Increasing Gd Content Research Articles

Optimization of structural, optical, dielectric and magnetic properties of Gd3+ substituted Mg-Mn mixed spinel ferrite ceramics

Manganese magnesium ferrite (Mg0.5Mn0.5Fe2O4) and Gd doped Mg0.5Mn0.5Fe2O4 (Mg0.5Mn0.5Fe2-xGdxO4 (x = 0.0, 0.1, 0.2, 0.3, 0.4, 0.5) were synthesized using the solid-state method. The structural study was performed using the powder X-ray diffraction (XRD) technique. The XRD plot confirms the presence of a spinel cubic structure for pure MgMn ferrite and the existence of a secondary GdFeO3 phase in addition to the cubic spinel phase for Gd-doped MgMn ferrite. The average crystallite size estimated from the Williamson-Hall plot decreases from 42.75 nm to 18.97 nm with the increase in Gd content. The microstructural study confirms the clear grains with well-defined grain boundaries. The Fourier Transform Infrared (FTIR) spectra of the samples show the vibrational bands at 3440 cm−1, 1636 cm−1, 1385 cm−1, 1100 cm−1, and 560 cm−1 assigned to tetrahedral and octahedral sites. The improvement in dielectric property has been observed for Gd-doped samples. The saturation magnetization and remnant magnetization decrease from 0.7 to 0.3 emu and 0.035 to 0.0273 emu respectively. The coercivity increases from 31 to 75 Oe with the increase in Gd content. The fabricated spinel ferrites have significant electrical and magnetic properties which may be promising candidates for microwave devices.

Effects of Gd on the microstructure and mechanical properties of GdxCoCrFeNiV0.4 high-entropy alloys

This study investigated the microstructure and mechanical properties of GdxCoCrFeNiV0.4 alloys. Various techniques such as XRD, SEM, EBSD, and TEM were utilized, alongside hardness and compression tests at room temperature. The findings revealed that the high-entropy alloy without Gd element exhibited a single face-centered cubic (FCC) phase. Upon the introduction of Gd element, the phase composition shifted to FCC + hexagonal structure (HS) phases, and further addition of Gd resulted in the presence of FCC + HS + body-centered cubic (BCC) phases. Additionally, the inclusion of Gd element led to the precipitation of Gd-rich particles within the alloy. The Vickers hardness test results revealed a significant increase in alloy hardness as the Gd content rose, from 177.5 HV for Gd0 to 848.4 HV for Gd0.4. This suggests that the presence of the HS phase and BCC phase notably influences alloy hardness. Furthermore, compressive test outcomes demonstrated that the alloy's yield strength rose from 173.74 MPa for Gd0 to 1356.17 MPa for Gd0.3 with increasing Gd content. However, the excessive addition of Gd elements results in significant precipitation of V and Cr elements, leading to grain coarsening, adversely affecting its mechanical properties. The high strength of Gd-containing high-entropy alloys can be attributed to various strengthening mechanisms, such as solid solution strengthening, the presence of the HS phase, the precipitation of a small number of Gd-rich particles, and the grain refinement caused by the addition of Gd.

Study on the room temperature compression deformation mechanism and microstructural evolution of Mg-Gd-Y-Zr alloy

This study explores the dynamic impact deformation mechanisms of Mg-Gd-Y-Zr alloys, specifically focusing on the influence of varying Gd content. Using metallographic observation, SEM, EDS, XRD, EBSD, and TEM, along with hardness and room-temperature compression tests, the research investigates the effects of Gd content on the microstructure, mechanical properties, and deformation behaviors of as-cast Mg-(x)Gd-3Y-0.5Zr (x = 6.5/7.5/8.5) alloys.The results show that increasing Gd content reduces grain size and increases the volume fraction of the non-equilibrium eutectic phase Mg24(Gd,Y)5, though with smaller phase dimensions. These alloys exhibit excellent compressive properties at room temperature, with the highest compression deformation rate of 27.8 % observed at 6.5 % Gd and the maximum compressive strength of 401 MPa recorded at 8.5 % Gd, surpassing some high-Gd-content cast and extruded alloys.At lower Gd content, basal slip and tensile twinning are the primary deformation mechanisms. As Gd content increases, these mechanisms evolve to include prismatic slip and compressive twinning. The fracture mode transitions from predominantly ductile to a combination of ductile and brittle features, with an increase in brittle cleavage at higher Gd levels.

