Increasing Er Concentration Research Articles

Lead-free (K0.5Na0.5)NbO3 co-substituted with Ta5+ and Er3+: Structural, optical, dielectric and electrical properties

The lead-free K0.5Na0.5NbO3 (KNN) ceramics co-substituted with 0.05 mol Ta5+ and x mol Er3+ ions (K, Na) (1-3x) ErxNb0.95Ta0.05O3, with x = 0.00 to 0.05, have been successfully manufactured by using the solid-state reaction. The XRD results showed that the ceramics crystalize in pure perovskite with a trace of secondary phase, for low Er levels (x ≤ 0.02). Above this rate, the presence of secondary phases became more significant. The optical band gap energy of the synthesis samples has been determined using UV–vis absorbance spectra using Tauc's relation. The Ta and Er co-substitution leads to decrease the Eg of KNN material. The grain size is found to be minimal ≈490 nm and 240 nm of sintered pellets at x = 0.02 and 0.05 of Er content respectively with a high density. The dielectric study of (K, Na) (1-3x) ErxNb0.95Ta0.05O3 ceramics was carried out and double peaks were observed in relative permittivity versus temperature data for pure KNN and KNNTa corresponding to orthorhombic-tetragonal-cubic phase transitions. While for Er doped-KNNTa samples only a broad ferroelectric-paraelectric phase transition is observed and it shifted to the high temperature with increasing Er content. This broad peak observed in dielectric data for x = 0.02 of Er content is due to inhomogeneity and will certainly open new applications in microwave dielectrics. The ac conductivity variation of KNErNTa ceramics with diverse Er concentration was analyzed according to the charge compensation mechanism. However, for KNNTa, a decrease in conductivity values is attributed to the reduction in leakage current density. Meanwhile, at x = 0.01 and 0.02 of Er concentration, Er-doped KNNTa became semi-conductor. Further investigation revealed that the resistance of grains and grains boundaries are both minimal for x = 0.02 sample which are responsible for the increase of ac conductivity. For high Er concentration ≥0.03, the RG and RGB values increase along with decrease of conductivity value related to the increase in grain size found in SEM micrographs.

Superconductivity of rare-earth borides Dy1–xErxRh3.8Ru0.2B4 (x = 0, 0.2, 0.4) and Dy0.6Y0.4Rh3.85Ru0.15B4

The effect on the superconductivity of the partial replacement of one magnetic rare-earth element (Dy) by another (Er) in rhodium borides Dy1–xErxRh3.8Ru0.2B4 with x = 0, 0.2, 0.4 is studied. It was found that in Dy1–xErxRh3.8Ru0.2B4, with increasing Er content, the temperature of the superconducting transition increases significantly: from 3.7 K for x = 0 to 6 K for x = 0.4. It was demonstrated that the replacement of magnetic Er3+ with nonmagnetic Y3+ in the isostructural compounds Dy0.6Er0.4Rh3.8Ru0.2B4 (Tc ≈ 6 K) and Dy0.6Y0.4Rh3.85Ru0.15B4 (Tc ≈ 7 K) does not lead to a significant change in the temperature of the superconducting transition. The suppression of the superconducting state by the magnetism of rare-earth elements is not observed down to 1.5 K the lowest available temperature in the experiment.

Anomalous Ferromagnetic Phase in the Gd1−xErxB4 Series: Crystal Growth, Thermal, and Magnetic Properties

