The Spectroscopic Study of Cr4 Doped CaO-GeO2-Li2O-B2O3(Al2O3) transparent glass-ceramics

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The Spectroscopic Study of Cr4 Doped
CaO-GeO2-Li2O-B2O3(Al2O3) transparent
glass-ceramics

• Presentation by Victor Ortiz
• School M.S./H.S. 141 David A. Stein
  Riverdale/Kingsbridge Academy
• Mentor Dr. Alexei Bykov, Prof. V. Petricevic
• IUSL-Physics Department

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Introduction

• Study the behavior of Cr-doped Calcium Germanium
  glass media during synthesis and devitrification
  (i.e., heat treatment)
• A number of glass compositions yield transparent
  glass-ceramics after heat treatment
• Crystallites 1?m
• Cr doped glass ceramics exhibit a broad band of
  fluorescence (1000-1600nm wavelength peaking at
  1280nm).
• Optical properties similar to CUNYITE crystals
  (i.e.,Cr4 Ca2GeO4 )
• Absorption and Fluorescence Spectra of the
  samples help better understand the optical
  properties of glass-ceramics

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Long Term Goal
To create new materials for optical amplifiers
and fiber-lasers to enhance telecommunication
systems and remote LIDAR applications
Summer Research Objective
New Methods For Analyzing Crystallites
To find the optimal temperature and time required
for mass crystallization of nanoscale crystallites

• The use of the Confocal Microscope is a new
  approach to a better view and understanding of
  the nanoscale crystallites
• Cr-doped glass ceramic emits fluorescence in NIR
  spectrum
• Manganese (II) Carbonate emits fluorescence in
  visible spectrum

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Recipe for Manganese-Doped Calcium Germanium
Glass 2.0 CaO 1.0 GeO2 1.0 Li2O 0.5 B2O3
0.2 (Al2O3) 0.04 (P2O5)
Mn-doped Glass Media
CaCO3 Calcium Carbonate Li2CO3 Lithium
Carbonate GeO2 Germanium Oxide B2O3 Boron
Oxide Al2O3 Aluminum Oxide NH4H2PO4 Ammonium
Dihydrogen Phosphate MnCO3 Manganese (II)
Carbonate
Powders
Checkpoint
Solid
Liquid
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Experimental Protocol
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Cr-doped Glass Media
No heat treatment
A large number of nanoscale crystallites were
formed or a few numbers of large size
crystallites
Few crystallites formed
8 hour in 501C
1 hour in 520C
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• All Materials absorb radiation in some ranges of
  the electromagnetic spectrum
• The term is used to describe the entire range of
  light radiation (gamma rays to radio waves)
• The amount of absorption depends of the
  wavelength, the amount of absorbing material in
  the radiation path, and absorption of that
  material at that wavelength

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Absorption of Cr-Doped Glass Media
1 hour in 520C
The higher the absorption, the more light will
scatter on crystallites in glass ceramics. Larger
size of crystallites.
The lower the absorption, the less light will
scatter on crystallites in glass ceramics.
Smaller size of crystallites.
8 hour in 501C
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Measuring Fluorescence Spectrum

• Fluorescence spectrum is the amount of
  electromagnetic radiation the atom emits when it
  is excited.
• When electrons in the element are excited, they
  jump to a higher energy level. Solid mediums tend
  to absorb light and store it as heat. As the
  electron falls back down and leave the excited
  state, light is re-emitted at longer wavelengths
  with less intensity.

680-nm laser
Excited State
Light
Fluorescence
Ground State
Electron
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Fluorescence of Cr-Doped Glass Media
Maximum of broad band emission
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Mn-doped Glass Media
No heat treatment
Crystallites were formed within the glass
ceramic, reasons for color changed are still
unknown
A small number of crystallites have formed, glass
ceramic still transparent
20 hours in 495C
45 minutes in 560C
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Absorption of Mn-Doped Glass Media
45 Minutes in 560C
10 Hours in 495C
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Fluorescence of Mn-Doped Glass Media
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Conclusion

• Crystallization in glass media varies according
  to temperature and heat treatment time.
• Chromium-doped glass ceramics emit fluorescence
  around wavelengths of 1200-1300nm, similar to
  CUNYITE crystals.
• Manganese-doped glass ceramics is expected to
  have a broad band fluorescence between 550700nm
  when excited at 488nm.
• The change in color is believed to have to occur
  due to crystallization all inside of the Mn-doped
  Glass Media.
• The behavior of this substance is still unsure

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Future Plan

• Study optical properties of crystallites with
  Mn-doped glass media with confocal microscope
• Compare the crystallites within the Mn-doped
  media with that of Cr-doped media
• Decide another metal to doped depending of
  results
• Continue running experiments with Cr-doped glass
  media and any other metal-doped glass material
• Long term goal is to create a new material for
  optical amplifiers and fiber-lasers to enhance
  telecommunication systems

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Reference

• Confocal microscopy of colloids V Prasad, D
  Semwogerere, ER Weeks, J. Phys. Cond. Mat. 19,
  113102 (2007)
• Synthesis and characterization of Cr4 -doped
  CaO-GeO2-LiO-B2O3(Al2O3) transparent
  glass-ceramics by A.B. Bykov, M. Yu Sharonov, V.
  Petricevic, I. Popov, L.L. Isaacs, J. Steiner,
  and R.R. Alfano
• Optical Properties Measurements of Laser Crystals
  by Dr. A. Bykov
• Guide for Absorption and Fluorescence
  Spectroscopy by Mr. G. C. Tang and Prof. R. R.
  Alfano
• Spectroscopic study of chromium-doped transparent
  calcium germanate glass-ceramics by M. Yu.
  Sharonov, A.B. Bykov, T. Myint, V.Petricevic, R.R
  Alfano

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Acknowledgements
National Aeronautics and Space Administration
(NASA) NASA Goddard Space Flight Center
(GSFC) NASA Goddard Institute for Space Studies
(GISS) NASA New York City Research Initiative
(NYCRI) The City College of New York (CCNY) Dr.
Alexei Bykov, Prof. V. Petricevic Dr. Frank
Scalzo, Dr. Manuel Zevallos, Mr. Daniel Moy Mr.
Jose Lai, Mr. Jorge Franco Mr. David Deutsch, Ms.
Charlene Chan-Lee