ZrNiAl-type Structure Research Articles

Enhancement of the anomalous Hall effect by distorting the Kagome lattice in an antiferromagnetic material

In topological magnetic materials, the topology of the electronic wave function is strongly coupled to the structure of the magnetic order. In general, ferromagnetic Weyl semimetals generate a strong anomalous Hall conductivity (AHC) due to a large Berry curvature that scales with their magnetization. In contrast, a comparatively small AHC is observed in noncollinear antiferromagnets. We investigated HoAgGe, an antiferromagnetic (AFM) Kagome spin-ice compound, which crystallizes in a hexagonal ZrNiAl-type structure in which Ho atoms are arranged in a distorted Kagome lattice, forming an intermetallic Kagome spin-ice state in the ab-plane. It exhibits a large topological Hall resistivity of ~1.6 µΩ-cm at 2.0 K in a field of ~3 T owing to the noncoplanar structure. Interestingly, a total AHC of 2,800 Ω-1 cm-1 is observed at ~45 K, i.e., 4 TN, which is quite unusual and goes beyond the normal expectation considering HoAgGe as an AFM Kagome spin-ice compound with a TN of ~11 K. We demonstrate further that the AHC below TN results from the nonvanishing Berry curvature generated by the formation of Weyl points under the influence of the external magnetic field, while the skew scattering led by Kagome spins dominates above the TN. These results offer a unique opportunity to study frustration in AFM Kagome lattice compounds.

Crystal structure and electrochemical hydrogenation of HoNiIn1-xAlx (x = 0-1) solid solution

The influence of the substitution of indium by aluminum in HoNiIn compound at 873 K was investigated in the full concentration range by means of powder X-ray diffraction and EDX analysis. The formation of continuous solid solution was determined and changes of the unit cell parameters were calculated: HoNiIn1.0–0Al0–1.0 (ZrNiAl-type structure, space group P-62m, a = 0.74343(4)–0.69959(6) nm and c = 0.37472(3)–0.38289(4) nm, V = 0.17936(2)–0.16229(3) mn3). The best discharge capacity after electrochemical hydrogenation studies of HoNiIn1-xAlx solid solution is observed for battery prototypes with HoNiIn0.2Al0.8- and HoNiIn0.4Al0.6-based electrodes.

Growth, structural characterization, DFT study, and magnetic properties of the NdAuIn crystal

A crystal of NdAuIn was successfully grown using the optical floating zone technique. Single-crystal and powder XRD studies confirmed that NdAuIn adopts a hexagonal ZrNiAl-type structure. Comparative analysis of the crystal morphology was performed using the Bravais-Friedel, Donnay-Harker (BFDH) model. DTA analysis revealed that the NdAuIn phase melts congruently at 1136°C. The DFT-calculated enthalpy of formation is −774.192 meV/atom. A thermal expansion coefficient α = 4.1(3) × 10−5 K−1 was derived from the single crystal XRD measurements at 100, 200, and 300 K. The Sommerfeld coefficient γ of 1.262 (mJ/mol × K2) derived from the DFT calculations and the distribution of the density of electronic states, predict metallic conductivity for NdAuIn. The analysis of the charge density difference and Bader charge analysis show that the NdAuIn compound might be treated as polar intermetallic with negatively charged [AuIn]n− and positively charged Ndn+ sublattices. Magnetization measurements with the field parallel and perpendicular to the six-fold axis of the crystal revealed that NdAuIn is a Curie-Weiss paramagnet down to 25 K with an effective magnetic moment of ∼3.62 μB/Nd, which corresponds to the Nd3+ ion. The compound exhibits antiferromagnetic ordering at TN ∼2.4 K.

LaNiIn1–x Sn x and CeNiIn1–x Sn x solid solutions at T = 870 K

Abstract The solid solutions LaNiIn1–x Sn x and CeNiIn1–x Sn x were studied by means of X-ray powder diffraction and EDX analyses in the full concentration range for samples annealed at T = 870 K. The limited solubility of the fourth component in the starting compounds with equiatomic composition, and the limits and the unit cell parameters of the solid solutions have been determined. The crystal structure of CeNiIn0.57Sn0.43 was refined from single-crystal X-ray diffraction data: ZrNiAl-type structure; hexagonal space group P 6 ‾ $\overline{6}$ 2m, a = 0.74213(10), c = 0.40825(8) nm, R 1 = 0.0155, wR 2 = 0.0303, 282 independent hkl reflections and 15 refined parameters. The existence ranges within the solid solutions are discussed.

