Isothermal section of the Al-Dy-Zr ternary system at 773 K

The phase relations in the Al-Dy-Zr ternary system at 773 K have been investigated by X-ray powder diffraction (XRD) and scanning electron microscope (SEM) with energy disperse X-ray spectroscopy (EDX) in backscattered electron imaging (BSE) modes. The isothermal section at this temperature is featured with 17 single-phase regions, 32 two-phase regions and 16 three-phase regions. Besides, the ternary compound Al₃₀Dy₇Zr₃ has been confirmed to be existed. The maximum solid solubility of Zr in AlDy₂, Al₂Dy₃, AlDy, Al₂Dy and Al₃Dy at 773 K is determined to be 11.5 at.%, 7.8 at.%, 2.4 at.%, 22.5 at.% and 2.5 at.%, respectively.     

The Isothermal Section of the Phase Diagram of Dy-Sm-Ge Ternary System at 873 K

The interaction of components in the Dy-Sm-Ge system at 873 K was investigated by means of x-ray phase and structural analyses, microstructural analysis and energy dispersive x-ray spectroscopy. The existence of the continuous solid solutions between the isostructural binary germanides of the Dy_1?xSm_xGe (CrB-type), Dy_5-xSm_xGe₄ (Sm₅Ge₄-type) and Dy_5-xSm_xGe₃ (Mn₅Si₃-type) were established. The limited solid solutions based on the binary germanides of the SmGe₂ (α-ThSi₂-type), DyGe₂ (TbGe₂-type) and Dy₁₁Ge₁₀ (Ho₁₁Ge₁₀-type) are formed. The solubility of Dy in SmGe₂ is 15 at.%, Sm in DyGe₂ and Dy₁₁Ge₁₀ ? 10 at.%, Sm. Two ternary Sm_xDy_1?xGe_1.5 (x?=?0.15-0.50) and Sm₂Dy₂Ge₇ compounds were found. Sm_xDy_1?xGe_1.5 crystallizes in AlB₂ structure type. The crystal structure of the new ternary compound of the Sm₂Dy₂Ge₇ (ordered superstructure to Nd₄Ge₇-type, Pearson symbol oS44, space group C222₁, a?=?0.5942(1), b?=?1.3823(4), c?=?1.1801(3) nm, V?=?0.9694 nm³) was investigated by means of x-ray single crystal diffraction. The germanium atoms form 3D anionic network the existence of which was confirmed by electronic structure calculations.     

The isothermal section of Dy-Co-Cr ternary system at 500 °C

The isothermal section of the Dy-Co-Cr ternary system at 500 °C was investigated by X-ray powder diffraction (XRD), metallography and scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS). The isothermal section consists of 11 single-phase regions, 20 two-phase regions and 10 three-phase regions. The only ternary compound DyCo_12−xCr_x (space group I4/mmm) with ThMn₁₂-type structure was confirmed in this system. The homogeneity range in DyCO_12−xCr_x was found to be about x = 3.6-4.4. The lattice parameters for DyCO_12−xCr_x with 3.6 ≤ x ≤ 4.4 are a = 0.8312-0.8334 nm and c = 0.4706-0.4722 nm. The maximum solid solubilities of Cr in Dy₂Co₁₇, DyCo₃ and DyCo₂ are about 16.0, 5.0 and 17.0 at.%, respectively.     

The studies of phase relation, microstructure, magnetic transition, magnetocaloric effect in (Gd1−xErx)5Si1.7Ge2.3 compounds

The phase relation, microstructure, Curie temperatures (T_C), magnetic transition, and magnetocaloric effect of (Gd_1−xEr_x)₅Si_1.7Ge_2.3 (x = 0, 0.05, 0.1, 0.15, and 0.2) compounds prepared by arc-melting and then annealing at 1523 K (3 h) using purity Gd (99.9 wt.%) are investigated. The results of XRD patterns and SEM show that the main phases in those samples are mono-clinic Gd₅Si₂Ge₂ type structure. With increase of Er content from x = 0 to 0.2, the values of magnetic transition temperatures (T_C) decrease linearly from 228.7 K to 135.3 K. But the (Gd_1−xEr_x)₅Si_1.7Ge_2.3 compounds display large magnetic entropy near their transition temperatures in a magnetic field of 0-2 T. The maximum magnetic entropy change in (Gd_1−xEr_x)₅Si_1.7Ge_2.3 compounds are 24.56, 14.56, 16.84, 14.20, and 13.22 J/kg K⁻¹ with x = 0, 0.05, 0.1, 0.15, and 0.2, respectively.     

