Increase In Lattice Parameter Research Articles

The effect of Fe-doping in magnetic properties of frustrated spinel CoAl2O4

In this work, we study the effect of Fe-doping in the magnetic properties of CoAl 2 O 4 , which presents a very high level of frustration. Samples are synthesized via solid state reaction by mixing stoichiometric amounts of CoO, Fe 2 O 3 and Al 2 O 3 starting oxides. The analysis of X-ray data show that our samples are single phase with cubic symmetry and space group f d − 3 m . A decrease of lattice parameter as a function of iron concentration is also inferred from the X-ray data. As compared with the pure sample, temperature dependence of magnetization of doped samples show an additional phase transition at high temperature. The enhancement of thermal hysteresis effect and the increasing of the Curie-Weiss temperatures with the Fe-doping can be an indicative of magnetic phase competition leading to a frustrated ground state. Indeed, the unsaturated state of the M v s H loops measured at T = 2 K is consistent with the strong frustration phenomenon. Finally, we argue that the displace of the low temperature peak, which is associated with the freezing temperature in the pure sample, into high temperature region as a function of Fe-doping can be relieving the frustration effect due the next-nearest-neighbor antiferromagnetic interaction J 2 . • Increase of lattice parameters a function of iron concentration. • Fe-doping the highly frustrated material CoAl 2 O 4 . • Magnetic phase competition in low temperature region.

Magnetic properties and Curie temperature tuning in copper-Permalloy alloys obtained by electrodeposition

Permalloy copper (CuPy) structures, produced by low cost vacuum free pulsed electrodeposition technique, present relevant results as magnetic material properties hardening and Curie temperature decay in function of Cu concentration. Such properties modification are here related to the slight crystalline phase shift of face cubic centered (FCC) structure to lower angles, evidenced by X-ray measurements, with lattice parameter increase and successively magnetization weakening by Ni atoms substitution by Cu. The fine tuning of Curie temperature decrease reported here, Tc≈800K from pure Permalloy to Tc≈380K for alloy with 67% of Cu, could allow utilization of such technique to develop magnetic sensors and memories with thermal activation achieved near room temperature.

Influence of ion irradiation-induced defects on phase formation and thermal stability of Ti0.27Al0.21N0.52 coatings

The influence of changes induced by ion irradiation on structure and thermal stability of metastable cubic (Ti,Al)N coatings deposited by cathodic arc evaporation is systematically investigated by correlating experiments and theory. Decreasing the nitrogen deposition pressure from 5.0 to 0.5 Pa results in an ion flux-enhancement by a factor of three and an increase of the average ion energy from 15 to 30 eV, causing the stress-free lattice parameter to expand from 4.170 to 4.206 Å, while the chemical composition of Ti0.27Al0.21N0.52 remains unchanged. The 0.9% lattice parameter increase is a consequence of formation of Frenkel pairs induced by ion bombardment, as revealed by density functional theory (DFT) simulations. The influence of the presence of Frenkel pairs on the thermal stability of metastable Ti0.27Al0.21N0.52 is investigated by scanning transmission electron microscopy, differential scanning calorimetry, atom probe tomography and in-situ synchrotron X-ray powder diffraction. It is demonstrated that the ion flux and ion energy induced formation of Frenkel pairs increases the thermal stability as the Al diffusion enabled crystallization of the wurtzite solid solution is retarded. This can be rationalized by DFT predictions since the presence of Frenkel pairs increases the activation energy for Al diffusion by up to 142%. Hence, the thermal stability enhancement is caused by a hitherto unreported mechanism - the Frenkel pair impeded Al mobility and thereby retarded formation of wurtzite solid solution.

