toward oxygen reduction reaction (ORR) and methanol oxidation reaction (MOR) remains a major challenge. In this study, the growth of strontium decorated 2-methylimidazole zinc salt (Sr/ZIF-8) is prepared as a carrier to vapor deposited iron formation Sr doped Fe-based nitrogen-doped carbon framework (named as Sr/FeNC). After high-temperature pyrolysis and vapor deposition, strontium carbonate nanocrystals are evenly dispersed on the shrunk dodecahedron carbon frame and multitudinous Fe-based active catalytic sites are embedded in carbon skeleton. The optimal Sr/FeNC-2 catalyst demonstrates the outstanding ORR performance in terms of a half-wave potential of 0.851 V and an onset potential of 0.90 V, while Sr/FeNC-2 exhibits a high current density of 18.2 mA cm−2 and a lower Tafel slope of 21 mV dec-1 in MOR. The exceptional catalytic activity could be ascribed to the synergistic coupling effect of strontium compounds with Fe-based catalytic sites (Fe-N x , Fe, and iron oxide). In particular, the formation of SrCO 3 affects the bonding configuration of the iron species sites, leading to an optimization of the electronic structure within the multihole carbon matrix. The synthetic approach presents a prospective strategy for future endeavors in developing innovative and advanced bifunctional catalysts for ORR and MOR. [ABSTRACT FROM AUTHOR]

In this work, we demonstrate the preparation of easy-to-fabricate nanogranular strontium ferromolybdate/strontium molybdate core-shell ceramics and examine their properties, including tunnel magnetoresistance, magnetic field sensitivity, and temperature coefficient of the tunnel magnetoresistance. The tunnel magnetoresistance of nanogranular strontium ferromolybdate/strontium molybdate core-shell ceramics was modeled, yielding values suitable for magnetoresistive sensor applications. Such structures possess a narrow peak of magnetic flux sensibility located at about 80 mT. For magnetic flux measurement, single-domain granules with superparamagnetic behavior should be applied. The predicted TMR magnetic flux sensitivities for granules with superparamagnetic behavior amount to about 7.7% T−1 and 1.5% T−1 for granule sizes of 3 nm and 5 nm, respectively. A drawback of the tunnel magnetoresistance of such nanogranular core-shell ceramics is the unacceptably large value of the temperature coefficient. Acceptable values, lower than 2% K−1, are obtained only at low temperatures (less than 100 K) or large magnetic flux densities (exceeding 6 T). Therefore, a Wheatstone bridge configuration should be adopted for magnetoresistive sensor design to compensate for the effect of temperature. [ABSTRACT FROM AUTHOR]

Sr(OH)2 is an indispensable strontium compound extensively harnessed in sugar refining, strontium lubricating wax formulation, and polymer plastic stabilization. Sr(OH)2·8H2O is the prevalent hydrate form of Sr(OH)2. Deprived of moisture via vacuum drying, Sr(OH)2 can be procured from Sr(OH)2·8H2O. Sr(OH)2·8H2O particles with larger sizes exhibit impressive attributes such as facile solid–liquid divergence, elevated product purity, expedient drying, and resilience to agglomeration, which have garnered significant interest. Given the superior quality of the product and the dependability of the process, process analytical technology (PAT) has been extensively employed in the pharmaceutical sector, rendering it feasible to employ PAT to fabricate large-particle Sr(OH)2·8H2O crystals. This study utilizes industrial SrCO3 to prepare high-purity Sr(OH)2·8H2O with a purity of over 99.5%. The growth process of single crystals was observed using a hot-stage microscope, and the growth process of large-particle Sr(OH)2·8H2O was optimized and regulated online using PAT. The optimal process conditions were optimized, and large-particle Sr(OH)2·8H2O crystals were obtained by adding crystal seeds. On this basis, we proposed a seed control mechanism for Sr(OH)2·8H2O. [ABSTRACT FROM AUTHOR]

Reported are the synthesis and structural characterization of a series of quaternary lithium-alkaline earth metal alumo-silicides and alumo-germanides with the base formula A2LiAlTt2 (A = Ca, Sr, Ba; Tt = Si, Ge). To synthesize each compound, a mixture of the elements with the desired stoichiometric ratio was loaded into a niobium tube, arc welded shut, enclosed in a silica tube under vacuum, and heated in a tube furnace. Each sample was analyzed by powder and single-crystal X-ray diffraction, and the crystal structure of each compound was confirmed and refined from single-crystal X-ray diffraction data. The structures, despite the identical chemical formulae, are different, largely dependent on the nature of the alkaline earth metal. The differing cation determines the structure type—the calcium compounds are part of the TiNiSi family with the Pnma space group, the strontium compounds are isostructural with Na2LiAlP2 with the Cmce space group, and the barium compounds crystallize with the PbFCl structure type in the P4/nmm space group. The anion (silicon or germanium) only impacts the size of the unit cell, with the silicides having smaller unit cell volumes than the germanides. [ABSTRACT FROM AUTHOR]

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The direct conversion of celestine (SrSO4) to strontium carbonate as well as its enrichment by hydrometallurgy were investigated. A study was also conducted to investigate whether acid concentration affected the quality of strontium sulfate in celestine concentrates. Based on the results of a laboratory assay, it was determined that 98.04% SrSO4 was leached optimally under agitation. The ground sample of celestine concentrate was then leached by agitation for three hours after the dimensional analysis had determined the appropriate grinding time. To determine the optimal approach for the agitated leaching of strontium carbonate, different approaches were tested. Various factors, including temperature, return water, solid percentage, and sodium carbonate to strontium sulfate ratio, were studied. At 90°C, celestine completely converts into strontium carbonate with a solid percentage of 20% and a sodium carbonate to strontium sulfate ratio of 4:5. As part of the investigation into the possibility of producing strontium oxide, samples of celestine concentrate and strontium carbonate produced under optimal conditions were heated at 500 and 1000°C to determine which phase would form the oxidized phase. An X-ray analysis indicates that the oxidation phase forms at a temperature of more than 750°C.

