New Ternary and Quaternary Layered Arsenides

• Author / Creator

  Tabassum, Danisa

• New layered ternary and quaternary arsenides have been synthesized by direct reactions of the elements at high temperatures and their crystal structures were determined by powder and single-crystal X-ray diffraction. These arsenides include: RE1−yMnxZn2−xAs2 (RE = Eu−Lu) and RE2−yMnxZn4−xAs4 (RE = La−Nd, Sm, Gd) (Chapter 2); RE4Mn2As5 (RE = La–Pr) (Chapter 3); and RE4−yZn4As6 (RE = La–Nd), RE5−yZn4As7 (RE =Pr, Nd, Sm, Gd), and RE6−yZn4As8 (RE = La–Nd, Sm, Gd) belonging to a homologous series RE2−yZn4As4·n(REAs) (n = 2, 3, 4) (Chapter 4). They adopt similar crystal structures related to the CaAl2Si2-type, in accordance with predictions. Band structure calculations of representative members of these series were performed by tight-binding linear muffin tin method to determine electronic structures and to rationalize bonding. Metal site deficiencies were found in the series RE1−yMnxZn2−xAs2, RE2−yMnxZn4−xAs4, and RE2−yZn4As4·n(REAs) to form charge balanced compounds, whereas the presence of extra electrons in the series RE4Mn2As5 can be rationalized by the metallic behavior or no band gap at the Fermi level. The effect of Mn atoms on the electronic structure of RE2−yMnxZn4−xAs4 and RE4Mn2As5 compounds was analyzed by spin-polarized calculations.

• Subjects / Keywords

  • Arsenides
  • ternary
  • quaternary
  • layered structure

• Graduation date

  Spring 2017

• Type of Item

  Thesis

• Degree

  Master of Science

• DOI

  https://doi.org/10.7939/R3NG4H43J

• 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.