Multi-functional attributes of rare earth double doped SrBi2Nb2O9 ferroelectric system

The ferroelectric perovskite SrBi2Nb2O9 (SBN) material with a low concentration of double doping at the Bi-site of SBN was studied to understand its influence and usefulness in integrated optoelectronic, soft magnetic memory devices and wear-resistant tribomaterials. The aim of the present study is double doping of SBN with a set of rare earth elements Pr3+/Dy3+ (SBPDN), Pr3+/Gd3+ (SBPGN), Pr3+/Sm3+ (SBPSN), and Pr3+/Y3+ (SBPYN) at the Bi-site of SBN to establish the multifunctional ceramic nature pertaining to diverse applications. XRD with Rietveld refinement analysis acknowledged a single-phase orthorhombic structure with an increase in lattice parameters and unsystematic changes in crystallite size. SEM study indicated that the samples possessed non-uniformly distributed needle-shaped grains. The purity of the material and the detection of functional groups were received from the EDS and FTIR spectroscopy. Structural modifications in SBN have been determined based on a diffuse reflectance spectroscopy (DRS) study and therefore the band gap values decrease from 2.98 eV (SBN) to 2.70 eV (double doping) because of the growth of distortion in the structure and pronounced increase in the density of localized states. Photoluminescence (PL) study on double doped SBN material with an excitation wavelength of 320 nm has yielded a novel red emission at 609 nm, that may be useful for white LEDs. The ferromagnetic signature in the studied materials was confirmed from the room temperature VSM study. Noticed mild wear and a low coefficient of friction in the studied materials of SBPDN and SBPSN compared to other studied ceramic samples from mechanical studies. The simultaneous manifestation of optical, magnetic, and mechanical properties by double-doped SBN ceramics keeps the materials as multi-functional candidates for optoelectronic devices, soft magnetic memory devices, and wear-resistant tribomaterials.

Optimization of dielectric and magnetoresistive response in Nd2-xLaxCe2O7 (0 ≤ x ≤ 2.0) for efficient energy storage applications

Magnetoresistive and temperature-dependent dielectric response of La-substituted Nd2Ce2O7 pyrochlores is comprehensively presented in this work. The samples were synthesized using a facile chemical route. Structural investigations confirmed that La-substitution resulted in a slight increase in lattice parameters without any phase transformation of cubic fluorite structure. The credibility of structural information is further affirmed via Rietveld's refined parameters. The spherical-shaped particles with increased agglomeration were revealed in morphological analysis. The elemental purity of all the compositions was verified via energy-dispersive X-ray spectroscopy. The dielectric constant increased significantly by rising temperature from 300 to 500 K. The maximum value of the dielectric constant was noted as 5213 at 500 K for x = 0.8, which highlighted the potential of this composition for energy storage devices, operating at elevated temperatures. When 40% Nd was substituted at La-site, the sample exhibited maximum dispersion in magnetoresistive coupling which revealed the potential of these compositions for magnetoresistive devices.

Effect of Transition Metal Doping on the Structural, Morphological, and Magnetic Properties of NiFe2O4.

Sol-gel route followed by thermal treatment was used to produce NiFe2O4 doped with transition metal ions (Zn2+, Mn2+, Co2+). The structural, morphological, and magnetic properties of the doped NiFe2O4 were compared with those of virgin NiFe2O4. The metal-glyoxylates’ formation and decomposition as well as the thermal stability of the doped and virgin ferrites were assessed by thermal analysis. The functional groups identified by Fourier-transform infrared spectroscopy confirmed the decomposition of metal nitrates, the formation and decomposition of precursors, and the formation of the SiO2 matrix. The X-ray diffraction indicated that the sol-gel synthesis produced single-phase crystalline ferrites in case of virgin, Zn2+ and Co2+-doped Ni-ferrites. By doping with Mn2+, several secondary phases derived from the SiO2 matrix accompanied the crystalline spinel ferrite. The crystallite sizes depended on the annealing temperature and type of doping ion. The gradual increase of lattice parameters suggested the uniform distribution of doping metal ions in the NiFe2O4 lattice. The saturation magnetization, remanent magnetizations, coercivity, and anisotropy were found to depend on the doping ion, annealing temperature, and particle size. The high saturation magnetization values of the obtained nanocomposites make them suitable for a wide range of applications in the field of sensors development and construction.

