Dy Tm Research Articles

Synthesis, Crystal Structure and Properties of the New Laminar Quaternary Tellurides SrLnCuTe3 (Ln = Sm, Gd–Tm and Lu)

This paper reports for the first time on the new laminar quaternary orthorhombic heterometallic quaternary tellurides SrLnCuTe3, the fabrication of which has been a challenge until this work. Data on the crystal structure of tellurides complete the series of quaternary strontium chalcogenides SrLnCuCh3 (Ch = S, Se, Te). Single crystals of the compounds were synthesized from the elements by the halogenide-flux method at 1070 K. The compounds are crystallizing in two space groups Pnma (Ln = Sm, Gd and Tb) and Cmcm (Ln = Dy–Tm and Lu). For SrSmCuTe3 (a = 11.4592(7), b = 4.3706(3), c = 14.4425(9) Å, space group: Pnma) with the largest lanthanoid cation, Sr2+ shows C.N. = 7, whereas Sm3+ reveals a diminished coordination number C.N. = 6. For SrLuCuTe3 (a = 4.3064(3), b = 14.3879(9), c = 11.1408(7) Å, space group: Cmcm) with the smallest lanthanoid cation, coordination numbers of six are realized for both high-charged cations (Sr2+ and Lu3+: C.N. = 6). The cations Sr2+, Ln3+, Cu+ each take independent positions. The structures are built by distorted [CuTe4]7– tetrahedra, forming the infinite chains {∞1[Cu(Te1)1/1t(Te2)1/1t(Te3)2/2e]5−} along [010] in SrLnCuTe3 (Ln = Sm, Gd and Tb) and [100] in SrLnCuTe3 (Ln = Dy–Tm and Lu). The distortion of the polyhedra [CuTe4]7– was compared for the whole series SrLnCuTe3 by means of τ4-descriptor for the four coordinating Te2– anions, which revealed a decrease in the degree of distortion with a decreasing radius at Ln3+. The distorted octahedra [LnTe6]9– form layers {∞2[Ln(Te1)2/2(Te2)2/2(Te3)2/2]3−}. The distorted octahedra and tetrahedra fuse to form parallel layers {∞2[CuLnTe3]2−} and between them, the Sr2+ cations providing three-dimensionality of the structure are located. In the SrLnCuTe3 (Ln = Sm, Gd and Tb) structures, the Sr2+ cations center capped the trigonal prisms [SrTe6+1]12−, united in infinite chains {∞1[Sr(Te1)2/2(Te2)3/3(Te3)2/2]4−} along the [100] direction. The domains of existence of the Ba2MnS3, BaLaCuS3, Eu2CuS3 and KZrCuS3 structure types are defined in the series of orthorhombic chalcogenides SrLnCuCh3 (Ch = S, Se and Te). The tellurides SrLnCuTe3 (Ln = Tb–Er) of both structure types in the temperature range from 2 up to 300 K are paramagnetic, without showing clear signs of a magnetic phase transition.

New members of the tetragonal RE14T3Al3 (RE = Sc, Y, Dy–Tm, Lu; T = Cu, Rh, Pd) series

The rare-earth metal-rich RE14T3Al3 series (RE = Y, Gd–Tm, Lu) was extended to the transition metals T = Cu, Rh, and Pd. All compounds have been prepared by arc-melting the rare-earth elements with appropriate amounts of TAl precursors. The compounds crystallize in the tetragonal Gd14Co3In2.7-type structure with space group P42/nmc. Two structures (Y14Rh2.97(1)Al3.03(1): a = 952.99(4) pm, c = 2292.98(10) pm, wR2 = 0.0423, 2225 F2 values, 63 variables; Y14Pd3.16(1)Al2.84(1): a = 955.06(5) pm, c = 2298.77(10) pm, wR2 = 0.0416, 2225 F2 values, 63 variables) have been refined from single-crystal data, indicating T/Al mixing on two crystallographic sites. The lattice parameters of all synthesized representatives have been refined from Guinier powder X-ray diffraction data. The Y and Lu containing compounds show Pauli paramagnetic behavior, indicating that the transition metal atoms have filled d bands and exhibit no localized magnetic moment. From the other compounds only Er14Pd3Al3 was obtained as an X-ray pure sample. It shows paramagnetism, in line with the rare-earth atoms in the trivalent oxidation state and antiferromagnetic ordering below TN = 8.0(1) K. Detailed magnetic investigations on the other members were impossible due to the presence of, e.g., RE3T trace impurities.

Two series of rare earth metal-rich ternary aluminium transition metallides – RE 6Co2Al (RE=Sc, Y, Nd, Sm, Gd–Tm, Lu) and RE 6Ni2.25Al0.75 (RE=Y, Gd–Tm, Lu)

Abstract The rare earth metal-rich cobalt and nickel aluminium compounds with the general compositions RE 6Co2Al (RE=Sc, Y, Nd, Sm, Gd–Tm, Lu) and RE 6Ni2.25Al0.75 (RE=Y, Gd–Tm, Lu) have been synthesised from the elements by arc-melting, followed by annealing. Single-crystal X-ray diffraction experiments on Y6Co2.02(1)Al0.98(1) (Ho6Co2Ga type; Immm; a=944.1(2), b=952.4(2), c=999.0(2) pm; wR2=0.0452, 1123 F 2 values, 35 variables) and Y6Ni2.26(1)Al0.74(1) (Ho6Co2Ga type; Immm; a=938.30(5), b=959.45(5), c=996.05(6) pm; wR2=0.0499, 1131 F 2 values, 35 variables) revealed that the compounds form solid solutions according to the general formula RE 6(Co/Ni)2+ x Al1−x with different homogeneity ranges. The compounds of the Ni series can be obtained in X-ray pure form only with the nominal composition RE 6Ni2.25Al0.75. A significant increase of the U 22 component of the anisotropic displacement parameters of the Co/Ni2 atoms (4g site) was observed that requires a description of the structure with a split-position model at RT. Further investigations by low temperature (90 K) single-crystal X-ray diffraction experiments of Y6Co2.02(1)Al0.98(1) showed a significant decrease of U 22. Magnetic measurements were conducted on the X-ray pure members of the RE 6Co2Al (RE=Y, Dy–Tm, Lu) series. Antiferromagnetic ordering was observed for the members with unpaired f electrons with Néel temperatures up to T N=48.0(1) K and two spin reorientations for Dy6Co2Al.

Ternary indides RE 3 T 2In4 (RE=Dy–Tm; T=Pd, Ir)

Abstract The ternary rare earth transition metal-indides RE 3 T 2In4 (RE=Dy–Tm; T=Pd, Ir) were obtained from high-temperature reactions in sealed niobium ampoules. These indides adopt a hexagonal structure of the Lu3Co1.87In4 type (space group P6̅), a ternary ordered superstructure of the aristotype Fe2P. The structures of three different compounds were refined from single-crystal X-ray diffractometer data: a=768.20(6), c=381.97(3) pm, 1441 F 2 values, 24 parameters, wR2=0.0338 (Ho3Pd1.90In4); a=774.98(3), c=378.51(2) pm, 577 F 2 values, 23 parameters, wR2=0.0742 (Ho3Ir1.69In4.31) and a=780.3(1), c=369.4(1) pm, 573 F 2 values, 22 parameters, wR2=0.0403 (Tm3Ir1.51In4.49). Refinements of the occupancies revealed homogeneity ranges in case of the iridium-based crystals resulting from Ir/In mixing. The refined composition of the palladium compound was Ho3Pd1.90In4 resulting from defects on the Wyckoff position 1d, which was already reported for the prototype Lu3Co1.87In4. The geometrical motifs of the RE 3 T 2In4 structures are three different types of tricapped trigonal prisms around the transition metal and indium atoms which are condensed via common edges and triangular faces. Temperature dependent magnetic susceptibility measurements of Dy3Ir2In4 and Tm3Ir2In4 showed Curie-Weiss behavior and the experimental magnetic moments of 10.59(2) μB (Dy3Ir2In4) and 7.40(2) μB (Tm3Ir2In4) confirming stable trivalent RE 3+ states. Dy3Ir2In4 and Tm3Ir2In4 order antiferromagnetically with Néel temperatures of T N=13.6(5) and 5.4(5) K, respectively.