Microstructural regulation, work hardening and fracture behavior of Tip reinforced Mg‐xGd‐2Y‐3Zn (x=5, 7, 9 wt%) composites

In this work, Tip/Mg‐xGd‐2Y‐3Zn (x=5, 7, 9 wt%, Tip/GWZx23) composites were fabricated using semi-solid stirring casting and hot extrusion. The Tip/Mg laminar-like configuration was regulated by Gd content. The effect of Tip/Mg laminar-like configuration on the microstructure, mechanical properties, work hardening and fracture behavior of Tip/GWZx23 composites was thoroughly studied. The results revealed that the Tip elongated along the extrusion direction (ED) after extrusion and formed Tip/Mg laminar-like configuration with the Mg matrix. With the increase of Gd content, the hardness of the matrix increased, which was beneficial to the elongation of Tip. The elongation of Tip reduced its hardness value, released the stress and promoted the DRXed grain refinement. The refined grain enhanced the ability of grain boundaries to absorb dislocations and improved the recovery effect. Furthermore, the formation of Tip/Mg laminar-like configuration induced back stress strengthening at the Tip/Mg interface, enhancing the work hardening rate of the Tip/GWZx23 composites. The Tip/Mg laminar-like configuration changed the strain distribution and the strain was transferred from the Tip sharp corner to the elongated Tip, which was effectively alleviates stress concentration at the Tip/Mg interface and inhibited crack propagation.

Phase engineered enhancement of photocatalytic and Opto-magnetic properties of CuO nanoparticles through fluorine and gadolinium doping

The present study comprises co-doping of CuO nanoparticles with gadolinium (Gd) and fluorine (F) using the sol-gel method to achieve phase stabilization and tune their physicochemical properties. X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS) analyses revealed successful incorporation of the dopants and the stabilization of the CuO phase with increasing Gd content. Morphological studies revealed grain refinement and an enhanced surface-to-volume ratio upon co-doping. Average particle size decreased from 194 nm to 138 nm for pure and 5%F to 126 nm, 101 nm, and 81 nm for, 1mol%, 2mol% and 3mol% Gd along with 5mol% F co-doped CuO nanoparticles. Increasing the Gd ratio also tuned the band structure and significantly improved the optical properties of the CuO nanoparticles. Additionally, a transition from weak ferromagnetic ordering to paramagnetic behavior is observed. Coercivity decreased to 2.5 Oe for Cu0.97Gd0.03F0.05O0.95 as opposed to 396.3 Oe for CuF0.05O0.95. Photocatalytic activity studies using rhodamine B (Rh B) as a model probe revealed a pronounced enhancement in degradation kinetics with increasing gadolinium (Gd) doping, culminating in around 2.9 times faster degradation rate for 3 % Gd-doped CuO nanoparticles compared to pure CuO nanoparticles. After 3 h of UV light irradiation, the photodegradation efficiency of Cu0.97Gd0.03F0.05O0.95 was 94 %, which is significantly higher than the 80 % and 69 % efficiency of CuF0.05O0.95 and CuO, respectively. These remarkable optical, magnetic, and photocatalytic properties of the co-doped nanoparticles offer promising candidacy for various applications, including photocatalysis, solar energy harvesting, magnetic switching, and magnetic sensing.