Rare-earth tetraborides RB4 are of great interest due to the occurrence of geometric magnetic frustration and corresponding unusual magnetic properties. While the Gd3+ spins in GdB4 align along the ab plane, Er3+ spins in the isomorphic ErB4 are confined to the c–axis. The magnetization in the latter exhibits a plateau at the midpoint of the saturation magnetization. Therefore, solid solutions of (Gd, Er)B4 provide an excellent playground for exploring the intricate magnetic behavior in these compounds. Single crystals of Gd1−xErxB4 (x = 0, 0.2, and 0.4) were grown in aluminum flux. X-ray diffraction scans revealed single-phase materials, and a drop in the unit cell volume with increasing Er content, suggesting the partial substitution of Er at the Gd sites. Heat capacity measurements indicated a systematic decrease of the Néel temperature (TN) with increasing Er content. The effective magnetic moment determined from the magnetization measurement agreed with the calculated free ion values for Gd3+ and Er3+, providing further evidence for the successful substitution of Er for Gd. The partial substitution resulted in an anomalous ferromagnetic phase below TN, exhibiting significant anisotropy, predominantly along the c-axis. This intriguing behavior merits further studies of the magnetism in the Gd1−xErxB4 borides.

Erbium induced softening in isothermal compressed AA6061 alloy

This study investigates the dynamic softening mechanism of the AA6061 alloy with different Er contents during high-temperature compression. The findings reveal that the increase of Er content can continuously reduce the flow stress of the AA6061 alloy, which was attributed to the enhanced DRV and DRX. The presence of Er induces the precipitation of iron-rich phases that promote the PSN effect, increasing the recrystallization fraction. In addition, the decrease of the fine Mg2Si weakens its pinning effect on the dislocation, which facilitates dislocation motion.

Analysis of Phase Diagram of CaO-CoOx-ErOy and Crystal Structure of Perovskite (Ca3−xErx)Co2O6−z Solid Solution

In this work, a series of compounds in the CaO-CoOx-ErOy ternary oxide system were synthesized in air at 885 °C, using a high temperature solid-phase synthesis method. The phase boundary of each solid solution region in the CaO-CoOx-ErOy system was determined by X-ray powder diffraction techniques. The phase diagram of the CaO-CoOx-ErOy system at 885 °C includes three series of ternary oxide solid solutions: (Ca3−xErx)Co4O9−z (0 ≤ x ≤ 0.9), (Ca3−xErx)Co2O6−z (0 ≤ x ≤ 1.25), and (Er1−xCax)CoO3−z (0 ≤ x ≤ 0.33). Four three-phase regions and five solid solution tie-line regions were obtained. The structure of the perovskite solid solution (Ca3−xErx)Co2O6−z has been analyzed by Rietveld refinements. With the increase of Er content, the cell parameters of (Ca3−xErx)Co2O6−z exhibit a decreasing trend in a and b directions and an increasing trend in c direction. A brief comparison of the phase diagrams of the CaO-CoOx-ROy (R = La, Dy, and Er) systems in air at 885 °C is provided.

Electrical and photoluminescence studies of GeSbSeEr chalcogenide films

In a recent study, we investigated the effect of erbium doping in Ge18Sb8Se75 chalcogenide systems to improve their electrical and photoluminescence properties. The chalcogenide glasses (ChG) were synthesized using the traditional melt-quenching technique, and the thin film was deposited using the thermal evaporation technique. Photoluminescence studies of the synthesized samples were obtained at room temperature with intense emission bands at 844 nm, 864 nm, and 876 nm after excitation with a solid-state laser at 980 nm. For the electrical study, the current–voltage (I-V) characteristics of pure Ge17Sb8Se75 and Er-doped Ge17Sb8Se74 were investigated using the 2-probe method, which shows that the electrical properties of the sample are improved by the addition of Er. The conductivity of pure Ge17Sb8Se75 increases to 6.6 times with the addition of Er in Ge17Sb8Se75, which could be due to the electronic transition Er(4f) → Er(5d) and movement, which causes an increase in conductivity. Furthermore, The DC conductivity increases with increasing Er content. The large number of band transitions in the near-infrared region makes the material suitable for bio-imaging.

