The crystal structure of new YNi4Si-type RNi4Si (R=Y, La, Ce, Sm, Gd-Ho) compounds has been established using powder X-ray diffraction. The YNi4Si structure is a new structure type, which is orthorhombic derivative of CaCu5-type structure (space group Cmmm N 65, oC12). GdNi4Si and DyNi4Si compounds order ferromagnetically at 25 and 19 K, respectively whereas YNi4Si shows antiferromagnetic nature. At 15 K, DyNi4Si shows second antiferromagnetic-like transition. The magnetic moment of GdNi4Si at 5 K in 50 kOe field is ~7.2 μB/f.u. suggesting a completely ordered ferromagnetic state. The magnetocaloric effect of GdNi4Si is calculated in terms of isothermal magnetic entropy change and it reaches the maximum value of -12.8 J/kg K for a field change of 50 kOe near TC ~25 K. © 2013 Elsevier Inc.

R. Nirmala

Department Of Physics

ANTIFERROMAGNETIC-LIKE TRANSITION

Antiferromagnetics

Ferromagnetic state

Isothermal magnetic entropy change

Powder X ray diffraction

Space Groups

STRUCTURE TYPE

Type structures

Antiferromagnetism

Crystal Structure

Gadolinium alloys

Lanthanum compounds

Magnetic moments

Magnetic properties

Magnetocaloric effects

Semiconducting Silicon Compounds

Silicon

X ray diffraction

Lanthanum

IIT Madras is a public technical and research university located in Chennai, Tamil Nadu. Founded in 1959, it is recognised as an Institute of National Importance.

IIT Madras has been ranked as the top engineering institute in India for four years in a row by the National Institutional Ranking Framework of the MHRD

It currently offers undergraduate, postgraduate and research degrees across 16 disciplines in Engineering, Sciences, Humanities and Management. About 596 faculty belonging to science and engineering departments and centres of the Institute are engaged in teaching, research and industrial consultancy.

IIT Madras

Journal of Solid State Chemistry

Magnetic ordering of the polycrystalline YNi4Si-type YNi4Si, disordered YNi4Si-type TbNi4Si and NdNi3CoSi (space group Cmmm, N 65, oC12), and CaCu5-type NdNi3TSi (T = Mn, Fe, Cu) and Sm1-xTbxNi3FeSi (x = 0.25 and 0.5) solid solutions (space group P6/mmm, N 191, hP6) have been studied by magnetization measurements. Down to 2 K, YNi4Si is paramagnetic, whereas TbNi4Si, NdNi3MnSi, NdNi3FeSi, NdNi3CoSi and NdNi3CuSi show ferromagnetic ordering (TC) at 30 K, 71 K, 120 K, 20 K and 5.6 K and field sensitive transitions (Tm) at 10 K, 43 K, 63 K, 16 K and 3.8 K, respectively. Sm.75Tb.25Ni3FeSi and Sm.5Tb.5Ni3FeSi show ferromagnetic-antiferromagnetic transformations below ferromagnetic ordering at 166 K and 120 K, respectively. Magnetocaloric effect (MCE) of TbNi4Si, NdNi3{Mn, Co, Cu}Si, Sm.75Tb.25Ni3FeSi and Sm.5Tb.5Ni3FeSi compounds were estimated in terms of isothermal magnetic entropy change (ΔSm). Among these compounds, TbNi4Si and NdNi3CuSi show maximal MCE with ΔSm of − 9.95 J/kg K (RCP50 kOe ~ 180 J/kg) at 26–30 K and − 6.29 J/kg K (RCP50 kOe ~ 31 J/K) at 6 K in a field change of 50 kOe, respectively. Below Tm, TbNi4Si, NdNi3MnSi, NdNi3FeSi, NdNi3CoSi, NdNi3CuSi and Sm.5Tb.5Ni3FeSi show hard magnetic properties with coercivity of 2.2 kOe, 4.8 kOe, 4.8 kOe, 9.5 kOe, 1 kOe and 15 kOe at 2 K, respectively. Sm.75Tb.25Ni3FeSi shows a coercivity of 39 kOe at 40 K. © 2018 Elsevier Inc.