P -type behavior of CrN thin films via control of point defects

We report the results of a combined experimental and theoretical study on nonstoichiometric $\mathrm{Cr}{\mathrm{N}}_{1+\ensuremath{\delta}}$ thin films grown by reactive magnetron sputtering on $c$-plane sapphire and MgO (100) substrates in an $\mathrm{Ar}/{\mathrm{N}}_{2}$ gas mixture using different percentages of ${\mathrm{N}}_{2}$. There is a transition from $n$-type to $p$-type behavior in the layers as a function of nitrogen concentration varying from 48 to 52 at. % in CrN films. The compositional change follows a similar trend for all substrates, with a N/Cr ratio increasing from approximately 0.7 to 1.06--1.11 by increasing the percentage of ${\mathrm{N}}_{2}$ in the gas flow ratio. As a result of the change in stoichiometry, the lattice parameter and the Seebeck coefficient increase together with the increase of N in $\mathrm{Cr}{\mathrm{N}}_{1+\ensuremath{\delta}}$; in particular, the Seebeck value coefficient transitions from $\text{--}50\phantom{\rule{0.16em}{0ex}}\ensuremath{\mu}\mathrm{V}\phantom{\rule{0.16em}{0ex}}{\mathrm{K}}^{\text{--}1}$ for ${\mathrm{CrN}}_{0.97}$ to $+75\phantom{\rule{0.16em}{0ex}}\ensuremath{\mu}\mathrm{V}\phantom{\rule{0.16em}{0ex}}{\mathrm{K}}^{\text{--}1}$ for ${\mathrm{CrN}}_{1.1}$. Density functional theory calculations show that Cr vacancies can account for the change in the Seebeck coefficient, since they push the Fermi level down in the valence band, whereas N interstitial defects in the form of ${\mathrm{N}}_{2}$ dumbbells are needed to explain the increasing lattice parameter. Calculations including both types of defects, which have a strong tendency to bind together, reveal a slight increase in the lattice parameter and a simultaneous formation of holes in the valence band. To explain the experimental trends, we argue that both Cr vacancies and ${\mathrm{N}}_{2}$ dumbbells, possibly in combined configurations, are present in the films. We demonstrate the possibility of controlling the semiconducting behavior of CrN with intrinsic defects from $n$ to $p$ type, opening possibilities to integrate this compound in energy-harvesting thermoelectric devices.

Negative linear compressibility in Se at ultra-high pressure above 120 GPa.

A series of in situ synchrotron X-ray diffraction (XRD) measurements were carried out, combined with first-principles calculations, to study structural phase transitions of selenium at high pressures and room temperature. Several phase transitions were observed, among which an isostructural phase transition was found at around 120 GPa for the first time. Evolved from the rhombohedral (space group R 3 m) structure (Se-V), the new phase (Se-V') exhibited an interesting increase of lattice parameter a at pressures from 120 to 148 GPa, known as negative linear compressibility (NLC). The discovery of NLC behavior observed in this work is mainly attributed to the accuracy and fine steps controlled by the membrane system for in situ XRD data collected with an exposure time of 0.5 s. After 140 GPa, a body-centered cubic (b.c.c.) structure Se-VI (space group Im 3 m) was formed, which remains stable up to 210 GPa, the highest pressure achieved in this study. The bulk moduli of phases Se-V, Se-V' and Se-VI were estimated to be 83 ± 2, 321 ± 2 and 266 ± 7 GPa, respectively, according to the P-V curve fit by the third-order Birch-Murnaghan equation of state. The Se-V' phase shows a bulk modulus almost 4 times larger than that of the Se-V phase, which is mainly due to the effect of its NLC. NLC in a higher pressure range is always more significant in terms of fundamental mechanism and new materials discovery, yet it has barely been reported at pressures above 100 GPa. This will hopefully inspire future studies on potential NLC behaviors in other materials at ultra-high pressure.