The system Hf–Re–Si at 10000C

The interaction of the components in the ternary system Hf–Re–Si was investigated by X-ray powder diffraction, scanning electron microscopy and energy-dispersive X-ray spectroscopy. The isothermal section of the phase diagram at 10000C was constructed in the full concentration range. The limits of solubility of Si in the binary compounds Hf5Re24 and HfRe2 were found to be 11 and 16 at.%, respectively. The existence of three ternary compounds was confirmed and their crystal structures were refined: HfReSi2 (ZrCrSi2-type structure, space group Pbam, a=9.1271(3) Å, b=10.0356(4) Å, c=8.0708(3) Å), HfReSi (ZrNiAl-type structure, space group P-62m, a=6.9240(2) Å, c=3.3890(1) Å) and k-phase Hf9+xRe4–xSi (Hf9Mo4B-type structure, space group P63/mmc, a=8.5835(12) Å, c=8.7135(13) Å). The character of the interaction between the components in the Hf–Re–Si system and related ternary systems is briefly discussed.

Synthesis and Crystal Structure of the Zintl Phases NaSrSb, NaBaSb and NaEuSb.

This work details the synthesis and the crystal structures of the ternary compounds NaSrSb, NaBaSb and NaEuSb. They are isostructural and adopt the hexagonal ZrNiAl-type structure (space group P6¯2m; Pearson code hP9). The structure determination in all three cases was performed using single-crystal X-ray diffraction methods. The structure features isolated Sb3- anions arranged in layers stacked along the crystallographic c-axis. In the interstices, alkali and alkaline-earth metal cations are found in tetrahedral and square pyramidal coordination environments, respectively. The formal partitioning of the valence electrons adheres to the valence rules, i.e., Na+Sr2+Sb3-, Na+Ba2+Sb3- and Na+Eu2+Sb3- can be considered as Zintl phases with intrinsic semiconductor behavior. Electronic band structure calculations conducted for NaBaSb are consistent with this notion and show a direct gap of approx. 0.9 eV. Additionally, the calculations hint at possible inverted Dirac cones, a feature that is reminiscent of topological quantum materials.

Ternary magnesium gallides – synthesis, crystal chemistry and properties of CaMgGa, SrMgGa, BaMgGa and YbMgGa

AbstractThe gallides CaMgGa, SrMgGa, BaMgGa and YbMgGa were synthesized from the elements in sealed tantalum ampoules in muffle furnaces. The phase purity of the samples was checked by powder X‐ray diffraction. CaMgGa and YbMgGa crystallize with the ZrNiAl type structure, space group P 2m, whereas SrMgGa and BaMgGa adopt an ordering variant of the Cu2Sb/PbFCl type, space group P4/nmm. The structures of SrMg0.884(7)Ga1.116(7) (a=459.23(9), c=792.43(12) pm, wR2=0.0371, 226 F2 values, 11 variables) and YbMgGa (a=774.55(7), c=411.95(4) pm, wR2=0.0329, 342 F2 values, 15 variables) were refined from single crystal X‐ray diffractometer data. Refinement of the occupancy parameters indicated a small degree of Mg/Ga mixing on the 2a site for the strontium compound. The [MgGa] substructures in both compounds are composed of condensed Mg@Ga4 tetrahedra with 4×287 pm Mg−Ga in SrMg0.884Ga1.116 vs 2×282 and 2×296 pm in YbMgGa. The SrMgGa structure has a stacking of layers of edge‐sharing Mg@Ga4 and Sr4 tetrahedra. Electronic structure calculations indicate a net charge transfer from strontium and magnesium to gallium. YbMgGa completes the series of REMgGa gallides. Temperature dependent magnetic susceptibility studies reveal weak Pauli paramagnetism, confirming divalent ytterbium.