Isothermal section of the Ho-Co-Fe system at 773 K

The 773 K isothermal section of the phase diagram of the Ho-Co-Fe ternary system was investigated by using X-ray diffraction technique, metallographic analysis and scanning electron microscopy with energy dispersive analysis. The isothermal section of the ternary system consists of 6 three-phase regions, 16 two-phase regions and 11 single-phase regions. Three pairs of corresponding compounds of Ho-Co and Ho-Fe systems, i.e., Ho₂Co₁₇ and Ho₂Fe₁₇, HoCo₃ and HoFe₃, HoCo₂ and HoFe₂, form a continuous series of solid solution. At 773 K the compound Ho₆Fe_23−xCo_x was found to have a wide homogeneity range from 0 to 29 at.% Co. The maximum solid solubilities of Fe in Co, Ho₂Co₇, Ho₁₂Co₇ and Ho₃Co were determined to be about 10, 9, 2 and 5 at.% Fe, respectively. The maximum solid solubility of Co in Fe is found to be 78 at.% Co.     

Isothermal section of the Y-Co-V ternary system at 500 °C

The isothermal section of the Y-Co-V system at 500 °C has been investigated by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray spectroscopy. Only one ternary compound YV_xCo_12−x with a homogeneity range of 1.30 ≤ x ≤3.64 was found in this system. The maximum solid solubilities of V in Y₂Co₁₇, Y₂Co₇, YCo₃, YCo₂ and Y₃Co are about 10.0, 1.0, 3.0, 4.0 and 4.0 at.% V, respectively. The compounds VCo and VCo₃ have a homogeneity range of 46-66 at.% V and 22-30 at.% V, respectively. The maximum solid solubility of Y in VCo is about 2.0 at.% Y.     

Phase Equilibria of the Al-Mo-Dy Ternary System at 873 K

The phase relationship in the Al-Mo-Dy ternary system at 873 K has been investigated mainly by means of x-ray powder diffraction and scanning electron microscopy. The existences of ten binary compounds (i.e. AlMo₃, Al₈Mo₃, Al₄Mo, Al₅Mo, Al₁₂Mo, AlDy₂, Al₂Dy₃, AlDy, Al₂Dy and Al₃Dy) and one ternary compound (Al₄₃Mo₄Dy₆) have been confirmed. A new ternary compound Al₄Mo₂Dy (with a similar structure of the reported Al₄Mo₂Er) was found in the system. The 873 K phase diagram of this system consists of 15 single-phase regions, 29 two-phase regions and 15 three-phase regions. The maximum solid solubility of Al in AlMo₃ and Al₈Mo₃ is about 6 and 5 at.%, respectively.     

Effect of non-magnetic doping on multi-step magnetization behavior of Dy50−xAlxAg50

The electrical transport and magnetization measurements have been carried out on Al-doped polycrystalline intermetallic compounds Dy_50−xAl_xAg₅₀ (x = 0, 0.3, 0.6, 1.2, 1.8) in a pulsed high magnetic field, in which multi-step magnetization is observed. Partial substitute of non-magnetic Al³⁺ for Dy³⁺ ions in the compounds increases the critical magnetic fields and the relative area of the magnetic hysteresis loop, which result from the pinning effect, lattice distortion, the change of coupling strength and dilution effect related to the Al³⁺ doping.The experimental results indicate that non-magnetic Al³⁺ ions and induced amorphous phase can pin the rotation and/or growth of magnetic domains, thus, the critical magnetic field can be enhanced by doping non-magnetic ions in the magnetic materials, especially in the permanent magnet materials.     

Experimental study of the isothermal section of the Ho-Fe-Cr system at 873 K

The isothermal section of the Ho-Fe-Cr ternary system was investigated by means of X-ray powder diffraction (XRD), metallography and scanning electron microscopy (SEM) equipped with energy dispersive X-ray spectroscopy (EDS). The ternary compound HoFe_12−xCr_x (x = 2) was characterized and the homogeneity range of the various ternary solutions was studied. It crystallizes with ThMn₁₂-type structure, space group I4/mmm and unit parameters a = 0.8406 nm and c = 0.4756 nm. The homogeneity range in HoFe_12−xCr_x was determined as x = 1.9-3.6, i.e. 14.6-27.7 at.% Cr. The maximum solid solubilities of Cr in Fe, Ho₂Fe₁₇, Ho₆Fe₂₃, HoFe₃ and HoFe₂ are about 28.0 at.%, 4.0 at.%, 13.0 at. %, 3.0 at.% and 11.0 at.%, respectively.     