Mechanism of Gd doping on microstructure and mechanical properties of FeCrNiCuTi0.4 high entropy alloy

The study focused on investigating the impact of rare earth element Gd content on both the microstructure and mechanical properties of FeCrNiCuTi0.4Gdx (x = 0, 0.01, 0.02, 0.03, 0.04, 0.05, 0.06, 0.08, 0.1, 0.12, and 0.15, in mole ratio) high-entropy alloys, as well as elucidating the underlying mechanisms involved. The microstructure analysis revealed that the alloy exhibited a diphase structure consisting of FCC and BCC phases at low Gd content, and precipitation of the Cu5Gd phase occurred alongside the FCC and BCC phases at x = 0.05. The phase evolution of the current alloy system was assessed using the Ω - δ, △χ, and VEC (valence electron concentration) criteria. The mechanical properties indicated that the Vickers hardness increased with the increase of Gd content. Additionally, the compressive strength, yield strength, and plastic strain exhibit an initial increase followed by a decrease, while the average friction coefficient and wear demonstrated an initial increase followed by a subsequent decrease. The fracture mechanism shifted from plastic fracture to ductile fracture, ultimately transitioning to dissociative fracture with ductile fracture as the predominant mode. Similarly, the wear mechanism progressed from abrasive wear to a combination of abrasive wear with oxidation wear. The strengthening mechanisms of the present alloys included solid solution strengthening, fine crystal strengthening, and second-phase strengthening.

Phase equilibria and solidification behavior of Mg–Al–Gd casting alloys

The Mg–Al–Gd ternary system was re-assessed by the CALPHAD (CALculation of PHAse Diagrams) method and a set of self-consistent thermodynamic parameters of the system were obtained. The long-period stacking ordered (LPSO) phases, 14H and 18R, were described by thermodynamic model of Mgx(TM,Mg)6(RE,Mg)8 (TM=Transition Metal, RE=Rare Earth). Representative isothermal sections, vertical sections, liquidus projections and the related invariant reactions were calculated and compared with the experimental data, showing the reliability of the obtained thermodynamic parameters. Reaction scheme for the whole ternary system was also presented. The Scheil solidification paths and the phase fractions of several Mg–Al–Gd alloys were calculated and analyzed. The phase formation during solidification and the phase content of γ and LPSO phases are clearly described with the increase of Gd content, which is crucial to the microhardness, ultimate tensile strength and yield strength of Mg–Al–Gd casting alloys.

Novel integrated structure and function of Mg–Gd neutron shielding materials

Abstract As the lightest metal structural materials, magnesium (Mg) alloys offer extensive application potential. Gadolinium (Gd), as the primary alloying element in Mg alloys and recognized for its notable thermal neutron capture cross-section, is considered one of the most efficient neutron absorbers. Thus, the Mg–Gd alloy is highly expected to emerge as a material with remarkable neutron absorption capacity. Hence, in this study, the thermal neutron-shielding capabilities of Mg–Gd alloys were comprehensively examined by fabricating four as-cast Mg–xGd alloys with varying compositions (x = 0, 5, 10, and 15 wt%). The obtained results were further corroborated by sophisticated modeling and calculations using SuperMC. The results revealed a direct correlation between the thermal neutron absorption capacity of the Mg–Gd alloys and the increase in Gd content, with a noteworthy neutron attenuation factor of 22.33. Moreover, in an Au ion irradiation experiment conducted at 200°C, the Mg–15Gd alloy exhibited exceptional radiation resistance, with a displacement per atom (dpa) of 10. The matrix and second-phase regions were devoid of any cavity formation. Instead, a finite number of dislocation rings were observed, forming both leaf-like and granular Gd-rich nanoscale precipitates. This study underscores the versatility of Mg–Gd alloys as efficient neutron shielding materials and structural materials tailored for applications demanding radiation resistance in diverse environments.

Influence of gadolinium content on magnetic property and oxidation mechanism of Fe-B-Nb-Gd metallic glass