Semimetallic Kondo lattice behavior in YbPdAs with a distorted kagome structure

We have synthesized YbPdAs with the hexagonal ZrNiAl-type structure, in which the Yb-atoms form a distorted kagome sublattice in the hexagonal basal plane. Magnetic, transport, and thermodynamic measurements indicate that YbPdAs is a low-carrier Kondo lattice compound with an antiferromagnetic transition at $T_\mathrm{N}$ = 6.6 K, which is slightly suppressed in applied magnetic fields up to 9 T. The magnetic entropy at $T_\mathrm{N}$ recovers only 33\% of $R\ln{2}$, the full entropy of the ground state doublet of the Yb-ions. The resistivity displays a $-\ln T$ dependence between 30 and 15 K, followed by a broad maximum at $T\rm_{coh}$ = 12 K upon cooling. Below $T\rm_{coh}$, the magnetoresistance changes from negative to positive, suggesting a crossover from single-ion Kondo scattering processes at intermediate temperatures to coherent Kondo lattice behaviors at low temperatures. Both the Hall resistivity measurements and band structure calculations indicate a relatively low carrier concentration in YbPdAs. Our results suggest that YbPdAs could provide an opportunity for examining the interplay of Kondo physics and magnetic frustration in low carrier systems.

The system Ho–Ni–In at 870 K

The components interaction in the Ho–Ni–In system was investigated by X-ray powder diffraction and, partially, scanning electron microscopy with energy-dispersive X-ray spectroscopy. Isothermal section of the phase diagram was constructed in full concentration range at 870 K. The samples were synthesized in an arc-furnace on a water-cooled Cu-plate under an argon atmosphere and annealed in silica tubes at 870 K for 720 h. The phase analysis was performed by X-ray powder diffraction method. Twelve ternary compounds, namely HoNi 9 In 2 (YNi 9 In 2 -type structure), Ho 4 Ni 11 In 2 0 (U 4 Ni 11 Ga 2 0 -type structure), HoNi 4 In (MgCu 4 Sn-type structure), Ho 10 Ni 9 In 20 (Ho 10 Ni 9 In 20 -type structure), HoNi 1.0-0.5 In 1.0-1.5 (ZrNiAl-type structure), Ho 2 Ni 2 In (Mn 2 AlB 2 -type structure), Ho 2 Ni 1.8 In (Mo 2 FeB 2 -type structure), Ho 5 Ni 2 In 4 (Lu 5 Ni 2 In 4 -type structure), Ho 11 Ni 4 In 9 (Nd 11 Pd 4 In 9 -type structure), Ho 6 Ni 2 In (Ho 6 Co 2 Ga-type structure), ~ Ho 6 NiIn 2 (unknown structure) і Ho 13.35 Ni 3.17 In 3.48 (Lu 14 Co 3 In 3 -type structure) exist in the Ho–Ni–In system at the temperature of annealing. The substitution of Ni for In was observed for HoNi 1.00-0.50 In 1.00-1.50 compound. Besides, Ho can enter the structure of NiIn (CoSn-type structure) compound leading to formation of including subtraction type solid solution, which is stable up to 8 at. % Ho. The composition of this solid solution can be described by the formula Ho 0-0 . 08 NiIn 1-0 . 94 . The inclusion of holmium and indium atoms in position (2 e ) with the simultaneous exclusion of a small amount of indium atoms from position (1 a ) takes place in the homogeneity range of this solid solution. The character of interaction between the components in the ternary Ho–Ni–In system is similar to other related system R – T –In ( R – rare earth of the yttrium subgroup). The common feature of all these systems is the existence of large number isotypical ternary compounds, the formation of homogeneity range for compounds with ZrNiAl-type structure and including-subtraction type solid solutions based on the binary compound NiIn. Ke y words: holmium, indium, ternary compound, ternary system, isothermal section.