Quantum chemical calculations using ab initio methods at the MRCI+Q(6,8)/def2‐QZVPP and CCSD(T)/def2‐QZVPP levels as well as density functional theory are reported for the diatomic molecules AeB− and isoelectronic AeC (Ae=Ca, Sr, Ba). The boride anions AeB− have an electronic triplet (3Σ−) ground state. The quintet (5Σ−) state is 5.8–12.3 kcal/mol higher in energy and the singlet (1Δ) state is 13.1–15.3 kcal/mol above the triplet. The isoelectronic AeC molecules are also predicted to have a low‐lying triplet (3Σ−) state but the quintet (5Σ−) state is only 2.2 kcal/mol (SrC) and 2.9 kcal/mol (CaC) above the triplet state. The triplet (3Σ−) and quintet (5Σ−) states of BaC are nearly isoenergetic. All systems have rather strong bonds. The calculated bond dissociation energies of the triplet (3Σ−) state are between De=38.3–41.7 kcal/mol for AeB− and De=49.4–57.5 kcal/mol for AeC. The barium species have always the strongest bonds whereas the calcium and strontium compounds have similar BDEs. The bonding analysis indicates that there is little charge migration in AeB− in the direction Ae→B− where the alkaline earth atoms carry positive charges between 0.09 e–0.22 e. The positive charges at the Ae atoms are much larger in AeC where the charge migration Ae→C is between 0.90 e–0.91 e. A detailed analysis of the interatomic interactions with the EDA‐NOCV method shows that all diatomic species AeB− and AeC are built from dative interactions between Ae (1S, ns2) and B− or C (3P, 2 s22pπ12pπ′1). The eventually formed bonds in AeC are better described in terms of interactions between the ions Ae+ (2S, ns1)+C− (4S, 2 s22pπ12pπ′12pσ1). Inspection of the orbital interactions suggests that the alkaline earth atoms Ca, Sr, Ba use mainly their (n‐1)d AOs besides the (n)s AOs for the covalent bonds. This creates a second energetically low‐lying σ‐bonding MO in the molecules, which feature valence orbitals with the order ϕ1 (σ‐bonding)<ϕ2 (σ‐bonding)<ϕ3 (degenerate π‐bonding). All four occupied valence MOs of AeB− and AeC are bonding orbitals. Since the degenerate π orbitals ϕ3 are only singly occupied, the formal bond order is three. [ABSTRACT FROM AUTHOR]

Recent studies have demonstrated that bismuth oxyhalides with a 2D structure inhibit the recombination of electron–hole pairs. Further, perovskite-like strontium bismuth-based compounds with a special layered Sillen X1 structure have shown potential for use as effective visible-light photocatalysts. Here, a series of strontium bismuth oxyhalide composites were prepared under different calcination conditions. The sample compositions were controlled by modulating the calcination temperature and the secondary calcination time. The synthesised catalysts were characterised by various techniques to identify the product compositions. Under visible-light irradiation, the degradation efficiencies and photocatalytic activities of the different catalysts towards rhodamine B (RhB) and 2-hydroxybenzoic acid (2-HBA) were measured via UV–Vis PDA and electron paramagnetic resonance analyses. To explore the degradation mechanism, scavengers were utilised to detect the radicals produced in the photodegradation test. SrBiO2Cl exhibited the best RhB degradation efficiency, of 0.0685 h−1, and SrBiO2Br exhibited a rate of 0.0984 h−1. At 25 °C and 1 atm, the CO2–CH4 photocatalytic conversion efficiencies of the optimised SrBiO2Cl and SrBiO2Br samples increased to 0.037 and 0.053 μmol g−1 h−1, respectively. The findings confirm that the catalysts are highly recyclable and effective for environmental remediation, achieving the objectives of green chemistry. [ABSTRACT FROM AUTHOR]

The site preference and magnetic properties of Zn, Sn, and Zn-Sn substituted M-type strontium hexaferrite ( SrFe 12 O 19) have been investigated using first-principles total-energy calculations based on density-functional theory. The site occupancy of substituted atoms was estimated by calculating the substitution energies of different configurations. The distribution of different configurations during the annealing process at high temperature was determined using the formation probabilities of configurations to calculate magnetic properties of substituted strontium hexaferrite. We found that the magnetization and magnetocrystalline anisotropy are closely related to the distributions of Zn-Sn ions on the five Fe sites. Our calculation shows that in SrFe 11.5 Zn 0.5 O 19 , Zn atoms prefer to occupy 4 f 1 , 12 k , and 2 a sites with occupation probabilities of 78%, 19%, and 3%, respectively, while in SrFe 11.5 SnO 19 , Sn atoms occupy the 12 k and 4 f 2 sites with occupation probabilities of 54% and 46%, respectively. We also found that in SrFe 11 Zn 0.5 Sn 0.5 O 19 , (Zn,Sn) atom pairs prefer to occupy the (4 f 1 , 4 f 2), (4 f 1 , 12 k), and (12 k , 12 k) sites with occupation probabilities of 82%, 8%, and 6%, respectively. Our calculation shows that the increase of magnetization and the reduction of magnetic anisotropy in Zn-Sn substituted M-type strontium hexaferrite as observed experimentally are due to the occupation of (Zn,Sn) pairs at the (4 f 1 , 4 f 2) sites. [ABSTRACT FROM AUTHOR]

