Gd Er Research Articles

Effect of extrusion temperature on microstructure and tensile properties of Mg–Gd–Er–Zn–Zr alloy containing LPSO phase

Effect of extrusion temperature on microstructure and tensile properties of Mg–Gd–Er–Zn–Zr alloy containing LPSO phase

Experimental investigation of phase equilibria in the Mg–Gd–Er system

Phase relations of the Mg-Gd-Er system at the Mg-rich corner were investigated experimentally through alloy sampling approach. Isothermal sections at 673 K and 773 K were determined according to electron probe microanalysis (EPMA) and X-ray diffraction (XRD) results. No ternary compounds were detected at the investigation temperatures. MgEr and MgGd can form a continuous solid solution. Five three-phased fields were measured and deduced in both isothermal sections at 673 K and 773 K.

Phase Relations in the Ln2O3-Cr2O3-B2O3 (Ln = Gd-Lu) Ternary Oxide Systems.

In this work, isothermal sections of the Ln2O3-Cr2O3-B2O3 (Ln = Gd-Lu) ternary oxide systems at 900, 1000, and 1100 °C were constructed by determining the phase relations by using a powder X-ray diffraction technique. As a result, these systems were divided into subsidiary subsystems. Two types of double borates, LnCr3(BO3)4 (Ln = Gd-Er) and LnCr(BO3)2 (Ln = Ho-Lu), were observed in the investigated systems. Regions of phase stability for LnCr3(BO3)4 and LnCr(BO3)2 were determined. It was shown that the LnCr3(BO3)4 compounds crystallized in rhombohedral and monoclinic polytype modifications up to 1100 °C; above this temperature and up to the melting points, the monoclinic modification was predominantly formed. The LnCr3(BO3)4 (Ln = Gd-Er) and LnCr(BO3)2 (Ln = Ho-Lu) compounds were characterized by using a powder X-ray diffraction method and thermal analysis.

Gd–Er interaction promotes NaGdF4:Yb, Er as a new candidate for high-power density applications

Efficient Gd–Er bidirectional energy transfer in NaGdF4:Yb, Er nanoparticles makes this upconversion system relevant for high-power density applications.

Correction: Gd–Er interaction promotes NaGdF4:Yb, Er as a new candidate for high-power density applications

Correction for ‘Gd–Er interaction promotes NaGdF4:Yb, Er as a new candidate for high-power density applications’ by Daniel Avram et al., J. Mater. Chem. C, 2023, https://doi.org/10.1039/d3tc01391j.

Hot Compression Mechanical Behavior of Solution Heat-Treated and Pre-aged Mg–Zn–Gd–Er Alloys

Hot Compression Mechanical Behavior of Solution Heat-Treated and Pre-aged Mg–Zn–Gd–Er Alloys

The crystal structure, magnetic phase transition and magnetocaloric effect in R5CoSb2 (R = Pr, Nd, Gd–Er) alloys

The crystal structure, magnetic phase transition and magnetocaloric effect in R5CoSb2 (R = Pr, Nd, Gd–Er) alloys are investigated. All alloys are crystallized in the Yb5Sb3-type orthorhombic structure. R5CoSb2 (R = Pr, Nd, Gd–Er) alloys undergo ferromagnetic (FM)-paramagnetic (PM) transition under 1 T. The magnetic phase transition of the R5CoSb2 (Gd–Er) alloys is of second-order nature, whereas the first-order phase transition takes place in the R5CoSb2 (R = Pr and Nd) alloys at a low temperature. For Δμ0H of 0–5 T, the values of the maximum of entropy change (the relative cooling power) are 6.4 J/kgK (97.8 J/kg), 2.2 J/kgK (108.7 J/kg), 7.5 J/kgK (592.5 J/kg), 5.2 J/kgK (400.4 J/kg), 6.2 J/kgK (413.5 J/kg), 9.0 J/kgK (423.0 J/kg) and 10.4 J/kgK (299.5 J/kg) in R5CoSb2 (R = Pr, Nd, Gd–Er) alloys near the phase transition temperature.

Investigations of the Magnetocaloric and Thermal Expansion Properties of the Ln3(adipate)4.5(DMF)2 (Ln = Gd-Er) Framework Series.

