Direct Chemical Fine-Tuning of Electronic Properties in Sc2 Ir6-x Pdx B

Dimitrios Koumoulis; Jan P Scheifers; Rachid St Touzani; Boniface P T Fokwa; Louis-S Bouchard

doi:10.1002/cphc.201600512

Direct Chemical Fine-Tuning of Electronic Properties in Sc₂ Ir_6-x Pd_x B

Chemphyschem. 2016 Oct 5;17(19):2972-2976. doi: 10.1002/cphc.201600512. Epub 2016 Aug 2.

Authors

Dimitrios Koumoulis¹, Jan P Scheifers², Rachid St Touzani², Boniface P T Fokwa^{3

4}, Louis-S Bouchard^{5

6}

Affiliations

¹ Department of Chemistry and Biochemistry, University of California at Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California, 90095-1569, USA.
² Institut für Anorganische Chemie, Rheinisch-Westfälische Technische Hochschule Aachen, 52056, Aachen, Germany.
³ Institut für Anorganische Chemie, Rheinisch-Westfälische Technische Hochschule Aachen, 52056, Aachen, Germany. bfokwa@ucr.edu.
⁴ Department of Chemistry, University of California Riverside, Chemical Sciences Building, 501 Big Springs Road, Riverside, CA, 92521, USA. bfokwa@ucr.edu.
⁵ Department of Chemistry and Biochemistry, University of California at Los Angeles, 607 Charles E. Young Drive East, Los Angeles, California, 90095-1569, USA. bouchard@chem.ucla.edu.
⁶ California NanoSystems Institute, University of California at Los Angeles, 570 Westwood Plaza, Building 114, Los Angeles, California, 90095-1569, USA. bouchard@chem.ucla.edu.

PMID: 27415033
DOI: 10.1002/cphc.201600512

Abstract

Crystal orbital Hamilton population (COHP) bonding analysis has predicted that ScPd₃ B_0.5 is the least stable compound of the entire series Sc₂ Ir_6-x Pd_x B. Here, we report a systematic study of Sc₂ Ir_6-x Pd_x B (x=3, 5 and 6) by means of ¹¹ B nuclear magnetic resonance (NMR), Knight shift (K) and nuclear spin-lattice relaxation rate (1/T₁ ). NMR results combined with theoretical band structure calculations provide a measure of s- and non-s-character Fermi-level density of states. We present direct evidence that the enhanced s-state character of the Fermi level density of states (DOS) in ScPd₃ B_0.5 reduces the strength of the B 2p and Pd 4d hybridized states across the entire Sc₂ Ir_6-x Pd_x B series. This hybridization strength relates to the opening of a deep pseudogap in the density of states of Sc₂ IrPd₅ B and the chemical bonding instability of ScPd₃ B_0.5 . This study is an experimental realization of a chemical fine-tuning of the electronic properties in intermetallic perovskites.

Keywords: 11B NMR; Fermi level; chemical bonding; intermetallic perovskite; superstructure.