Hybrid improper ferroelectricity, which is induced by the coupling of oxygen octahedral rotation and tilt in oxide materials, has great potential to create single-phase multiferroic materials with intrinsic electric field-controlled magnetism. Based on previous experiments with bi-layered Ruddlesden-Popper Sr-based materials, hybrid improper ferroelectricity in Sr3Hf2O7 was investigated by first-principle calculations in the present work. The results show that the ferroelectric A21am phase has the lowest energy among all possible phases, indicating that it is the ground state. The spontaneous polarization calculated by the Berry phase approach and Born effective charge model is approximately 4.6 μC/cm2, in agreement with those reported for other Sr-based compounds. Compared to Ca3Ti2O7, the smaller polarization of Sr3Hf2O7 is attributed to the negative contribution of the HfO2 layer to global polarization. The possible ferroelectric switching path was determined using the nudged elastic band method. The energy barriers of the two four-step paths across the non-polar Pbnm and Pnab phases are almost the same, and they are the lowest energies among all possible paths. Competition between these paths can help us understand complex phase transitions in analogous compounds. In summary, hybrid improper ferroelectricity was predicted in Sr3Hf2O7 for the first time, and the possible ferroelectric switching paths were determined. [ABSTRACT FROM AUTHOR]

Hybrid improper ferroelectricity, which is induced by the coupling of oxygen octahedral rotation and tilt in oxide materials, has great potential to create single-phase multiferroic materials with intrinsic electric field-controlled magnetism. Based on previous experiments with bi-layered Ruddlesden-Popper Sr-based materials, hybrid improper ferroelectricity in Sr3Hf2O7 was investigated by first-principle calculations in the present work. The results show that the ferroelectric A21am phase has the lowest energy among all possible phases, indicating that it is the ground state. The spontaneous polarization calculated by the Berry phase approach and Born effective charge model is approximately 4.6 μC/cm2, in agreement with those reported for other Sr-based compounds. Compared to Ca3Ti2O7, the smaller polarization of Sr3Hf2O7 is attributed to the negative contribution of the HfO2 layer to global polarization. The possible ferroelectric switching path was determined using the nudged elastic band method. The energy barriers of the two four-step paths across the non-polar Pbnm and Pnab phases are almost the same, and they are the lowest energies among all possible paths. Competition between these paths can help us understand complex phase transitions in analogous compounds. In summary, hybrid improper ferroelectricity was predicted in Sr3Hf2O7 for the first time, and the possible ferroelectric switching paths were determined. [ABSTRACT FROM AUTHOR]

Nanopowders of strontium fluoroapatite Sr5(PO4)3F (SFAP) were synthesized using a co-precipitation method with different starting strontium compounds. Based on the data of XRD, BET and SEM measurements, the nitrate-derived powders were chosen as the least agglomerated. The SFAP powders were hot pressed at 1000 °C to ceramic samples with a transmittance up to 82% in a mid-IR region. The designed approach was adopted to prepare 2 mol % of Er-doped SFAP powders and ceramics. It was established that Er:SFAP ceramics have luminescence in the range of 1.5–1.7 μm, the intensity of which increases with the calcination temperature of the initial powders. [ABSTRACT FROM AUTHOR]

The gallides CaMgGa, SrMgGa, BaMgGa and YbMgGa were synthesized from the elements in sealed tantalum ampoules in muffle furnaces. The phase purity of the samples was checked by powder X‐ray diffraction. CaMgGa and YbMgGa crystallize with the ZrNiAl type structure, space group P6‾ ${\bar 6}$ 2m, whereas SrMgGa and BaMgGa adopt an ordering variant of the Cu2Sb/PbFCl type, space group P4/nmm. The structures of SrMg0.884(7)Ga1.116(7) (a=459.23(9), c=792.43(12) pm, wR2=0.0371, 226 F2 values, 11 variables) and YbMgGa (a=774.55(7), c=411.95(4) pm, wR2=0.0329, 342 F2 values, 15 variables) were refined from single crystal X‐ray diffractometer data. Refinement of the occupancy parameters indicated a small degree of Mg/Ga mixing on the 2a site for the strontium compound. The [MgGa] substructures in both compounds are composed of condensed Mg@Ga4 tetrahedra with 4×287 pm Mg−Ga in SrMg0.884Ga1.116vs 2×282 and 2×296 pm in YbMgGa. The SrMgGa structure has a stacking of layers of edge‐sharing Mg@Ga4 and Sr4 tetrahedra. Electronic structure calculations indicate a net charge transfer from strontium and magnesium to gallium. YbMgGa completes the series of REMgGa gallides. Temperature dependent magnetic susceptibility studies reveal weak Pauli paramagnetism, confirming divalent ytterbium. [ABSTRACT FROM AUTHOR]

[Display omitted] • The high-pressure crystal structures of SrB x C 9- x system are studied. • The boron-rich phases are energetically more favorable than the carbon-rich compounds. • SrB 6 C 3 and SrB 7 C 2 exhibit remarkable mechanical properties. • The CeH 9 -type clathrate SrB 7 C 2 is a superconductor with T c of 5.7 K. The experimental synthesis of superconducting clathrate SrB 3 C 3 has attracted considerable attention to strontium B-C compounds. We conducted a systematic prediction of the crystal structures for the SrB x C 9- x system under low-pressure conditions, using an effective unbiased structure search method. By evaluating the formation enthalpies and phonon dispersions, we established the thermodynamic and dynamic stability of two new compounds, SrB 6 C 3 and SrB 7 C 2. These compounds exhibit remarkable mechanical properties, characterized by the calculated Vickers hardness values ranging from 21.4 to 34.0 GPa. Both SrB 6 C 3 and SrB 7 C 2 are metallic, as shown by the crossing of the bonding and antibonding states of the B- p orbitals at the Fermi level. Using the Migdal-Eliashberg theory to evaluate the electron–phonon coupling, we found that SrB 6 C 3 lacks superconductivity, whereas clathrate SrB 7 C 2 is calculated to exhibit superconductivity of 5.7 K under ambient pressure conditions. This discovery provides valuable insights into the exploration of boron–carbon clathrate superconducting materials with exceptional mechanical properties. [ABSTRACT FROM AUTHOR]

