Impurity-driven nanocrystallization of Zr-based bulk amorphous alloys

The effect of oxygen content and Ti addition on the glass forming ability (GFA) and crystallization kinetic of Zr-based bulk glass forming alloys have been studied by means of thermal analysis and X-ray diffraction techniques. Presence of oxygen triggers the formation of a nanocrystalline metastable f.c.c. Zr-2 Ni-type phase which can act as heterogenous nucleation sites for the formation of dendrites during solidification. An increase in oxygen content changes the crystallization behaviour from a single- to a double-step process and triggers the crystallization of stable Zr-2(Cu,Al) besides metastable Zr-2 Ni-type phase. Oxygen-triggered nucleation of a nanocrystalline metastable Zr-2 Ni-type phase is found to be the initial step of crystallization. The important parameters of GFA such as glass transition temperatures, T-g, the crystallization temperatures, T-x, and crystallization enthalpies, Delta H, were determined by using DSC. It was observed that the presence of oxygen, even in a very small amount, and Ti addition cause a drastic reduction of the supercooled liquid region, Delta T-x, accompanied by a change of the crystallization kinetic. This leads to the decrease in stability of the supercooled liquid, consequently results in a deterioration of the glass forming ability of the alloy.


Hydrothermal synthesis of nanostructured TiO2 particles and characterization of their photocatalytic antimicrobial activity
ERDURAL, Beril K.; YÜRÜM, Alp; BAKIR, Ufuk; Karakaş, Gürkan (American Scientific Publishers, 2008-02-01)
Nanostructured titania particles were synthesized by using hydrothermal processing and the photocatalytic antimicrobial activities were characterized. Both sol-gel synthesized and commercial TiO2 (anatase) samples were processed with two step hydrothermal treatments, under alkaline and neutral conditions. Scanning Electron Microscope (SEM) images showed that alkaline treatment yields nanofibers and lamellar structured particles from the commercial anatase and sol-gel synthesized samples respectively. Furthe...
Li+ and Li interactions with carbon nanocage structures
Pekoez, Rengin; Erkoç, Şakir (American Scientific Publishers, 2008-02-01)
Molecular dynamics simulations have been carried out to explore the structural properties of Li and Li+ confined inside single-walled carbon nanotubes (SWCNTs) and fullerene molecules. C-Li, C-Li+, Li-Li and Li+-Li+ interactions have been represented by pair functions and parameterized for the corresponding interactions. C-C interactions have been modeled by Tersoff potential. Open-ended SWCNTs with various sizes and chirality, as well as fullerenes with various sizes have been considered in the simulations...
Heterojunction solar cells with integrated Si and ZnO nanowires and a chalcopyrite thin film
KARAAĞAÇ, Hakan; Parlak, Mehmet; YENGEL, Emre; Islam, M. Saif (Elsevier BV, 2013-06-15)
ZnO nanowires (NWs) have been successfully synthesized using a hydrothermal technique on both glass and silicon substrates initially coated with a sputtered ZnO thin film layer. Varying ZnO seed layer thicknesses were deposited to determine the effect of seed layer thickness on the quality of ZnO NW growth. The effect of growth time on the formation of ZnO NWs was also studied. Experimental results show that these two parameters have an important effect on formation, homogeneity and vertical orientation of ...
Scanning Hall Probe Microscopy (SHPM) using quartz crystal AFM feedback
Dede, M.; Uerkmen, K.; Girisen, Oe.; Atabak, M.; Oral, Ahmet; Farrer, I.; Ritchie, D. (American Scientific Publishers, 2008-02-01)
Scanning Hall Probe Microscopy (SHPM) is a quantitative and non-invasive technique for imaging localized surface magnetic field fluctuations such as ferromagnetic domains with high spatial and magnetic field resolution of similar to 50 nm and 7 mG/Hz(1/2) at room temperature. In the SHPM technique, scanning tunneling microscope (STM) or atomic force microscope (AFM) feedback is used to keep the Hall sensor in close proximity of the sample surface. However, STM tracking SHPM requires conductive samples; ther...
Anisotropic electrical and dispersive optical parameters in InS layered crystals
QASRAWI, ATEF FAYEZ HASAN; Hasanlı, Nızamı (Elsevier BV, 2010-02-01)
The anisotropy effect on the current transport mechanism and on the dispersive optical parameters of indium monosulfide crystals has been studied by means of electrical conductivity and polarized reflectance measurements along the a-axis and the b-axis, respectively. The temperature-dependent electrical conductivity analysis in the range 10-350 K for the a-axis and in the range 30-350 K for the b-axis revealed the domination of the thermionic emission of charge carriers and the domination of variable range ...
Citation Formats
M. V. Akdeniz and A. Mehrabov, “Impurity-driven nanocrystallization of Zr-based bulk amorphous alloys,” JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY, pp. 894–900, 2008, Accessed: 00, 2020. [Online]. Available: