Synthesis

1
Synthesis Study of Fluorescence Properties of
Cr-doped LiInSiO4-Ca2SiO4 Solid State Solutions

• By Caesar Pereira (Archbishop Stepinac H.S.)
• Supervising Scientist Prof. V. Petricevic (CCNY)
• Senior Scientist Dr. A. Bykov (CCNY)

2
Background

• The goal of my research is to develop the most
  effective crystallites for near-infrared optical
  amplifiers using the Cr4 ion
• This research will aid in the development of new
  and more effective lasing media.
• The results will bring a deeper understanding of
  the different olivine structures optical
  properties, such as fluorescence.

3
What are LASERs?

• LASER is an acronym for Light Amplification by
  Stimulated Emission of Radiation
• When a laser ion is pumped with energy, its
  electrons move to a higher energy level
• The electrons after being excited will
  spontaneously fall back to the ground state
• At this moment spontaneous light emission
  occurs. This is called fluorescence.

4
Laser Properties

• Monochromatic
• It contains one specific wavelength of light (one
  color)
• Coherent
• Each photon moves in phase
  with each other (organized)
• Directional
• A laser light has a highly focused tight beam and
  is very strong and concentrated

5
Solid-State Lasers

• Although the amplifying media can be solid,
  liquid, or gas, we chose to use solid-state media
  for our research, such as crystals
• In my project, the amplifying medium is a crystal
  containing Cr4 ions as dopands.
• The reason crystals are different colors is
  because the electron configuration of the ion
  determines what color we perceive.
• In our samples the electron configuration of the
  Cr4 ion appears to be the color green.

6
History

• Previous research in this project revealed the
  optimal amount of CrO2 to be used in an olivine
  crystallite structure is between 0.5 and 0.1 of
  the total weight.
• The Cr4 ion is the desired valence state for Cr
  because its fluorescence is greater than the Cr3
  ion and also it encompasses a larger range of
  wavelengths in the near-infrared region we are
  investigating.

7
Abstract

• The goal of my project, now, is to find the best
  suitable host for the Cr4 ion by combining the
  elements calcium, lithium, indium, silicon, and
  oxygen to achieve the optimal Host crystal
  structure, in particular of LixInxCaySiO4. These
  compounds will be combined in different
  concentrations to find which mixture gives the
  desired fluorescence. The crystals obtained from
  this research will be effective amplifying media
  for use in optical fiber communications, remote
  sensing and other photonics applications.

8
Materials

• The following compounds are being studied as host
  materials indium oxide
  (In2O3), lithium carbonate (Li2CO3), silicon
  oxide (SiO3), and calcium oxide (CaO2) with
  chromium oxide (Cr2O3) as the dopand
• Temperature-Controlled Furnace
• Electronic Scale
• Mortars
• Crucibles
• Round paper
• Fluorescence setup

9
Methods

• Before preparing the powders, stoichiometry was
  used to calculate the weights of each of the
  compounds
• After weighing out each compound carefully on a
  very precise scale, the compounds were mixed in a
  mortar
• Ethanol was added to each powder to make it
  homogeneous (uniform) but later on evaporated out
  under a fume hood so as not to change the
  properties of our compounds

10
Methods (continued)

• The compounds underwent long periods of heating
  in the furnace 24 hours.
• Each powder was heated at 1100C to obtain the
  Cr4 ions needed for our crystal synthesis
• Eight different mixtures were made
• The difference between each mixture was how much
  lithium, indium, and calcium each one contained

11
Compounds Used

• Place chart here

12
Characterization of Fluorescence
13
Cr4 Sample Fluorescence Readings after 1100ºC

• Under Construction

14
Results

• Further analysis required

15
Acknowledgements

• Mentors Dr. Bykov Prof. Petricevic
• NASA SHARP / NYCRI
• NASA COSI DoD NPC Summer Program
• City College of New York
• CREST-CMMS
• NYC-MTA

16
References

• "The Causes of Color," K. Nassau, Scientific
  American, Volume 243, Number 4, October1980, pp.
  124-154.
• Introduction in optical properties measurements
  of laser crystals Introduction in absorption
  measurements, A. Bykov.
• Illustrations http//www.howstuffworks.com
• Source 4
• Source 5
• Source 6
• Source 7

17
The End