Crystal Structure, Spectroscopic Investigations, and Physical Properties of the Ternary Intermetallic REPt2Al3 (RE = Y, Dy–Tm) and RE2Pt3Al4 Representatives (RE = Tm, Lu)

The REPt2Al3 compounds of the late rare-earth metals (RE = Y, Dy–Tm) were found to crystallize isostructural. Single-crystal X-ray investigations of YPt2Al3 revealed an orthorhombic unit cell (a = 1080.73(6), b = 1871.96(9), c = 413.04(2) pm, wR2 = 0.0780, 942 F2 values, 46 variables) with space group Cmmm (oC48; q2pji2hedb). A comparison with the Pearson database indicated that YPt2Al3 forms a new structure type, in which the Pt and Al atoms form a [Pt2Al3]δ− polyanion and the Y atoms reside in the cavities within the framework. Via a group-subgroup scheme, the relationship between the PrNi2Al3-type structure and the new YPt2Al3-type structure was illustrated. The compounds with RE = Dy–Tm were characterized by powder X-ray diffraction experiments. While YPt2Al3 is a Pauli-paramagnet, the other REPt2Al3 (RE = Dy–Tm) compounds exhibit paramagnetic behavior, which is in line with the rare-earth atoms being in the trivalent oxidation state. DyPt2Al3 and TmPt2Al3 exhibit ferromagnetic ordering at TC = 10.8(1) and 4.7(1) K and HoPt2Al3 antiferromagnetic ordering at TN = 5.5(1) K, respectively. Attempts to synthesize the isostructural lutetium compound resulted in the formation of Lu2Pt3Al4 (Ce2Ir3Sb4-type, Pnma, a = 1343.4(2), b = 416.41(8), c = 1141.1(2) pm), which could also be realized with thulium. The structure was refined from single-crystal data (wR2 = 0.0940, 1605 F2 values, 56 variables). Again, a polyanion with bonding Pt–Al interactions was found, and the two distinct Lu atoms were residing in the cavities of the [Pt3Al4]δ– framework. X-ray photoelectron spectroscopy (XPS) measurements were conducted to examine the electron transfer from the rare-earth atoms onto the polyanionic framework.

Rare earth-rich cadmium compounds RE 10 TCd3 (RE=Y, Tb, Dy, Ho, Er, Tm, Lu; T=Rh, Pd, Ir, Pt) with an ordered Co2Al5-type structure

Abstract Eighteen new rare earth-rich intermetallic phases RE 10 TCd3 (RE=Y, Tb, Dy, Ho, Er, Tm, Lu; T=Rh, Pd, Ir, Pt) were obtained by induction melting of the elements in sealed niobium ampoules followed by annealing in muffle furnaces. All samples were characterized by X-ray powder diffraction. The structures of four representatives were refined from single-crystal X-ray diffractometer data: ordered Co2Al5 type, P63/mmc, a=951.2(1), c=962.9(2) pm, wR=0.0460, 595 F 2 values, 20 parameters for Er10RhCd3; a=945.17(4), c=943.33(4), wR=0.0395, 582 F 2 values, 21 parameters for Lu9.89PdCd3.11; a=964.16(6), c=974.93(6) pm, wR=0.0463, 614 F 2 values, 21 parameters for Y10Ir1.09Cd2.91; a=955.33(3), c=974.56(3) pm, wR=0.0508, 607 F 2 values, 22 refined parameters for Dy9.92IrCd3.08. Refinements of the occupancy parameters revealed small homogeneity ranges resulting from RE/Cd, respectively T/Cd mixing. The basic building units of the RE 10 TCd3 phases are transition metal-centered RE 6 trigonal prisms (TP) that are condensed with double-pairs of empty RE 6 octahedra via common triangular faces. A second type of rods is formed by slightly distorted RE3@Cd6 RE 6 icosahedra which are condensed via Cd3 triangular faces. The shortest interatomic distances occur for RE–T, compatible with strong covalent bonding interactions. Temperature dependent magnetic susceptibility measurements were performed for RE 10RhCd3 (RE=Dy–Tm, Lu), RE 10IrCd3 (RE=Er, Tm, Lu) and RE 10PtCd3 (RE=Y, Lu). While Y10PtCd3 and Lu10 TCd3 (T=Rh, Ir, Pt) show Pauli paramagnetic behavior, the compounds containing paramagnetic rare earth elements show Curie-Weiss behavior (the experimental magnetic moments indicate stable trivalent RE 3+) and magnetic ordering at low temperatures: T C=80.5 K for Dy10RhCd3 and Neél temperatures of 42.1, 23.3, 12.6, 5.9, 10.0 K for Ho10RhCd3, Er10RhCd3, Er10IrCd3, Tm10RhCd3, Tm10IrCd3, respectively.

