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Synthesis, Crystal Growth, Magnetic and Transport Properties of Ln-M-X (Ln=lanthanide, M=transition metal, X=In, Ga) Compounds

by Williams, Willa Maria

Abstract (Summary)
ABSTRACT This dissertation focuses on the structural stability, magnetic and transport properties of ternary lanthanide compounds grown using indium and gallium flux. Single crystals of TbRhIn5 were synthesized using indium flux. TbRhIn5 is isostructural to the well known LnnMIn3n+2 (n = 1, 2, ?; Ln = La, Ce; M = Rh, Ir) and adopts the HoCoGa5 structure type and crystallizes in the space group P4/mmm, Z = 1. Lattice parameters are a = 4.6000(6) Å and c = 7.4370(11) Å, V = 157.29(6) Å3. A sharp antiferromagnetic transition is observed at TN = 48 K for TbRhIn5. Single crystals of SmPd2Ga2 have been synthesized by flux growth methods. SmPd2Ga2 adopts the tetragonal space group I4/mmm, Z=2, with lattice parameters, a = 4.2170(3) Å and c = 10.4140(3) Å. This new material has physical properties similar to other Sm intermetallics and has, most notably, a large positive magnetoresistance at low temperatures. Magnetic measurements indicate that SmPd2Ga2 is ferromagnetic with Tc ~ 5 K. Single crystals of Tb4MGa12 (M = Pd, Pt) have been synthesized. The isostructural compounds crystallize in the cubic space group, , with Z = 2 and lattice parameters: a = 8.5930(7) Å and a = 8.5850(3) Å for Tb4PdGa12 and Tb4PtGa12, respectively. Magnetic measurements suggest that Tb4PdGa12 and Tb4PtGa12 order antiferromagnetically Néel temperatures of 16 K and 12 K, respectively. Single crystals of Ln4MGa12 (Ln = Dy, Ho, Er; M = Pd, Pt) were synthesized and characterized by single crystal X-ray diffraction. Ln4MGa12 (Ln = Dy, Ho, Er; M = Pd, Pt) are isostructural to Tb4PdGa12. Magnetic measurements show that Dy4PdGa12 and Ho4PdGa12 do not show any magnetic ordering down to 2 K, while Er4PdGa12 shows an antiferromagnetic transition at TN = 3 K, as well as, magnetic transitions at 13 K and 21 K. Dy4PtGa12 orders antiferromagnetically at TN = 11 K and Ho4PtGa12 shows magnetic transitions at 26 K and 92 K. Er4PtGa12 shows an antiferromagnetic transition at TN = 5.5 K and magnetic transitions at 25 K and 93 K. The structure, magnetic, and transport behavior of these phases are discussed and compared.
Bibliographical Information:

Advisor:David P. Young; George G. Stanley; Steven F. Watkins; Karsten Thompson; Julia Y. Chan

School:Louisiana State University in Shreveport

School Location:USA - Louisiana

Source Type:Master's Thesis

Keywords:chemistry

ISBN:

Date of Publication:07/17/2006

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