Local structure in marginal glass forming Al-Sm alloy

Kalay, Yunus Eren
Kramer, M. J.
Anderson, I. E.
The local structure in rapidly quenched Al(100-x)Smx (x = 8, 10, 11, and 12) and liquid Al89Sm11 has been investigated using a combination of transmission electron microscopy (TEM) and high-energy synchrotron X-ray diffraction (HEXRD). TEM analysis showed a featureless microstructure with diffuse scattering in rapidly quenched Al(100-x)Smx (x = 8, 10, 11, and 12) within the glass formation composition range under the bright field (BF) conditions. Total structure factor analysis of the liquid and as-quenched alloys revealed a pre-peak located well below the main amorphous peak and a distinct side peak. The presence of the pre-peak and the side peak is related to the formation of Sm rich medium range order (MRO) clusters in the liquid that is retained in the as-quenched alloys. Atomic structure models constructed using Reverse Monte Carlo (RMC) simulations from experimentally determined total structure factors and coupled with Voronoi Tessellation analysis indicated icosahedral and deformed bcc-like Voronoi polyhedron (VP) surrounding Al and Sm atoms, respectively. Sm atoms were found to be highly coordinated with Al atoms in the first shell neighborhood. The structural unit sizes corresponding to the extra broad peaks and the first shell neighborhood around Sm atoms have remarkable similarities with the high temperature metastable Al11Sm3 tetragonal phase. The existence of the Sm rich MRO clusters in the as-quenched state is believed to promote the high nucleation density of fcc-Al nanocrystals that form when the material is devitrified by acting as catalyst sites.


Acoustic phonons scattering mobility and carrier effective mass in In6S7 crystals
Qasrawi, A. F.; Hasanlı, Nızamı (Elsevier BV, 2006-12-21)
Systematic dark electrical resistivity and Hall coefficient measurements have been carried out in the temperature range of 170-320 K on n-type In6S7 crystals. The analysis of the electrical resistivity and carrier concentration reveals the intrinsic type of conduction with an average energy band gap of similar to 0.75 eV The carrier effective masses of the conduction and valence bands were calculated from the intrinsic temperature-dependent carrier concentration data and were found to be 0.565m(0) and 2.020...
Size dependent stability and surface energy of amorphous FePt nanoalloy
Akdeniz, Mahmut Vedat; Mehrabov, Amdulla (Elsevier BV, 2019-06-05)
The effects of particle size (2-6 nm) and temperature (300-2700 K) on the stability and local structural evolutions of amorphous equiatomic FePt bulk/nanoalloys have been investigated by combining Embedded Atom Model (EAM) with classical molecular dynamics (MD) simulation method. The three dimensional (3D) atomic configuration of amorphous FePt NPs by means of Voronoi analysis reveals that, deformed bcc (d-bcc) and icosahedron (d-ico) type structures are most probable local atomic configurations for 2-6 nm ...
Structural and electrical properties of TlGa(SxSe1-x)(2) mixed crystals
KARABULUT, ORHAN; Parlak, Mehmet; Mamedov, G. M. (Elsevier BV, 2007-01-21)
Systematic investigations of crystal structure, electrical conductivity and photoconductivity have been carried out on the complete series of TlGa(SxSe1-x)(2) solid solutions. X-ray diffraction (XRD) analyses together with TREOR90 computer program have revealed that this compound shows different structural modifications at each composition. The possible charge transfer mechanisms have been investigated by performing temperature dependent electrical conductivity measurements in the temperature range of 100-4...
Temperature- and excitation-dependent photoluminescence in TlGaSeS layered crystals
Hasanlı, Nızamı (Elsevier BV, 2011-03-17)
Photoluminescence (PL) spectra of TlGaSeS layered single crystals have been studied in the wavelength region of 695-1010 nm and in the temperature range of 20-56K. Two PL bands centered at 773 (1.605 eV, A-band) and 989 nm (1.254 eV, B-band) were observed at T = 20 K. Variations of both bands have been investigated as a function of excitation laser intensity in the range from 4.2 to 111.4 mW cm(-2). These bands are attributed to recombination of charge carriers through donor-acceptor pairs located in the ba...
Effects of annealing temperature on the structural and optical properties of ZnO hexagonal pyramids
BACAKSIZ, EMİN; YILMAZ, ŞERİFE; Parlak, Mehmet; Varilci, A.; Altunbas, M. (Elsevier BV, 2009-06-10)
ZnO thin films were deposited on quartz substrate at 550 degrees C by using spray pyrolysis method and subsequently annealed between 600-900 degrees C with a step of 100 degrees C. The characterizations of the structural and optical properties of the films have been carried out by means of X-ray diffraction, scanning electron microscopy (SEM) and optical transmittance measurements. XRD ans SEM images indicated that annealing temperature did not play a great role on the microstructure of ZnO films. ZnO thin ...
Citation Formats
Y. E. Kalay, M. J. Kramer, and I. E. Anderson, “Local structure in marginal glass forming Al-Sm alloy,” INTERMETALLICS, pp. 1676–1682, 2010, Accessed: 00, 2020. [Online]. Available: https://hdl.handle.net/11511/38130.