The solid solution TbNiIn1−x Ga x

Abstract Phase formation in the solid solution TbNiIn1−x Ga x at 873 K was investigated in the full concentration range by means of powder X-ray diffraction and EDX analysis. The samples were synthesized by arc-melting of the pure metals with subsequent annealing at 873 K for one month. The influence of the substitution of indium by gallium on the type of structure and solubility was studied. The solubility ranges have been determined and changes of the unit cell parameters were calculated on the basis of powder X-ray diffraction data: TbNiIn1–0.4Ga0–0.6 (ZrNiAl-type structure, space group P 6 ‾ 2 m $P\bar{6}2m$ , a = 0.74461(8)–0.72711(17) and c = 0.37976(5)–0.37469(8) nm); TbNiIn0.2–0Ga0.8–1.0 (TiNiSi-type structure, space group Pnma, а = 0.68950(11)–0.68830(12), b = 0.43053(9)–0.42974(6), с = 0.74186(10)–0.73486(13) nm). The crystal structures of TbNiGa (TiNiSi type, Pnma, a = 0.69140(5), b = 0.43047(7), c = 0.73553(8) nm, wR2=0.0414, 525 F 2 values, 21 variables), TbNiIn0.83(1)Ga0.17(1) (ZrNiAl type, P 6 ‾ 2 m $P\bar{6}2m$ , a = 0.74043(6), c = 0.37789(3) nm, wR2 = 0.0293, 322 F 2 values, 16 variables) and TbNiIn0.12(2)Ga0.88(2) (TiNiSi type, Pnma, a = 0.69124(6), b = 0.43134(9), c = 0.74232(11) nm, wR2 = 0.0495, 516 F 2 values, 21 variables) have been determined. The characteristics of the solid solutions and the variations of the unit cell parameters are briefly discussed.

Curie temperature adjustment in the solid solution Gd1–x Y x PtMg

Abstract GdPtMg and YPtMg (both crystallize with the ZrNiAl-type structure) form a complete solid solution Gd1–x Y x PtMg. Samples in x = 0.1 steps were synthesized from the elements in sealed tantalum ampoules in an induction furnace and characterized by Guinier powder patterns. The structures of four members of the solid solution were refined from single-crystal X-ray diffractometer data, confirming the mixed occupation of the Gd/Y site; however, without any indication for Gd/Y ordering. Temperature dependent magnetic susceptibility measurements reveal Curie-Weiss behavior for all samples and ferromagnetic ordering in the low-temperature regime. The Curie temperature drops linearly from 97.6 K for GdPtMg to 3.7 K for Gd0.1Y0.9PtMg. All samples are soft ferromagnets. The Gd/Y substitution is a suitable tool for adjusting magnetic ordering temperatures of gadolinium intermetallics over a broad temperature range.

A Noncentrosymmetric Polymorph of LuRuGe.

We report a new polymorph of LuRuGe, obtained in indium flux. This phase exhibits the noncentrosymmetric ZrNiAl-type structure with the space group P6̅2m as determined by single-crystal X-ray diffraction. This polymorph can convert into another centrosymmetric polymorph (TiNiSi-type structure, space group Pnma) at high temperatures. We performed electrical transport, magnetization, and specific heat measurements on this new phase. It shows metallic behavior with a Hall sign change from negative at 2 K to positive at 125 K. LuRuGe exhibits Pauli paramagnetism as the ground state with no local magnetic moments from either the Ru or Lu site. The Debye temperature Θ = 348 K and electronic coefficient γe = 3.6 mJ K-2 mol-1 are extracted from the low-temperature specific heat data in LuRuGe. We also carried out first-principles density functional theory calculations to map out the electronic band structure and density of states. There are several electronic bands crossing the Fermi level, supporting a multiband scenario consistent with the Hall sign change. The density of states around the Fermi level is mainly from Ru 4d and Ge 4p electrons, indicating a strong hybridization between those atomic orbitals.