In this work, we use the rapid solidification technique to prepare five kinds of metallic glasses with different Gd content, and investigate in depth the influences of Gd content on the amorphous formation capability, thermal stability, and magnetic properties of (Fe<sub>73</sub>B<sub>22</sub>Nb<sub>5</sub>)<sub>100–<i>x</i></sub>Gd<sub><i>x</i></sub> (<i>x</i> = 0, 0.5, 1.0, 1.5, 2.0) alloys. By comparing the microstructural morphology and solute distribution of oxidation products before adding Gd and those after adding Gd, the amorphous oxidation mechanism is analyzed systematically. With the addition of Gd, the atomic size difference of the alloys exceeds 13%, and the configuration entropy increases from 7.27 kJ/(mol·K) to 9.44 kJ/(mol·K). The glass-forming ability of the alloy is significantly improved. The increase of Gd content can increase the glass transition temperature of the alloy to 864 K, and the undercooled liquid region can reach 73 K, significantly enhancing the thermal stability of the metallic glasses. The Gd limits the local anisotropy of the alloy and reduces the density of quasi-dislocation dipole defects. This can effectively reduce the pinning sites that hinder the rotation of magnetic domain walls, thereby improving the soft magnetic property. By comparing with the metallic glasses without Gd, only 2% (atomic percentage) Gd can reduce the coercivity by 8%. Moreover, the Gd makes the metallic glasses more sensitive to temperature variation in the oxidation process, and the temperature of the maximum oxidation rate is reduced by 15 K. However, their antioxidant performance does not deteriorate. The Gd atoms are influenced by binding energy and migrate to the surface, forming Gd-rich oxides. They fill surface defects and occupy a large part of the top space, leading to the structure becoming more compact near the surface. This structure reduces the channels for oxygen atoms to diffuse through the microstructure interface, which helps to improve antioxidant capability. This work provides a new approach for designing high performance Fe-based metallic glasses.

White light emitting nanocrystalline Y1−xGdxPO4:Dy3+ and improved PLQY on Gd3+ co-doping

White Light emitting phosphors are in the realm of scientific evolution owing to their several superior photophysical features and maximum commercial reach. Here in this work we have carried out doping of Dy3+ in Y1-xGdxPO4 wherein we have moved from YPO4 to GdPO4 to harness the potential of dysprosium ion in achieving white light emission and correlating the structural evolution in these phosphates with luminescence properties. Y1-xGdxPO4:Dy3+ phosphor has been synthesized using co-precipitation method and characterized using x-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), time resolved photoluminescence (TRPL) and positron annihilation lifetime spectroscopy (PALS). Based on emission spectroscopy it was deciphered that Dy3+ lacks inversion symmetry in all the samples with asymmetry ratio of ∼1.2 in YPO4 and 2.75 in GdPO4. The same is correlated structurally wherein YO8 is in dodecahedron with D2d symmetry while GdO8 is highly distorted. The photoluminescence quantum yield (PLQY) increases monotonically with Gd3+ insertion and GdPO4:Dy3+ showing the highest PLQY endowed by enhanced asymmetry around Dy3+ making the f-f transitions more relaxed and allowable. The surface defects as revealed by positrons also decreased with increase in Gd content and that also aids the increase in emission intensities. Moreover PLQY value was higher with 274 nm compared to excitation with f-f transitions (∼351 nm) due to Gd3+ to Dy3+ energy transfer. The phosphors have similar color coordinate value and correlated color temperature of (∼0.33, ∼0.36), ∼5400 K, respectively, which are close to the bluish cool-white emission. Therefore, the GdPO4:Dy3+ phosphor with longer excited state lifetime, moderate PLQY, effective CIE coordinates close to white and high CCT can be explored for generation of cool white light emission excitable by UV/NUV LED for solid-state lighting and optoelectronic devices.

Accelerating and decelerating effects of Gd content and peak-aging treatment on the grain growth of magnesium

This short communication concerns the dependence of thermal stability of fine grains in Mg alloy on the Gd content. The enhanced thermal stability via increasing Gd content can be reflected by the SRX mechanism and corresponding boundary migration ability. In the low Gd-alloyed Mg, continuous SRX dominates the annealing process via dislocation re-arrangement. The grain boundaries composed by dislocations can easily migrate, since the uniform Gd solute distribution provides limited delaying effect. In the high Gd-alloyed Mg, discontinuous SRX dominates the annealing process via consuming dislocations for grain nucleation. The grain boundaries can hardly migrate due to the strong delaying effect provided by the Gd-segregation along grain boundaries. But unexpectedly, peak-aging can deteriorate the decelerated effect of high Gd-alloying owing to the absent Gd-segregation. Consequently, an accelerated grain growth rate is attained, even faster than that in the low Gd-alloyed Mg.

