Magnetic behaviors of Ti 50 Zr 33 Ni 17 quasicrystals measured by VSM Yunman Lee, Jae-kyun Jeon, Hyemin Shin and Jae-yong Kim * Department of Physics, Hanyang University, Seoul, 133-791, Korea Received June 15, 2008; accepted September 1, 2008 Ti –– Zr –– Ni / Quasicrystals / Magnetic properties / VSM Abstract. Quasicrystals made with Ti, Zr and Ni are good candidate materials studying the magnetic properties of aperiodic structure because the role of Ni in stabiliza- tion of the quasicrystal phase is important. Various mag- netic states in quasicrystals have been reported including diamagnetism, paramagnetism, spin glass, ferromagnetism and ferrimagnetism. We prepared Ti––Zr––Ni quasicrystals by rapid quenching method. The magnetization (M) of Ti 50 Zr 33 Ni 17 quasicrystal was measured as a function of applied magnetic field (H) and a temperature by using a vibrating sample magnetometer (VSM). When the mag- netic fields of higher than 2000 G were applied, the mag- netization values were decreased as increasing tempera- ture. The field-cooling (FC) and zero-field-cooling (ZFC) magnetization of the samples were also measured and showed no significant difference in magnetization beha- vior. Our combined results demonstrated that the rapidly quenched Ti––Zr––Ni quasicrystals exhibit paramagnetic properties with no hint of a measurable magnetic hyster- esis. It is shown that Ti 50 Zr 33 Ni 17 quasicrystals demon- strate paramagnetic characteristic to the maximum applied magnetic field of 10 000 Oe. Interestingly, magnetization fluctuation was noticed in the regions of high magnetic field and at low temperature (25–300 K). 1. Introduction Although most of quasicrystals are found in Al-based al- loys, the structural and physical characteristics of Ti-based quasicrystals are still interesting in terms of the structural stability [1, 2] and potential applications in hydrogen sto- rage materials [3, 4]. Among Ti-based quasicrystals, Ti––Zr––Ni alloys are known to be the best ordered of forming quasicrystal without silicon (comparing with other two exceptions, Ti ––Zr–– Co and Ti––Zr––Fe) [5, 6]. Although the structural and mechanical properties of qua- sicrystals have lively researched [7, 8], not many studies on the magnetic properties have yet reported. To the best of our knowledge, two representative studies on the mag- netic properties of quasicrystals are reported. The first are the rare-earth (RE) element containing RE––Mg––Zn and RE––Mg––Cd family, where the magnetic moments of f- electrons of the rare earth atoms are sizable and well loca- lized [9–12]. The second are the quasicrystals of AlPdMn and AlCuFe family, where the d-electrons of transition metal elements represent the reoriented magnetic dipoles [13–15], and other Al-based quasicrystals [16, 17]. For the Ti-based quasicrystals, only a few results are reported on the magnetic properties including magnetic susceptibil- ities of Ti ––Cr––Si–– O alloys [18], a superconductivity property of quasicrystals dominant Ti––Zr––Ni alloys [19], and combined with the role of hydrogen in magnetism [20]. Therefore, we investigated magnetic properties of the rapidly quenched Ti––Zr––Ni alloys by using a vibrating sample magnetometer (VSM) to enhance the understand- ing of the magnetic properties of Ti––Zr––Ni quasicrystals. The magnetic properties were studied by measuring the magnetization (M) as a function of temperature (T) and magnetic field (H). 2. Experimental procedure Pieces of Ti, Zr, Ni with purities of higher than 99.9% were arc-melted in an argon atmosphere on a Cu hearth which is cooled by water. To minimize the oxygen con- tamination, the sample chamber was evacuated to the 10 5 torr and was back filled using a high purity argon gas for several times. For the homogeneity of the samples, the ingots were melted at least three times and were flipped at each melting-cooling cycle. After the elements were homogeneously mixed, the melted alloys were subse- quently quenched on a high speed rotating stainless wheel which rotates 1000–5000 rpm and produce a thin metallic ribbons. The metallic ribbons obtained by this method have about a few micrometers thick, 2  5 cm length and 2 mm width. This technique can achieve a cooling rate from 10 5 to 10 6  C/s, which is fast enough to solidify the liquids and form a non-equilibrium phase. The studies of microstructure and the phases appeared during the investigations were analyzed by using X-ray diffraction (XRD) and transmission electron microscope (TEM). X-ray diffraction patterns were obtained by using a CuK a radiation. The magnetization measurements were carried out by using a vibrating sample magnetometer (model 7307 VSM Z. Kristallogr. 224 (2009) 67–70 / DOI 10.1524/zkri.2009.1071 67 # by Oldenbourg Wissenschaftsverlag, Mu ¨nchen * Correspondence author (e-mail: kimjy@hanyang.ac.kr) Properties / Applications Unauthenticated Download Date | 7/26/18 12:55 AM