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Dy is Tungsten structured and crystallizes in the cubic Im-3m space group. The structure is three-dimensional. Dy is bonded in a distorted body-centered cubic geometry to eight equivalent Dy atoms. All Dy–Dy bond lengths are 3.47 Å.
Dy is Magnesium structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. Dy is bonded to twelve equivalent Dy atoms to form a mixture of face, edge, and corner-sharing DyDy12 cuboctahedra. There are six shorter (3.50 Å) and six longer (3.63 Å) Dy–Dy bond lengths.
Here, we describe magnetic, thermal, and magnetocaloric properties of rare earth intermetallic compounds Tm x Dy 1-x Al 2 with 0.25, 0.5 and 0.75. Using model Hamiltonian we consider contributions of the crystalline electric field anisotropy in both Tm and Dy magnetic sublattices, disorder in exchange interactions among Tm-Tm, Dy-Dy and Tm-Dy magnetic ions, and the Zeeman effect. Employing earlier reported and new experimental measurements, we first determine a single free variable – the intersublattice magnetic exchange parameter – to properly model the temperature and magnetic field dependencies of heat capacity and magnetization, and then use the modeling results to explain the emergence of an anomalous spin reorientation transition and its influence on the magnetocaloric effect in the title compounds. Theoretical results agree with experimental data reasonably well.
Magnetic and magnetocaloric properties of H o 1 - x D y x A l 2 compounds with x = 0 , 0.05 , 0.10 , 0.15 , 0.25 and 0.50 , modelled using a Hamiltonian that includes the exchange interactions between Ho-Dy, Ho-Ho and Dy-Dy ions in addition to the crystalline electric field and the Zeeman effects, have been compared with those determined experimentally. In order to reproduce experimentally observed global ferromagnetic ordering temperatures and spin reorientation transition temperatures as x Dy varies, the exchange interactions between Ho-Dy and Ho-Ho were set as free parameters and adjusted to match the experimental results. We demonstrate that heat capacity of polycrystalline materials in non-zero magnetic fields can be satisfactory reproduced by using the average of multiple magnetic field directions with respect to the crystallographic coordinate system, while reasonably good agreement between experimentally determined and theoretically predicted magnetocaloric effects can be achieved considering an average of only three field directions.
Tb 1–x Dy x Fe 2 system has attracted more research interest due to the large magnetostrictive effect. The crystal structures and physical properties have been well studied, but research studies on their local structures are still rare. As such, in this work, the local structure of Tb 1–x Dy x Fe 2 samples was studied using the pair distribution function and x-ray absorption spectroscopy techniques. The results demonstrate that the system owns the same local crystal symmetry with its average structure in the ferromagnetic phase, and the crystal lattice of the system is more ordered with increasing Dy content, indicating that the Dy-rich tetragonal phase is more stable than the Tb-rich rhombohedral phase. The different roles of metallic bonds in affecting the crystal lattice are presented. The weak Fe 1 –Fe 2 bonds influenced by the local environment such as local stress from randomly distributed nanodomains could originate the anomalies in the lattice, resulting in the more ordered and stable Dy-rich phase than the Tb-rich phase.
Low-temperature crystal structure of the Er x Dy 1-x Al 2 alloys with x = 0.45, 0.67, 0.90 was examined using temperature-dependent powder X-ray diffraction. The Er-rich sample, Er 0.9 Dy 0.1 Al 2 , exhibits a rhombohedral distortion associated with the magnetic ordering that occurs around 20 K. The rhombohedral distortion is suppressed in Er 0.67 Dy 0.33 Al 2 , while a weak low-temperature tetragonal distortion is observed in Er 0.45 Dy 0.55 Al 2 . The mean-field theory supports the correlation between the type of structural distortion and the variable easy magnetization axis in Er x Dy 1-x Al 2 intermetallics.
Dy(CrGe)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Dy is bonded in a 8-coordinate geometry to eight equivalent Ge atoms. All Dy–Ge bond lengths are 3.04 Å. Cr is bonded to four equivalent Ge atoms to form a mixture of edge and corner-sharing CrGe4 tetrahedra. All Cr–Ge bond lengths are 2.45 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Dy, four equivalent Cr, and one Ge atom. The Ge–Ge bond length is 2.58 Å.
DyMn6Ge6 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. Dy is bonded to eight Ge atoms to form distorted edge-sharing DyGe8 hexagonal bipyramids. There are two shorter (2.80 Å) and six longer (2.99 Å) Dy–Ge bond lengths. Mn is bonded in a 12-coordinate geometry to six Ge atoms. There are a spread of Mn–Ge bond distances ranging from 2.52–2.70 Å. There are three inequivalent Ge sites. In the first Ge site, Ge is bonded in a 8-coordinate geometry to one Dy, six equivalent Mn, and one Ge atom. The Ge–Ge bond length is 2.53 Å. In the second Ge site, Ge is bonded in a 9-coordinate geometry to three equivalent Dy and six equivalent Mn atoms. In the third Ge site, Ge is bonded in a 6-coordinate geometry to six equivalent Mn atoms.