The system ErNiAl–ZrNiAl at 600 °С and the high-temperature high-pressure modification of ErNiAl

A series of samples along the line ErNiAl–ZrNiAl was synthesized by arc-melting, and annealed at 600 °C or at 1400 °C / 8 GPa. Phase and structural analyses were performed based on X-ray powder diffraction data collected at room temperature on a diffractometer STOE Stadi P (Cu K α 1 radiation, angular range 6° ≤ 2 θ ≤ 110°, scan step 0.015°). The structures were refined by the Rietveld method, using the program DBWS. The formation of limited solid solutions Er 1-0.79(4) Zr 0-0.21(4) NiAl and Zr 1-0.77(3) Er 0-0.23(3) NiAl, which both crystallize with ZrNiAl-type structures, was observed. It was found that high-temperature high-pressure annealing of the three-component (ErNiAl) and four-component (Er 2 ZrNi 3 Al 3 ) samples caused a transformation from the low-temperature modification of the compound ErNiAl with ZrNiAl-type structure to its high-temperature high-pressure modification with MgZn 2 -type structure. The latter showed low solubility of Zr (Er 0.91(3) Zr 0.09(3) NiAl). The structure of ht-hp ErNiAl (MgZn 2 -type) belongs to the family of Friauf-Laves phases: the coordination polyhedra of the Er atoms are 16-vertex Friauf polyhedra, and those of the Ni and Al atoms are 12-vertex icosahedra. The structure of the solid solutions Er 1- x Zr x NiAl and Zr 1- x Er x NiAl (ZrNiAl-type structure) belongs to the family of structures with trigonal prismatic coordination of the smallest atoms (Ni). The structures of the investigated compounds contain similar nets of atoms, in particular nets of triangles and pentagons. They are characterized by high packing coefficients (space filling), which reach 82 %. The highest value was observed for the compound ErNiAl in the sample annealed at 1400 °C / 8 GPa. It may be noted that high pressures generally increase the density, whereas high temperatures have the opposite effect. Key words : aluminide, X-ray powder diffraction, solid solution, crystal structure.

Phase equilibrium in the system Y-Ni-In at 870 K

Interaction of the components in Y ‑ Ni ‑ In system was investigated by X-ray powder methods and isothermal section of phase diagram was constructed at 870 K in full concentration range. The samples were synthesized in an arc-furnace on a water-cooled Cu-plate under an argon atmosphere and annealed in silica tubes at 870 K for one month. The phase analysis was performed by X-ray powder diffraction method. Twelve ternary compounds, namely YNi 9 In 2 (YNi 9 In 2 -type structure), Y 1-1 . 40 Ni 4 In 1-0 . 60 (MgCu 4 Sn-type structure), YNiIn 2 (MgCuAl 2 -type structure), Y 4 Ni 11 In 20 (U 4 Ni 11 Ga 20 -type structure), YNi 1 . 00-0 . 50 In 1 . 00-1 . 50 (ZrNiAl-type structure), Y 2 Ni 2 In (Mn 2 AlB 2 -type structure), Y 2 Ni 1 . 78 In (Mo 2 FeB 2 -type structure), Y 5 Ni 2 In 4 (Lu 5 Ni 2 In 4 -type structure), Y 11 Ni 4 In 9 (Nd 11 Pd 4 In 9 -type structure), Y 12 Ni 6 In (Sm 12 Ni 6 In-type structure), Y 13.84 Ni 3.19 In 2.97 (Lu 14 Co 3 In 3 -type structure), ~Y 3 Ni 0.05 In 0.95 (AuCu 3 -type structure) exist in the Y ‑ Ni ‑ In system at the temperature of annealing. Compound Y 3 Ni 2.26 In 3.74 exists at higher temperature. The substitution of Ni for In was observed for YNi 1.00-0.50 In 1.00-1.50 and In for Y in the case of Y 1-1,40 Ni 4 In 1-0,60 compound. Besides, yttrium can enter the structure of NiIn (CoSn-type) leading to formation of including-subtraction type solid solution, which is stable for 0 ‑ 8 at. % Y. The composition of this solid solution can be described by the formula Y 0-0 . 16 NiIn 1-0 . 93 . The inclusion of yttrium and indium atoms in position (2 e ) with the simultaneous exclusion of a small amount of indium atoms from position (1 a ) takes place in the homogeneity range of this solid solution. The character of component interaction in the ternary Y ‑ Ni ‑ In system is similar to other related ternary system R ‑ T ‑ In ( R – rare earth of the yttrium subgroup). The common feature of all these systems is the existence of large number isotypical ternary compounds, the formation of homogeneity range for compounds with ZrNiAl and including-subtraction type solid solutions based on the binary compound NiIn. Keywords: yttrium, indium, nickel, phase equilibria, ternary compound, crystal structure.

