Magnetic properties of Er2Mn3Si5
TL;DR: In this paper, magnetization measurements have been carried out on the Er 2 Mn 3 Si 5 compound in the temperature range 1.8-300 K and the magnetic susceptibility in the paramagnetic region, above 100 K, follows simple Curie-Weiss type behavior.
Abstract: Magnetization measurements have been carried out on the Er 2 Mn 3 Si 5 compound (tetragonal Sc 2 Fe 3 Si 5 -type, space group P 4/ mnc ) in the temperature range 1.8–300 K. There is a crossover from a room temperature paramagnetic phase to a ferromagnetic phase at 75 K ( T C1 ). A second magnetic transition is observed at 11.5 K ( T C2 ). The magnetic susceptibility in the paramagnetic region, above 100 K, follows simple Curie–Weiss type behavior. The magnetization does not saturate at 2 K even in applied fields of 7 T. Neutron diffraction data collected at 300 and 9.2 K confirm that both the rare earth and the Mn moments in this compound carry magnetic moments. There are two Mn sublattices (Mn1 and Mn2) coupled orthogonal to each other. Both the rare earth and the Mn1 sublattice order along the positive a axis but the Mn2 moments order along the positive c axis, thus leading to a competition of magnetic interactions at low temperatures.
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TL;DR: The rare earth ruthenium gallides Ln2Ru3Ga5 (Ln = La, Ce, Pr, Nd, Sm) were prepared by arc-melting of cold-pressed pellets of the elemental components as discussed by the authors.
Abstract: The rare earth ruthenium gallides Ln2Ru3Ga5 (Ln = La, Ce, Pr, Nd, Sm) were prepared by arc-melting of cold-pressed pellets of the elemental components. They crystallize with a tetragonal structure (P4/mnc, Z = 4) first reported for U2Mn3Si5. The crystal structures of the cerium and samarium compounds were refined from single-crystal X-ray data, resulting in significant deviations from the ideal compositions: Ce2Ru2.31(1)Ga5.69(1), a = 1135.10(8) pm, c = 580.58(6) pm, RF = 0.022 for 742 structure factors; Sm2Ru2.73(2)Ga5.27(2), a = 1132.95(9) pm, c = 562.71(6) pm, RF = 0.026 for 566 structure factors and 32 variable parameters each. The deviations from the ideal compositions 2:3:5 are discussed. A mixed Ru/Ga occupancy occurs only for one atomic site. The displacement parameters are relatively large for atoms with mixed occupancy within their coordination shell and small for atoms with no neighboring sites of mixed occupancy. Chemical bonding is analyzed on the basis of interatomic distances. Ln–Ga bonding is stronger than Ln–Ru bonding. Ru–Ga bonding is strong and Ru–Ru bonding is weak. The Ga–Ga interactions are of similar strength as in elemental gallium.
8 citations
TL;DR: In this article, the existence of seven binary compounds ErFe 2, ErFe 3, Er 6 Fe 23, Er 2 Fe 17, ErMn 12, Er 6 Mn 23, and one intermediate solid solution γ(Fe·Mn) have been confirmed in the Er-Fe-Mn system at 773 K.
Abstract: In order to determine the existence of phases and relationships in the Er–Fe–Mn system at 773 K, we have carried out this work mainly by X-ray powder diffraction with the aid of differential thermal analysis and have obtained the conclusions below. The existence of seven binary compounds ErFe 2 , ErFe 3 , Er 6 Fe 23 , Er 2 Fe 17 , ErMn 12 , Er 6 Mn 23 , ErMn 2 and one intermediate solid solution γ(Fe·Mn) have been confirmed in this system. Er 6 Fe 23 and Er 6 Mn 23 form continuous solid solution Er 6 (Fe 23− X Mn X ) (0 ≤ X ≤ 23). At 773 K, the maximum solid solubility of Fe in αMn, ErMn 12 , ErMn 2 phases and Mn in ErFe 2 , Er 2 Fe 17 , αFe phases are about 31, 69, 13 at% Fe and 47, 28, 8 at% Mn, respectively. The homogeneity range of γ(Fe·Mn) phase extended from about 34 at% Mn to 52 at% Mn. The maximum solid solubility of Er in γ(Fe·Mn) phase is about 2 at% Er. The isothermal section consists of ten single-phase regions, sixteen two-phase regions and seven three-phase regions. No ternary compounds were observed at 773 K in this system.