This work presents the results of evaluating the effect of some organic compounds on the efficiency of strontium removal by a granular sorbent based on manganese oxide. Sodium dodecyl sulfate has not a noticeable effect on the sorption characteristics of the sorbent. It has been shown that Trilon-B in concentrations up to 10–3 mol/L has a positive effect on the efficiency of strontium removal, which is, probably, the result of the processes of partial reduction of the surface of the material. Under dynamic conditions, the presence of Trilon-B leads to rapid destruction of the sorbent due to the formation of Mn-EDTA complexes. The presence of humic and fulvic acids in the solution at a concentration of less than 10–4 g/L in neutral media increases the efficiency of strontium removal in micro- and macro-concentration. Under dynamic conditions, the presence of humic acid increases the value of the effective filter cycle up to 50% breakthrough by 1.9 times compared to the control experiment; however, it reduces the value of the decontamination factor coefficient due to the formation of Sr-HA complexes. [ABSTRACT FROM AUTHOR]

The samples SrSn1-xTixO3 with composition 0 ≤ x ≤ 0.08 have been prepared using sol-gel chemical route by sintering at 1173 K. All the samples are found to be single phase crystallized in orthorhombic structure. The dielectric properties indicate the existence of interfacial and orientation polarization in samples found to be stable up to 300 °C. Thermal dependence of electrical conductivity represents two conduction regions with activation energy (0.77-0.94) eV in region-1 and (0.19-0.27) eV in region-2 respectively. The plot of dc conductivity with hopping frequency results unit slope representing that the charge carriers remain same in both processes. DC conductivity of samples are found to be increased with Ti4+, due to reduction in polaron size. The present materials can be potentially used in thermally stable capacitor and mixed ionic and electronic conductors (MIECs) applications. [ABSTRACT FROM AUTHOR]

In the ferrite magnets, the magnetoplumbite-type strontium hexaferrite (SrFe12O19) is an important base material with a relatively high Curie temperature. The La-Co substitution in the Sr hexaferrites ((Sr,La)(Fe,Co)12O19) significantly improves magnetic coercivity. We have investigated the electronic states of Sr1-xLaxFe12-yCoyO19 by 57Fe Mössbauer and Co Kβ x-ray emission spectroscopies using the single-crystalline samples. The Co Kβ x-ray emission spectrum shows that all Co2+ ions are in the high-spin state. The hyperfine parameters extracted from the observed 57Fe Mössbauer spectra clearly show the Co and La substitution dependences at two Fe sites of the five crystallographically nonequivalent Fe sites, revealing that most Co2+ ions occupy the 4f1 and 2a Fe sites in Sr1-xLaxFe12-yCoyO19. These Co site occupations are consistent with the higher magnetic coercivity without a decrease in remanent magnetization in the La-Co substituted Sr hexaferrites. [ABSTRACT FROM AUTHOR]

Quenching processes of the self-trapped exciton luminescence were studied analyzing the shape of X-ray luminescence decay kinetics curves of SrF2 nanoparticles of different sizes. To describe the curves of luminescence decay kinetics, an equation was obtained which is based on the model which takes into account the diffusion of self-trapped excitons and which considers the case of strong surface quenching. The obtained relation was shown to describe the shape of the experimental curves of X-ray luminescence decay kinetics of SrF2 nanoparticles if their size distribution is bi-modal, i.e., a log-normal distribution about a mean size in the tens of nanometers range plus a distribution of particles larger than 130 nm. The presence of large particles is implied in this model by the single-exponential decay with time constant of 1.2 μs. From the fitting of kinetics curves using the proposed relation, the average diffusion length of self-trapped excitons in SrF2 was estimated to be (15 ± 2) nm. [ABSTRACT FROM AUTHOR]

We studied the effective net charge density (Qeff) of strontium silicate (SrxSiOx+2, x = 1, 2, 3) films grown on silicon (Si) (100) substrates. The SrxSiOx+2 layers were deposited from a Sr2SiO4 polycrystalline target by pulsed laser deposition, and then annealed at 400–600 °C in an oxygen atmosphere with a tube furnace. The Qeff values of the SrxSiOx+2/Si (100) samples were obtained from the shift in the voltage of the flat band state in their capacitance–voltage curves. The SrxSiOx+2/ Si (100) samples with a thickness of 15 nm annealed at 400 °C showed the maximum Qeff/q value of 1.03 × 1013 cm-2, where q is the elementary charge. With increasing annealing temperature, the SrxSiOx+2 layer penetrated into the Si (100) substrate. This penetration may degrade the interfacial properties and decrease the Qeff value of the layers. For all the samples, the charges concentrated near the SrxSiOx+2/Si (100) interface. Our results suggest that anion and cation migration plays an important role in charge generation at the SrxSiOx+2/Si (100) interface, consistent with the findings of a previously reported molecular dynamics calculation. [ABSTRACT FROM AUTHOR]