Different universality classes of isostructural UTX compounds (T=Rh,Co,Co0.98Ru0.02;X=Ga,Al)

Magnetization isotherms of the $5f$-electron ferromagnets URhGa, UCoGa, and $\mathrm{U}{\mathrm{Co}}_{0.98}{\mathrm{Ru}}_{0.02}\mathrm{Al}$ were measured at temperatures in the vicinity of their Curie temperature to investigate the critical behavior near the ferromagnetic phase transition. These compounds adopt the layered hexagonal ZrNiAl-type structure and exhibit huge uniaxial magnetocrystalline anisotropy. The critical \ensuremath{\beta}, \ensuremath{\gamma}, and \ensuremath{\delta} exponents were determined by analyzing Arrott-Noakes plots, Kouvel-Fisher plots, critical isotherms, scaling theory, and Widom scaling relations. The values obtained for URhGa and UCoGa can be explained by the results of the renormalization group theory for a two-dimensional (2D) Ising system with long-range interactions similar to URhAl reported by other investigators. On the other hand, the critical exponents determined for $\mathrm{U}{\mathrm{Co}}_{0.98}{\mathrm{Ru}}_{0.02}\mathrm{Al}$ are characteristic of a three-dimensional (3D) Ising ferromagnet with short-range interactions suggested in previous studies also for the itinerant $5f$-electron paramagnet UCoAl situated near a ferromagnetic transition. The change from the 2D to the 3D Ising system is related to the gradual delocalization of $5f$ electrons in the series of the URhGa, URhAl, and UCoGa to $\mathrm{U}{\mathrm{Co}}_{0.98}{\mathrm{Ru}}_{0.02}\mathrm{Al}$ and UCoAl compounds and appears close to the strongly itinerant nonmagnetic limit. This indicates possible new phenomena that may be induced by the change of dimensionality in the vicinity of the quantum critical point.

YIrIn with ZrNiAl-type structure

Abstract The indide YIrIn was synthesized from the elements in a sealed tantalum ampoule in a high-frequency furnace. YIrIn adopts the ZrNiAl type. The crystal structure was refined from single-crystal X-ray diffractometer data: P6–2m, a = 750.63(6), c = 392.04(3) pm, wR = 0.0346, 308 F 2 values and 16 variables. Refinement of the occupancy parameters revealed a small degree of Ir/In mixing (0.912(9) Ir2/0.088(9) In1) on the 2d site. The YIrIn structure contains two crystallographically independent iridium sites, both with tri-capped trigonal prismatic coordination: Ir1@In6Y3 and Ir2@In3Y6.

Structural transition and antiferromagnetic ordering in the solid solution CePd1−x Au x Al (x = 0.1–0.9)

Abstract The intermetallic solid solution CePd1−x Au x Al (x = 0.1–0.9) has been synthesized from the elements by arc-melting and subsequent annealing in induction followed by tube furnaces. The samples were characterized using the Guinier powder diffraction technique and the structures of the nominal compositions CeAuAl and CePd0.2Au0.8Al were refined from single crystal X-ray diffractometer data. For small values of x = 0.1–0.3, the compounds crystallize in the hexagonal ZrNiAl-type structure (space group P 6 ‾ $‾{6}$ 2m), while for x = 0.5–0.9 the orthorhombic TiNiSi-type structure (space group Pnma) was observed. In both structure types, the transition metal and aluminum atoms form a complex polyanionic network with the cerium atoms filling the respective cavities. The transition metal atoms are in both cases surrounded in the shape of a tri-capped trigonal prism, the connectivity of these units, however, is different. Temperature-dependent magnetic susceptibility measurements of all compounds indicated a stable trivalent oxidation state for the cerium atoms along with antiferromagnetic ordering around T N ∼ 3 K.