Strong magnetic coupling in the hexagonal R5Pb3 compounds (R=Gd–Tm)

We have synthesized the R5Pb3 (R=Gd–Tm) compounds in polycrystalline form and performed neutron scattering and magnetization measurements. For all R5Pb3 reported here the Weiss temperatures θW are several times smaller than the ordering temperatures TORD, while the latter are remarkably high (TORD up to 275K for R=Gd) compared to other known R–M binaries (M=Si, Ge, Sn and Sb). The magnetic order changes from ferromagnetic (FM) in R=Gd, Tb to antiferromagnetic (AFM) in R=Dy–Tm. Below TORD, the magnetization measurements together with neutron powder diffraction show complex magnetic behaviors and reveal the existence of up to three additional phase transitions, believed to be a result of large anisotropic exchange and/or crystal electric field effects, induced high anisotropy. The R5Pb3 magnetic unit cells for R=Tb–Tm can be described with incommensurate magnetic wave vectors with spin modulation either along the c axis in R=Tb, Er and Tm, or within the ab plane in R=Dy and Ho.

Rare-earth rich indides RE8CoIn3 (RE = Y, Dy–Tm, Lu)

New ternary indides RE8CoIn3 (RE = Y, Dy–Tm, Lu) have been prepared by arc-melting and subsequent annealing at T = 870 K. The crystal structures have been studied using X-ray powder diffraction. The RE8CoIn3 indides are isotypic with Pr8CoGa3, space group P63mc, Pearson code hP24: a = 10.3678(2), c = 7.0069(2) Å for Y8CoIn3; a = 10.3370(4), c = 6.9246(3) Å for Dy8CoIn3; a = 10.2856(2), c = 6.9030(2) Å for Ho8CoIn3; a = 10.2374(2), c = 6.8759(2) Å for Er8CoIn3; a = 10.1863(2), c = 6.8461(2) Å for Tm8CoIn3; a = 10.1168(4), c = 6.7977(4) Å for Lu8CoIn3. The coordination polyhedra of the RE atoms have 12-, 13- and 14-vertices. The polyhedron around the Co atom is an octahedron with one additional atom, and around the In atoms it is a strongly distorted trigonal prism with five additional atoms.

Structure and homogeneity ranges of the REAuZn series

The intermetallic compounds REAuZn ( RE = Y, La, Pr, Nd, Sm, Gd–Tm, Lu) were synthesized from the elements in sealed tantalum ampoules in an induction furnace. They were characterized on the basis of powder and single crystal X-ray diffraction. Seven crystal structures have been refined from diffractometer data. The compounds with RE = Y, Dy–Tm, Lu crystallize with the hexagonal ZrNiAl type structure, space group P 6 ¯ 2 m, while those with the larger rare earth elements La, Pr, Nd, Sm, Gd, and Tb adopt the orthorhombic TiNiSi type, space group Pnma. No temperature driven dimorphism has been observed for TbAuZn and DyAuZn. The structure refinements indicate small homogeneity ranges REAu 1±xZn 1±x with a pronounced tendency for a higher gold content.

Magnetic Properties of Ho5Ni2In4

Intermetallic rare earths (R)–nickel–indides have attracted broad interest in recent years [1]. These compounds form different 19 crystal structures [2]. Only for RNiIn magnetic measurements were performed indicating that this compound is ferromagnet [3]. The R5Ni2In4 compounds with a large concentration of the rare-earth element exist for R = Dy–Tm and Lu, Y [4, 5] and crystallize in an orthorhombic crystal structure of the Lu5Ni2In4-type [6]. This work reports the results of the X-ray diffraction and magnetic measurements of Ho5Ni2In4.

Formation and characterization of Lu silicate nanoparticles in amorphous SiO 2

Reaction of nanocrystalline lutetium oxide with amorphous SiO 2 was studied at 600–1200 °C with X-ray powder diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), Fourier transform infrared spectroscopy (FT-IR), FT-Raman spectroscopy and Yb 3+ emission spectroscopy. It has been shown that up to loading corresponding to ca. 10 μmol Lu 2O 3/1 m 2 SiO 2, Lu can be dispersed over SiO 2 as an amorphous, nanometre thick Lu–O–Si layer. At 1000 °C formation of crystalline silicate, isomorphous with B-type Ln 4[Si 3O 10][SiO 4] (Ln Dy–Tm) was observed. It has been shown that emission bands of Yb 3+, introduced as contamination present in Lu 2O 3, appearing in anti-Stokes region of Raman spectra, could be used as convenient tool for identification of the Lu-phases formed in the samples.