Phase relationships in the Al-rich region of the Al-Cu-Er system

The Al-rich region of the ternary Al-Cu-Er system is investigated using the method of X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectroscopy. Phase equilibria in the Al-rich region of the Al-Cu-Er system at 673 K have been obtained, and the microstructures of as-cast alloys in the Al-rich region are also investigated. One ternary phase τ₁-Al₈Cu₄Er with a composition of 59.4-60.4 at.% Al, 32.2-33.8 at.% Cu, and 6.4-7.7 at.% Er is observed in both as-cast and annealed alloys. At 673 K, the binary Al₃Er phase dissolves about 3.51 at.% Cu. The calculated solidification paths (based on the CALPHAD method) of as-cast alloys are in agreement with the experimental results.     

Effect of Hf on structure and age hardening of Ti-Al-N thin films

Protective coatings for high temperature applications, as present e.g. during cutting and milling operations, require excellent mechanical and thermal properties during work load. The Ti_1 − xAl_xN system is industrially well acknowledged as it covers some of these requirements, and even exhibits increasing hardness with increasing temperature in its cubic modification, known as age hardening. The thermally activated diffusion at high temperatures however enables for the formation of wurtzite AlN, which causes a rapid reduction of mechanical properties in Ti_1 − xAl_xN coatings. The present work investigates the possibility to increase the formation temperature of w-AlN due to Hf alloying up to 10 at.% at the metal sublattice of Ti_1 − xAl_xN films. Ab initio predictions on the phase stability and decomposition products of quaternary Ti_{1 − x − y}Al_xHf_yN alloys, as well as the ternary Ti_1 − xAl_xN, Hf_1 − xAl_xN and Ti_1 − zHf_zN systems, facilitate the interpretation of the experimental findings. Vacuum annealing treatments from 600 to 1100 °C indicate that the isostructural decomposition, which is responsible for age hardening, of the Ti_{1 − x − y}Al_xHf_yN films starts at lower temperatures than the ternary Ti_1 − xAl_xN coating. However, the formation of a dual phase structure of c-Ti_1 − zHf_zN (with z = y/(1 − x)) and w-AlN is shifted to ~ 200 °C higher temperatures, thus retaining a film hardness of ~ 40 GPa up to ~ 1100 °C, while the Hf free films reach the respective hardness maximum of ~ 38 GPa already at ~ 900 °C. Additional annealing experiments at 850 and 950 °C for 20 h indicate a substantial improvement of the oxidation resistance with increasing amount of Hf in Ti_{1 − x − y}Al_xHf_yN.     

Structural, magnetic and electrical properties of Al substituted Ni-Zn ferrite nanoparticles

Nanocrystalline ferrite materials having the general formula Ni_0.7Zn_0.3Fe_2−xAl_xO₄ (0.0 ≤ x ≤ 0.5) have been synthesized by citrate-gel auto combustion method and characterized using X-ray diffraction (XRD), energy dispersive X-ray (EDX), field emission scanning electron microscopy (FE-SEM), dc magnetization, dielectric and impedance spectroscopy measurements. XRD studies confirm that all the samples show single phase cubic spinel structure. The crystallite size of Ni_0.7Zn_0.3Fe_2−xAl_xO₄ (0.0 ≤ x ≤ 0.5) nanoparticles calculated using the Debye-Scherrer formula was found in the range of 13-17 nm. The value of lattice parameter ‘a’ is found to decrease with increasing Al³⁺ content. EDX patterns confirm the compositional formation of the synthesized samples. FE-SEM micrographs show that all the samples have nano-crystalline behavior and particles show spherical shape. The variation of dielectric properties ?′,?″, and tan δ with frequency shows the dispersion behavior which is explained in the light of Maxwell-Wagner type of interfacial polarization in accordance with the Koop's phenomenological theory. The dc magnetization studies infer that magnetic moment of Ni_0.7Zn_0.3Fe_2−xAl_xO₄ (0.0 ≤ x ≤ 0.5) nanoparticles was found to decrease with Al doping. Impedance spectroscopy techniques have been used to investigate the effect of grain and grain boundary on the electrical properties of the synthesized compounds.     