The development of sustainable and efficient cryogenic cooling materials is currently the subject of extensive research, with the aim of relieving the dependence of current low-temperature cooling methods on expensive and nonrenewable liquid helium. One potential method to achieve this is the use of materials demonstrating the magnetocaloric effect, where the cycling of an applied magnetic field leads to a net cooling effect due to changes in magnetic entropy upon application and removal of an external magnetic field. This study details the synthesis and characterization of a Ln3(adipate)4.5(DMF)2 series (where Ln = Gd–Er) of metal–organic framework (MOF) materials incorporating a flexible adipate ligand and their associated magnetocaloric and thermal expansion properties. The magnetocaloric performance of the Gd3(adipate)4.5(DMF)2 material was found to exhibit the highest magnetic entropy changes of the series, with a peak entropy change of 36.4 J kg–1 K–1 for a 5-0 T field change at a temperature of 2 K, which is suited for ultra-low-temperature cooling applications. Thermal expansion properties were also investigated within these materials, demonstrating modest negative and large positive thermal expansion identified along the different crystallographic axes within the MOF structures over a 100–300 K temperature range that demonstrated the novel mechanical properties of these adipate framework structures.

Analysis on the combined effect of Gd3+ and Er3+ lanthanides in the microscopic, physicochemical and photocatalytic characteristics of MgO nanoparticles

The production of rare earth metal Gd3+ and Er3+ co-doped MgO nanoparticles using a simple precipitation technique are described in this article. The microscopic structure and physicochemical characteristics of the synthesized particles were investigated using a variety of conventional analytical methodologies. The photocatalytic performance of co-doped MgO nanoparticles was evaluated by examining the decomposition of methyl orange (MO) and methylene blue (MB) under UV light illumination and is compared with pure one. All rare earth metal doped MgO nanoparticles demonstrated increased photocatalytic activity toward dye degradation, in that 3 wt% Gd–Er co-doped MgO showing the best activity and highest deterioration percentage. Furthermore, the impact of point of zero charge (PZC) and pH on dye photo deterioration was explored and addressed in depth.

Anomalous magnetoresistance and magneto-thermal properties of the half-Heuslers, RPdSi (R = Y, Gd–Er)

Here, we present a detailed study on the magnetic, magneto-transport, and magneto-thermal properties of the equiatomic half-Heusler compounds with the general formula, RPdSi (R = Y and rare-earth, Gd–Er). These materials crystallize in two different superstructures of the TiNiSi-type orthorhombic unit cell with the space groups Pnma and Pmmn. Our magnetic and heat capacity measurements reveal the onset of an antiferromagnetic (AFM) ordering in the temperature range 3–16 K for all the local moments bearing RPdSi compounds, while the non-magnetic analog, YPdSi exhibits a Pauli-paramagnetic behaviour. The AFM state of these compounds can be tuned by magnetic field and temperature as demonstrated by the magnetic measurements below the Neel temperature (T N). Most importantly, this tuning of the magnetic structure is well documented in the complex temperature and field dependence of magnetoresistance (MR) and magnetocaloric effect (MCE). Our study establishes a striking correlation of the commensurate/incommensurate AFM structure with that of positive/negative MR and MCE in this series of compounds. We emphasize that such a framework applies to a large number of AFM intermetallic systems.

Sm26Co11Ga6-type R26{Co, Ni}6.5-9.4Ga10.5-7.6 compounds (R = Gd–Er): Crystal structure, magnetic ordering and heat capacity

The crystal structure of novel Sm26Co11Ga6-type {Gd - Er}26Ni6.5-8Ga10.5-9 compounds (space group P4/mbm, N 127, tP86) has been established using powder X-ray diffraction. The magnetic ordering and magnetocaloric effect of polycrystalline Er26Co9Ga8, Tb26Ni8Ga9 and Tb26Co9.4Ga7.6 have been investigated using magnetic and heat capacity measurements. Er26Co9Ga8 and Tb26Ni8Ga9 show mixed ferro-antiferromagnetic ordering and remarkable permanent magnet properties at low temperatures. Er26Co9Ga8 exhibits a large magnetocaloric effect with magnetic entropy change of −11.8 ​J/kg⋅K at 12 ​K and adiabatic temperature of 9.6 ​K for a field change of 50 ​kOe. The ‘Gd26Ni8Ga9’ alloy is composed of 88 ​wt% of Gd26Ni8Ga9 and 12 ​wt% of GdNi which are both soft ferromagnetic. Due to their close Curie temperatures, the composite of Gd26Ni8Ga9 and GdNi displays a table-like magnetocaloric effect with a wide temperature range from 68 ​K to 103 ​K.