We have fabricated (Pr1-yYy)1-xCaxCoO3 (PYCCO) epitaxial films with various thicknesses by pulsed laser deposition on the SrLaAlO4 (SLAO) substrate that applied an in-plane compressive stress to the film, and investigated the temperature dependence of the electrical resistivity, ρ(T), of the films. An anomalous ρ (T) upturn with a broad hysteresis could be clearly observed only for the thinnest film (d=50 nm), and the ρ (T) anomaly decreased by increasing film thickness, d. The temperature dependence of the X-ray absorption near-edge structure (XANES) spectra at Pr L2-edge was measured for the films, and the valence states of praseodymium (Pr) ion were determined using the analysis of the XANES spectra. As a result, the average valence of the Pr ion in the d=50 nm film slightly increases with decreasing temperature from the common value of 3.0+ around room temperature to 3.15+ at 8K. The valence shift of Pr is thus similar to what was observed on the PYCCO polycrystalline bulks with an abrupt metal-insulator transition, accompanied by a spinstate (SS) transition of Co ions. Furthermore, the low-temperature SQUID measurements evidenced a paramagnetic behavior down to the lowest temperature, which suggests that the dominant part of Co3+ ions in the film grown on the SLAO substrate tends to be in the low spin state characteristic for the insulating ground state. These results strongly suggest that the anomalous ρ(T) upturn in the thin films on the SrLaAlO4 (SLAO) substrate is closely related to the SS transition of Co ions. On the other hand, PYCCO films grown on the LaAlO3 (LAO) substrate that applied an in-plane tensile stress showed no valence shift of Pr ions and developed a long range ferromagnetic order, which points to a complete suppression of the low-temperature transition. The behaviors of the epitaxial films are discussed in terms of the in-plane stress exerted by different substrates and accumulated elastic energy. [ABSTRACT FROM AUTHOR]

The effect of flux on photoluminescence properties of Strontium cerium oxide doped Sm3+ phosphor was studied. The Strontium cerium oxide doped Sm3+ phosphor was synthesized by conventional solid state reaction method at temperature 1200°C for 4h. The powder samples were characterized by X-ray diffraction (XRD), Scanning Electron microscope (SEM) and Fourier transforms infrared spectroscopy (FTIR) spectrum. The X-Ray diffraction pattern reveals the crystallite size and the structure is orthorhombic. Photoluminescence excitation and emission spectra of SR2CEO4:Sm3+ (0.5mol %) without and with different fluxes like as Citric acid, Glycin and Urea were recorded at room temperature. The color co-ordinates (CIE-1913chromaticity diagram) for the SR2CEO4:Sm3+ (0.5mol %) with different fluxes were x =0.542 and y = 0.334 (without flux), x=0.577 and y=0.336 (with different fluxes). This phosphor has a good potential for applications in display devices. [ABSTRACT FROM AUTHOR]

A series of new strontium complexes, [Sr(tmtad)(btsa)]2 (1), [Sr(ptmtad)(btsa)]2 (2), [Sr(etmtad)(btsa)]2 (3), [Sr(tmtad)(tmhd)]2 (4), [Sr(ptmtad)(tmhd)]2 (5), and [Sr(etmtad)(tmhd)]2 (6), were successfully synthesized by substitution reactions between btsa, aminoalkoxide ligands, and tmhdH (btsa=bis(trimethylsilyl) amide, tmtadH=2,5,9,12‐tetramethyl‐2,5,9,12‐tetraazatridecan‐7‐ol, ptmtadH=2,5,7,9,12‐pentamethyl‐2,5,9,12‐tetraazatridecan‐7‐ol, etmtadH=7‐ethyl‐2,5,9,12‐tetramethyl‐2,5,9,12‐tetraazatridecan‐7‐ol, tmhdH=2,2,6,6‐tetramethyl‐3,5‐heptanedione). Thermogravimetric analysis (TGA) of the new strontium compounds showed low residual masses (4‐11 %) where complex 4 displayed the highest volatility and thermal stability. Single crystal X‐ray study of complexes 1, 3, and 6 revealed that the respective complexes crystalize in a triclinic space group as a dimer with a hexa‐ or hepta‐coordination. Furthermore, dimethylamino nitrogen atoms of aminoalkoxide ligands are freely pendent without coordinating to the central strontium metal due to their steric hindrance on the coordination sphere. Compounds 1–6 were characterized by 1H‐ and 13C‐nuclear magnetic resonance (NMR) spectroscopy, Fourier‐transform infrared (FT‐IR) spectroscopy, elemental analysis (EA), and thermogravimetric analysis. [ABSTRACT FROM AUTHOR]

Magneto-transport properties of SrIrO3 thin films epitaxially grown on SrTiO3, using reactive RF sputtering, are investigated. A large anisotropy between the in-plane and the out-of-plane resistivities is found, as well as a signature of the substrate cubic to tetragonal transition. Both observations result from the structural distortion associated to the epitaxial strain. The low-temperature and field dependences of the Hall number are interpreted as due to the contribution of Coulomb interactions to weak localization, evidencing the strong correlations in this material. The introduction of a contribution from magnetic scatters, in the analysis of magnetoconductance in the weakly localized regime, is proposed as an alternative to an anomalously large temperature dependence of the Landé coefficient. [ABSTRACT FROM AUTHOR]

The optical properties of pulsed laser deposited highly crystalline SrMoO3 thin films were investigated. Due to their low resistivity below 30 µΩ cm, thin films of SrMoO3 are candidates for transparent conductor applications. The transparency of SrMoO3 extends into the ultraviolet range to about 300 nm. In this range, SrMoO3 has a higher transparency at similar sheet resistance as compared to alternative oxide or metallic materials. Density functional theory shows that electron-electron correlation effects are small in SrMoO3 as compared to other low-resistivity transition metal oxides and predicts the optical properties in good agreement with experiment. [ABSTRACT FROM AUTHOR]