Effects of doping by copper on electrical properties of LaCrO3 based perovskite

The use of nickel-yttria-stabilized zirconia (Ni/YSZ) as anode material for solid oxide fuel cell (SOFC) applications, presents some limitations such as poor stability in reduction/oxidation cycling, and poor sulphur tolerance which results in carbon deposition when utilizing hydrocarbon fuels. Even though lanthanum chromite (LaCrO3 noted LCO) is an excellent alternative to Ni/YSZ, it is rarely used in SOFC applications due to its poor conductivity. In order to further progress in developing LCO materials, this work was conducted to improve the conductivity of LCO by copper doping. In particular, LaCr1-xCuxO3 compounds with x = 0, 0.1, and 0.3 were synthesized via a solid-solid method. The followed preparation process allows obtaining a cubic structure with Pm-3m space group. The substitution of Cr with Cu resulted in a slight increase in lattice parameter a, but no change in structure or space group. Whereas, the band gap energy decreased from 3.68 eV for x = 0–3.06 eV for x = 0.3. The crystallite size increases with doping level. With regard to the obtained data from electrical measurements, a thermally activated and frequency depended conductivity was obtained for all samples. Furthermore, the correlated barrier hopping mechanism was proposed as a conduction mechanism, and an electrical transition from semiconductor to metallic behavior was observed. The conductivity increased also monotonously with Cu content and shows a maximum value of 4.5 S/m for x = 0.3. Besides, the tangent loss shows a maximum value of around 104 for x = 0.1. The LaCr0.7Cu0.3O3 compound could be a good candidate for SOFC applications, while LaCr0.9 Cu0.1O3 can be used as a heating element.

Optical, Structural, and Mechanical Properties of Gd3Ga5O12 Single Crystals Irradiated with 84Kr+ Ions

Herein, the optical absorption, X‐ray diffraction (XRD) analysis data, and mechanical properties along the ion path are analyzed for gadolinium gallium garnet (Gd3Ga5O12 or GGG) single crystals irradiated with fast 84Kr ions to fluences of 1013–1014 ion cm−2. It is found that the optical absorption spectra of Czochralski‐grown unirradiated GGG crystal consist of relatively narrow lines in the UV spectral range associated with the 4f–4f transitions in Gd3+ ions. Transitions from the 6S7/2 ground state to the 6P, 6J, and 6D states in the Gd3+ cation are visible. An additional absorption band is also observed at 350 nm, which is associated with an uncontrolled Ca impurity. In irradiated GGG single crystals, a shift of the fundamental absorption edge by ≈30 nm to the long‐wavelength part of the spectrum is observed. The observed changes are caused by structural disturbances caused by depletion of the surface layer and an increase in the number of displaced atoms accompanied by an increase in the crystal lattice parameter. XRD analysis shows the presence of size effects and deformation of interplanar distances due to the displacement of atoms from the sites of the crystal lattice with subsequent migration. Hardness measurements show ion‐induced softening, which may be due to ion‐induced amorphization.

Physical nature of hardening of heat-resistant metal of high hardness formed by plasma in nitrogen medium

The structure, phase and chemical composition of a heat­resistant alloy formed by plasma in a nitrogen medium with subsequent high­ temperature tempering have been studied by scanning electron microscopy and microrentgenospectral analysis. It was found that in the deposited alloy, the main phases are a solid solution of α­iron and carbonitrides based on iron, tungsten, chromium, molybdenum, and aluminum (Fe 6 W 6 NC and AlN). High­temperature treatment (four­fold high­temperature tempering at a temperature of 580 °C for 1 h) of the deposited coating leads to an increase in the crystal lattice parameters (from 2.866 to 2.89 Å) and in the sizes of coherent scattering regions (from 25 to 100 nm), and to a decrease in internal elastic stresses (from 1000 to 600 MPa). A pronounced oriented dendritic structure is observed on the deposited surface. After surfacing and high­temperature tempering, the oriented dendritic structure is practically not visible. The distribution of microhardness over the depth of the deposited layer in the state after surfacing is characterized by a significant spread at its high average value on the surface of 4.142 GPa (dispersion 1.0956) and the middle part of the surfacing – 5.153 GPa (dispersion 1.5697). The spread of microhardness values is associated with the complex thermal effect of multilayer plasma surfacing along a helical line and mixing of the substrate material with the surfacing coating. High-temperature tempering leads to an equalization of the microhardness values and an increase in its average value to 5.7 – 6.5 GPa. The nature of hardening of the deposited heat­ resistant metal of high hardness, additionally alloyed with nitrogen and aluminum, was clarified. The main hardening of the deposited metal occurs at high temperature tempering due to an increase in the carbide and carbonitride phases and the formation of fine aluminum nitride.