6 citations
TL;DR: In this article, the isothermal section of the Er-Mn-Nd ternary system at 773 K was investigated mainly by X-ray powder diffraction with the aid of differential thermal analysis.
Abstract: The isothermal section of the Er-Mn-Nd ternary system at 773 K was investigated mainly by X-ray powder diffraction with the aid of differential thermal analysis. The 773 K isothermal section of the ternary system consists of 9 single-phase regions, 14 two-phase regions, and 6 three-phase regions. At 773 K, the maximum solid solubility of Er in Nd and Nd in Er is about 20% (atom fraction) Er and 26% (atom fraction) Nd, respectively. Er 6 Mn 23 and Nd 6 Mn 23 form a continuous solid solution. The homogeneity range of δ phase extends from about 38% (atom fraction) Er to 43% (atom fraction) Er. No ternary compounds were observed at 773 K in this system.
6 citations
TL;DR: In this paper , the silicide Eu2Ru3Si5 was synthesized from the elements in a sealed tantalum tube in a high-frequency furnace, while the gallide Eu 2Ir3Ga5 was obtained by arc-melting.
Abstract: Abstract The silicide Eu2Ru3Si5 was synthesized from the elements in a sealed tantalum tube in a high-frequency furnace, while the gallide Eu2Ir3Ga5 was obtained by arc-melting. Both structures were refined from single-crystal X-ray diffractometer data: P4/mnc, a = 1072.69(8), c = 569.55(5) pm, wR = 0.0453, 617 F2 values, 31 variables for Eu2Ru3Si5 and a = 1122.18(7), c = 583.17(4) pm, wR = 0.0546, 729 F2 values, 31 variables for Eu2Ir3Ga4.95(1). The gallide shows small defects on one 8h site. The transition metal atoms in Eu2Ru3Si5 and Eu2Ir3Ga5 have octahedral p element coordination. These Ru@Si6 respectively Ir@Ga6 polyhedra are condensed to three-dimensional [Ru3Si5]6− respectively [Ir3Ga5]4− polyanionic networks. The ground states of Eu(III) in Eu2Ru3Si5 and Eu(II) in Eu2Ir3Ga5 were determined by 151Eu Mössbauer spectroscopy.
1 citations
TL;DR: The compound Ho2Mn3Si5 exhibits multiple magnetic transitions: (i) an ordering at ∼78 K, (ii) a second magnetic transition at ∼16 K, and (iii) an anomaly at ∼4 K as discussed by the authors.
Abstract: The compound Ho2Mn3Si5 exhibits multiple magnetic transitions: (i) an ordering at ∼78 K, (ii) a second magnetic transition at ∼16 K, and (iii) an anomaly at ∼4 K. Its paramagnetic Curie temperature is found to be small but positive. Assuming a free ion effective paramagnetic moment of 10.6μB for Ho3+ ion, the effective paramagnetic moment per Mn in this compound is calculated to be 1.73μB, which indicates the itinerant nature of Mn d electrons. The various transitions in magnetization data are perhaps due to the ordering of rare earth and Mn moments. The magnetization at 2 K in applied fields of up to 7 T has linear field dependence, indicating dominant antiferromagnetic interactions in the system. Neutron diffraction studies point to a complex amplitude modulated incommensurate magnetic structure at 9 K.
References
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TL;DR: In this article, the main formulas governing the analysis of the Bragg magnetic scattering are summarized and shortly discussed and the method of profile fitting without a structural model to get precise integrated intensities and refine the propagation vector(s) of the magnetic structure is discussed.