Effect of epoxy resin and barium zirconate titanate contents on the piezoelectric properties of a 0–3 barium zirconate titanate-Portland cement composite with epoxy resin addition

A 0–3 piezoelectric ceramic-Portland cement (PC) composite with different compositions was fabricated and investigated with the following components: BZT (40, 50, and 60 vol% represented as BZT40, BZT60, and BZT60, respectively) and epoxy resin (0, 3, 5, and 7 vol% represented as ER0, ER3, ER5, and ER7, respectively). Experimental results show that increasing ER content (0–7 vol%) led to an increase in density (ρc), for 50% BZT increased from 3.42 to 3.55 g/cm3 and a decrease in porosity, from 12.71 to 11.67% (for 50%BZT) and acoustic impedance (Zc) value increased from 9.67 to 8.84 × 106 kg/m·s2. Both εr and tanδ decreased with increasing ER content. ER as the third phase resulted in a lower leakage current and the BZT60ER7 composite is found to have the lowest leakage current (20 μA). Increasing ER content led to a decrease in the piezoelectric charge coefficient (d33). However, a notable increase in piezoelectric voltage coefficient (g33) with increasing ER content up to 3 vol% was found. The optimization of both Zc and g33 in this study can be observed in BZT50ER3 composite (Zc = 9.16 × 106 kg/m2·s and g33 = 13.9 × 10−3 V m/N). In addition, the highest planar electromechanical coupling factor (kp = 17.97%) and thickness electromechanical coupling factor (kt = 17.75%) can be observed in BZT60ER7 composite.

Effect of Er substitution on the specific heat of GdNiSi

We measured the specific heat (C) of Gd1−xErxNiSi. The values of C for x=0 (GdNiSi) peaked at 11.5 K due to the antiferromagnetic order. The Néel temperature and the values of the entropy of Gd1−xErxNiSi decreased with increasing Er content up to x=1 (ErNiSi). The end member ErNiSi showed two successive transitions at 2.8 K and 2.3 K. The values of C at a temperature at which a peak appeared decreased with an increase in x, except for x=1. These results originate from the reduction of the multiplicity of the crystalline electric field ground state and the atomic randomness due to the Er substitution.

The thermal property and failure behaviors of SmErZrO thermal barrier coatings by EB-PVD

Sm2Zr2O7 material has attracted much attention due to the good thermal stability and high melting point over the past decades. However, the improvement of thermal durability and the study of failure still remain a challenge. In this work, we focuses on phase structure, thermal property and failure mechanism of the SmErZrO thermal barrier coatings (TBCs) by EB-PVD technology. The SZ, SE1Z, SE2Z and SE3Z TBCs both exhibit the pyrochlore structure after EB-PVD deposition. The as-deposited TBCs exhibit three coatings microstructure (top and middle ceramic coating with columnar structure, and NiCoCrAlYHf bottom coatings). The thermal conductivity of SZ ceramics decreases with the increase of Er content. The SE2Z TBCs exhibit long thermal durability (thermal shock life and thermal cycling life) at 1100°C. After thermal durability test, the horizontal cracks occur and develop in TGO and interface. The cracks and element evolution might be the key factor leading to the SE2Z/YSZ TBCs failure. The SE2Z/YSZ TBCs might be a potential TBCs in advanced aircraft engines.

Optimization of the luminescence and structural properties of Er-doped ZnO nanostructures: effect of dopant concentration and excitation wavelength

The present study reports the effect of Er doping on the structural, morphological, and optical properties of ZnO nanostructures. ZnO: Er nanorods with different doping concentrations were successfully synthesized via a hydrothermal method. X-ray diffraction and Energy-dispersive X-ray spectroscopy analyses suggest the successful incorporation of Er into the wurtzite structure of ZnO; A secondary phase of Er2O3 appears when the Er concentration exceeds 2.5 wt%. The optical band-gap of ZnO was determined from the analysis of ultraviolet–visible spectra, and a decrease of the band gap is emphasized with increasing Er concentration. Photoluminescence spectra display a strong and broad deep-level emission band, which intensified with increasing Er concentration. The current work provides more details about the excitation wavelength effect on the luminescence of pure and Er-doped ZnO materials, finding that the visible photoluminescence emission intensity could be controlled by adjusting the Er concentration as well as the excitation wavelength; better luminescence was obtained with high Er concentration and high excitation wavelength. Moreover, the DFT calculations support the experimental results and confirm that the presence of oxygen vacancies has an effect on the structural and electronic properties of ZnO. Hence, the research findings of this work could provide an experimental and theoretical reference that may motivate future research on the study of ZnO-based optoelectronic applications.

