PMID- 29417973
OWN - NLM
STAT- PubMed-not-MEDLINE
DCOM- 20180323
LR  - 20180323
IS  - 1477-9234 (Electronic)
IS  - 1477-9226 (Linking)
VI  - 47
IP  - 10
DP  - 2018 Mar 6
TI  - Boron-phil and boron-phob structure units in novel borides Ni(3)Zn(2)B and 
      Ni(2)ZnB: experiment and first principles calculations.
PG  - 3303-3320
LID - 10.1039/c7dt04769j [doi]
AB  - The crystal structures of two novel borides in the Ni-Zn-B system, 
      tau(5)-Ni(3)Zn(2)B and tau(6)-Ni(2)ZnB, were determined by single crystal X-ray 
      diffraction (XRSC) in combination with selected area electron diffraction in a 
      transmission electron microscope (SAED-TEM) and electron probe microanalysis 
      (EPMA). Both compounds crystallize in unique structure types (space group C2/m, a 
      = 1.68942(8) nm, b = 0.26332(1) nm, c = 0.61904(3) nm, beta = 111.164(2) degrees , R(F) = 
      0.0219 for Ni(3)Zn(2)B, and space group C2/m, a = 0.95296(7) nm, b = 0.28371(2) 
      nm, c = 0.59989(1) nm, beta = 93.009(4) degrees , R(F) = 0.0163 for Ni(2)ZnB). Both 
      compounds have similar building blocks: two triangular prisms centered by boron 
      atoms are arranged along the c-axis separated by Zn layers, which form empty 
      octahedra connecting the boron centered polyhedra. Consistent with the (Ni+Zn)/B 
      ratio, isolated boron atoms are found in tau(5)-Ni(3)Zn(2)B, while B-B pairs exist 
      in tau(6)-Ni(2)ZnB. The crystal structure of Ni(2)ZnB is closely related to that of 
      tau(4)-Ni(3)ZnB(2), i.e. Ni(2)ZnB can be formed by removing the nearly planar 
      nickel layer in Ni(3)ZnB(2) and shifting the origin of the unit cell to the 
      center of the B-B pair. The electrical resistivity and specific heat of 
      tau(5)-Ni(3)Zn(2)B reveal the metallic behavior of this compound with an anomaly at 
      low temperature, possibly arising from a Kondo-type interaction. Further analysis 
      on the lattice contribution of the specific heat reveals similarity with 
      tau(4)-Ni(3)ZnB(2) with some indications of lattice softening in tau(5)-Ni(3)Zn(2)B, 
      which could be related to the increasing metal content and the absence of B-B 
      bonding in tau(5)-Ni(3)Zn(2)B. For the newly found phases, tau(5)-Ni(3)Zn(2)B and 
      tau(6)-Ni(2)ZnB as well as for tau(3)-Ni(21)Zn(2)B(20) and tau(4)-Ni(3)ZnB(2) density 
      functional theory (DFT) calculations were performed by means of the Vienna Ab 
      initio Simulation Package (VASP). Total energies and forces were minimized in 
      order to determine the fully relaxed structural parameters, which agree very well 
      with experiment. Energies of formations in the range of -25.2 to -26.9 kJ mol(-1) 
      were calculated and bulk moduli in the range of 179.7 to 248.9 GPa were derived 
      showing hardening by increasing the B concentration. Charge transfer is discussed 
      in terms of Bader charges resulting in electronic transfer from Zn to the system 
      and electronic charge gain by B. Ni charge contributions vary significantly with 
      crystallographic position depending on B located in the neighbourhood. The 
      electronic structure is presented in terms of densities of states, band 
      structures and contour plots revealing Ni-B and Ni-Zn bonding features.
FAU - Failamani, F
AU  - Failamani F
AD  - Institute of Materials Chemistry and Research, University of Vienna, 
      Wahringerstrasse 42, A-1090 Vienna, Austria. peter.franz.rogl@univie.ac.at.
FAU - Podloucky, R
AU  - Podloucky R
FAU - Bursik, J
AU  - Bursik J
FAU - Rogl, G
AU  - Rogl G
FAU - Michor, H
AU  - Michor H
FAU - Muller, H
AU  - Muller H
FAU - Bauer, E
AU  - Bauer E
FAU - Giester, G
AU  - Giester G
FAU - Rogl, P
AU  - Rogl P
LA  - eng
PT  - Journal Article
PL  - England
TA  - Dalton Trans
JT  - Dalton transactions (Cambridge, England : 2003)
JID - 101176026
EDAT- 2018/02/09 06:00
MHDA- 2018/02/09 06:01
CRDT- 2018/02/09 06:00
PHST- 2018/02/09 06:00 [pubmed]
PHST- 2018/02/09 06:01 [medline]
PHST- 2018/02/09 06:00 [entrez]
AID - 10.1039/c7dt04769j [doi]
PST - ppublish
SO  - Dalton Trans. 2018 Mar 6;47(10):3303-3320. doi: 10.1039/c7dt04769j.