Mixed orthorhombic Srx doped α-Sb2O4 (x=2,4,8 and 10 wt. %) nanostructures (NS) were successfully synthesized by simple chemical precipitation method. Crystal structure, morphologies and microstructures of the as-synthesized Srx: α-Sb2O4 NS were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques. XRD displayed that the NS were extensively crystalized and crystallite size increases with increase in the concentration of Sr2+ ions. SEM revealed spherical like morphologies and grain size varies between ~ 88 nm to 110 nm. Red shift in the optical absorptivity and increase in the optical band gap (Eg) displayed in UV-visible spectra as the Sr concentration increases in α-Sb2O4 NS. In Fourier transform infrared spectra (FT-IR), intensity of the characteristic peak Sb-OH gradually increases as Sr2+ dopant concentration increases in NS. Electrochemical performances of Srx: α-Sb2O4 (x =10 wt. %) NS exhibited specific capacitance of 890 F/g at a current density of 1 A/g in 6 M KOH solution. Srx: α-Sb2O4 NS showed cyclic retention of 88.95 %, long term cyclic stability up to 1000 cycles and excellent repeatability and reproducibility. Srx:α-Sb2O4 NS act as a promising electrode material for super capacitor and can be used in high energy storage device applications. [ABSTRACT FROM AUTHOR]

Antiferromagnetic-paraelectric SrMnO3 (SMO) has aroused interest because of the theoretical strong coupling between the ferroelectric and ferromagnetic states with increasing epitaxial strain. In strained SMO films, the <110> polarized state and polar distortions have been observed, although high leakage currents and air degradation have limited their experimental verification. We herein provide a conclusive demonstration of room-temperature ferroelectricity and a high dielectric constant (εr = 138.1) in tensile-strained SMO by securing samples with insulating properties and clean surfaces using selective oxygen annealing. Furthermore, a paraelectricity and low dielectric constant (εr = 6.7) in the strain-relaxed SMO film have been identified as properties of the bulk SMO, which directly proves that the ferroelectricity of the tensile-strained SMO film is due to strain-induced polarization. We believe that these findings not only provide a cornerstone for exploring the physical properties of multiferroic SMO but also inspire new directions for single-phase multiferroics. Strain engineering: oxygen locks in room-temperature ferroelectricity Thin cracks and other defects which appear in multifunctional next-generation memory materials can be suppressed through a new synthetic technique. Compounds such as strontium manganese oxide (SrMnO3) transform from insulators into electrically and magnetically active materials when fabricated into thin films that strain the crystal's natural atom-atom separations. Sanghan Lee from the Gwangju Institute of Science and Technology, South Korea, and colleagues now report the first example of room-temperature electrical activity in strained SrMnO3 thin films. The team achieved this result by capping SrMnO3 with a layer of strontium ruthenium oxide (SrRuO3), and then annealing their new material in an oxygen-rich atmosphere. The team showed that the upper capping layer maintained the strained structure while also permitting oxygen to incorporate into the lower SrMnO3 film to eliminate vacancy defects. We provide a conclusive demonstration of strain-induced room-temperature ferroelectricity in SrMnO3 thin films by securing samples with insulating properties and clean surfaces using selective oxygen annealing. These findings will not only provide a cornerstone for exploring the physical properties of multiferroic SrMnO3 but will also inspire new directions for single-phase multiferroics. [ABSTRACT FROM AUTHOR]

Direct integration of proton conductor films on Pt-coated substrates opens the way to film-based proton transport devices. Columnar SrZr0.95Y0.05O3-δ (SZY) films with dense microstructure were deposited on Pt-coated MgO(100) substrates at 830?°C by pulsed laser deposition. The optimal window of ambient O2 pressure for good crystallinity of SZY films is from 400 to 600 mTorr. The ambient O2 compresses the plasma plume of SZY and increases the deposition rate. The 10?nm thick Ti adhesion layer on MgO(100) greatly affects the orientation of the sputtered Pt layers. Pt deposited directly on MgO shows a highly (111)-preferred orientation and leads to preferentially oriented SZY films while the addition of a Ti adhesion layer makes Pt show a less preferential orientation that leads to randomly oriented SZY films. The RMS surface roughness of preferentially oriented SZY films is larger than that of randomly oriented SZY films deposited under the same ambient O2 pressure. As the O2 pressure increased, the RMS surface roughness of preferentially oriented SZY films increased, reaching 45.7?nm (2.61% of film thickness) at 600 mTorr. This study revealed the ambient O2 pressure and orientation dependent surface roughness of SZY films grown on Pt-coated MgO substrates, which provides the potential to control the surface microstructure of SZY films for electrochemical applications in film-based hydrogen devices. [ABSTRACT FROM AUTHOR]

A systematic study on structural, microstructural, optical, dielectric, and electrical properties of phase-pure silicon-modified SrTiO3 polycrystalline electroceramics synthesized using high energy solid state reaction techniques is presented. The asymmetry and splitting in the x-ray diffractometer spectra and the observation of first order transverse optical TO2 and longitudinal optical LO4 modes in Raman spectra (nominally forbidden) revealed the distortion in the cubic lattice as a result of breaking of inversion symmetry due to doping. A bandgap Eg of 3.27?eV was determined for the sample by diffuse reflectance spectroscopy. A high dielectric constant of ~400 and very low dielectric loss of ~0.03 were obtained at 100?kHz near ambient conditions. The temperature dependence of the dielectric data displayed features of high temperature relaxor ferroelectric behavior as evidence of existence of polar nano-regions. The ac conductivity as a function of frequency showed features typical of universal dynamic response and obeyed a power law σac = σdc + Aσn . The temperature dependent dc conductivity followed an Arrhenius relation with activation energy of 123?meV in the 200-500?K temperature range. The linear dielectric response of Pt/SrSi0.03Ti0.97O3/Pt dielectric capacitors was well characterized. The measured leakage current was exceptionally low, 13?nA/cm2 at 8.7?kV/cm, revealing an interface blocked bulk conduction mechanism. [ABSTRACT FROM AUTHOR]

