X

As-SeX
2XX
X
X
As-Se
As

ESRF

J-PARC
As-Se- 85 -SeLoc al- and intermediate-range loc al structures of As-Se
glasses in a wide c onc entration region inc luding thestiffness transitio nS. Hosokawa,1 J. R. Stellhorn,2 E. Magome,3 P. Boolchand,4 K. Ikeda,5 and T. Otomo5
1Kumamoto Univ., Japan, 2Hiroshima Univ., Japan, 3Saga Light Source, Japan, 4Univ. Sincinatti, USA, 5KEK, Japan

Abstract
The stif f ness transition [1,2] is an attractive and simple idea f or describing physicalproperties of network glasses. This idea was substantially developed by Boolchand andcoworkers [3] as the so-called intermediate phase (I P) using thermodynamic and Raman
scattering experiments. Bauchy et al. [4] carried out ab initio molecular dynamics
simulation on As-Se glassy system, and f ound the specif ic structural signatures f or theI P in the f irst sharp dif f raction peak of the As-Se partial structure f actor, SAsSe (Q),in the reciprocal space, and the f raction of the As-As wrong bonds in the real space.
They requested experimentalists in their paper to f ind the partial structural
signatures f or the I P.
We carried out an anomalous x-ray scattering (AXS) experiment on As-Se [5,6] glasses
at BL15/ Saga-LS and BM02/ ESRF, and analyzed the results using reverse Monte Carlo(RMC) modeling to obtain its partial inf ormation, such as partial structure f actors,
S ij (Q), and partial pair-distribution f unctions, gij (r), and three-dimensional (3D) atomic
conf iguration. However, results f rom RMC modeling highly depend on the constraints inthe RMC f it procedure, such as shortest interatomic distances and bond angles. For
the f urther structural investigations, we carried out neutron dif f raction (ND)
measurements using the NOVA dif f ractometer installed at the J-PARC, and real-spacegN(r) f unctions could be included in t he RMC modeling, which supports thedetermination of the above constraints.
I n this presentation, we will exhibit a better quality of S ij (Q), gij (r), and 3D atomic
conf iguration, and the obtained results will be caref ully discussed in relation to thestif f ness transition by comparing with the above theoretical results by Bauchy et al.
[4]. AXS experiments were carried out at BL15 of the Saga-LS (Proposal No.
1802007A). ND experiments were perf ormed at BL21 of MLF/ J-PARC (Proposal No.
2017B0047). This work was supported by J ST CREST (No. JPMJCR1861).

Experimental results: Anomalous x-ray scattering
(a)

7(b)

glassy As Se 1-

76

60.25

0.25

54

40.33

32

20.40

050

0100

10(d)

7(e)

glassy As Se1-

50.25

S ij (Q)4(a) 720.29

30.33

1twof oldthreef old

10.40

50

100150-1[nm ]= 0.20

0.33
0.37

30.40

2-1

0100

150

200(a)

14

Normalized scattering data

0.6

7glassy As Se1-0.25

50.25

0.29

40.29

0.33

30.33

0.37

0.37

0.40

10.40
0050

100

150200-1050(b) 50

100

150

[nm ]
(c) 20glassy As Se1-

glassy As Se1-

= 0.20= 0.20= 0.20

40
15
0.25

0.25

0.25

30

0.29

0.29

0.33

20

0.29

100.33

0.33

0.37

0.37

102

50.37

0.40

0.40

0.40

As40Se 60 As edge

00.20.40.60.800.2

0.40.60.80[nm][nm]0.20.40.6[nm]3D atomic conf igurations

200020406080100120-1

Q [nm ]

AXS experiment at BL15/ Saga-LSx = 0.20x = 0.25x = 0.33

- 86 -200-1-1[nm ]glassy As Se 1-= 0.2062

1500.5(c)4000.4[nm]= 0.205640013.2

glassy As Se16-1<r> > 2.4

0.37[nm ]gij (r)

0.2

0.29

1

rigid

0.1

0.25

24/ 25200(b)glassy As Se1-600

12.012.412.8Energy (keV)

5003f ourf old3/ 23800

11.6

100.374510150.37

51000

Se K edge

200.333420 eVglassy As Se1-30= 0.200.29

4f (Q,E) = f 0(Q) + f (E) + if (E)As K edge

100-1

250.258200 eV50[nm ]= 0.206Principle of AXS-100Experimental results: Neutron dif f raction

10-50100-1[nm ]12050-1

[nm ]

0.40

Number of constraintsf loppy<r> = 2. 4<r> < 2.4
Degree of f reedom: 350.40

100.3720.40

103

Usual terms Anomalous terms

0.33

30.37

122/ 210.29

40.33
36Constraints
per atoms
bondangle

0.25

50.29

0.29

[1] J. C. Phillips, J. Non-Cryst. Solids 34, 153 (1979).
[2] M. F. Thorpe, J. Non-Cryst. Solids 57, 355 (1983).
[3] D. Selvanathan et al., Phys. Rev. B 61, 15061 (2000).
[4] M. Bauchy et al., Phys. Rev. Lett. 110, 165501 (2013).
[5] S. Hosokawa et al., Europhys. Lett. 102, 66008 (2013).
[6] S. Hosokawa et al., J. Non-Cryst. Solids 431, 31 (2016).

J. C. Phillips 1979
M. F. Thorpe 1983

glassy As Se 1= 0.20

657= 0.20

2

Stif f ness transition theory(c)glassy As Se 1-= 0.20

x = 0.29x = 0.40

0.8