Interplay of 3d and 4f Magnetism in Chiral Y 6 FeSi 2 S 14 and Tb 6 FeSi 2 S 14 Chalcogenides
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The overall objectives of this project were (1) to develop methods for the production and separation of a diagnostic and therapeutic or “theranostic” pair of radioisotopes, terbium-155 ( 155 Tb) and terbium-161 ( 161 Tb) and (2) to train graduate students and postdoctoral fellows in technologies and methods used in radionuclide production. Radionuclides can be incorporated into drugs called radiopharmaceuticals that target a specific disease (e.g., cancer). The need for theranostic radionuclides is escalating with the clinical translation of radiopharmaceuticals due to their implementation in personalized medicine, which has demonstrated enhanced patient treatments. High purity and high specific activity radionuclides are critical for theranostic agent development, for example to maintain diagnostic image quality, to minimize radiation dose to the patient, and to increase uptake in the targeted tissue (e.g., tumor), especially in the case of receptor- and antigen-targeted agents. The 155 Tb (diagnostic) and 161 Tb (therapeutic) radioisotopes that were generated through this project are a theranostic pair with demonstrated potential for the development and translation into individualized, targeted, and dosimetry-driven radiotherapies. However, the development of such radiotherapies has been hindered by the lack of a routine and reliable supply of these isotopes in the United States. Methods for the production, separation, and supply of 155 Tb and 161 Tb were investigated and developed in this project. Further, the strong emphasis throughout the project on the training of graduate students and postdoctoral fellows has helped to ensure and enhance the nuclear science workforce through the training of the next generation of highly qualified scientists in nuclear and radiochemistry. This grant also continued a collaboration between scientists at the University of Washington (UW), the University of Missouri (MU) and Brookhaven National Laboratory (BNL). All three institutions were involved in the project, but to different degrees on the various tasks through which the overall objectives were met.
The Co-rich end of the Co–Tb binary phase diagram (Co x Tb 1−x , x = 0.66–0.82) has been investigated to understand the phases which form in the bulk and how they interact to yield magnetic behavior which has been reported to be ideal for use in spintronic devices. Here, this work shows that the phases and phase fractions present across this composition range follow those predicted by the binary phase diagram, and all compounds in this composition range are multiphase. Magnetic measurements show similar behavior in this composition range to related thin film work, and we attribute the observed behavior to the respective binary phases present in each compound. Ideal magnetic behavior of minimized magnetic saturation and maximized coercivity is observed in the range of x= 0.78 − 0.80 related to the majority phase Co 7 Tb 2 in these two compounds. High pressure magnetic measurements show magnetic saturation and coercivity at 300 K change little with respect to external pressure. The extension of the synthesis of these binaries into the bulk allows for specific binary phases to be targeted and analyzed for consideration in future devices.
By developing models of increasing complexity, we show that a model without single-ion anisotropy (SIA) cannot explain the magnetic properties of J eff = 1 / 2 Tb 3+ moments in the orthorhombically distorted, honeycomb material Tb 2 Ir 3 Ga 9 . In four different models for the magnetization of a single honeycomb layer, the only sources of anisotropy are symmetric exchange interactions J nαβ = J nβα along three different bonds n , an anisotropic $\underline{g}$ tensor, and a Dzyalloshinskii-Moriya interaction (asymmetric exchange) that produces the observed canted moment along b . With 21 parameters, the best such model yields χ 2 = 0.065 , which is substantially smaller than χ 2 = 0.112 obtained using a Heisenberg model containing six parameters including easy-axis anisotropy. However, models without SIA fail to reproduce the linear dependence of the magnetization with a field perpendicular to the Ising axis while predicting a saturation magnetization that is far too low. Due to the complex crystal-field environments, we argue that SIA is necessary to study low-symmetry, three-dimensional J eff = 1 / 2 materials containing Tb 3+ ions.
Radioisotopes are essential for the development and application of radiopharmaceuticals that target specific diseases, such as cancer, offering unique potential for precision medicine. The growing demand for theranostic radioisotopes underscores their critical role in personalized medicine, where they enhance diagnostic imaging, minimize patient radiation exposure, and improve targeted tissue uptake, particularly in receptor- and antigen-directed therapies. The theranostic pair terbium-155 (diagnostic) and terbium-161 (therapeutic) holds significant promise for advancing individualized, targeted, and dosimetry-driven radiotherapies. However, the United States currently lacks routine and reliable production of these isotopes. This project made significant progress toward addressing this supply issue by developing production and separation methods for terbium-155 and terbium-161 while also training the next generation of the nuclear and radiochemistry workforce. This grant also strengthened collaboration between scientists at the University of Washington, the University of Missouri and Brookhaven National Laboratory. The research effort focused on evaluating target preparation methods, optimizing irradiation parameters, and refining isolation processes. In addition, the project provided extensive hands-on training to graduate students and postdoctoral fellows, equipping them with expertise in radioisotope production technologies and fostering the growth of the nuclear science workforce.