A DFT study on the electronic structure, magnetic and optical properties of Er doped ZnO: Effect of Er concentration and native defects

We report on first-principles study of the effect of Er concentration and intrinsic defects (VO and VZn) on the electronic structure and optical properties of Er-doped ZnO using the GGA + U method. The lattice constants and band gap of ZnO calculated in this work are in agreement with experimental values. The results showed that the band gap of Er-doped ZnO decreases with increasing Er concentration, while it increases with the presence of O or Zn vacancies. Furthermore, the existence of VO causes the formation of a deep donor level in the band gap. Er–ZnO + VZn is a degenerate p-type semiconductor, and shallow acceptor states are created near the Fermi level. The magnetic moment of doped ZnO increases and Er 4f electrons are responsible for the induced magnetic moments. The absorption coefficient enhances in the visible range in Er doped ZnO. In the Er–ZnO + VO model, both absorption and reflection are relatively enhanced in the visible range, leading to a decrease in light transmittance. Hence, the magneto-optoelectronic properties of ZnO could be improved by an optimal concentration of Er as well as with the presence of oxygen vacancies.

Influence of Er content on microstructural evolution and mechanical properties of Al-2Fe alloy

Herein, Al-10 wt% Er master alloy (Er) is used to modify the Al-2Fe alloy, and the effect of physical state of Er during solidification and homogenous annealing is systematically examined by using XRD, SEM, TEM and EDS. The results reveal that the addition of Er can refine α-Al secondary dendrite spacing and reduce the length of Al3Fe phase. For instance, the secondary dendrite spacing of α-Al decreased from 30–60 μm to 14–19 µm with the increase of Er content. Moreover, the L12-structured Al3Er particles preferentially formed in the liquid alloy can be used as heterogeneous nucleation core for α-Al grains. The granular Al3Er is formed between dendrites during solidification and hinders the growth of α-Al grains and Al3Fe phases. Furthermore, the lamellar Al+Al3Er eutectic is formed with an increase of Er content. In addition, Al10Fe2Er is formed at the Al/Al3Fe phase boundary in Al-2Fe alloys with 0.7 wt% and 0.9 wt% Er. The Al3Er within grains and among dendrites partially dissolved in the matrix after annealing at 480 °C for 24 h. The micron-sized Al10Fe2Er particles are formed around eutectic Al3Fe in Al-2Fe alloys with 0.3 wt% and 0.5 wt% Er. The size of Al10Fe2Er, which already exists in as-cast Al-2Fe alloys with 0.7 wt% and 0.9 wt% Er, is increased due to atomic diffusion, which compromised mechanical properties.

Multiferroic properties in [formula omitted] ceramics

The effect of Er3+ substitution on the physical properties of SmFeO3 was studied through magnetic and electrical measurements. The X-ray diffraction patterns of Sm1-xErxFeO3 samples showed that the lattice constants decrease with increasing Er content. As a result, the distortion of Er -doped SmFeO3became significant. The magnetic hysteresis loops of samples indicate that the antiferromagnetic trend increases with Er concentration. The anomaly in Ac susceptibility (χ) and dielectric constant curves for Sm1-xErxFeO3 provided evidence for occurring spin reorientation transition (SRT) in these compounds and are also observed the gradual decrease in SR temperature with increasing Er3+ions. Furthermore, the electrical measurements exhibited a considerable enhancement in the dielectric constant. Sm0.3Er0.7FeO3 is the only compound that presented a colossal dielectric constant (CDC) (103) at room temperature which is attributed to relaxor-ferroelectrics. Likewise, the appearance of magnetic and ferroelectric hysteresis loops indicated the coexistence of magnetism and ferroelectricity.