Structural changes in acetylurea complexes with rare-earth (Gd–Er) bromides: Coexistence of different coordination polyhedra in Dy and Ho compounds

Crystal structures of acetylurea (AcUr) complexes with middle rare-earth bromides, [Ln(AcUr)2(H2O)5]Br3·H2O (Ln = Gd, Tb), [Ln(AcUr)2(H2O)4.5][Ln(AcUr)2(H2O)4]Br6·2H2O (Ln = Dy, Ho) and [Er(AcUr)2(H2O)4]Br3, were studied by X-ray diffraction. Complex cations contain two bidentate AcUr molecules and five (Gd and Tb) or four (Er) inner-sphere water molecules; coordination numbers 9 or 8, respectively. Compounds of Dy and Ho contain two types of complex cations with coordination numbers 9 and 8.

Cooling rate controlled basal precipitates and age hardening response of solid-soluted Mg–Gd–Er–Zn–Zr alloy

The precipitation and age hardening response of the solid-soluted Mg–10Gd–1Er–1Zn–0.6Zr (wt.%) alloy performed by water-quenching (QC), air-cooling (AC) and furnace-cooling (FC) in terms of the volume fraction of precipitates and tensile properties were investigated in present paper. Results indicated the solid-soluted alloy contained stacking faults (SFs) and long period stacking ordered (LPSO) phase on the basal planes regardless of the cooling rate, but a larger volume fraction of the LPSO phase was formed with decreasing in the cooling rate. After aging, β′ and β1 phases precipitated on the prismatic planes, and their number density decreased but mean particle size increased with decreasing in the cooling rate. The solid-soluted alloys (QC, AC and FC samples) showed no apparent difference in yield strength (YS), but their correspondent peak-aged alloys exhibited sharp difference in hardening response. The strongest hardening response took place in the QC sample and showed 82 MPa enhancement in YS, which was much larger than that of AC (+26 MPa) and FC samples (+5 MPa). The reason lies in that the higher cooling rate promotes the precipitation and reduces the average size of β′ precipitate. A novel cooling-rate controlled precipitation model with respect to the correlation of precipitates on basal and prismatic planes was established. From this model, the basal precipitates showed a restrictive effect on the growth and/or coarsening of β′ precipitate, and composite precipitates containing the β′ phase with fine size as well as high area-number density and lower volume fraction of the LPSO phase are preferred to strengthen the Mg–10Gd–1Er–1Zn–0.6Zr alloy.

Obtaining Ultra-High Strength and Ductility in a Mg–Gd–Er–Zn–Zr Alloy via Extrusion, Pre-deformation and Two-Stage Aging

The Mg–12Gd–1Er–1Zn–0.9Zr (wt%) alloy with ultra-high strength and ductility was developed via hot extrusion combined with pre-deformation and two-stage aging treatment. The age-hardening behavior and microstructure evolution were investigated. Pre-deformation introduced a large number of dislocations, resulting in strain hardening and higher precipitation strengthening in the subsequent two-stage aging. As a result, the alloy showed a superior strength–ductility balance with a yield strength of 506 MPa, an ultimate tensile strength of 549 MPa and an elongation of 8.2% at room temperature. The finer and denser β′ precipitates significantly enhanced the strength, and the bimodal structure, small β-Mg5RE phase as well as dense γ′ precipitates ensured the good ductility of the alloy. It is suggested that the combination of pre-deformation and two-stage aging treatment is an effective method to further improve the mechanical properties of wrought Mg alloys.