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Tb is alpha La-like structured and crystallizes in the hexagonal P6_3/mmc space group. The structure is three-dimensional. there are five inequivalent Tb sites. In the first Tb site, Tb is bonded to twelve Tb atoms to form a mixture of edge, face, and corner-sharing TbTb12 cuboctahedra. There are a spread of Tb–Tb bond distances ranging from 3.55–3.58 Å. In the second Tb site, Tb is bonded to twelve Tb atoms to form a mixture of edge, face, and corner-sharing TbTb12 cuboctahedra. There are six shorter (3.56 Å) and six longer (3.58 Å) Tb–Tb bond lengths. In the third Tb site, Tb is bonded to twelve Tb atoms to form a mixture of edge, face, and corner-sharing TbTb12 cuboctahedra. There are a spread of Tb–Tb bond distances ranging from 3.55–3.58 Å. In the fourth Tb site, Tb is bonded to twelve Tb atoms to form a mixture of edge, face, and corner-sharing TbTb12 cuboctahedra. All Tb–Tb bond lengths are 3.58 Å. In the fifth Tb site, Tb is bonded to twelve Tb atoms to form a mixture of edge, face, and corner-sharing TbTb12 cuboctahedra. All Tb–Tb bond lengths are 3.58 Å.
Tb is alpha Samarium structured and crystallizes in the trigonal R-3m space group. The structure is three-dimensional. there are two inequivalent Tb sites. In the first Tb site, Tb is bonded to twelve Tb atoms to form a mixture of edge, face, and corner-sharing TbTb12 cuboctahedra. There are six shorter (3.55 Å) and six longer (3.58 Å) Tb–Tb bond lengths. In the second Tb site, Tb is bonded to twelve Tb atoms to form a mixture of edge, face, and corner-sharing TbTb12 cuboctahedra. There are three shorter (3.55 Å) and six longer (3.58 Å) Tb–Tb bond lengths.
Tb(Mg4Al3)4 is gamma-brass-derived structured and crystallizes in the trigonal R3m space group. The structure is three-dimensional. there are five inequivalent Mg sites. In the first Mg site, Mg is bonded in a 3-coordinate geometry to five Mg, one Tb, and five Al atoms. There are a spread of Mg–Mg bond distances ranging from 3.06–3.18 Å. The Mg–Tb bond length is 3.59 Å. There are a spread of Mg–Al bond distances ranging from 2.88–3.22 Å. In the second Mg site, Mg is bonded in a 10-coordinate geometry to three equivalent Mg, one Tb, and twelve Al atoms. All Mg–Mg bond lengths are 3.16 Å. The Mg–Tb bond length is 3.32 Å. There are a spread of Mg–Al bond distances ranging from 3.14–3.25 Å. In the third Mg site, Mg is bonded in a 11-coordinate geometry to five Mg and six Al atoms. There are two shorter (3.05 Å) and one longer (3.37 Å) Mg–Mg bond lengths. There are a spread of Mg–Al bond distances ranging from 3.05–3.13 Å. In the fourth Mg site, Mg is bonded in a 6-coordinate geometry to five Mg, one Tb, and five Al atoms. There are two shorter (3.12 Å) and two longer (3.14 Å) Mg–Mg bond lengths. The Mg–Tb bond length is 3.12 Å. There are a spread of Mg–Al bond distances ranging from 2.81–3.16 Å. In the fifth Mg site, Mg is bonded in a 12-coordinate geometry to seven Mg and five Al atoms. Both Mg–Mg bond lengths are 3.05 Å. There are a spread of Mg–Al bond distances ranging from 2.96–3.32 Å. Tb is bonded in a 12-coordinate geometry to seven Mg and nine Al atoms. All Tb–Al bond lengths are 3.22 Å. There are three inequivalent Al sites. In the first Al site, Al is bonded in a 11-coordinate geometry to eight Mg and three Al atoms. There are one shorter (2.68 Å) and two longer (2.75 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 12-coordinate geometry to eight Mg, one Tb, and three Al atoms. Both Al–Al bond lengths are 2.75 Å. In the third Al site, Al is bonded in a distorted q6 geometry to seven Mg, one Tb, and three Al atoms. There are one shorter (2.72 Å) and one longer (2.78 Å) Al–Al bond lengths.
