3+
Al
concentration dependence
3+
of Tb fluorescence in sol gel
glasses
Independent Study in Physics
Jonathan Baker
What I hope to communicate

Who, what, when, where, why?
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Solution 1: Base Catalysis
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What is a Sol-Gel
What we do with it
Problems with sol-gel samples
Why do it
Results
Solution 2: Acid Catalysis with Al3+ dopant
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Why do it
Results…We found something NEW!
we think
What is a Sol-Gel?
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Alternative process for
making glass
Mix rare earth elements
(Tb3+) into sample
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Examine local environment of
host
Examine energy dynamics of
RE
Why do we care about
fluorescent yield?
How the process works
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Densified
Gel
Densified
It’s like cooking, only
with toxic chemicals
Key ingredient for me:
the catalyst
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Gel
Sodium Hydroxide
Nitric Acid
Base Catalysis
Acid Catalysis
Factors that hurt luminescent yield
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Presence of OH ions
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Phonon relaxation
Also non-radiative
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Clustering
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Radiation-less energy
migration among RE’s
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We think we can minimize
these effects
Base Catalysis (theory)
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Addresses OH problem
Gel is dryer (less water)
than acid catalysis
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Smaller pore size
Acts less like a sponge
Base
Catalysis
Acid Catalysis
Base Catalysis (What I did)
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Adapted acid catalysis recipe
Calculated amount of NaOH
needed
Trial and error finally led to
success
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Still cooking
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Blank samples look hopeful
Added Tb3+ into samples
Success remains to be seen
In the meantime…
Return to Acid Catalysis
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Adding Al3+ to solution
breaks up Terbium
clusters
Decreases cross
relaxation
That’s the idea…before I
tell you if it worked,
here’s what I did
5D
3
5D
4
7F
6
Ion 1
Ion 2
7F
0
Ion 1
Ion 2
Making Glass
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Heating
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Densifies dry gel to form
a glass
Organics (carbon) burned
off
Residual OH’s removed
Pore size reduced
Approaching melt glass
quality
Gel
Densified
Analyzing Glass
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5D
4
0.015
Background
Fluorescing levels
0.2%
0.02%
I hope you like Excel
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0.065
volts vs. time
Subtracting the baseline
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542nm and 437nm minus
450 nm
0.000
-0.035
0.001
0.001
0.002
437nm
0.002
0.003
0.003
0.004
0.004
437
437 - 450
-0.085
Analyzed two
concentrations of Tb3+
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437nm data: 0.2%Tb:0.1%Al
5D
3
volts
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Excite 5D3 using Laser
Detected at three
wavelengths
450
-0.135
542nm
-0.185
time (seconds)
542nm
data: 0.2%Tb:0.8%Al
0.1
0
-0.005 -0.10.000
7F
6
7F
5
7F
4
7F
0
0.005
0.010
0.015
-0.2
volts
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-0.3
-0.4
-0.5
-0.6
-0.7
tim e (seconds)
0.020
0.025
Analyzing Data
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Three level diagram
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Two pathways to ground
state
Considered independently
Modeled data using
MathCAD
Imported Excel files into
MathCAD
Fit data in MathCAD
dY 0
  R1Y 0  R 3Y 0
dt
dY 1
  R1Y 0  R 2Y 1
dt
dY 2
  R3Y 0  R 2Y 1
dt
dY 0 dY 1 dY 2


0
dt
dt
dt
More MathCAD Fits
0.2% Tb_data analysis_20to10
0.02% Tb_data analysis_10to1_reheated
Back to Excel

Plotted various rates and initial
populations vs. concentration of
aluminum
R3 and R2: 5D3 to 7F6 and 5D4 to 7F6
R1: 5D3 to 5D4
45000
1600
40000
1400
35000
1200
1000
25000
rate
rate
30000
20000
R3
R2
800
600
15000
10000
400
5000
200
0
0
0
0.5
1
1.5
3+
3+
%Al :0.02%Tb
2
2.5
0
0.5
1
1.5
%Al3+:0.02%Tb3+
2
2.5
Previous papers
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Montiel (1999)
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Tb3+ in silicate sol-gel glass doped with Al3+
Al3+ as cluster buster
First proposed in 1994
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Ishizaka (2001)
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Tb3+ in pure alumina sol-gel glass
Gives R2 in pure alumina
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Montiel (2004)
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Just kidding!
New Conclusions!
(R2)
R2: 5D4 to 7F6
600
500
rate
400
300
200
100
0
0
0.5
1
1.5
3+
%Al :0.02%Tb
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2.5
Ishizaka results in pure alumina samples
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2
3+
Our data: small percentage of aluminum (0% to 4%)
Their smallest Tb concentration is too large to neglect cross relaxation
contributions
Ergo…a reasonable value for R2 for small (<0.1%) concentrations of Tb in
pure alumina environment would be in the range from 200 to 300 s-1
This is the value we get for >0.25% Al in silicate glass
Our data supports Montiel’s suggestion that Al is not a cluster buster
Thank you Dr. Boye!