Bridging the Gap: From Metal-Rich to Pnicogen-Rich Quaternary Phosphides and Arsenides

• Author / Creator

  Ramachandran, Krishna Kumar

• Several series of rare-earth and transition-metal-containing pnictides such as RE2Mn3Cu9Pn7,1 REMnCu4P3,2 REMM'Pn2 (M = Mn, Cu, Ag; M' = Cu, Zn, Cd; Pn = P, As),3 and REAg1-xZnyAs2 4 were synthesized, and their crystal structures were determined using X-ray diffraction methods. The electronic properties and bonding interactions were examined using TB-LMTO computational calculations. The electrical and magnetic properties of the samples were measured using QD-PPMS and the optical properties were measured by diffuse reflectance spectroscopy. The flexibility of metal positions is examined in different ternary systems to evaluate how the physical properties such as magnetism, electrical resistivity, and optical band gaps are affected. Both metalrich and pnicogen-rich (P, As) compounds were synthesized to examine the applicability of the Zintl-Klemm concept and under what conditions it fails. Detailed crystal structure determinations have been carried out for these phases. The bonding in these compounds was evaluated using band structure calculations. As a secondary objective, the thesis discusses the structural relationship with physical properties such as electrical conductivity, magnetism, and optical band gap of these new quaternary phosphides and arsenides. Combining these two ideas, it is possible to successfully tune the physical properties of new materials.

• Subjects / Keywords

  • Rare-earth
  • Rare-Earth Manganese Copper Pnictides RE2Mn3Cu9Pn7 (Pn = P, As): Quaternary Ordered Variants of the Zr2Fe12P7-Type Structure
  • Zintl phases
  • Transition metal
  • Quaternary Rare-Earth Arsenides REAg1–xZnyAs2 (RE = La–Nd, Sm, Gd–Dy) with Tetragonal SrZnBi2- and HfCuSi2-Type Structures
  • Quaternary Rare-Earth Transition-Metal Phosphides Adopting CaAl2Si2-Type Structures: REMnCuP2 (RE = La–Nd, Sm, Gd–Dy) and REAgCdP2 (RE = La-Nd)
  • Band gap
  • Three Series of Quaternary Rare-Earth Transition-Metal Pnictides with CaAl2Si2-Type Structures: RECuZnAs2, REAgZnP2 and REAgZnAs2
  • Soild state chemistry
  • Quaternary phosphides and arsenides
  • Rare-Earth Manganese Copper Phosphides REMnCu4P3 (RE = Gd–Ho): The First Quaternary Ordered Variants of the YCo5P3-Type Structure

• Graduation date

  Fall 2016

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3DJ58W6V

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.