Crystal structure and complex magnetic properties of R11Pd4In9 compounds (R = Y, Gd–Er)

Magnetic properties of the R11Pd4In9 compounds (R = Y, Gd–Er) were investigated by means of X-ray diffraction and magnetic measurements. Three of these compounds, namely those with R = Y, Ho and Er, are newly synthesized. The compounds crystallize in the orthorhombic Nd11Pd4In9-type crystal structure (oC48, Cmmm) in which the rare earth atoms occupy five nonequivalent sublattices. Magnetic properties of the investigated compounds are related mainly to the R3+ ions, except the case of Y11Pd4In9 which is a Pauli paramagnet. For R = Gd-Er, the values of effective magnetic moments in the paramagnetic state are close to the free R3+ ion values while the moments in the ordered state at T = 2 K and H = 90 kOe are lower than the respective R3+ moments. The compounds have complex magnetic properties. All paramagnetic Curie temperatures are positive suggesting that the ferromagnetic interactions are predominant. However, the low temperature data indicate an antiferromagnetic order. With increase of temperature the magnetic properties change from antiferro-to ferrimagnetic and finally to paramagnetic ones. The critical temperatures of magnetic ordering do not fulfill the de Gennes scaling, indicating a crystalline electric field contribution to stabilization of the magnetic order at low temperatures. The neutron diffraction measurements, performed for Ho11Pd4In9, reveal a coexistence of two magnetic phases at low temperatures: the antiferromagnetic with propagation vector k = [0,0,½] and the ferrimagnetic one with k = [0,0,0]. The antiferromagnetic order is predominant at low temperatures while the ferrimagnetic one dominates at intermediate temperatures.

Effect of Adding Rare Earth Elements Er and Gd on the Corrosion Residual Strength of Magnesium Alloy

Abstract The effects of the single and compound addition of rare earth Gd and Er on corrosion resistance and residual strength of as-cast AM50 magnesium alloy were studied using XRD, SEM, EDS, the weightlessness test, electrochemistry method, and tensile test. The results of XRD and SEM showed that Al3Er, Al2Gd3, and Al–Mn–Gd(Er) phases appeared in the alloy structure after the addition of rare earth Er and Gd. The results from the weightlessness test and Tafel curves show that the corrosion resistance of the modified composite rare earth was improved. Stress concentration caused by a corrosion pit is the direct cause of the tensile samples after corrosion. The corrosion residual strength of modified composite rare earth specimens is better than that of modified single rare earth samples. Fracture analysis indicates that the addition of rare earth elements did not change the fracture mechanism of the alloy, and the fracture was still the cleavage fracture.

Quaternary rare-earth sulfides RE3M0.5M′S7 (M = Zn, Cd; M′ = Si, Ge)

The four series of quaternary sulfides RE3Zn0.5SiS7 (RE = La–Nd, Sm, Gd–Er), RE3Zn0.5GeS7 (RE = La–Nd, Sm, Gd–Er), RE3Cd0.5SiS7 (RE = La–Nd, Sm, Gd–Ho), and RE3Cd0.5GeS7 (RE = La–Nd, Sm, Gd, Tb) were prepared by reactions of the elements at 1050 °C. Analysis of their powder X-ray diffraction patterns indicates that they adopt the noncentrosymmetric hexagonal La3Mn0.5SiS7-type structure (space group P63, Z = 2). The structures of two Cd-containing members were refined from single-crystal X-ray diffraction data (Gd3Cd0.5SiS7, a = 9.9737(8) Å, c = 5.6287(4) Å; Gd3Cd0.5GeS7, a = 9.9739(3) Å, c = 5.7296(4) Å). La3Zn0.5GeS7 melts incongruently above 1300 °C. Ce3Zn0.5GeS7 shows simple paramagnetic behaviour arising from non-interacting Ce3+ species. Optical band gaps of 2.7 eV for La3Cd0.5SiS7, 2.3 eV for La3Cd0.5GeS7, and 1.8 eV for Ce3Zn0.5GeS7 were measured. Band structure calculations on La3Cd0.5SiS7 and La3Cd0.5GeS7 confirm the presence of band gaps whose magnitude is controlled by Si–S or Ge–S bonding interactions.