MICROSTRUCTURE AND MARTENSITIC TRANSFORMATION OF Ni_{50}Ti_{50-x}Er_{x} SHAPE MEMORY ALLOYS

The effect of rare earth element Er addition on the microstructure and phase transformation behavior of Ni_{50}Ti_{50-x}Er_{x} (x =0, 1, 5) shape memory alloy was investigated experimentally. The results showed that the microstructure of Ni-Ti-Er ternary alloys consists of the NiEr precipitate and the NiTi matrix. A one-step martensitic transformation was observed in all alloys. The martensitic transformation temperature M_s increased gradually with increasing Er content.

Effect of Er substitution on the magnetic, Mössbauer spectroscopy and dielectric properties of CoFe2−xErxO4 (x = 0.00, 0.01, 0.03, 0.05) nanoparticles

The effect of Er content on sol-gel derived CoFe2−xErxO4, (x = 0.00, 0.01, 0.03, 0.05) nanoparticles was investigated by XRD, FTIR, SEM, Mössbauer spectroscopy, magnetic and dielectric measurements. The formation of cubic spinel structure and the presence of molecular bonding of functional groups were confirmed by XRD and FTIR spectroscopy. The average crystallite size is reduced from 61 to 18 nm with the increase of Er content. The decrease in crystallite size is due to the suppression of grain growth upon Er3+ occupation at the octahedral site. SEM study revealed the formation of nano size particles which dispersed uniformly. Mössbauer spectra, taken at room temperature (RT) confirmed the presence of ferromagnetic sextets demonstrating the existence of Fe both in the tetrahedral and octahedral sites. The magnetic properties were measured at 300 K, 100 K and 5 K using a Physical Properties Measurements System (PPMS). The saturation magnetization (Ms) of CoFe2O4 was found to be 95.92 emu/g which is much higher than the bulk ferrite (80.8 emu/g) and the maximum Ms 120 emu/g was found for 0.01 Er content. The coercivity increases with the increase of Er content which has a direct relationship with crystallite size and single-domain behavior of nanoparticles. The maximum coercivity is found to be 855 KA/m at 5 K which is the highest compared to the rare earth doped ferrites. The impedance analysis fallouts the relative permittivity and dielectric loss decrease while AC conductivity increases with increasing frequency for all samples. The obtained results signify CoFe2−xErxO4 as a potential candidate for magneto-electric sensors and high frequency electromagnetic devices application.

Effect of Erbium on Microstructure, Hardness and Electrochemical Properties of Al-5Zn-0.03In Alloy

Al-5Zn-0.03In series alloys have been widely studied and used as sacrificial anode materials. Adding rare-earth (RE) element to Al-5Zn-0.03In sacrificial anode is the important way to improve its microstructure and properties. This paper focused on the effect of Er addition on the microstructure and properties of the Al-5Zn-0.03In-xEr alloy. Thermal analysis showed that the presence of Er in the series alloys reduced the solidification ranges and made their liquidus and solidus move to lower temperature. The microstructural analysis and hardness testing reveal that Er existed in the form of precipitation, refined the dendrites of the series alloys and improved the hardness of the series alloys. Investigation of the potentiodynamic polarization and the electrochemical impedance measurements were performed in 3.5 wt. % NaCl solution. The potentiodynamic polarization results indicated that the corrosion potential increased and the corrosion current density reduced with the increase of the Er addition. The Al-5Zn-0.03In alloy shows higher corrosion resistance with the increase of Er content. The EIS electrochemical impedance results showed that Al-5Zn-0.03In anode presented relatively uniform dissolution due to the refined microstructure by the addition of Er.

