Assoc. Prof. Dr. Ayşen YILMAZ
Department of Chemistry
Middle East Technical University
Ankara, TURKEY
Prof. Dr. Gülhan ÖZBAYOĞLU
Dean Faculty of Engineering
Atılım University Ankara, Turkey
RAD, 24-27 April 2012
OBJECTIVES
To synthesize metal doped Li2B4O7 to be used in TL dosimetry by using
different synthesis methods.
• high temperature solid state synthesis
• solution assisted synthesis
• doping with Cu and Mn
• Co-doping with Ag and In together with Cu, of Ag, P and Mg together
with Mn
To determine the thermoluminescence response.
THERMOLUMINESCENCE
RADIATION
EXPOSURE
AND
RESULTANT
RADIATION
STORAGE
HEATING
LIGHT
EMISSION
LITHIUM TETRABORATE
SYNTHESIS
 Powder:
 by heating hydrated precursors
 by wet reaction
 by solid state reactions
Pellet: ease in lab work, final product is fragile
Glass: cautious control of temperature (up to 1150oC) rapid cooling
employed
Crystal: require complicated systems, seed crystal
LITHIUM TETRABORATE
TL RESPONSE
▫ Glow Curve: Generally around 200 O C
MATERIALS AND METHODS
2- METHODS
Synthesis
Method
Material
Li2B4O7
High Temp.
Solid State
Doping
High Temp.
Solid State
Solution Assisted
Water /Solution
Assisted
Solution Assisted
• Li2CO3 + 4H3BO3  Li2B4O7 + CO2 +6 H2O
MATERIALS AND METHODS
High Temperature Solid State Synthesis
• Stoichiometric quantities of Li2CO3 and H3BO3
Mixing
Initial
Heating
Secondary
Heating
• 0-400 oC by 400 oC per hr
• Retention Time: 3 hr
• Mixing,Pounding, Blending
•
•
•
•
400-750 oC by 400 oC per hr
2 hr exposure
Intermittent mixing
2 more hours
MATERIALS AND METHODS
Water / Solution Assisted Synthesis
Stirring
Initial
Heating
Secondary
Heating
• Li2CO3 and H3BO3 in 15 ml water
• At 100-150 oC for 15-20 min
• 0-150 oC by 400 oC per hr
• Retention Time: 3 hr
• Mixing
• 400-750 oC by 400 oC per hr
• 4 hr exposure
MATERIALS AND METHODS
High Temperature Solid State Doping
 Applied to high temp. solid state synthesis product only
 0.1-1.0% Cu, 0.1-10% Mn doped
Heating  25-750oC by 400oC per hr
 Retention2+1 hr with intermittent mixing
MATERIALS AND METHODS
Solution Assisted Doping
For water/solution assisted synthesis product
0.1-1% Cu
 For high temp solid state synthesis product
0.1% Cu and 1.0 % Mn  best results
Heating
 150oC - 3 hrs, 700oC - 2 hrs
MATERIALS AND METHODS
Dopant amounts for double doping experiments
LBO Weight (g)
Cu %
Ag %
Cu %
In %
1
0.1
0.01
0.1
0.01
1
0.1
0.02
0.1
0.02
1
0.1
0.03
0.1
0.03
1
0.1
0.04
0.1
0.04
1
0.1
0.05
0.1
0.05
1
0.3
0.01
0.3
0.01
1
0.3
0.02
0.3
0.02
1
0.3
0.03
0.3
0.03
1
0.3
0.04
0.3
0.04
1
0.3
0.05
0.3
0.05
MATERIALS AND METHODS
Dopant amounts for triple doping experiments
LBO
Cu %
Ag %
In %
1
0.1
0.04
0.01
1
0.1
0.04
0.03
1
0.1
0.04
0.05
1
0.1
0.05
0.01
1
0.1
0.05
0.03
1
0.1
0.05
0.05
1
0.3
0.04
0.01
1
0.3
0.04
0.03
1
0.3
0.04
0.05
1
0.3
0.05
0.01
1
0.3
0.05
0.03
1
0.3
0.05
0.05
Weight (g)
RESULTS AND DISCUSSION-xrd-tl
• X RAY DIFFRACTION high temperature solid state synthesis
a
b
c
a) Undoped lithium tetraborate
produced by high temperature
solid state synthesis b) Lithium
tetraborate doped by solid state
doping method c) Lithium
tetraborate doped by solution
assisted doping method.
RESULTS AND DISCUSSION-xrd-tl
Undoped lithium tetraborate produced by water assisted method b)Lithium tetraborate solution assisted doping
Intensity (arbitrary units)
b
10
20
30
40
50
2 degree)
60
70
80
• THERMOLUMINESCENCE ANALYSES
0.1% Cu
0.2% Cu
0.3% Cu
0.4% Cu
0.5% Cu
0.6% Cu
0.7% Cu
0.8% Cu
0.9% Cu
1% Cu
5
1.0x10
Intensity (arbitrary units)
H.T. Solid State
Synthesized
4
8.0x10
4
6.0x10
Cu doped by H.T.