Abstract: In spite of intrinsic limitations, neutron powder diffraction is, and will still be in the future, the primary and most straightforward technique for magnetic structure determination. In this paper some recent improvements in the analysis of magnetic neutron powder diffraction data are discussed. After an introduction to the subject, the main formulas governing the analysis of the Bragg magnetic scattering are summarized and shortly discussed. Next, we discuss the method of profile fitting without a structural model to get precise integrated intensities and refine the propagation vector(s) of the magnetic structure. The simulated annealing approach for magnetic structure determination is briefly discussed and, finally, some features of the program FullProf concerning the magnetic structure refinement are presented and discussed. The different themes are illustrated with simple examples.
11,923 citations
TL;DR: An overall survey of the structural and magnetic features of the La2NiO4+ delta system is presented as a result of neutron diffraction experiments in this article, where a tentative phase diagram is proposed.
Abstract: An overall survey of the structural and magnetic features of the La2NiO4+ delta system is presented as a result of neutron diffraction experiments. The stoichiometric compound ( delta =0) presents two structural phase transitions. At T0 approximately=770 K, La2NiO4 transforms from tetragonal (I4/mmm) to orthorhombic (Bmab); at T1 approximately=80 K, from orthorhombic to a new tetragonal (P42/ncm) phase. Associated with this second phase transition a strong microstrain produces anisotropic broadening of Bragg reflections. La2NiO4 is three-dimensional (3D) antiferromagnetically ordered at room temperature (TN=330 K). A weak ferromagnetic component appears below T1. Oxygen excess suppress the 3D magnetic ordering and the structural phase transformations, giving rise to a non-stoichiometric compound with interstitial oxygens. A tentative phase diagram is proposed.
365 citations
TL;DR: In this article, the magnetic phase diagram of Sm 1- x Gd x Mn 2 Ge 2 has been determined and the p-T diagram has been also determined, showing that the transition from antiferro-to ferromagnetic phase is strongly correlated with interatomic distances.
Abstract: Susceptibility and magnetization measurements have been carried out to study the magnetic phase diagram of Sm 1- x Gd x Mn 2 Ge 2 . The p-T diagram has been also determined. The results indicate that the transition from antiferro- to ferromagnetic phase is strongly correlated with interatomic distances.
27 citations
TL;DR: Magnetic susceptibility, electrical resistivity and thermoelectric power measurements on new rare earth ternary intermetallic R2Mn3Si5 (R=Dy, Ho and Er) compounds were carried out in the temperature range 15-300 K as discussed by the authors.
Abstract: Magnetic susceptibility, electrical resistivity and thermoelectric power measurements on new rare earth ternary intermetallic R2Mn3Si5 (R=Dy, Ho and Er) compounds crystallizing in the Sc2Fe3Si5-type tetragonal crystal structure were carried out in the temperature range 15–300 K. Dy- and Ho-based alloys show two successive magnetic transitions (Dy2Mn3Si5 at 76 and 32 K; Ho2Mn3Si5 at 67 and 19 K) and the Er-based compound undergoes a magnetic transition around 55 K. The electrical resistivity is ferromagnetic metal-like, displaying typical low temperature T2 dependence and a high temperature spin-disorder contribution. Thermoelectric power is negative at room temperature, crosses zero and has a broadened peak feature centered around 50 K indicating a phonon drag effect at low temperatures and it does not have the signature of magnetic ordering. The successive magnetic transitions are suggestive of the presence of competing magnetic interactions in these systems.
8 citations
TL;DR: In this article, magnetic properties of polycrystalline Sc 2 Fe 3 Si 5 -type Tb 2 Mn 3 Si5 compound (space group P4/mnc ) in the temperature range of 1.8-300 K were investigated.
Abstract: Magnetization (M) and neutron diffraction measurements have been carried out on a polycrystalline Sc 2 Fe 3 Si 5 -type Tb 2 Mn 3 Si 5 compound (space group P4/mnc ) in the temperature range of 1.8–300 K. The compound undergoes a transition from a room temperature paramagnetic phase to a ferromagnetic phase at 89 K ( T C1 ). A Curie–Weiss type behaviour is observed in the paramagnetic region at temperatures above 150 K. In this compound, both the rare earth (Tb) and Mn ions carry magnetic moments and there are two Mn magnetic sublattices, one coupling ferromagnetically and the other coupling antiferromagnetically with that of rare earth.
4 citations