The Effective of Pressure on the Physical Proprieties of Y<sub>2</sub>Ba<sub>4</sub>Cu<sub>7</sub>O<sub>15</sub> Superconductor

The major problems that facing sustainability is the heat production with electricity transmission. The research and engineering communities hope that superconductive materials will be employed in the power transmission, without any losses along the way. Solid-state reaction is a one of the methods for preparing compound samples. This method was used to prepare the nominal chemical formula Y2Ba4Cu7O15. The calcining of the mixed powder at constant temperature of 800C0, followed by compressing the mixed, under (7, 8, 9) tons/cm2 pressures, as pallets shape with diameter 1.5 cm and thickness (0.2-0.3) cm inducing. The prepared samples were encounter many sintering processes through constant temperature. The sintering processes were done in the furnace by rising and cooling temperature with Oxygen rate 0.5 L/min. The samples were measured electrically to determine the resistivity changes in different temperatures (77–300) K, using four-probe technique. The results for the samples A, B and C shows the onset superconducting transition temperatures (Tc (onset)) at 88 K, 93 K, and 99 K respectively. The XRD data illustrated a polycrystalline structure for all samples. The transition temperature, oxygen content (δ) and the lattice parameter increase with increasing the pressure.

Influence of Molybdenum on the Microstructure, Mechanical Properties and Corrosion Resistance of Ti20Ta20Nb20(ZrHf)20-xMox (Where: x = 0, 5, 10, 15, 20) High Entropy Alloys.

The presented work was focused on investigating the influence of the (hafnium and zirconium)/molybdenum ratio on the microstructure and properties of Ti20Ta20Nb20(ZrHf)20−xMox (where: x = 0, 5, 10, 15, 20 at.%) high entropy alloys in an as-cast state. The designed chemical composition was chosen due to possible future biomedical applications. Materials were obtained from elemental powders by vacuum arc melting technique. Phase analysis revealed the presence of dual body-centered cubic phases. X-ray diffraction showed the decrease of lattice parameters of both phases with increasing molybdenum concentration up to 10% of molybdenum and further increase of lattice parameters. The presence of two-phase matrix microstructure and hafnium and zirconium precipitates was proved by scanning and transmission electron microscopy observation. Mechanical property measurements revealed decreased micro- and nanohardness and reduced Young’s modulus up to 10% of Mo content, and further increased up to 20% of molybdenum addition. Additionally, corrosion resistance measurements in Ringers’ solution confirmed the high biomedical ability of studied alloys due to the presence of stable oxide layers.

Structural analysis, FTIR study and optical characteristics of graphene doped Bi2O3 thin film prepared by modified sol–gel technique

Bismuth oxide(Bi2O3) and Graphene doped bismuth oxide thin films were synthesized using modified Sol-gel technique at a temperature about 180–220 °C in a cost effective procedure. In this experiment, self synthesized graphene was used as dopant. The effect of graphene doping on the microstructure and crystalline nature of bismuth oxide were studied after the samples had been subjected to XRD. The prepared graphene was found to be in hexagonal crystal structure and the bismuth oxide was monoclinic in structure. A increase in lattice parameters and decrease in crystallite size and an increase in microstrain and dislocation density was also resulted in this work for graphene doped bismuth oxide (Bi2O3). A detailed structure study from rietveld refinement was carried out in terms of atomic position of various partipating atom, their bond angles and lengths. Finally, a simulated structure was also generated for Bi2O3 and graphene doped Bi2O3. Obtained bandgap of doped Bi2O3 was low. Also the optical properties like refractive index, SELF, interband transition strength etc. were studied.

Efficacy of surface-functionalized Mg1-x Co x Fe2O4 (0 ≤ x ≤ 1; Δx = 0.1) for hyperthermia and in vivo MR imaging as a contrast agent.