TbFe6Ge6 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Tb is bonded to twelve Fe and eight Ge atoms to form distorted TbFe12Ge8 hexagonal bipyramids that share corners with four equivalent TbFe12Ge8 hexagonal bipyramids, faces with eight equivalent FeTb2Fe4Ge6 cuboctahedra, and faces with four equivalent TbFe12Ge8 hexagonal bipyramids. There are a spread of Tb–Fe bond distances ranging from 3.25–3.30 Å. There are a spread of Tb–Ge bond distances ranging from 2.84–3.00 Å. There are three inequivalent Fe sites. In the first Fe site, Fe is bonded in a 12-coordinate geometry to two equivalent Tb, four Fe, and six Ge atoms. All Fe–Fe bond lengths are 2.56 Å. There are a spread of Fe–Ge bond distances ranging from 2.48–2.68 Å. In the second Fe site, Fe is bonded in a 12-coordinate geometry to two equivalent Tb, four Fe, and six Ge atoms. Both Fe–Fe bond lengths are 2.57 Å. There are four shorter (2.52 Å) and two longer (2.67 Å) Fe–Ge bond lengths. In the third Fe site, Fe is bonded to two equivalent Tb, four Fe, and six Ge atoms to form distorted FeTb2Fe4Ge6 cuboctahedra that share corners with four equivalent FeTb2Fe4Ge6 cuboctahedra, edges with two equivalent FeTb2Fe4Ge6 cuboctahedra, faces with four equivalent FeTb2Fe4Ge6 cuboctahedra, and faces with four equivalent TbFe12Ge8 hexagonal bipyramids. Both Fe–Fe bond lengths are 2.57 Å. There are a spread of Fe–Ge bond distances ranging from 2.51–2.69 Å. There are five inequivalent Ge sites. In the first Ge site, Ge is bonded in a 8-coordinate geometry to two equivalent Tb and six Fe atoms. In the second Ge site, Ge is bonded in a 6-coordinate geometry to six Fe atoms. In the third Ge site, Ge is bonded in a 9-coordinate geometry to three equivalent Tb and six Fe atoms. In the fourth Ge site, Ge is bonded in a 8-coordinate geometry to one Tb, six Fe, and one Ge atom. The Ge–Ge bond length is 2.50 Å. In the fifth Ge site, Ge is bonded in a 7-coordinate geometry to one Tb and six Fe atoms.
TbFe6Sn6 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Tb is bonded to twelve Fe and eight Sn atoms to form distorted TbFe12Sn8 hexagonal bipyramids that share corners with four equivalent TbFe12Sn8 hexagonal bipyramids, faces with twenty-four FeTb2Fe4Sn6 cuboctahedra, and faces with four equivalent TbFe12Sn8 hexagonal bipyramids. There are a spread of Tb–Fe bond distances ranging from 3.48–3.53 Å. There are a spread of Tb–Sn bond distances ranging from 3.03–3.18 Å. There are three inequivalent Fe sites. In the first Fe site, Fe is bonded to two equivalent Tb, four Fe, and six Sn atoms to form distorted FeTb2Fe4Sn6 cuboctahedra that share corners with fourteen FeTb2Fe4Sn6 cuboctahedra, edges with six FeTb2Fe4Sn6 cuboctahedra, faces with ten FeTb2Fe4Sn6 cuboctahedra, and faces with four equivalent TbFe12Sn8 hexagonal bipyramids. There are two shorter (2.71 Å) and two longer (2.72 Å) Fe–Fe bond lengths. There are a spread of Fe–Sn bond distances ranging from 2.72–2.83 Å. In the second Fe site, Fe is bonded to two equivalent Tb, four Fe, and six Sn atoms to form distorted FeTb2Fe4Sn6 cuboctahedra that share corners with fourteen FeTb2Fe4Sn6 cuboctahedra, edges with seven FeTb2Fe4Sn6 cuboctahedra, faces with nine FeTb2Fe4Sn6 cuboctahedra, and faces with four equivalent TbFe12Sn8 hexagonal bipyramids. There are two shorter (2.71 Å) and two longer (2.72 Å) Fe–Fe bond lengths. There are a spread of Fe–Sn bond distances ranging from 2.71–2.82 Å. In the third Fe site, Fe is bonded to two equivalent Tb, four Fe, and six Sn atoms to form distorted FeTb2Fe4Sn6 cuboctahedra that share corners with fourteen FeTb2Fe4Sn6 cuboctahedra, edges with seven FeTb2Fe4Sn6 cuboctahedra, faces with nine FeTb2Fe4Sn6 cuboctahedra, and faces with four equivalent TbFe12Sn8 hexagonal bipyramids. There are a spread of Fe–Sn bond distances ranging from 2.71–2.83 Å. There are five inequivalent Sn sites. In the first Sn site, Sn is bonded in a 8-coordinate geometry to two equivalent Tb and six Fe atoms. In the second Sn site, Sn is bonded in a 7-coordinate geometry to one Tb and six Fe atoms. In the third Sn site, Sn is bonded in a 8-coordinate geometry to one Tb, six Fe, and one Sn atom. The Sn–Sn bond length is 2.93 Å. In the fourth Sn site, Sn is bonded in a 12-coordinate geometry to three equivalent Tb and six Fe atoms. In the fifth Sn site, Sn is bonded in a 6-coordinate geometry to six Fe atoms.