Thermoelectric properties of n-type Ca1−xDyxMn1−yNbyO3−δ compounds (x = 0, 0.02, 0.1 and y = 0, 0.02) prepared by spray-drying method

We report the high temperature thermoelectric properties of Ca_1−xDy_xMn_1−yNb_yO_3−δ (x = 0, 0.02, 0.1 and y = 0, 0.02) synthesized by spray-drying method. A maximum power factor (PF) value of 2.65 μW K⁻² cm⁻¹ is obtained at 1100 K for CaMn_0.98Nb_0.02O_3−δ. This represents an improvement of about 75% with respect to undoped CaMnO_3−δ sample at the same temperature. We also provide a complete structural characterization of the samples.     

Activity determination in the alumina-dysprosia system by Knudsen effusion mass spectrometry

The vaporization of Al-Dy-O mixtures has been investigated by the Knudsen effusion mass spectrometry technique. The saturated vapor has been found to consist of the atoms Al, O and the molecules AlO, Al₂O, DyO. At the initial stage the vaporization of Dy₂O₃ and Al₂O₃-Dy₂O₃ mixtures was found to be incongruent and accompanied by some loss of oxygen. An attainment of congruently vaporizing composition and equilibrium state takes quite a long time. The activities of binary oxides have been measured at T = 2130 K. The Gibbs energies and enthalpies have been derived for formation of the compounds Dy₄Al₂O₉, DyAlO₃ and Dy₃Al₅O₁₂ from sesquioxides.     

Peculiarities of component interaction in {Gd, Er}-V-Sn Ternary systems at 870 K and crystal structure of RV6Sn6 stannides

The phase equilibria in the Gd-V-Sn and Er-V-Sn ternary systems were studied at 870 K by means of X-ray and metallographic analyses in the whole concentration range. Both Gd-V-Sn and Er-V-Sn systems are characterized by formation of one ternary compound at investigated temperature, with stoichiometry RV₆Sn₆ (SmMn₆Sn₆-type, space group P6/mmm, a = 0.55322(3) nm, c = 0.91949(7) nm for Gd, a = 0.55191(2) nm, c = 0.91869(8) nm for Er). Solubility of the third component in the binary compounds was not observed. Compounds with the SmMn₆Sn₆-type were also found with Dy, Ho, Tm, and Lu, while YV₆Sn₆ compound crystallizes in HfFe₆Ge₆ structure type. All investigated compounds are the first ternary stannides with rare earth elements and vanadium.     

First-principles phase stability calculations and estimation of finite temperature effects on pseudo-binary Mg6(PdxNi1−x) compounds

The stability of pseudo-binary Mg₆(Pd_xNi_1?x) compounds has been studied at T = 0 K via first-principles calculations and at 673 K by thermodynamic modelling of finite temperature effects. At 0 K, these compounds are not stable since their formation energy is above the convex hull defined by the Mg, Mg₂Ni and Mg₆Pd phases, although the energy difference is not very high. However, at 673 K, vibrational and configurational entropic effects allow the stabilisation of some of the calculated pseudo-binary Mg₆(Pd_xNi_1?x) compounds. The vibrational contribution to the thermodynamic properties of the studied compounds has been calculated from Debye temperatures in the harmonic approximation. Also, the configurational entropy has been estimated taking into account the possible distribution of Pd and Ni between the several sites available in the pseudo-binary structure. The identification of intrinsic disorder and the associated energies and entropy are innovative features of this work. The phase diagram at the Mg-rich corner derived from these calculations is in fairly good agreement with recently published experimental results. In addition, the Ni for Pd substitution has been studied for the several sites available for Pd in the binary Mg₆Pd compound. The calculated preferential site occupancy is in agreement with the site occupancy factors determined in recent neutron diffraction experiments.     

Thermodynamics of Al1−xGaxN solid solution: Inclination for phase separation and ordering

Although Al_1−xGa_xN semiconductors are used in lighting, displays and high-power amplifiers, there is no experimental thermodynamic information on nitride solid solutions. Thermodynamic data are useful for assessing the intrinsic stability of the solid solution with respect to phase separation and extrinsic stability in relation to other phases such as metallic contacts. The activity of GaN in Al_1−xGa_xN solid solution is determined at 1100 K using a solid-state electrochemical cell: Ga + Al_1−xGa_xN/Fe, Ca₃N₂//CaF₂//Ca₃N₂, N₂ (0.1 MPa), Fe. The solid-state cell is based on single crystal CaF₂ as the electrolyte and Ca₃N₂ as the auxiliary electrode to convert the nitrogen chemical potential established by the equilibrium between Ga and Al_1−xGa_xN solid solution into an equivalent fluorine potential. Excess Gibbs free energy of mixing of the solid solution is computed from the results. Results suggest an unusual mixing behavior: a mild tendency for ordering at three discrete compositions (x = 0.25, 0.5 and 0.75) superimposed on predominantly positive deviation from ideality. The lattice parameters exhibit slight deviation from Vegard’s law, with the a-parameter showing positive and the c-parameter negative deviation. Although the solid solution is stable in the full range of compositions at growth temperatures, thermodynamic instability is indicated at temperatures below 410 K in the composition range 0.26 ? x ? 0.5. At 355 K, two biphasic regions appear, with terminal solid solutions stable only for 0 ? x ? 0.26 and 0.66 ? x ? 1. The range of terminal solid solubility reduces with decreasing temperature.     

