Synthesis, Structural and Magnetic Properties of Rare-Earth Intermetallic Compounds

Abstract

<p>Series of rare-earth intermetallic compounds were synthesized and studied.</p> <p>The Gd₄Ge_3-<em>x</em><em>Pn_x</em> (<em>Pn</em> = P, Sb, Bi; <em>x</em> = 0.5 - 3) series of compounds were synthesized to explore the stability of the non-existent Gd₄Ge₃ binary through partial <em>Pn</em> substitutions to increase valence electron concentrations. Electronic band structure calculations were performed to elucidate the relationships between the hypothetical "Gd₄Ge₃" and Gd₅Ge₄ binaries. All Gd₄Ge_3-<em>x</em><em>Pn_x</em> phases order ferromagnetically with relatively high Curie temperatures of 234 to 356 K.</p> <p>The Gd₅Ge_4-<em>x</em>P<em>_x</em> phases were synthesized to explore the effects of both atomic size and valence electron concentration differences between Ge and P atoms. Partial substitution of P for Ge atoms occur on the interslab site, which causes the interslab distances to increase. In Gd₅Ge_4-<em>x</em>P<em>_x</em>, only a small amount of P substitution (<em>x</em> = 0.25) is required to induce ferromagnetic ordering. The appearance of a Griffiths phase is also discussed.</p> <p>The temperature dependence of the different <em>RE</em>₂Fe₁₇ (<em>RE</em> = Gd - Ho) phases was tracked by reciprocal space images generated from single crystal X-ray diffraction.</p> <p>GdCo₄B was synthesized by arcmelting and tri-arc techniques to confirm the presence of magnetostriction. Single crystal and powder X-ray diffraction, dilatometer and magnetic measurements were done.</p>