Surface-functionalized Mg1−xCoxFe2O4 (0 ≤ x ≤ 1; Δx = 0.1) can be an exciting candidate as an MRI contrast agent and for thermotherapeutic applications. The figure-of-merit, T2, relaxivity, r2, of MRI and specific loss power, SLP, of hyperthermia depend on the structural and magnetic properties of the nanoparticles. We synthesized cobalt-substituted magnesium ferrite Mg1−xCoxFe2O4 (0 ≤ x ≤ 1 with Δx = 0.1) nanoparticles using a chemical co-precipitation method. The lattice parameter and average crystallite size increase with the increase in cobalt content. The force-constant of FTIR of the tetrahedral sites increases, and that of the octahedral sites decreases with an increase in cobalt content. The room temperature Mössbauer spectra of Mg1−xCoxFe2O4 show that the Mössbauer absorption area of the A site decreases, and the Mössbauer absorption area of the B site increases with x. The Mössbauer spectra and M–H hysteresis loops at room temperature confirmed that a transition from fast relaxation (superparamagnetic) to mixed slow/fast (superparamagnetic/ferrimagnetic) relaxation occurs with changing cobalt content. The cobalt ion tends to occupy the octahedral B site, which makes the A–B interaction stronger; therefore, we see the above transition. Cytotoxicity experiments on HeLa cells revealed that both chitosan and chitosan-coated magnesium cobalt ferrite nanoparticles are biocompatible. In the Mg1−xCoxFe2O4 series, both r2 and SLP increase with x because of the increase in magnetization and anisotropy.

Boron in Ni-Rich NCM811 Cathode Material: Impact on Atomic and Microscale Properties

Doping of Ni-rich cathode active materials with boron is a promising way to improve their cycling stability and mitigate their degradation, but it is still not understood how this effect is achieved and where the boron is located. To receive deeper insights into the impact of doping on atomic and microscale properties, B-doped Li[Ni0.8Co0.1Mn0.1]O2 (NCM811) cathode materials were synthesized by a hydroxide coprecipitation as a model compound to verify the presence and location of boron in B-doped, Ni-rich NCM, as well as its impact on the microstructure and electrochemical properties, by a combined experimental and theoretical approach. Besides X-ray diffraction and Rietveld refinement, DFT calculation was used to find the preferred site of boron absorption and its effect on the NCM lattice parameters. It is found that boron shows a trigonal planar and tetrahedral coordination to oxygen in the Ni layers, leading to a slight increase in lattice parameter c through an electrostatic interaction with Li ions. Therefore, B-doping of NCM811 affects the crystal structure and cation disorder and leads to a change in primary particle size and shape. To experimentally prove that the observations are caused by boron incorporated into the NCM lattice, we detected, quantified, and localized boron in 2 mol % B-doped NCM811 by ion beam analysis and TOF-SIMS. It was possible to quantify boron by NRA with a depth resolution of 2 μm. We found a boron enrichment on the agglomerate surface but also, more importantly, a significant high and constant boron concentration in the interior of the primary particles near the surface, which experimentally verifies that boron is incorporated into the NCM811 lattice.

Phase transformations during fluidized bed reduction of New Zealand titanomagnetite ironsand in hydrogen gas

Direct reduction of iron ore in a fluidized bed reactor is usually limited by the onset of particle sticking at temperatures ≳ 800 °C. This paper examines the phase and microstructural evolution of New Zealand titanomagnetite (TTM) ironsand during fluidized bed reduction by hydrogen gas at temperatures ranging from 750 °C to 1000 °C. All samples were characterized using quantitative X-ray diffraction and scanning electron microscope/energy dispersive spectroscopy. No sticking was observed at any point during this series of experimental reduction reactions. At higher temperatures sticking appears to be prevented by the formation of a Ti-rich oxide shell around each partially-reduced particle. At lower temperatures, no shell is observed to form, but temperatures are not high enough to drive particle sticking/agglomeration.The reduction mechanism appears to vary within different temperature regimes. At high temperatures (950 °C and 1000 °C), the reduction of TTM proceeds via the wüstite phase during the initial reduction stage, although the TTM is not completely converted to wüstite. The formation of wüstite results in an enrichment of Ti within the residual TTM phase. This is observed as an increase in the TTM lattice parameter, which is stretched by Ti substitution into the spinel. For reactions at low temperatures (750 °C and 800 °C), the TTM is directly reduced to metallic iron without any evidence of the appearance of the wüstite phase. At ‘intermediate temperatures’ (850 °C and 900 °C), a mixed behaviour is observed with the appearance of low levels of short-lived wüstite during the reduction reaction. Overall, these results indicate that the fluidized bed processing of NZ TTM ironsand in hydrogen can be completed over a wide temperature range without incurring sticking.