Dy(Ni2P)2 crystallizes in the tetragonal P4_2/mnm space group. The structure is three-dimensional. Dy is bonded in a 6-coordinate geometry to six equivalent P atoms. There are two shorter (2.81 Å) and four longer (2.85 Å) Dy–P bond lengths. Ni is bonded in a 3-coordinate geometry to three equivalent P atoms. There are two shorter (2.30 Å) and one longer (2.32 Å) Ni–P bond lengths. P is bonded in a 9-coordinate geometry to three equivalent Dy and six equivalent Ni atoms.
Dy(CuS)2 crystallizes in the trigonal P-3m1 space group. The structure is three-dimensional. Dy is bonded to six equivalent S atoms to form distorted DyS6 octahedra that share corners with twelve equivalent CuS4 tetrahedra, edges with six equivalent DyS6 octahedra, and edges with six equivalent CuS4 tetrahedra. All Dy–S bond lengths are 2.84 Å. Cu is bonded to four equivalent S atoms to form distorted CuS4 tetrahedra that share corners with six equivalent DyS6 octahedra, corners with six equivalent CuS4 tetrahedra, edges with three equivalent DyS6 octahedra, and edges with three equivalent CuS4 tetrahedra. The corner-sharing octahedra tilt angles range from 25–53°. There are three shorter (2.33 Å) and one longer (2.51 Å) Cu–S bond lengths. S is bonded in a 7-coordinate geometry to three equivalent Dy and four equivalent Cu atoms.
DyMn6Sn6 crystallizes in the hexagonal P6/mmm space group. The structure is three-dimensional. Dy is bonded to eight Sn atoms to form distorted edge-sharing DySn8 hexagonal bipyramids. There are two shorter (3.00 Å) and six longer (3.15 Å) Dy–Sn bond lengths. Mn is bonded in a 12-coordinate geometry to six Sn atoms. There are a spread of Mn–Sn bond distances ranging from 2.74–2.83 Å. There are three inequivalent Sn sites. In the first Sn site, Sn is bonded in a 12-coordinate geometry to three equivalent Dy and six equivalent Mn atoms. In the second Sn site, Sn is bonded in a 6-coordinate geometry to six equivalent Mn atoms. In the third Sn site, Sn is bonded in a 8-coordinate geometry to one Dy, six equivalent Mn, and one Sn atom. The Sn–Sn bond length is 3.01 Å.
Layered nickel-rich materials are promising next-generation cathode materials for lithium ion batteries due to their high capacity and low cost. However, the poor thermal stability and longtime cycling performance hinders the commercial applications of high nickel materials. Doping with heteroatoms has been an effective approach for improving electrochemical performance of cathode materials. Controlling doping concentration and geometrical distribution is desired for optimal electrochemical performance, but it is challenging in traditional co-precipitation methods. In this work, controlled dysprosium (Dy) doping to NCM811 was studied in an aerosol synthesis method by controlling the precursor concentrations and heating parameters. The obtained materials were characterized by SEM, XRD, and XPS, and their electrochemical properties and thermal stability were evaluated. By controlling the doping concentration (1.5%), Dy-doped NCM811 was improved simultaneously in long-term cycling and high-rate performance. Here, the thermal-chemical stability of the Dy-doped cathode materials was examined in a microflow reactor with a mass spectrometer. The results showed that Dy-doping shifted the O 2 onset temperature to a higher temperature and reduced O 2 release by 80%, thus dramatically increasing the thermal-chemical stability and improving the fire safety of cathode materials. Since high temperature aerosol synthesis is a low-cost and scalable method, the findings in this work have broad implications for commercial synthesis of novel materials with controlled doping modification to achieve high electrochemical performance and safety in lithium ion batteries.
Abstract In order to eliminate the influence of scene illumination on the evaluation of the color difference of dyed fabrics, this paper proposes a dyed fabric illumination correction algorithm based on the extreme learning machine (ELM) with grey wolf optimizer (GWO)‐optimized ant lion optimizer (ALO). Firstly, the Grey Edge framework is used to extract the features of the dyed fabric image as the input vector. Then, to improve the optimization ability of the ALO algorithm, the GWO algorithm is used to provide a set of optimized initial populations to the ALO algorithm, and then the improved ALO algorithm is used to optimize the parameters of the ELM. Finally, the proposed GWO‐ALO‐ELM algorithm is used to correct the illumination of the dyed fabric, and restore the graphics to the effect display under standard illumination through the diagonal reduction model. Compared with the experimental results of GWO‐ELM, ALO‐ELM, backpropagation (BP), ELM, random vector function link (RVFL), and other algorithms, it can be seen that the GWO‐ALO‐ELM algorithm proposed in this paper has good predictive value and quasi‐bias effect, and good stability.