Effect of rare earth substitution on electromagnetic and microwave absorption properties of nickel-cobalt nano ferrite

Oxygen vacancy engineering is one of the most effective strategies for tuning the microstructural properties of oxide nanomaterials. However, the connection between oxygen vacancies and electromagnetic (EM) wave absorption capacities is unclear. Herein, oxygen vacancy-boosted microwave absorption is realized over Gd-doped Ni0.5Co0.5Fe2O4 (NCFO) nanoceramics. All magnetic properties are studied with the influence of induced lattice strain. Except for Ni0.5Co0.5 Gd0.075Fe1.925O4 (NCFOG3), which has an elevated saturation magnetization (Ms) of 63 emu/g, the Ms decreases with increasing Gd content. In addition, remnant magnetization (Mr), coercivity (Hc), and anisotropic constant (K) increased until Ni0.5Co0.5 Gd0.050Fe1.95O4 (NCFOG2) and then declined. The EM wave parameters: dielectric permittivity (ϵ'), magnetic permeability (μ'), dielectric loss (ϵ''), and magnetic loss (μ'') are systematically examined and found in the ranges of 2.07–3.5, 1.73–4.7, (4 × 10-2) – (2.2 × 10-1) and 0.18–0.35 respectively. Our finding shows that a small amount of Gd favors the high oxygen vacancy concentration, an appropriate lattice defect, and high magnetic and dielectric losses. The possible mechanism for EM wave absorption revealed the largely localized electrons and dipole centers created by the numerous oxygen vacancies causing the multiple reflection and scattering, which enhanced conductive loss, defect, and dipole polarizations. The maximum reflection loss (RL) -28.37 dB is observed at 17.80 GHz of a 2 mm thick sample for NCFOG3. This research reveals a distinct link between oxygen vacancy defects and EM wave dissipation capability, providing important information for developing better EM wave absorbents.

Microstructure, thermophysical properties and neutron shielding properties of Gd/316 L composites for spent nuclear fuel transportation and storage

In this paper, (0.5–5.0 wt%)Gd/316 L composites were prepared by vacuum arc melting, and the microstructure, thermophysical properties, and neutron shielding properties were analyzed deeply. The results showed that the Gd/316 L composites started solidification in primary ferrite mode and terminated solidification by a peritectic-type reaction forming (Fe, Ni, Cr)3Gd that is rich in Ni and Gd. In the peritectic-type reaction, local convection in the Ni-rich and Gd-rich peritectic liquid phase leads to the formation of multiple variants of (Fe, Ni, Cr)3Gd. The higher the Gd content, the greater the amount of (Fe, Ni, Cr)3Gd and ferrite, and the harder it is to keep the austenitic matrix of 316 L stainless steel. The solidification temperature range of Gd/316 L composites is 1074–1460 °C, which severely limits the ability to further process it by high-temperature deformation techniques such as hot rolling or hot forging. (Fe, Ni, Cr)3Gd preferentially nucleates and grows in the triangular region of austenite grain boundaries at 1074 °C. At 50–500 °C, with increasing Gd content, thermal expansion and thermal diffusion coefficients become decrease, and thermal conductivity and specific heat capacity increase. The trend of thermophysical property changes is favorable for SNF transportation and storage applications. The thermal neutron shielding properties of 1.0 wt%Gd/316 L composite is comparable to that of 4.45 wt% B content boron steel and 15 wt%B4C/Al composite. The Gd content in Gd/316 L composites material should not exceed 2.5 wt%. If the Gd content continues to increase, it is of little significance to improving shielding properties and material thinning. A shielding thickness of 3 mm is more appropriate for Gd/316 L composites. Too thin would not provide sufficient mechanical properties and increase processing and manufacturing costs.