Preparation, structure and electrical conductivity of the pyrochlore-type phase Sm2Zr2O7 codoped with bivalent magnesium and trivalent dysprosium cations

The pyrochlore-type phases with the compositions of SmDy_1−xMg_xZr₂O_7−x/2 (0 ≤ x ≤ 0.20) have been prepared by pressureless-sintering method for the first time as possible solid electrolytes. The structure and electrical conductivity of SmDy_1−xMg_xZr₂O_7−x/2 ceramics have been studied by the X-ray diffraction (XRD), scanning electron microscopy (SEM) and impedance spectroscopy measurements. SmDy_1−xMg_xZr₂O_7−x/2 (x = 0, 0.05, 0.10) ceramics exhibit a single phase of pyrochlore-type structure, and SmDy_1−xMg_xZr₂O_7−x/2 (x = 0.15, 0.20) ceramics consist of pyrochlore phase and a small amount of the second phase magnesia. The total conductivity of SmDy_1−xMg_xZr₂O_7−x/2 ceramics obeys the Arrhenius relation, and the total conductivity of each composition increases with increasing temperature from 673 to 1173 K. SmDy_1−xMg_xZr₂O_7−x/2 ceramics are oxide-ion conductors in the oxygen partial pressure range of 1.0 × 10⁻⁴ to 1.0 atm at all test temperature levels. The highest total conductivity value is about 8 × 10⁻³ S cm⁻¹ at 1173 K for SmDy_1−xMg_xZr₂O_7−x/2 ceramics.     

Electrical, magnetic, and Hall properties of AlxCoCrFeNi high-entropy alloys

This investigation explores the electrical and magnetic properties of as-cast, -homogenized, and -deformed Al_xCoCrFeNi (C-x, H-x, and D-x, respectively) alloys at various temperatures from 4.2 to 300 K. Experimental results reveal that carrier density of the alloys is of 10^22-23 cm⁻³. H-x has a carrier mobility of 0.40-2.61 cm² V⁻¹ s⁻¹. The residual electrical resistivity of the alloys varies from 100 to 220 μΩ cm. The temperature coefficient of resistivity (TCR) of H-2.00 is small (82.5 ppm/K). Therefore, defects in the lattice dominate electrical transportation. Some compositions exhibit Kondo-like behavior. At 300 K, H-0.50, H-1.25, and H-2.00 are ferromagnetic, while H-0.00, H-0.25, and H-0.75 are paramagnetic. Al and AlNi-rich phases reduce the ferromagnetism of single FCC and single BCC H-x, respectively. Spin glass behavior of some compositions is also observed. Alloys H-x are of the hole-like carrier type, and ferromagnetic H-x exhibits an anomalous Hall effect (AHE).     

Magnetic behaviour and experimental study of the magnetocaloric effect in the pseudobinary Laves phase Er1−xDyxCo2

We have investigated the crystal structure, the bulk magnetization characteristics and the magnetocaloric properties of Er_1−xDy_xCo₂ compounds. X-ray diffraction (XRD) analyses confirm that all these Laves phase type compounds crystallize in the cubic MgCu₂-type structure. First, the magnetization behaviour and the magnetic transition are analyzed in terms of Landau theory. Then, a direct correlation was pointed out between the character of the magnetic transition and the behaviour of the cell parameter versus x. Substitution of Dy to Er enhances markedly the Curie temperature T_C from 35 to 142 K, while ΔS the corresponding change of isothermal entropy decreases significantly. The refrigerant capacity of the Er_1−xDy_xCo₂ compounds is discussed and our experimental data are compared with the corresponding theoretical results reported in the literature [de Oliveira, von Ranke, J. Magn. Magn. Mater. 264 (2003) 55].