Magnetic ordering and coercivity of {Y, Tb}Ni4Si, NdNi3TSi (T = Mn - Cu) and Sm1-xTbxNi3FeSi solid solutions

The Gd-Ni-Si system has been investigated at 1070 K by X-ray and microprobe analyses. The existence of the known compounds, i.e.: GdNi10Si2, GdNi8Si3, GdNi5Si3, GdNi7Si6, GdNi6Si6, GdNi4Si, GdNi2Si2, GdNiSi3, Gd3Ni6Si2, GdNiSi, GdNiSi2, GdNi0.4Si1.6, Gd2Ni2.35Si0.65, Gd3NiSi2, Gd3NiSi3 and Gd6Ni1.67Si3, has been confirmed. Moreover, five new phases have been identified in this system. The crystal structure for four of them has been determined: Gd2Ni16-12.8Si1-4.2 (Th2Zn17-type), GdNi6.6Si6 (GdNi7Si6-type), Gd3Ni8Si (Y3Co8Si-type) and Gd3Ni11.5Si4.2 (Gd3Ru4Ga12-type). The compound with composition ~Gd2Ni4Si3 still remains with unknown structure. Quasi-binary phases, solid solutions, were detected at 1070 K to be formed by the binaries GdNi5, GdNi3, GdNi2, GdNi, GdSi2 and GdSi1.67; while no appreciable solubility was observed for the other binary compounds of the Gd-Ni-Si system. Magnetic properties of the GdNi6Si6, GdNi6.6Si6 and Gd3Ni11.5Si4.2 compounds have also been investigated and are here reported. © 2015 Elsevier Inc. All rights reserved.

The isothermal section of Gd-Ni-Si system at 1070 K

The Ce-Ni-Si system has been investigated at 870/1070 K by X-ray and microprobe analyses. The existence of the known compounds, i.e.: Ce2Ni15.8Si1.2 (Th2Ni17-type), Ce2Ni15-14Si2-3 (Th2Zn17-type), CeNi8.6Si2.4 (BaCd11-type), CeNi8.8Si4.2 (LaCo9Si4-type), CeNi6Si6 (CeNi6Si6-type), CeNi5Si1-0.3 (TbCu7-type), CeNi4Si (YNi4Si-type), CeNi2Si2 (CeGa2Al2-type), Ce2Ni3Si5 (U2Co3Si5-type), Ce3Ni6Si2 (Ce3Ni6Si2-type), Ce3Ni4Si4 (U3Ni4Si4-type), CeNiSi2 (CeNiSi2-type), ~CeNi1.3Si0.7 (unknown type structure), Ce6Ni7Si4 (Pr6Ni7Si4-type), CeNiSi (LaPtSi-type), CeNi0.8-0.3Si1.2-1.7 (AlB2-type), ~Ce2Ni2Si (unknown type structure), ~Ce4.5Ni3.5Si2 (unknown type structure), Ce15Ni7Si10 (Pr15Ni7Si10-type), Ce5Ni1.85Si3 (Ce5Ni1.85Si3-type), Ce6Ni1.4Si3.4 (Ce6Ni1.67Si3-type), Ce7Ni2Si5 (Ce7Ni2Si5-type) and Ce3NiSi3 (Y3NiSi3-type) has been confirmed in this section. Moreover, the type structure has been determined for ~Ce2Ni2Si (Mo2NiB2-type Ce2Ni2.5Si0.5) and ~Ce4.5Ni3.5Si2 (W3CoB3-type Ce3Ni3-2.7Si1-1.3) and new ternary phases Ce2Ni6.25Si0.75 (Gd2Co7-type), CeNi7-7.6Si6-5.4 (GdNi7Si6-type) and ~Ce27Ni42Si31 (unknown type structure) have been identified in this system. Quasi-binary phases, solid solutions, were detected at 870/1070 K for CeNi5, CeNi3 and CeSi2; while no appreciable solubility was observed for the other binary compounds of the Ce-Ni-Si system. As a prolongation of Rare Earth-Ni-Si system's isostructural rows, LaNi7Si6 and YNi6.6Si6.1 (GdNi7Si6-type), ScNi6Si6 (YCo6Ge6-type), NdNi6Si6 (YNi6Si6-type), {Tb, Ho}2Ni15Si2 (Th2Zn17-type), Nd2Ni2.3Si0.7 and Sm2Ni2.2Si0.8 (Mo2NiB2-type), Nd3Ni2.55Si1.45 (W3CoB3-type) and {Tb, Dy}7Ni50Si19 (Y7Ni49Si20-type) compounds were synthesized and investigated. Magnetic properties of the CeNi6Si6, CeNi7Si6, CeNi8.8Si4.2, Ce6Ni7Si4, CeNi5Si, Ce2Ni2.5Si0.5, Nd2Ni2.3Si0.7 and Dy7Ni50Si19 compounds have also been investigated and are presented here. © 2016 Elsevier Inc.