Solid State
Very low
intensity
around 200oC
4
4.0x10
4
2.0x10
0.0
0
50
100
150
200
250
300
o
Temperature ( C)
350
400
450
Very complicated
glow curve , no
noticable trend
Cu: 0.1%
Cu: 0.2%
Cu: 0.3%
Cu: 0.4%
Cu: 0.5%
Cu: 0.6%
Cu: 0.7%
Cu: 0.8%
Cu: 0.9%
Cu: 1%
5
5.0x10
5
4.5x10
Intensity (arbitrary units)
5
4.0x10
5
3.5x10
5
3.0x10
5
2.5x10
5
2.0x10
5
Water/Soln. Assisted
Synthesized
Cu doped by Solution
Assisted Technique
Higher
intensity
around 100oC
1.5x10
5
1.0x10
4
5.0x10
0.0
0
50
100
150
200
250
o
Temperature ( C)
300
350
400
Around 200oC
Best result:
0.1%Cu
5
2.0x10
Intensity (arbitrary units)
H.T. Solid State
Synthesized
0.1% Cu
0.2% Cu
0.3% Cu
0.4% Cu
0.5% Cu
0.6% Cu
0.7% Cu
0.8% Cu
0.9% Cu
1% Cu
Cu doped by
Solution Assisted
Technique
Lower intensity
around 100oC
5
1.0x10
0.0
0
50
100
150
200
250
o
Temperature ( C)
300
350
400
Main peak around
200oC
Best result:
0.1%Cu
Glow patterns for the samples produced by solid state synthesis method and (0.1-1 % Cu)
doped by solution assisted method.
with 0.1%Cu, 0.04% Ag coactivator gave the highest TL response.
Glow patterns for 0.1% Cu with varying
amounts of Ag (0.01-0.05)
Glow patterns for 0.3% Cu with
varying amounts of Ag (0.01-0.05)
Glow patterns for 0.1% and 0.3% Cu with varying amounts of In (0.01-0.05)
with 0.1%Cu, 0.04% Ag coactivator gave the highest TL response.
Glow patterns for 0.1% and 0.3% Cu-0.04%Ag with varying amounts of In (0.01-0.05)
Mn doping:
Intensity (a.u.)
d
c
b
a
0
10
20
30
40
50
60
70
2 theta (degree)
XRD patterns of solution assisted synthesized undoped LTB (a), high temperature
solid synthesized undoped LTB (b), solution assisted synthesized 1 wt % Mn
doped LTB (c), and high temperature solid synthesized 1 wt % Mn doped LTB
LTB synthesized with solution assisted method
and solution assisted doped
LTB synthesized with solution
assisted method and high
temperature solid state doped
LTB synthesized with high
temperature solid state synthesis
method and solution assisted
doped
LTB synthesized with high
temperature solid state synthesis
method and high temperature
solid state doped
Thermoluminescence measurements of LTB synthesized with high temperature solid
state synthesis method and high temperature solid state doped with 0.5 wt % Ag and
varying Mn content in the range of 0.1 - 1 wt %.
Thermoluminescence measurements of LTB synthesized with high temperature solid
state synthesis method and high temperature solid state doped with 0.5 wt % P and
varying Mn content in the range of 0.1 - 1 wt %.
Thermoluminescence measurements of LTB synthesized with high temperature solid
state synthesis method and high temperature solid state doped with 0.5 wt % Mg and
varying Mn content in the range of 0.1 - 1 wt %.
SEM images of solution assisted synthesized 1 wt % Mn solution assisted doped LTB (A),
solution assisted synthesized 1 wt % Mn high temperature solid doped LTB (B), high
temperature solid synthesized 1 wt % Mn solution assisted doped LTB (C), and high
temperature solid synthesized 1 wt % Mn high temperature solid doped LTB (D).
TEM Micrograph taken from high temperature solid synthesized 1 wt % Mn high
temperature solid doped LTB (A) and solution assisted synthesized 1 wt % Mn high
temperature solid doped LTB (B).
CONCLUSIONS
The radii of Ag+ is larger than Li+ radius and LTB lattice will be destroyed, and therefore
TL peaks are shifted.
Phosphorus co-doping increased the peak intensities of glow curves because when P is
doped into LTB, PO43- can replace the BO4 units, the radius of P is not too larger than
boron atom, no destruction in LTB lattice would be expected.
Electronegativity of P atom is higher than that of B atom, so impurity of P can produce
electron traps in LTB crystals to enhance TL sensitivity.
Mg2+ has approximately same ionic radii with Li+ ions however, the high charge on Mg
create great valance difference to destroy the LTB lattice.
In order to obtain high intensity glow peak the sample need to be the combinations of
nano sized crystallites. Having bigger single crystals reduces the glow peak intensity of
sample. Preparing lithium tetraborate by solution assisted synthesis method helps the
formation of bigger single crystals.
High temperature solid state synthesis method is the way to combine highly ordered
crystalline nanoparticles of the same phase because this method has diffusion control
step of reactants. This step increases the time duration during crystallization.
Acknowledgements
Prof. Dr. Necmeddin Yazici, Dept. of Eng. Physics, University of Gaziantep,
National BORON Research Institute for financial support
References:
1. E. Pekpak, A. Yilmaz, G. Ozbayoglu, “The Effect of Synthesis and Doping
Procedures on Thermoluminescent Response of Lithium Tetraborate”
Journal of Alloys and Compounds, 509 (2011) 2466–2472.
2. M. Kayhan, A. Yilmaz, “Effects of Synthesis, Doping Methods and Metal
Content on Thermoluminescence Glow Curves of Lithium Tetraborate“Journal
of Alloys and Compounds, 509 (2011) 7818-7825.
Thank you very much for your attention!