Effect of Er content on the interfacial microstructure, shear properties and creep properties of Sn58Bi joints

The influences of Er content on the interfacial microstructure shear properties and creep properties of Sn58Bi joints were investigated in this study. The intermetallic compound composition of Sn58Bi-xEr/Cu was Cu6Sn5 compound. The addition of Er suppressed the activity of Sn element, decreased the driving force for the growth of Cu6Sn5 intermetallic compound and decreased the thickness of Cu6Sn5 intermetallic compound layer. The shear properties and creep durability of Sn58Bi-xEr/Cu welded joints were improved to a certain extent. At the Er content of 0.1%, the shear strength and creep durability properties of the solder alloy are relatively optimal. When wt%Er was more than 0.1%, with the increasing Er content of rare earth elements, the internal organization of the joint interface is coarsened, and the flatness of the IMC layer at the interface is reduced, which leads to the decrease of the creep performance of the final joint.

Study of Erbium Doping Effect on Structural, Morphological and Optical Properties of Dip Coated ZnO Under Alkaline Conditions

Undoped Zinc oxide (ZnO) and erbium (Er) doped ZnO thin films have been grown on glass substrate by dip coating technique under alkaline conditions (pH 9). The pH was maintained at 9 for all prepared sols by controlling the amount of Monoethanolamine (MEA). The eff ;ects of Er doping concentration on the ZnO films properties was studied by using XRD, SEM, EDX, AFM, Raman spectroscopy, FTIR analysis and UV–vis spectrophotometer. The results showed that the incorporation of Er3+ under alkaline pH had a great effect on the ZnO properties. All samples exhibit a pure ZnO polycrystalline hexagonal wurtzite structure with a high crystalline quality. Homogenous, smooth and dense granular morphology nanostructures were revealed by AFM and SEM analysis. Raman spectroscopy and FTIR analysis confirm the formation of ZnO hexagonal wurtzite structure for samples. It was found that Er doping concentration enhance optical transmittance of ZnO based thin films. A red-shift was observed in the band gap of Er doped ZnO films with increasing Er concentration. The obtained results make EZO based thin films suitable for solar cells applications.

The effect of Er on optical and mechanical properties of As2S3 glasses quenched in different media

Er3+-doped As2S3 glasses were synthesized using As, S and Er2S3 as raw materials. In order to produce glasses with high mechanical properties along with high solubility of rare earth ions in these glasses, different media such as water, hydraulics and heat-resistant oil were selected for quenching specimens. Heat-resistant oil was selected as optimized medium. The effects of Er content (0.5–2 wt%) on transmission, mechanical and structural properties of the glasses were investigated. By increasing Er content in the base glass, some clusters were introduced to glass field which causes reduction in transmission in infrared (from 70 to 25%) and visible ranges (from 70 to 60%). Density and microhardness of samples were increased from 2.78 to 3.26 g/cm3 and 81.5 to 91.75 Mpa, respectively, by increasing Er content.

Canted surface spins driven exchange anisotropy in erbium substituted nickel ferrite nanoparticles

Single-phase nickel ferrite nanoparticles doped with rare earth Er3+ ions have been prepared using conventional chemical co-precipitation technique. Existence of pure spinel cubic structure of all samples was confirmed by the X-ray diffraction profiles and Raman modes. Average crystallite sizes ranged from 4 nm to 15 nm were estimated using Williamson-Hall plot. The crystallite size was found to decrease with increasing Er dopants in nanosized nickel ferrites. Compressive microstrain was detected for all the synthesized nanoferrites. Lattice constant increased with the increase of Er concentration due to its large ionic diameter. The crystal symmetry of octahedral sublattices was lowered for higher Er content nanoferrites as detected by the Raman spectra. Indirect optical band gaps increased with Er doping as observed in Tauc plots. Existence of exchange anisotropy in Er content nickel nanoferrites was seen by field cooled (7 T) M(H) plots recorded at 5 K. Both the exchange bias and coercivity were observed to increase at 5 K with the increment of Er percentage. Saturation magnetization also decreased with the increase of Er content. The highest Er content nanoferrites exhibited superparamagnetic nature at room temperature as seen from M(T) plots. The irreversibility temperature as well as blocking temperature was reduced because of mean size reduction of nanoparticles with increasing Er percentage.