1. Analysis Of Fluorescence and Optical Absorption of
Nd+3 doped Lead Boro-Tellurite Glasses.
Manoj Kumar Jamarkattel, Saisudha Mallur, PK Babu
Physics Department, Western Illinois University
Introduction:
2) fluorescence
The rapid development of laser research has led to an increased experimental investigation of fluorescence and optical absorption of neodymium (Nd3+) ions in glasses.
Nd3+ doped glasses such as silicates, tellurite, borates, phosphates etc. have been successfully used for laser applications.
Tellurite glasses are encouraging materials for laser optics as they have desirable properties like high refractive index, low phonon cut-off and low melting point.
Fig 1. Unpolished and polished glass samples.
Sample
Excitation
monochromator
(514 nm)
Light source 1
Fluorescence
monochromator
Experiment
Reference
Detector
Lead boro-tellurite glasses[xPbO:20TeO2:(80-x) B2O3 ] x=30,40,50,60 &70) are prepared by weighing and mixing the raw materials (PbO, TeO2 ,B2O3, Nd2O3) thoroughly in an agate mortar.
The mixture was melted in porcelain crucibles around 9000C and quenched by pouring onto a brass plate.
Resulting glass pieces were annealed at 300oC for around 3 hrs using a tubular furnace.
Annealed glasses were polished for further measurements. (fig 1)
Refractive indices were measured by Brewster’s Angle method whereas Archimedes principle is used to measure
densities.
Fluorescence spectra were recorded by laser excitation at 514 nm with a CCD spectrometer and optical absorption
spectra were recorded with Varian cary 5G-UV-VIS-NIR spectrophotometer.
Fluorescence
Detector
Fig4: Block Diagram of Fluorescence Spectrometer
Fig5: Energy level diagram of Nd+3 ions.
Fig6: Fluorescence Spectra
Table 2
Theories
Transition from
PbO concentration
4F3/2
PbO 19.5
PbO 29.5
PbO 39.5
PbO 49.5
PbO 59.5
PbO 69.5
υ (cm-1)
A(sec-1) βR
4I13/2
7576
679.7
0.15
723
0.17
334
1024
0.16
1226.8
1365
4I11/2
9523
2770
0.62
2813
0.67
1313
0.66
4074
0.65
4910.6
0.64
5435
4I9/2
11389
985
0.22
676
0.2
349
1207
1532
1626
∑A ( sec-1)
4434.7
4212
2001.6
6305.5
7669.4
8426
τR(µsec)
225
237.4
499.6
158.6
130.4
118.6
Refractive index:
Brewster’s angle Method TanƟB = n2
2) Density:
Archimedes Principle Density ( Sample) = Weight Air x Density Xylenes
Weight Air - Weight Xylenes
3) Judd- Ofelt Theory:
i) Oscillator strength
fexp = 2.302(mc2/NAπe2)∫ɛ(v)dv = 4.318∫ ɛ(v)dv and fcal= 8π2mv(n2d+2)2v / [3h(2J+1)9nd] ∑ Ωλ(ψJ║Uλ║2ψJ’)2
Radiative Transition Probability:
Arad(aJ;bJ’) = [64π4Ʋ3e2/3hc3(2J+1) ] x {n(n2+1)2/9 Sed + n3Smd}
iii) Fluorescence branching ratio( βR) = Arad(aJ;bJ’) / AT(aJ)
iv) Radiative lifetime (τR)=1/AT(aJ)
Radiative transition probability( number of relaxations per second of an electron from excited to ground state due to emission of photon) varies with change in PbO mol%.
Branching ratios and radiative life time vary with PbO concentration.
Describe the dependence of the spectroscopic parameters on the glass composition.
Fig7: Radiative transition probability vs PbO mol%.
Fig8: Area vs PbO mol %.
Results and Discussions
1)Optical absorption
4G5/2
4F5/2
4S3/2
4G7/2
4G9/2
4F3/2
4H11/2
4F9/2
Conclusions
Table 1
PbO mol%
BPN 20
BPN 30
BPN 40
BPN 50
BPN 60
BPN 70
RMS Deviation
17.00%
15.00%
16.00%
Density(gm/cm3)
3.958±0.01
4.4708±0.020
4.8152±0.023
5.2182±0.0021
5.7259±0.142
6.9491±0.1655
Number of Ions x 1020
2.005
2.0057
1.938
1.905
1.9124
2.139
Refractive index
1.73±0.05
1.79±0.05
1.82±0.05
1.98±0.05
2.17±0.05
2.35±0.05
Ω2 x cm2
6.7
6.218
10.3
5.7
4.8
3.5
Ω4 x cm2
21.2
0.1
0.5
0.6
0.04
0.4
Ω6 x cm2
8.5
8.08 14
7.9
6.8
5.6
The variation of Judd-Ofelt intensity parameters are discussed and vary with glass compositions.
Intensity parameters, radiative transition probability, branching ratios and radiative life-times of Nd3+ are studied.
There is good agreement between experimental and calculated oscillator strength.
Fluorescence spectra are studied and the intensity is found to be higher for 50 mol % of PbO.
The radiative transition probability is found to be minimum for 40 mol% of PbO
All spectroscopic parameters show the compositional dependence.
Fig2: Optical absorption spectra.
Reference
M. B. Saisudha and J. Ramakrishna
Physical review B, Vol. 53,Number 10,1 march 1996 II
Judd-Ofelt theory is used to measure oscillator strength and intensity parameters
Define three intensity parameters Ω2,Ω4 and Ω6.
Ω2 indicates R-O covalency and short range effect.
Ω4 and Ω6 indicate long range effect.
There is good agreement between two oscillator strength f measured and f cal .
Acknowledgement
Nano-Material research group, Physics Group, WIU
Materials research Laboratory, UIUC for fluorescence spectrometer
Fig3: intensity parameters vs Pbo mol%.