Elucidation of the corrosion rate enhancement mechanism in Mg–Er–Gd–Ni alloys with high volume fraction of LPSO phase and different Gd contents after extrusion

The microstructure evolution and corrosion mechanism of Mg–9Er–xGd–2Ni alloys, subjected to Gd addition and extrusion, were investigated in this study. Results shows that with the increase in Gd content from 1.0 wt.% to 5.0 wt.%, the second phase change from continuous network LPSO phase with intragranular γʹ phase to a monolithic continuous network LPSO phase, while the corresponding volume fraction of the second phase remains essentially unchanged. Moreover, it is noted that increasing Gd content contributed to a reduction in the corrosion rate of alloy by reducing galvanic corrosion couples and facilitating the formation of double Gd2O3 and Er2O3 corrosion-resistant films. Ultimately, what's most noteworthy is that compared with as-cast alloys, the corrosion rate of as-extruded alloys increased by 49.2%–125.3% with increasing Gd content, which is due to the streamlined LPSO phase distribution weakening the corrosion barrier effect of high-volume fraction network distribution LPSO phase alloy and grain refinement providing more corrosion interfaces that inhibited the formation of corrosion-resistant product films. This study provides new provides new insights for the development of highly degradable Mg–Er–Gd–Ni alloys that have high strength potential for applications in unconventional oil and gas extraction.

Compositional dependence of spintronic properties in Pt/GdCo films

GdCo films have been widely used in spintronic applications, owing largely to their tunable degree of ferrimagnetic compensation. However, all key properties likewise depend on the alloy composition, and a systematic study of the interdependent spintronic properties with composition has not been reported. Here, we report the compositional dependence of key spintronic properties, including anisotropy, symmetric, and antisymmetric (Dzyaloshinskii–Moriya, DMI) exchange interactions, effective spin Hall angle, and domain wall mobility in a 3 nm Pt/GdCo composition series. We measure the magnetic anisotropy and determine an interfacial Pt/Co and bulk GdCo pair-ordering contribution to total anisotropy. Additionally, we estimate the exchange stiffness of all three interactions in GdCo as a function of composition. We conduct two types of domain wall motion experiments on patterned racetracks to determine the effective spin Hall angle and current-driven domain wall mobility. We find a 5× increase in effective spin Hall angle with increasing Gd concentration, suggesting an improvement in spin transfer efficiency in rare earth materials. Finally, we observe a monotonic decrease in the DMI strength with increasing Gd content, suggesting that DMI arises from the Pt/Co interfacial interaction.

YAG:Ce Nanophosphors Synthesized by the Polymer–Salt Method for White LEDs with Isomorphic Substitution of Yttrium by Gadolinium

Fine-dispersed YGdAG:Ce nanopowders with various degrees of isomorphic substitution of yttrium by gadolinium were synthesized. The structure and luminescent properties were studied by X-ray diffraction, attenuated total reflection Fourier-transform infrared spectroscopy, luminescence spectroscopy and scanning electron microscopy. The possibility of synthesis of YGdAG:Ce nanopowders with a degree of gadolinium substitution up to 60% and nanocrystals with average sizes of 25–30 nm were shown. The red-shift of the cerium luminescence band with an increase in Gd content was studied. The CIE diagram for emission of YGdAG:Ce synthesized by the polymer–salt method shows that the degree 30–40% substitution of Y by Gd is optimal for the fabrication of a white light source based on LED with an emission wavelength of 470 nm.

Structural and Thermoelectric Properties of Gd2−2xSr1+2xMn2O7 Double-Layered Manganites

Double-layered manganites are natural superlattices with low thermal conductivity, which is of importance for potential thermoelectric applications. The Gd2-2xSr1+2xMn2O7 (x = 0.5; 0.625; 0.75) were prepared by the solid-state reaction method. All the samples crystallize in the tetragonal I4/mmm Sr3Ti2O7 type structure. The unit cell volume and the distortion in the MnO6 octahedra increase with increasing Gd content. Their thermoelectric properties were investigated between 300 and 1200 K. All exhibit an n-type semiconducting behavior. The electrical conductivity (σ) increases while the absolute value of the Seebeck coefficient (|S|) decreases with increasing Gd content. Simultaneous increases in σ and |S| with increasing temperature are observed at temperatures approximately higher than 600 K, and the power factor reaches a maximum value of 18.36 μW/(m K²) for x = 0.75 at 1200 K. The thermal conductivity (κ) is lower than 2 W/(m K) over the temperature range of 300-1000 K for all the samples and a maximum dimensionless figure of merit ZT of 0.01 is obtained for x = 0.75 at 1000 K.

