Effects of Hydrogen on Structure and Magnetic Properties in Pd-doped TiZrNi Quasicrystals

Abstract

Ti-based quasicrystals, regarded as the second-largest class of quasicrystal followed by the Al-based ones, are known to have high chemical affinity with hydrogen. Recently, much attention has been focused on the hydrogen storage properties of TiZrNi quasicrystals, because Ti-based quasicrystals are typically well ordered and thermodynamically stable. However, the hydrogenation of the quasicrystals is often limited due to the surface barrier of a thick oxygen layer. To prevent the oxidation, palladium has been selected, as an impurity and a coating material in TiZrNi alloys. Although many studies on the formation of quasicrystals and hydrogenation of TiZrNiPd alloys very little is known about the influence of hydrogen on magnetic and electrical properties of TiZrNiPd quasicrystals. The effect of hydrogen on electrical, magnetic, and structural properties of icosahedral Ti53Zr27-xNi20Pdx (x=0, 4, and 8) quasicrystals was investigated by analyzing the data obtained from X-ray diffraction(XRD), magnetic moment values, and resistivity measurements. The samples were prepared by mixing and arc-melting a total mass of 2~2.5 grams of Ti, Zr, Ni, and Pd pieces under an argon atmosphere. XRD patterns show that the quasilattice constants of Ti53Zr27Ni20 and Ti53Zr19Ni20Pd8 quasicrystals increased from 5.12 to 5.39 Å and from 5.06 to 5.24 Å, respectively, upon hydrogen uptaking while icosahedral phase was maintained after hydrogenation. The magnetization values measured by using a superconducting quantum interference device at 3000 Oe decreased from 0.00648 to 0.00491 emu/g for Ti53Zr23Ni20Pd4 quasicrystal at room temperature after hydrogenation. It is understood that the reasons are responsible for the reduced interactions of magnetic dipole moments between Ni atoms induced by the quasilattice expansion after hydrogen absorption. Hydrogen also contributes to significantly increase the resistivity values of Ti53Zr19Ni20Pd8 quasicrystal from 0.1651 to 0.3937 Ω∙cm at room temperature. The increasd electrical resistivity of the TiZrNiPd quasicrystal is understood due to increased electron activities after the formation of a hydride anion.