Effects of Ga on the microstructure and magnetostriction of Fe-Ga alloys for actuators

The microstructure and magnetostrictive properties of Arc melted Fe100-x-Gax alloys (x = 20, 25) were studied. The results of the X-Ray Diffraction study confirm the presence of the A2 and DO3 phases in the body-centered cubic structure, which is consistent with previous findings. The increased lattice parameter of the alloy containing 25% Ga results in an increase in the alloy's total magnetic moment. According to the results of an optical microscopy study, the substitution of more Ga atoms results in an increase in grain size and a decrease in the number of dark pits. Due to interactions between domain walls, the coercivity (HC) of the Fe80-Ga20 alloy is lower than that of its counterpart alloy. Fe atoms' magnetic moments are directly proportional to the distance between them and their nearest neighbours in the local environment, and Ga does interrupt the Fe's nearest neighbours, resulting in an increase in saturation magnetization. The formation of the Ga-rich phase is also responsible for the increase in saturation and remanent magnetization. The alloy exhibited enhanced magnetostriction because of the structure and local symmetry placed at different lattices. Its improved magnetostriction makes the Fe75-Ga25 alloy particularly well suited for use in sensor and actuator applications.

Mesoporous Sn@TiO2 nanostructures as excellent adsorbent for Ba ions in aqueous solution

Efficient adsorption of Ba ions was achieved using Sn@TiO2 nanocomposite generated by ultrasonication process with subsequent calcination at 300 °C. X-ray diffraction, nitrogen adsorption-desorption isotherm, X-ray photoelectron spectroscopy, Fourier transformer infra-red, and scanning/transmission electron microscopy analyses were performed to probe the structural and textural features of the adsorbent powder. The XPS, FTIR, and EDX analyses confirmed the Sn doping into TiO2 host lattice. Some interesting features, including the increase of crystallite size and lattice parameters, were attained due to the successful Sn incorporation into the TiO2 host, as indicated further by XRD analysis. The sorption results fitted the Langmuir isotherm model and the kinetic data complied with the pseudo-second-order kinetics. The adsorption process improved markedly above the pHzc due to the electrostatic attraction between the negatively charged Sn@TiO2 particles’ surface and the positively charged Ba ions. The achieved high-performance mesoporous Sn@TiO2 nanostructures for the adsorption of Ba2+ could be potentially utilized to remove other toxic metal cations.

Phase composition, microstructure, and microwave dielectric properties of non-stoichiometric yttrium aluminum garnet ceramics

A series of Y3+xAl5O12 (−0.12 ≤ x ≤ 0.12) ceramics were prepared via a solid-state reaction under a vacuum sintering environment to investigate the impact of variations in different cation composition on the phase composition, microstructure, and microwave dielectric properties of yttrium aluminum garnet (Y3Al5O12; YAG) ceramics. X-ray diffraction analyses revealed that Al2O3 precipitates in the Al-excess samples. In contrast, the YAlO3 secondary phase appeared in the Y-excess samples, and variations in the content of both contributed to an increase in lattice parameters. The Rietveld refinement results showed that the lattice parameters and unit cell volume increased as the |x| value increased. The secondary phases of granular Al2O3 and YAlO3 crystallized at the extended grain boundaries in samples with excess Al and Y were visible in the scanning electron microscopy images. The electron diffraction patterns confirmed that a small amount of Y2O3 promoted continuous phase boundaries and facilitated the release of internal stresses. Ultimately, after sintering at 1750 °C for 12 h and at x = 0.03, the microwave dielectric properties of the non-stoichiometric YAG ceramic sample were εr = 11.18, Q×f = 236936 GHz, and τf = −35.9 ppm/℃.