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PHYS 570 -Introduction to Synchrotron Radiation
Structure and melting of Bi
nanocrystals embedded in a
B2O3-Na2O glass
Mariana C. SiqueiraMariana C. Siqueira
December/2013
Introduction
� Potential use of nanometer�sized metallic particles as catalystics and heat exchange materials;
� Metallic clusters embedded in glass matrices has singular optical properties.
Experimental Details
� Material: Bi nanocrystals embedded in a B2O3$Na2O glass;
� SAXS and WAXS combined measurements at SAS beamline of LNLS;
� Record using one$dimensional gas x$ray position$sensitive detector;
� X$ray monitor placed before and after the sample;
� X$ray beam with λ=1.61Å;� Different temperatures measurements
from 304K to 503K.
Theoretical Background
� SAXS Intensity:
� WAXS Intensity:
� Scherrer equation for average chord lenght:
� Nanocrystal to Liquid Transition:
−−=
∆=
++=
−= ∫
∞
m
llcc
hklhklhkl
lgcWAXS
nmpSAXS
RLTbTm
M
TIITITI
dRqRFRRDqI
)(31
cos)2(
),()(),(),(
)]([)(3
4)()(
26
0
ρσρσ
θθ
λ
θθθθ
πρρ
Results and Discussion� Melting Temperature as
a function of the nanocrystal reciprocal radius.
� Volume fraction of spherical clusters determined by WAXS.
Results and Discussion
� The simultaneous use od SAX and WAXS techniques yield usefull and precise information on the structure and on the crystal$transition of nanocrystals in the glass matrix.
References
� G. Kellermann, A. F. Craievich. Phys. Rev. B, 65:134204 (2002);
� G. Kellermann, A. F. Craievich. Phys. Rev. B, 67:085405 (2003);
� F. Gonella, P. Mazzoldi, Handbook of Nanostructure MAterials and Nanotechnology (Academic, New York, 2000)