The study of the origin of heavy elements is one of the main goals of nuclear astrophysics. In this paper, we present new observational data for the heavy r-process elements gadolinium (Gd, Z= 64), dysprosium (Dy, Z= 66), and thorium (Th, Z= 90) in a sample of 276 Galactic disc stars (–1.0 < [Fe/H] < + 0.3). The stellar spectra have a high resolution of 42 000 and 75 000, and the signal-to-noise ratio higher than 100. The LTE abundances of Gd, Dy, and Th have been determined by comparing the observed and synthetic spectra for three Gd lines (149 stars), four Dy lines (152 stars), and the Th line at 4019.13 Å (170 stars). For about 70 percent of the stars in our sample, Gd and Dy are measured for the first time, and Th for 95 percent of the stars. Typical errors vary from 0.07 to 0.16 dex. This paper provides the first extended set of Th observations in the Milky Way disc. Here together with europium (Eu, Z= 63) data from our previous studies, we have compared these new observations with nucleosynthesis predictions and Galactic Chemical Evolution simulations. We confirm that [Gd/Fe] and [Dy/Fe] show the same behaviour of Eu. We study with GCE simulations the evolution of [Th/Fe] in comparison with [Eu/Fe], showing that unlike Eu, either the Th production is metallicity dependent in case of a unique source of the r-process in the Galaxy, or the frequency of the Th-rich r-process source is decreasing with the increase in [Fe/H].
Abstract As part of a broader study of ceramic nuclear waste‐forms, four different lanthanide titanates were fabricated; La 0.1 Sm 0.1 Gd 0.1 Tb 0.1 Dy 0.3 Ho 0.1 Er 0.2 YbTiO 5 , Sm 0.3 Gd 0.3 Dy 0.3 Yb 1.1 TiO 5 , Sm 0.1 Gd 0.4 Dy 0.4 Yb 1.1 TiO 5 , and Sm 0.2 Gd 0.2 Dy 0.2 Yb 1.4 TiO 5 . The aim was to produce single‐phase novel materials with cubic symmetry, capable of incorporating a wide variety of cations and with acceptable radiation tolerance. The chemistry flexibility and radiation tolerance are some of the major desirable properties for nuclear waste‐form materials. By using multiple lanthanides the average lanthanide radius can be controlled and consequently the structure, along with properties such as radiation tolerance. The radiation tolerance was assessed using in situ 1 MeV krypton irradiation and transmission electron microscopy characterization. Those materials for which cubic symmetry was achieved displayed better radiation tolerance; a greater critical fluence of ions ( F c ) was required for the crystalline to amorphous transition, and a lower temperature was required to maintain crystallinity ( T c ) during irradiation.
DyNi4As2 crystallizes in the tetragonal P4_2/mnm space group. The structure is three-dimensional. Dy is bonded to six equivalent As atoms to form a mixture of distorted edge and corner-sharing DyAs6 octahedra. The corner-sharing octahedral tilt angles are 40°. There are two shorter (2.89 Å) and four longer (2.92 Å) Dy–As bond lengths. Ni is bonded in a 3-coordinate geometry to three equivalent As atoms. There are two shorter (2.40 Å) and one longer (2.41 Å) Ni–As bond lengths. As is bonded in a 9-coordinate geometry to three equivalent Dy and six equivalent Ni atoms.
DyMn2Ge2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Dy is bonded in a 8-coordinate geometry to eight equivalent Ge atoms. All Dy–Ge bond lengths are 3.07 Å. Mn is bonded to four equivalent Ge atoms to form a mixture of edge and corner-sharing MnGe4 tetrahedra. All Mn–Ge bond lengths are 2.43 Å. Ge is bonded in a 9-coordinate geometry to four equivalent Dy, four equivalent Mn, and one Ge atom. The Ge–Ge bond length is 2.59 Å.
Dy(Pt4P)2 crystallizes in the monoclinic C2/m space group. The structure is two-dimensional and consists of one Dy(Pt4P)2 sheet oriented in the (0, 0, 1) direction. Dy3+ is bonded to twelve Pt+0.62- atoms to form distorted face-sharing DyPt12 cuboctahedra. There are a spread of Dy–Pt bond distances ranging from 3.06–3.30 Å. There are four inequivalent Pt+0.62- sites. In the first Pt+0.62- site, Pt+0.62- is bonded in a 1-coordinate geometry to two equivalent Dy3+ and one P1+ atom. The Pt–P bond length is 2.23 Å. In the second Pt+0.62- site, Pt+0.62- is bonded in a distorted single-bond geometry to two equivalent Dy3+ and one P1+ atom. The Pt–P bond length is 2.29 Å. In the third Pt+0.62- site, Pt+0.62- is bonded in a distorted single-bond geometry to one Dy3+ and one P1+ atom. The Pt–P bond length is 2.33 Å. In the fourth Pt+0.62- site, Pt+0.62- is bonded in a distorted bent 120 degrees geometry to one Dy3+ and two equivalent P1+ atoms. Both Pt–P bond lengths are 2.36 Å. P1+ is bonded in a 5-coordinate geometry to five Pt+0.62- atoms.