The absorption, excitation, and emission spectra of the Sr2CeO4 nanocrystals prepared by the modified sol-gel method were investigated. The impact of the average grain size of Sr2CeO4 nanocrystals on their optical properties was investigated. It was observed that with increasing the average grain size of Sr2CeO4 nanocrystals, the emission decay times decreased significantly. A similar behavior was observed for the emission quantum efficiencies and the Huang-Rhys factors. The grain size dependence of optical parameters of Sr2CeO4 nanocrystals was found well fitted by functions of the reciprocal of the grain diameter. It was shown that this dependence may be rationalized assuming that the correction for electric local field associated with effective refractive index affecting the spherical nanoparticle is governed by its shell. [ABSTRACT FROM AUTHOR]

A centrality measure based on the time of first returns rather than the number of steps is developed and applied to finding proton traps and access points to proton highways in the doped perovskite oxides: AZr0.875D0.125O3, where A is Ba or Sr and the dopant D is Y or Al. The high centrality region near the dopant is wider in the SrZrO3 systems than the BaZrO3 systems. In the aluminum-doped systems, a region of intermediate centrality (secondary region) is found in a plane away from the dopant. Kinetic Monte Carlo (kMC) trajectories show that this secondary region is an entry to fast conduction planes in the aluminum-doped systems in contrast to the highest centrality area near the dopant trap. The yttrium-doped systems do not show this secondary region because the fast conduction routes are in the same plane as the dopant and hence already in the high centrality trapped area. This centrality measure complements kMC by highlighting key areas in trajectories. The limiting activation barriers found via kMC are in very good agreement with experiments and related to the barriers to escape dopant traps. [ABSTRACT FROM AUTHOR]

The structural, mechanical, electronic, and thermodynamic properties of Mg2Sr with C14-type structure under pressures ranging from 0 to 40 GPa have been systematically studied within the framework of density functional theory in this work. The results at zero pressure were in good agreement with the available theoretical and experimental values. The pressure dependence of structure and elastic constants, elastic anisotropy, Cauchy pressure, melting points, and hardness was successfully calculated and discussed. In addition, the electronic density of states (DOSs) under various pressures were investigated. Debye temperature and the dependences of thermodynamic properties on temperature and pressure were also discussed in the present paper. [ABSTRACT FROM AUTHOR]

We investigated the nature of transport and magnetic properties in SrIr0.5Ru0.5O3 (SIRO), which has characteristics intermediate between a correlated non-Fermi liquid state and an itinerant Fermi liquid state, by growing perovskite thin films on various substrates (e.g., SrTiO3 (001), (LaAlO3)0.3(Sr2TaAlO6)0.7 (001), and LaAlO3 (001)). We observed systematic variation of underlying substrate dependent metal-to-insulator transition temperatures (TMIT ~ 80K on SrTiO3, ~90K on (LaAlO3)0.3(Sr2TaAlO6)0.7, and ~ 100K on LaAlO3) in resistivity. At temperature 300K⩾T⩾TMIT, SIRO is metallic and its resistivity follows a T3/2 power law, whereas insulating nature at T25 K, with negative MR ∼ B1/2 and positive MR ∼ B2; consistent with the localized-to-normal transport crossover dynamics. Furthermore, observed spin glass like behavior of SIRO on SrTiO3 (001) at T<25K in the localized regime validates the hypothesis that (Anderson) localization favors glassy ordering. These remarkable features provide a promising approach for future applications and of fundamental interest in oxide thin films. [ABSTRACT FROM AUTHOR]

Magnetotransport properties of La2/3Sr1/3MnO3/LaAlO3/Pt tunnel junctions have been thoroughly analyzed, as a function of temperature and magnetic field, to test the suitability of LaAlO3 for insulating barriers and spin injection processes. The insulating behavior of LaAlO3 maintained down to 1-2nm (corresponding to 4-5 unit cells) renders this material useful as tunnel barrier. The temperature dependence of the junction resistance, R(T), down to 200K confirms direct tunneling as the dominant conduction channel. The barrier parameters of the junctions, φ0 and s, are estimated using Simmons' model in the intermediate voltage range. The energy of the barrier was estimated to be φ0~0.4V at room temperature. The dependence of R(T) and φ0 on the magnetic field shows an anisotropic tunneling magnetoresistance of ~4% at low T when changing the direction of the magnetization with respect to the current flow. [ABSTRACT FROM AUTHOR]

Coral reefs face unprecedented threats from climate change and human activities, making reef restoration increasingly important for the preservation of marine biodiversity and the sustainability of coastal communities. One promising restoration method relies on coral breeding and larval settlement, but this approach requires further innovation to achieve high rates of settlement and survival. In this study, we built on our previous work engineering lime mortar-based coral settlement substrates by investigating three different compositions of a natural hydraulic lime (NHL) base material as well as composite NHL substrates containing alkaline earth metals. These materials were tested with larvae of three reef-building Caribbean coral species: Orbicella faveolata (Mountainous star coral), Diploria labyrinthiformis (Grooved brain coral), and Colpophyllia natans (Boulder brain coral). We found that the base material composition, including its silicate and calcium carbonate (CaCO 3) content, as well as the addition of the inorganic additives strontium carbonate (SrCO 3), magnesium carbonate (MgCO 3), and magnesium sulfate (MgSO 4), all influenced coral larval settlement rates. Overall, NHL formulations with lower concentrations of silicate and higher concentrations of calcium, strontium, and magnesium carbonates significantly increased coral settlement. Further, when dissolved ions of magnesium and strontium were added to seawater, both had a significant effect on larval motility, with magnesium promoting settlement and metamorphosis in C. natans larvae, supporting the observation that these additives are also bioactive when incorporated into substrates. Our results demonstrate the potential benefits of incorporating specific inorganic ion additives such as Mg2+ and Sr2+ into substrates to facilitate early coral life history processes including settlement and metamorphosis. Further, our results highlight the importance of optimizing multiple aspects of coral substrate design, including material composition, to promote settlement and survival in coral propagation and reef restoration. [ABSTRACT FROM AUTHOR]