The effect of Gd on the microstructure evolution and mechanical properties of Mg-4Zn-0.6Ca alloy

In this work, the effect of Gd on the microstructure evolution and mechanical properties of Mg–4Zn–0.6Ca–xGd (x = 0, 0.3, 0.6 and 1, wt%) alloys were investigated systematically. The results show that Mg-4Zn-0.6Ca alloy was composed of α-Mg, Mg7Zn3 and Ca2Mg6Zn3 phase. The W-phase (Mg3Zn3Gd2) was synthesized after addition of Gd. The dynamic recrystallization was restrained and the average grain size decreased after 0.6 wt% Gd addition, causing the increase of unrecrystallized region. In addition, the volume fraction of second phase increased with increasing Gd content up to 1 wt%, and the effect of particles stimulated nucleation (PSN) was enhanced, resulting in a decrease in unrecrystallized region. The addition of Gd promoted the occurrence of the overall texture split and TD-split texture component, causing decreased basal texture intensity. An optimal mechanical property of Mg–4Zn–0.6Ca–1Gd alloy, with the yield and ultimate tensile strength of 240 MPa and 297 MPa, respectively, was achieved. The values were increased by 82 MPa and 37 MPa, respectively, compared with that of Mg–4Zn–0.6Ca alloy. In initial deformation stage, strain-hardening rate of alloys decreased with increase of Gd content. Mg-4Zn-0.6Ca-0.6Gd alloy possessed the lowest strain-hardening rate because of fine grain size. However, strain-hardening rate was increased when Gd content was increased to 1 wt%, which may be related to decreased texture intensity and presence of many second phases. This work reveals the effect of co-addition of minor Ca and Gd on the microstructure evolution and mechanical properties of Mg-Zn alloys, which provides theoretical basis for the development of high strength Mg alloy.

Hybrid density functional theory study of substitutional Gd in [formula omitted]-Ga2O3

Substitutional Gd alloying in β-Ga2O3 is studied using hybrid density functional theory. Calculations of structural properties reveal a monotonic increase in lattice parameters, volume and interplanar spacing with increasing Gd content. Cohesive energy and formation energy calculations show monotonically decreasing energy for increased Gd concentrations, implying stability even for large concentration Gd alloying. Partial density of states and electronic band structures reveal that Gd substitution does not result in any inter band gap states, a requirement for p-type conductivity. The electronic band gap does, however, decrease with increasing Gd content where the pronounced Gd levels are deep lying f-orbital electronic states. The frequency dependent dielectric response spectra reveal spatial anisotropy and a red shift for all optical properties for Gd content up to 37.5%, which, coupled with the electronic structure results show how Gd alloying may be used to tune Ga2O3 without significantly modifying the band edge contributions.

Achievement of reversible table-like magnetocaloric effect in MnCo1-Gd Ge alloys around room temperature

• The table-like magnetocaloric effect in MnCo 1- x Gd x Ge alloys are achieved. • Two successive magnetic transitions appear in the MnCo 1- x Gd x Ge ( x = 0.04, 0.06). • The refrigerant capacity reach 282 J/kg in MnCo 0.94 Gd 0.06 Ge with Δ H = 50 kOe. • The relative cooling power reach 335 J/kg in MnCo 0.94 Gd 0.06 Ge with Δ H = 50 kOe. • The maximum temperature span are 128 K in MnCo 0.94 Gd 0.06 Ge with Δ H = 50 kOe. The structural, magnetic and magnetocaloric properties in the Gd doped MnCo 1- x Gd x Ge alloys were investigated. With the increase of Gd content, the coexistence of Ni 2 In-type hexagonal structure and TiNiSi-type orthorhombic structure appear from the pure Ni 2 In-type hexagonal structure of MnCoGe. All samples undergo the second-order magnetic transition (SOMT). MnCo 1- x Gd x Ge ( x = 0.04, 0.06) have two successive magnetic transitions and a large reversible table-like MCE has been achieved around room temperature (RT). Moreover, the relative cooling power ( RCP ) and effective refrigeration temperature span (δ T FWHM ) with the magnetic field change of 50 kOe reach 335 J/kg and 128 K, respectively.