Crystal and magnetic structures of the R(=Y, Dy–Tm)MnGe compounds

Powder and single-crystal X-ray diffraction, susceptibility measurements and powder neutron diffraction studies on RMnGe compounds (R=Dy–Tm, Y) are reported. The R(=Dy–Er, Y)MnGe compounds crystallize in the TiNiSi-type (S.G. Pnma) while two polytypic forms (H.T.-ZrNiAl and L.T.-TiNiSi) characterize the TmMnGe compound. All compounds exhibit antiferromagnetic ordering of the Mn sublattice above room temperature, while the R sublattice orders antiferromagnetically at 85 (5), 70 (5), 60 (5) and 30 (5) K for R=Dy, Ho, Er and Tm, respectively. At 2 K, DyMnGe is characterized by a cycloid structure ( q x ∼0.227) whereas HoMnGe exhibits a conical structure ( q x ∼0.259). YMnGe, ErMnGe and TmMnGe are simple collinear antiferromagnets, and a spin-reorientation process occurs in TmMnGe below 25 (2) K. At 2 K, the values of the magnetic moments are: μ Mn=3.37(14) μ B, μ Dy=8.87(13) μ B; μ Mn=3.35(9) μ B, μ Ho=8.03(12) μ B; μ Mn=3.25(18) μ B, μ Er=7.51(39) μ B; μ Mn=3.19(12) μ B, μ Tm=6.40(11) μ B; μ Mn=3.51(15) μ B for DyMnGe, HoMnGe, ErMnGe, TmMnGe and YMnGe, respectively. In all cases, the magnetic structures are characterized by antiferromagnetic [0 1 0] Mn chains. The results are discussed in terms of R–R, R–Mn, Mn–Mn interactions and anisotropy effects.

Effects of annealing temperature and time on the electrical resistivity of single crystal RNi 2B 2C (R=Gd–Lu, Y)

An optimal annealing temperature and time was determined for single crystal samples of the RNi 2B 2C series, R=Gd–Lu, Y. For R=Dy–Tm, Lu and Y dramatic improvements in the low temperature resistivity, residual resistivity ratio and implicitly the electronic mean free path were found for annealing temperature T=1000 °C and annealing time t≈75–100 h. This annealing schedule is somewhat less effective in changing the temperature dependent resistivities of TbNi 2B 2C and GdNi 2B 2C but it produces dramatic changes in the resistivity of the heavy Fermion compound YbNi 2B 2C.

Crystallographic data of new ternary TiNiSi (Co 2Si)-type RMnGe (R=Sm, Gd, Dy–Tm) compounds

Investigations made by powder X-ray diffraction on new ternary RMnGe compounds (R=Sm, Gd, Dy–Tm) are reported. They crystallize in the well-known orthorhombic Co 2Si (TiNiSi)-type structure (space group Pnma).

Preparation, properties and thermal decomposition of Y(III) and lanthanide(III) pyridine-2, 5-dicarboxylates

Abstract The conditions of the formation of Y(III) and lanthanide (III) (LaLu) isocinchomeronates were studied, and their quantitative compositions and solubilities in water at 293 K were determined. The IR spectra of the hydrated complexes were recorded and their thermal decomposition in static air were determined. During heating the hydrated isocinchomeronates Ln2(C7H3NO4)3·nH2O (n = 6−20) lose some (Ce, Pr, DyTm) or all (Y, La, NdTm, Dy, Lu) of their crystallization water molecules in one (Y, La, PrDy, Er, Yb, Lu) or two (Ce, Ho, Tm) steps then the hydrated complexes decompose directly to the oxides (Y, Ce, PrLu) or with intermediate formation of oxocarbonates Ln2O2CO3 (La).

New rare earth — Transition metal stannides with Sc 5Co 4Si 10 - and TiMnSi 2 - type structures. Atomic size effects on their stability

The following new stannides have been identified by X-ray powder diffraction : M 5Rh 4Sn 10 (M = CeSm and M 5Ir 4Sn 10 (M = LaPr) with Sc 5Co 4Si 10 type structures; MMnSn 2 (M = Y, DyTm, Lu) with TiMnSi 2 type structures. Their existence had been predicted using a simple geometric criterion. Because Sn atoms squeeze up together, there are less stannides than isostructural silicides and germanides.