Uniform quasi-one-dimensional integer spin compounds are of interest as a potential realization of the Haldane conjecture of a gapped spin liquid. This phase, however, has to compete with magnetic anisotropy and long-range ordered phases, the implementation of which depends on the ratio of interchain J′ and intrachain J exchange interactions and both uniaxial D and rhombic E single-ion anisotropies. Strontium nickel selenite chloride, Sr2Ni(SeO3)2Cl2, is a spin-1 chain system which passes through a correlations regime at Tmax ~ 12 K to long-range order at TN = 6 K. Under external magnetic field it experiences the sequence of spin-flop at Bc1 = 9.0 T and spin-flip transitions Bc2 = 23.7 T prior to full saturation at Bsat = 31.0 T. Density functional theory provides values of the main exchange interactions and uniaxial anisotropy which corroborate the experimental findings. The values of J′/J = 0.083 and D/J = 0.357 place this compound into a hitherto unoccupied sector of the Sakai-Takahashi phase diagram. [ABSTRACT FROM AUTHOR]

Lanthanum strontium aluminum ferrite (La0.8Sr0.2Al0.2Fe0.8O3±δ-LSAF) perovskites are drawing attention as cathodes in solid oxide fuel cells (SOFCs). The structural properties of these materials are mostly counting on the methods of preparation. In this study, two different preparation methods namely hydrothermal and sol-gel were applied to prepare LSAF perovskite. The characterization results including scanning electron microscopy (SEM), N2 adsorption-desorption, and Fourier transform infrared spectroscopy (FT-IR) are investigated in detail. The results showed that the preparation method played an important role on the microstructure of the LSAFs. It can be highlighted that the hydrothermal method is more successful in obtaining quite small nanoparticles. [ABSTRACT FROM AUTHOR]

The intermetallic phases Sr2Pt2Mg and Eu2Pt2Mg were obtained by reaction of the elements in sealed tantalum tubes at high temperature. Sr2Pt2Mg crystallizes with the monoclinic Ca2Ir2Si type (C2/c, a = 1020.7(7), b = 597.7(4), c = 827.0(4) pm, β = 103.37(5)°), while Eu2Pt2Mg adopts the orthorhombic W2CoB2-type structure (Immm, a = 440.31(5), b = 582.20(6), c = 914.11(9) pm, wR = 0.0359, 277 F2 values, 14 variables). The magnesium atoms in both structures are coordinated by four Pt2 dumb-bells with a rectangular planar coordination in Eu2Pt2Mg (268 pm Pt–Mg) and a distorted tetrahedral one in Sr2Pt2Mg (273–275 pm Pt–Mg). The Pt–Pt distances are 277 pm in the europium and 269 pm in the strontium compound. The polyanionic [Pt2Mg] units are planar in Eu2Pt2Mg and separated by the europium atoms. The Sr2Pt2Mg structure shows the motif of hexagonal rod packing for the [Pt2Mg] rows that are embedded in a strontium matrix. Chemical bonding and the influence of the valence electron count on the formation of the structure types are discussed. [ABSTRACT FROM AUTHOR]

Bi5FeTi3O15 (BFTO) based Aurivillius rerroelectrlc thin films were rabrlcated on strontium ruthanate coated amorphous ffised silica substrates using pulsed laser deposition technique. Optical, rerroelectrlc, and piezoresponse properties or these thin films were investigated. The estimated refractive index (n) and extinction coefficient (k) for these films were in the range from 2.40 to 2.59 and 0.012 to 0.19, respectively. The bandgap or the BFTO thin layers was estimated to be 2.88 eV. Domain switching and hysteresis loops or BFTO films were studied utilizing piezoresponse force microscopy (PFM). The measured apparent polarization (Pr) and coercive field (Ec) for the samples were 20 µC/cm² and 250kV/cm, respectively. The amplitude and phase hysteresis curves obtained from PFM characterization reveal that these films can be switched below 5 V. These results suggest that BFTO in thin film form is a promising material for photo rerroelectrlc and optoelectronic devices applications. [ABSTRACT FROM AUTHOR]

To design and discover new materials for next-generation energy materials such as solid-oxide fuel cells (SOFCs), a fundamental understanding of their ionic properties and behaviors is essential. The potential applicability of a material for SOFCs is critically determined by the activation energy barrier of oxygen along various diffusion pathways. In this work, we investigate interstitial-oxygen (Oi) diffusion in brownmillerite oxide SrCoO2.5, employing a first-principles approach. Our calculations indicate highly anisotropic ionic diffusion pathways, which result from its anisotropic crystal structure. The one-dimensional-ordered oxygen vacancy channels are found to provide the easiest diffusion pathway with an activation energy barrier height of 0.62 eV. The directions perpendicular to the vacancy channels have higher energy barriers for Oint diffusion. In addition, we have studied migration barriers for oxygen vacancies that could be present as point defects within the material. This in turn could also facilitate the transport of oxygen. Interestingly, for oxygen vacancies, the lowest barrier height was found to occur within the octahedral layer with an energy of 0.82 eV. Our results imply that interstitial migration would be highly one-dimensional in nature. Oxygen vacancy transport, on the other hand, could preferentially occur in the two-dimensional octahedral plane. © 2014 AIP Publishing LLC. [ABSTRACT FROM AUTHOR]