Tb(TiGa2)2 crystallizes in the tetragonal I4/mmm space group. The structure is three-dimensional. Tb is bonded in a distorted square co-planar geometry to twelve Ga atoms. There are four shorter (2.90 Å) and eight longer (3.32 Å) Tb–Ga bond lengths. Ti is bonded in a 10-coordinate geometry to two equivalent Ti and eight Ga atoms. Both Ti–Ti bond lengths are 2.72 Å. All Ti–Ga bond lengths are 2.80 Å. There are seven inequivalent Ga sites. In the first Ga site, Ga is bonded in a 11-coordinate geometry to three equivalent Tb, four equivalent Ti, and four Ga atoms. There are two shorter (2.68 Å) and two longer (2.91 Å) Ga–Ga bond lengths. In the second Ga site, Ga is bonded in a 11-coordinate geometry to three equivalent Tb, four equivalent Ti, and four Ga atoms. Both Ga–Ga bond lengths are 2.68 Å. In the third Ga site, Ga is bonded in a 11-coordinate geometry to three equivalent Tb, four equivalent Ti, and four Ga atoms. There are one shorter (2.68 Å) and two longer (2.91 Å) Ga–Ga bond lengths. In the fourth Ga site, Ga is bonded in a 11-coordinate geometry to three equivalent Tb, four equivalent Ti, and four Ga atoms. The Ga–Ga bond length is 2.68 Å. In the fifth Ga site, Ga is bonded in a 11-coordinate geometry to three equivalent Tb, four equivalent Ti, and four Ga atoms. There are one shorter (2.68 Å) and two longer (2.91 Å) Ga–Ga bond lengths. In the sixth Ga site, Ga is bonded in a 11-coordinate geometry to three equivalent Tb, four equivalent Ti, and four Ga atoms. There are one shorter (2.68 Å) and two longer (2.91 Å) Ga–Ga bond lengths. In the seventh Ga site, Ga is bonded in a 11-coordinate geometry to three equivalent Tb, four equivalent Ti, and four Ga atoms.
TbRu2Al10 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Tb is bonded in a 10-coordinate geometry to four equivalent Ru and sixteen Al atoms. All Tb–Ru bond lengths are 3.47 Å. There are a spread of Tb–Al bond distances ranging from 3.16–3.70 Å. Ru is bonded in a 10-coordinate geometry to two equivalent Tb and ten Al atoms. There are a spread of Ru–Al bond distances ranging from 2.57–2.76 Å. There are five inequivalent Al sites. In the first Al site, Al is bonded in a 2-coordinate geometry to one Tb, two equivalent Ru, and two equivalent Al atoms. Both Al–Al bond lengths are 3.06 Å. In the second Al site, Al is bonded in a distorted linear geometry to two equivalent Tb, two equivalent Ru, and two equivalent Al atoms. Both Al–Al bond lengths are 2.87 Å. In the third Al site, Al is bonded in a 2-coordinate geometry to two equivalent Tb, two equivalent Ru, and two equivalent Al atoms. Both Al–Al bond lengths are 2.93 Å. In the fourth Al site, Al is bonded in a distorted bent 120 degrees geometry to two equivalent Tb, two equivalent Ru, and two equivalent Al atoms. There are one shorter (2.67 Å) and one longer (2.82 Å) Al–Al bond lengths. In the fifth Al site, Al is bonded in a 12-coordinate geometry to one Tb, two equivalent Ru, and nine Al atoms. The Al–Al bond length is 2.71 Å.