The Ce-Ni-Si system as a representative of the rare earth-Ni-Si family: Isothermal section and new rare-earth nickel silicides

Magnetic properties and magnetocaloric effect of CaCu5-type RNi3TSi (R=Gd and Tb, T=Mn, Fe, Co and Cu) compounds have been investigated. Magnetic measurements of RNi3TSi display the increasing of Curie temperature and the decreasing of magnetocaloric effect and saturated magnetic moment in the row of 'RNi3CuSi-RNi3NiSi-RNi3CoSi-RNi3MnSi-RNi3FeSi'. In contrast to GdNi3{Mn, Fe, Co}Si, TbNi3{Mn, Fe, Co}Si exhibit significant magnetic hysteresis. The coercive field increases from TbNi4Si (~0.5 kOe) to TbNi3CoSi (4 kOe), TbNi3MnSi (13 kOe) and TbNi3FeSi (16 kOe) in field of 50 kOe at 5 K, whereas TbNi3CuSi exhibits a negligible coercive field. © 2015 Elsevier Inc.All rights reserved.

Magnetic properties of CaCu5-type RNi3TSi (R=Gd and Tb, T=Mn, Fe, Co and Cu) compounds

Magnetic properties and magnetocaloric effect of YNi4Si-type RNi4Si (R=Ce, Gd, Tb and Dy) compounds have been investigated. Magnetic measurements indicate the intermediate valence state of cerium in YNi4Si-type CeNi4Si. The magnetocaloric effect of GdNi4Si, TbNi4Si and DyNi4Si are calculated in terms of isothermal magnetic entropy change and they reach maximum values of -22.9 J/kg K, -13.5 J/kg K and -15.6 J/kg K for a field change of 140 kOe near ∼28 K, 47 K and 27 K and they show maximum values of -12.7 J/kg K, -7.8 J/kg K and -9.3 J/kg K for a field change of 50 kOe near ∼28 K, 42 K and 22 K, respectively. In contrast to GdNi4Si, the magnetization-field isotherms for TbNi4Si and DyNi4Si exhibit hysteresis loop at 2 K due to strong magnetocrystalline anisotropy. © 2014 Elsevier B.V. All rights reserved.

Journal of Magnetism and Magnetic Materials

Magnetism and magnetocaloric effect in YNi4Si-type RNi4Si (R=Ce, Gd, TB and DY) compounds

Journal of Alloys and Compounds

Magnetocaloric effect in the ferromagnetic GdNi4M (M=Al, Si) and antiferromagnetic NdNiAl4 compounds

Magnetocaloric effect in LaFe11.8−xCoxSi1.2 melt-spun ribbons

Solid State Communications

Valence state and magnetism of CeNi4Si and YbNi4Si

The Magnetocaloric Effect and its Applications

Physical Review Letters

Giant Magnetocaloric Effect inGd5(Si2Ge2)

New orthorhombic derivative of CaCu5-type structure: RNi 4Si compounds (R=Y, La, Ce, Sm, Gd-Ho), crystal structure and some magnetic properties

Journal	Journal of Solid State Chemistry
ISSN	00224596
Open Access	No