The rare earth metal hydride tellurides REHTe (RE=Y, La–Nd, Gd–Er)

Abstract The synthesis and crystal structure of a series of rare earth metal hydride tellurides with the composition REHTe (RE = Y, La–Nd, Gd–Er) is reported. These compounds have been obtained by the reaction of rare earth metal dihydrides (REH2) with elemental tellurium in sealed tantalum capsules at T = 700°C using cesium chloride (CsCl) as fluxing agent, which can be washed away with water due to the astonishing insensitivity of these hydride tellurides (REHTe) against hydrolysis. All of the compounds crystallize in the hexagonal space group P6̅m2 with a filled WC-type crystal structure, exhibiting a mutual trigonal-prismatic coordination of the heavy ions (RE 3+ and Te2−), while the hydride anions reside in the trigonal prismatic voids surrounded by three rare earth metal cations expanding their coordination pattern to a tricapped trigonal prism. This 1H-type crystal structure is compared with the 1H- and 2H-type structures of the respective hydride selenides (REHSe, RE = Y, La–Nd, Gd–Tm, Lu). Both hexagonal basic crystal structures can be derived from the AlB2-type structure as demonstrated in a Bärnighausen tree by group-subgroup relationships.

Tuning magnetocaloric effect of Gd–Er–Al–Co metallic glass through crystallization

Magnetization and magnetocaloric effect (MCE) of as-cast Gd-based bulk metallic glass (BMG) Gd24Er32Co24Al20 and the crystallized samples were investigated. Reentrant-spin-glass-like behavior was observed in the as-cast sample. With increasing degree of crystallization, the magnetic frustration increased, which could be seen from the increased divergence of the zero-field-cooled and field-cooled magnetization behavior (i.e., the spin-glass-like freezing behavior). The Curie temperature and magnetization decreased after crystallization. The as-cast BMG showed a large maximum magnetic entropy change (− ΔSm) of 9.9 (J kg−1 K−1) under a field change of 5 T, which was comparable with that of Gd metal and other Gd-based metallic glasses. The maximum − ΔSm reduced to 6.7 (J kg−1 K−1) after crystallization, which was still superior to the Fe-/Co-based amorphous alloys. Their good MCE combining with high electrical resistivity, outstanding mechanical properties, tunable nature, and sufficiently soft magnetic property makes them to be attractive candidate for magnetic refrigerants in the low-temperature range.

Ternary rhombohedral Laves phases RE 2Rh3Ga (RE = Y, La–Nd, Sm, Gd–Er)

Abstract: The ordered Laves phases RE 2Rh3Ga (RE=Y, La–Nd, Sm, Gd–Er) were synthesized by arc-melting of the elements and subsequent annealing. The samples were characterized by powder X-ray diffraction (XRD). They crystallize with the rhombohedral Mg2Ni3Si type structure, space group R3̅m. Three structures were refined from single crystal X-ray diffractometer data: a=557.1(1), c=1183.1(2), wR2=0.0591, 159 F 2 values, 10 variables for Y2Rh3Ga, a=562.5(2), c=1194.4(2) pm, wR2=0.0519, 206 F 2 values, 11 variables for Ce2Rh3Ga and a=556.7(2), c=1184.1(3) pm, wR2=0.0396, 176 F 2 values, 11 variables for Tb2Rh3Ga. The Rh3Ga tetrahedra are condensed via common corners and the large cavities left by the network are filled by the rare earth atoms. The RE 2Rh3Ga Laves phases crystallize with a translationengleiche subgroup of the cubic RERh2 Laves phases with MgCu2 type. Magnetic susceptibility measurements reveal Pauli paramagnetism for Y2Rh3Ga and La2Rh3Ga. Ce2Rh3Ga shows intermediate cerium valence while all other RE 2Rh3Ga phases are Curie–Weiss paramagnets which order magnetically at low temperatures. The 89Y and 71Ga solid state nuclear magnetic resonance (NMR) spectra of the diamagnetic representative Y2Rh3Ga show well-defined single resonances in agreement with an ordered bulk phase. In comparison to the binary Laves phase YRh2 a strongly increased 89Y resonance frequency is observed owing to a higher s-electron spin density at the 89Y nuclei as proven by density of states (DOS) calculations.