Tb(CuAl)6 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Tb is bonded in a 12-coordinate geometry to twelve Cu and eight Al atoms. There are four shorter (3.20 Å) and eight longer (3.30 Å) Tb–Cu bond lengths. There are a spread of Tb–Al bond distances ranging from 2.97–3.10 Å. There are two inequivalent Cu sites. In the first Cu site, Cu is bonded to two equivalent Tb, four Cu, and six Al atoms to form a mixture of distorted edge, face, and corner-sharing CuTb2Al6Cu4 cuboctahedra. There are two shorter (2.52 Å) and two longer (2.54 Å) Cu–Cu bond lengths. There are a spread of Cu–Al bond distances ranging from 2.52–2.65 Å. In the second Cu site, Cu is bonded in a 12-coordinate geometry to two equivalent Tb, four equivalent Cu, and six Al atoms. There are a spread of Cu–Al bond distances ranging from 2.64–2.74 Å. There are three inequivalent Al sites. In the first Al site, Al is bonded in a 10-coordinate geometry to one Tb, six Cu, and three Al atoms. There are one shorter (2.62 Å) and two longer (2.83 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 8-coordinate geometry to one Tb, six Cu, and three Al atoms. There are one shorter (2.63 Å) and two longer (2.88 Å) Al–Al bond lengths. In the third Al site, Al is bonded in a 12-coordinate geometry to two equivalent Tb, six Cu, and four Al atoms.
TbFe2Al10 crystallizes in the orthorhombic Cmcm space group. The structure is three-dimensional. Tb is bonded in a 10-coordinate geometry to four equivalent Fe and sixteen Al atoms. All Tb–Fe bond lengths are 3.41 Å. There are a spread of Tb–Al bond distances ranging from 3.10–3.66 Å. Fe is bonded in a 10-coordinate geometry to two equivalent Tb and ten Al atoms. There are a spread of Fe–Al bond distances ranging from 2.52–2.70 Å. There are five inequivalent Al sites. In the first Al site, Al is bonded in a 2-coordinate geometry to two equivalent Tb, two equivalent Fe, and eight Al atoms. There are a spread of Al–Al bond distances ranging from 2.59–2.83 Å. In the second Al site, Al is bonded to one Tb, two equivalent Fe, and nine Al atoms to form a mixture of distorted face and corner-sharing AlTbAl9Fe2 cuboctahedra. There are a spread of Al–Al bond distances ranging from 2.69–2.97 Å. In the third Al site, Al is bonded in a 12-coordinate geometry to two equivalent Tb, two equivalent Fe, and eight Al atoms. There are a spread of Al–Al bond distances ranging from 2.55–2.74 Å. In the fourth Al site, Al is bonded in a 2-coordinate geometry to one Tb, two equivalent Fe, and eight Al atoms. There are one shorter (2.69 Å) and two longer (2.77 Å) Al–Al bond lengths. In the fifth Al site, Al is bonded in a 2-coordinate geometry to two equivalent Tb, two equivalent Fe, and eight Al atoms.
Tb(MnAl)6 crystallizes in the orthorhombic Immm space group. The structure is three-dimensional. Tb is bonded in a 8-coordinate geometry to twelve Mn and eight Al atoms. There are four shorter (3.19 Å) and eight longer (3.32 Å) Tb–Mn bond lengths. There are a spread of Tb–Al bond distances ranging from 2.91–3.06 Å. There are two inequivalent Mn sites. In the first Mn site, Mn is bonded to two equivalent Tb, four Mn, and six Al atoms to form a mixture of distorted corner, edge, and face-sharing MnTb2Mn4Al6 cuboctahedra. There are two shorter (2.46 Å) and two longer (2.53 Å) Mn–Mn bond lengths. There are a spread of Mn–Al bond distances ranging from 2.52–2.64 Å. In the second Mn site, Mn is bonded to two equivalent Tb, four equivalent Mn, and six Al atoms to form a mixture of distorted corner, edge, and face-sharing MnTb2Mn4Al6 cuboctahedra. There are a spread of Mn–Al bond distances ranging from 2.61–2.67 Å. There are three inequivalent Al sites. In the first Al site, Al is bonded in a 10-coordinate geometry to one Tb, six Mn, and three Al atoms. There are one shorter (2.70 Å) and two longer (2.79 Å) Al–Al bond lengths. In the second Al site, Al is bonded in a 8-coordinate geometry to one Tb, six Mn, and three Al atoms. There are one shorter (2.77 Å) and two longer (3.01 Å) Al–Al bond lengths. In the third Al site, Al is bonded in a 12-coordinate geometry to two equivalent Tb, six Mn, and four Al atoms.