Crystal structures and magnetic properties of rare earth tantalates RE 3 TaO 7 (RE = rare earths)

Doi

2014

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Ternary rare-earth antimonates Ln 3 SbO 7 (Ln = rare earths) were prepared, and their structures were determined by X-ray diffraction measurements. They crystallize in an orthorhombic superstructure of cubic fluorite (space group Cmcm for Ln = La, Pr; Ccmm for Ln = Sm -Dy), in which Ln 3+ ions occupy two different crystallographic sites (the 8-coordinated and 7-coordinated). For Ln = Nd, two phases with the Cmcm and Ccmm space groups coexist at room temperature. When the temperature was increased, the Nd 3 SbO 7 compound transformed into a single phase with the space group Cmcm.Through magnetic susceptibility measurements, an antiferromagnetic transition was observed at 3.0 K (Ln = Nd) and 7.8 K (Ln = Tb). Analysis of the magnetic specific heat for Tb 3 SbO 7 indicates that the 8-coordinated Tb ions magnetically orders at 7.8 K, and with furthermore decreasing temperature, the 7-coordinated Tb ions shows antiferromagnetic ordering at 3.0 K.3

Section: Magnetic Properties Of Tb 3 Sbosupporting

confidence: 75%

High-temperature X-ray diffraction measurements of fluorite-related rare earth antimonates Ln3SbO7 (Ln=Nd, Tb) and their magnetic properties

Doi

2014

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“…Therefore, we believe that the magnetic transition at 2.6 K is due to the antiferromagnetic ordering of the 8-coordinated Gd(1) ions and that the magnetic anomaly at the lower temperature (T < 0.4 K) is ascribable to the magnetic interactions of the 7-coordinated Gd(2) ions, i.e., Gd 3+ ions occupying the 4b and 8c sites individually order in the Gd 3 SbO 7 compound. Similar "two-step" magnetic transitions have been found for Ln 3 TaO 7 (Ln = Nd, Tb) [24] and Ln 3 NbO 7 (Ln = Nd, Tb) [39].…”

Section: Gd 3 Sbosupporting

confidence: 75%

“…Although the space group for the La 3 NbO 7 now turned out to be Pnma [2], the space group Cmcm has been applied for many Ln 3 MO 7 compounds . For some compounds such as Ln 3 TaO 7 (Ln = Y, Sm -Ho) [20][21][22]24] and Ln 3 MoO 7 (Ln = La -Nd, Sm, Eu) [27][28][29][30], the space groups C222 1 and P2 1 2 1 2 1 have been applied, respectively.…”

Section: Introductionmentioning

confidence: 99%

Magnetic properties of orthorhombic fluorite-related oxides Ln3SbO7 (Ln=rare earths)

Ebisawa

Doi

2009

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Ternary rare earth antimonates Ln 3 SbO 7 (Ln = rare earths) were prepared and their structures were determined by x-ray diffraction measurements. They crystallize in an orthorhombic superstructure of cubic fluorite (space group Cmcm for Ln = La, Pr, Nd; C222 1 for Ln = Nd ~ Lu), in which Ln 3+ ions occupy two different crystallographic sites (the 8-coordinated and 7-coordinated sites). Their magnetic properties were characterized by magnetic susceptibility and specific heat measurements from 1.8 to 400 K. The Ln 3 SbO 7 (Ln = Nd, Gd -Ho) compounds show an antiferromagnetic transition at 2.2 ~ 3.2 K. Sm 3 SbO 7 and Eu 3 SbO 7 show van Vleck paramagnetism. Measurements of the specific heat down to 0.4 K for Gd 3 SbO 7 and the analysis of the magnetic specific heat indicate that the antiferromagnetic ordering of the 8-coordinated Gd ions occur at 2.6 K, and the 7-coordinated Gd ions order at a furthermore low temperature.3

“…This experimental result suggests that the anomalies observed at 0.8 and 2.5 K are due to the antiferromagnetic ordering of Sm 3+ ions independently in the 8-coordinated Sm(1) and 7-coordinated Sm(2) sites, respectively. Similar "two-step" antiferromagnetic transitions have been found in Ln 3 TaO 7 (Ln = Nd, Tb) [24], Ln 3 NbO 7 (Ln = Nd, Tb) [38], and Gd 3 SbO 7 [40]. …”

Section: Low-temperature Magnetic Properties Of Sm 3 Moosupporting

confidence: 70%

Magnetic properties and structural transitions of orthorhombic fluorite-related compounds Ln3MO7 (Ln=rare earths, M=transition metals)

Wakeshima

2010

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Magnetic properties and structural transitions of ternary rare-earth transition-metal oxides Ln 3 MO 7 (Ln = rare earths, M = transition metals) were investigated. In this study, we prepared a series of molybdates Ln 3 MoO 7 (Ln = La ~ Gd). They crystallize in an orthorhombic superstructure of cubic fluorite with space group P2 1 2 1 2 1 , in which Ln 3+ ions occupy two different crystallographic sites (the 8-coordinated and 7-coordinated sites). All of these compounds show a phase transition from the space group P2 1 2 1 2 1 to Pnma in the temperature range between 370 and 710 K. Their magnetic properties were characterized by magnetic susceptibility measurements from 1.8 to 400 K and specific heat measurements from 0.4 K to 400 K. Gd 3 MoO 7 shows an antiferromagnetic transition at 1.9 K.Measurements of the specific heat for Sm 3 MoO 7 and the analysis of the magnetic specific heat indicate a "two-step" antiferromagnetic transition due to the ordering of Sm magnetic moments in different crystallographic sites, i.e., with decreasing temperature, the antiferromagnetic ordering of the 7-coordinated Sm ions occur at 2.5 K, and then the 8-coordinated Sm ions order at 0.8 K. The results of Ln 3 MoO 7 were compared with the magnetic properties and structural transitions of Ln 3 MO 7 (M = Nb, Ru, Sb, Ta, Re, Os, or Ir).3