Effect of localization of 5f -electrons and pressure on magnetism in uranium intermetallics in spin-fluctuation theory

UCoGa and URhGa, two isostructural compounds show opposite signs of the initial response of Curie temperature to applied hydrostatic premenssure. To determine the physical origin of this contradiction the magnetization data measured with respect to temperature, magnetic field and hydrostatic pressure were analyzed in the framework of the Takahashi's spin-fluctuation theory. The parameters T0 and TA characterizing the distribution widths of the spin-fluctuation spectrum in the energy and wave vector space, respectively, and TC/T0, the degree of the 5f-electron localization have been determined. Examination of available experimental data for the other UTX (T = a transition metal, X = Al, Ga) ferromagnets having the ZrNiAl-type structure revealed some correlations between the degree of the 5f-electron localization represented by the spin-fluctuation parameters and the response of Curie-temperature on the applied pressure. These observations may be applied more generally to describe the localization and magnetic behaviors of the majority of the uranium ferromagnetic compounds.

Incoherent long period stacking ordered phases and age-hardening in Mg-Gd-Ga alloys

The intermetallic phases of as-cast and annealed Mg-5Gd-3.5Ga (at.%) alloys were characterized by means of electron microscopies. Coherent and incoherent 18R long period stacking ordered (LPSO) phases with α-Mg were observed in the alloys and the high diffusion coefficient of Ga was the key factor for the appearance of incoherent LPSO phases. Segregation and βF’ phases were observed in the peak-aged samples, which contributed to the large improvements of microhardness and compression properties after heat treatment. In addition, the GdMgGa phase with a hexagonal ZrNiAl-type structure was studied by transmission electron microscopy (TEM) and scanning transmission electron microscopy (STEM). The incoherent LPSO phases provided a new way of strengthening the mechanical properties of Mg alloys instead of introducing dispersive LPSO phases only.

The TbNiIn1-xMx (M = Al, Ge, Sb) systems

Interaction of the components in TbNiIn 1- x Al x , TbNiIn 1- x Ge x and TbNiIn 1- x Sb x systems at 873 K was investigated by means of X-ray phase and partially local analysis in full concentration range. The samples for the investigation were synthesized by arc-melting purity metals with subsequent annealing at 873 K for a month. Phase analysis was carried out by X-ray powder diffraction (DRON-2.0M, Fe K α-radiation, PANalytical X’Pert Pro, Cu K a- radiation, Guinier FR552, Cu K a-radiation). The EDX analysis of the samples and single crystal was carried out by REMMA-102-02 and Zeiss EVO MA10. The influence of Indium substitution by other p -element on the nature of interaction and solubility type was determined. Solubility ranges for solid solutions were found and changes of unit cell parameters were calculated: TbNiIn 1-0 Al 0-1 (ZrNiAl-type structure, space group P - 62 m , a = 0.7449–0.6997(2), c = 0.378–0.3889(1) nm); TbNiIn 1-0 . 6 Ge 0-0 . 4 (ZrNiAl-type structure, space group P - 62 m , а = 0.7449–0.74348(6), с = 0.378–0.38063(4) nm); TbNiGe 1-0 . 5 In 0-0 . 5 (TiNiSi-type structure, space group Pnma , а = 0.69499–0.69598(7), b = 0.42306–0.42475(4), с = 0.72813–0.72996(7) nm); TbNiSb 1 . 0-0 . 6 In 0-0 . 4 (MgAgAs-type structure, space group F -43 m , a = 0.62662(2)–0.62011(5) nm). The crystal structures of the TbNiIn 0 . 28 Al 0 . 72 compound were investigated by single crystal X-ray analysis (Stoe IPDS II diffractometer, Mo K α-radiation). The refined compositions are confirmed by the results of the EDX analysis (Zeiss EVO MA10 scanning electron microscope). The structures were solved and refined using JANA2006 package: ZrNiAl-type structure, space group P - 62 m, Pearson symbol hP 9, a = 0.71452(6), c = 0.38394(3) nm, R 1 = 0.0152, 307 F 2 values, 15 variables). The formation of solid solutions and the character of the unit cell parameters variation in the studied and related systems briefly discussed. Keywords: indium, solid solution, powder data, single crystal, crystal structure.