Time-Resolved X-ray Scattering Investigation of Ordering Kinetics in Fe3Ai

1990 ◽  
Vol 205 ◽  
Author(s):  
B. Park ◽  
G. B. Stephenson ◽  
K. F. Ludwig ◽  
S. M. Allen
Keyword(s):  
Long Range ◽  
Short Range ◽  
Short Range Order ◽  
Range Order ◽  
Long Range Order ◽  
Time Resolved ◽  
X Ray ◽  
X Ray Scattering ◽  
Disordered Phase ◽  
Kinetics Of

AbstractWe have investigated the kinetics of the B2/DO3 transition in Fe3AI (28 at. %) using in situ time-resolved x-ray scattering. In these experiments, the evolution of the diffuse and/or Bragg intensity near the (½ ½ ½) DO3 superlattice peak is observed after the temperature of the sample is abruptly changed. H-ere we present results for the kinetics of re-equilibration of short-range order within the disordered (B2) phase, and of short- and long-range order within the ordered (DO3) phase. The short-range order is characterized by the diffuse peak intensity IDIFFUSE and correlation length ξ;the long-range order is characterized by the Bragg intensity IBRAGG. For quenches within the disordered phase, IDIFFUSE and ξ both relax exponentially at the same rate. The temperature dependence of the relaxation time shows evidence of a divergence at the critical temperature. For shallow quenches within the ordered phase, IBRAGG, IDIFFUSE and ξ all relax exponentially, but with different rates. However, for deep quenches within the ordered phase, IDIFFUSE and ξ do not show simple exponential relaxation. Instead, coarsening of short-range order into long-range order is seen, as in quenches from the disordered phase into the ordered phase. Investigation of up-quenches and down-quenches to the same temperature within the ordered phase indicates that disordering is faster than ordering.

Kinetics of Surface Ordering on Au-Rich Cu3Au(001)

1990 ◽  
Vol 205 ◽  
Author(s):  
S. B. Rivers ◽  
W. N. Unertl ◽  
H. H. Hung ◽  
K. S. Liang
Keyword(s):  
Short Range ◽  
Short Range Order ◽  
Grazing Incidence ◽  
Range Order ◽  
X Ray ◽  
Disorder Phase Transition ◽  
Surface Ordering ◽  
X Ray Scattering ◽  
Kinetics Of ◽  
Plane Diffraction

Abstractwe report grazing-incidence x-ray scattering measurements of the order-disorder phase transition near a Au-rich Cu3Au (001) surface. The bulk transition temperature TB = 648 K is lower than for stoichiometric Cu3Au(001). Surface ordering persists above TB in a layer several monolayers thick up to Ts = 667 K. Kinetics of the ordering were studied by quenching from Ts + 9 K to final temperatures of TF = 661 K and 645 K. Short-range order is established in the bulk within the quench time and does not appear to change subsequently. The bulk short-range order differs from that reported for stoichiometric Cu3Au. For TB < TF = 661 K < TS, the (100) in-plane diffraction beam intensity grows approximately as t1/4 for t > 1000 s and the width continues to narrow. For TF = 645 K < TB, power law growth is not observed for the longest times studied. In both cases the growth is substantially slower than predicted.

Pb()O3-type Perovskites: Part I. Pair-correlation Theory of Order-disorder Phase Transition

1997 ◽  
Vol 12 (8) ◽  
pp. 2117-2126 ◽  
Author(s):  
Hyun M. Jang ◽  
Su-Chan Kim
Keyword(s):  
Long Range ◽  
Order Parameter ◽  
Short Range ◽  
Short Range Order ◽  
Pair Correlation ◽  
Range Order ◽  
Statistical Thermodynamic ◽  
Range Order Parameter ◽  
Long Range Order ◽  
Short Range Order Parameter

The limitation of the long-range order parameter and the necessity of the short-range order parameter for the thermodynamic description of Pb()O3-type perovskites are discussed. Based on the discussion, a statistical thermodynamic model that takes into account the configuration of the neighboring B-site ions (B′ and B″ cations) was developed. A pair-correlation approximation was used in the calculation of the configurational entropy and the long-range coulombic interaction energy between the nearest B-site ions. The theoretical calculations using Pb(Sc1/2Ta1/2)O3 (PST) and Pb(Sc1/2Nb1/2)O3 (PSN) systems indicate that the short-range order parameter persists over a wide range of temperatures examined (0–1800 K) and that there possibly occur consecutive long-range order-disorder transitions in the configuration of B-site cations. The possibility of the existence of short-range ordering above the long-range order-disorder transition temperature was also examined using the annealed PSN specimen as a typical example of Pb()O3-type perovskites.

Short range order in liquid acetic acid as studied by X-ray scattering and DFT calculations

2012 ◽  
Vol 173 ◽  
pp. 164-171 ◽  
Author(s):  
Nourhane Ben Zineb ◽  
Abir Chebaane ◽  
Ferid Hammami ◽  
Mohamed Bahri ◽  
Salah Nasr
Keyword(s):  
Acetic Acid ◽  
Dft Calculations ◽  
Short Range ◽  
Short Range Order ◽  
Range Order ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering

Short range order and its transformation to long range order in Ni4Mo

1998 ◽  
Vol 46 (3) ◽  
pp. 881-892 ◽  
Author(s):  
Satoshi Hata ◽  
Syo Matsumura ◽  
Noriyuki Kuwano ◽  
Kensuke Oki
Keyword(s):  
Long Range ◽  
Short Range ◽  
Short Range Order ◽  
Range Order ◽  
Long Range Order

Anomalous-X-ray scattering associated with short-range order in an Al70Ni15Co15 decagonal quasicrystal

2000 ◽  
Vol 294-296 ◽  
pp. 299-302 ◽  
Author(s):  
Hiroshi Abe ◽  
Nobumichi Tamura ◽  
D Le Bolloc’h ◽  
Simon C Moss ◽  
Yoshie Matsuo ◽  
...  
Keyword(s):  
Short Range ◽  
Short Range Order ◽  
Range Order ◽  
Decagonal Quasicrystal ◽  
X Ray ◽  
X Ray Scattering ◽  
Ray Scattering
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