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Synthesis and Characterization of a Pb 1-x Sr x CrO 4 Solid Solution

Synthesis and Characterization of a Pb 1-x Sr x CrO 4 Solid Solution. Ohio State University CHEM 123 REEL Poster Session. Matthew W. Stoltzfus Thad Matta Jim Tressel Bob Todd. 22 May 2007. Pb(SbO 3 ) 2. CdS. PbCrO 4. Goals.

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Synthesis and Characterization of a Pb 1-x Sr x CrO 4 Solid Solution

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  1. Synthesis and Characterization of a Pb1-xSrxCrO4 Solid Solution Ohio State University CHEM 123 REEL Poster Session Matthew W. Stoltzfus Thad Matta Jim Tressel Bob Todd 22 May 2007

  2. Pb(SbO3)2 CdS PbCrO4 Goals What are the goals of your research. What scientific concepts are you trying to understand? What pigments are you trying to replace and why? Traditional pigments:

  3. Synthesis: End Members All reactions were carried out using traditional solid state synthesis overnight at 750°C. 2 PbCO3 + Cr2O3 + 3/2 O2 2 PbCrO4 + 2 CO2 9 PbCO3 + 5 Cr2O3 + SrCO3 + 15/2 O2 10 Pb0.9Sr0.1CrO4 + 10 CO2 8 PbCO3 + 5 Cr2O3 + 2 SrCO3 + 15/2 O2 10 Pb0.8Sr0.2CrO4 + 10 CO2 5 PbCO3 + 5 Cr2O3 + 5 SrCO3 + 15/2 O2 10 Pb0.5Sr0.5CrO4 + 10 CO2 2 PbCO3 + 5 Cr2O3 + 8 SrCO3 + 15/2 O2 10 Pb0.2Sr0.8CrO4 + 10 CO2 PbCO3 + 5 Cr2O3 + 9 SrCO3 + 15/2 O2 10 Pb0.1Sr0.9CrO4 + 10 CO2 Cr2O3 + 2 SrCO3 + 3/2 O2 2 SrCrO4 + 2 CO2

  4. Synthesis: Solid Solution All reactions were carried out using traditional solid state synthesis overnight at 750°C. 2 PbCO3 + Cr2O3 + 3/2 O2 2 PbCrO4 + 2 CO2 9 PbCO3 + 5 Cr2O3 + SrCO3 + 15/2 O2 10 Pb0.9Sr0.1CrO4 + 10 CO2 8 PbCO3 + 5 Cr2O3 + 2 SrCO3 + 15/2 O2 10 Pb0.8Sr0.2CrO4 + 10 CO2 5 PbCO3 + 5 Cr2O3 + 5 SrCO3 + 15/2 O2 10 Pb0.5Sr0.5CrO4 + 10 CO2 2 PbCO3 + 5 Cr2O3 + 8 SrCO3 + 15/2 O2 10 Pb0.2Sr0.8CrO4 + 10 CO2 PbCO3 + 5 Cr2O3 + 9 SrCO3 + 15/2 O2 10 Pb0.1Sr0.9CrO4 + 10 CO2 Cr2O3 + 2 SrCO3 + 3/2 O2 2 SrCrO4 + 2 CO2

  5. Color and UV-Vis Spectra: End Members PbCrO4 Pb0.9Sr0.1CrO4 Pb0.8Sr0.2CrO4 Pb0.5Sr0.5CrO4 Pb0.2Sr0.8CrO4 Pb0.1Sr0.9CrO4 SrCrO4

  6. Color and UV-Vis Spectra: Solid Solution PbCrO4 Pb0.9Sr0.1CrO4 Pb0.8Sr0.2CrO4 Pb0.5Sr0.5CrO4 Pb0.2Sr0.8CrO4 Pb0.1Sr0.9CrO4 SrCrO4

  7. X-Ray Diffraction Data: Solid Solution SrCrO4 PbCrO4 The XRD patterns show the SrCrO4 and PbCrO4 form a complete solid solution from x = 0.0 to x = 1.0.

  8. Isothermal Phase Diagram: Solid Solution Increasing Sr PbCrO4 SrCrO4 Complete Solid Solution, Pb1-xSrxMoO4 x=0 x=0.2 x=0.5 x=0.8 x=1.0 Monoclinic Monoclinic Sr Pb CrO4

  9. Origins of Color What electronic excitations are responsible for color in each of your end members? What electronic excitations are responsible for color across your solid solution? Why/how might you expect the color to vary across the solid solution?

  10. Band Gaps (or Absorption Peaks) 2.50 eV 2.53 eV 2.48 eV 2.41 eV 2.32 eV 2.27 eV 2.27 eV PbCrO4 Pb0.9Sr0.1CrO4 Pb0.8Sr0.2CrO4 Pb0.5Sr0.5CrO4 Pb0.2Sr0.8CrO4 Pb0.1Sr0.9CrO4 SrCrO4

  11. Band Gap as a Function of Composition Be sure to define which composition corresponds to x = 0 and which to x = 1.

  12. Conclusions and Future Directions Did you form a solid solution? If so over what composition ranges? What colors were your samples? Are the colors what you would expect from the UV-Vis spectra? How did the band gap vary as a function of composition? Would these samples make good pigments? What would you do next to reach the goal stated on the first slide? What other compositions might be tried? What have you learned about the relationship between composition, optical absorption and color?

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