TY - JOUR
T1 - Structure and properties of α-NaFeO2-type ternary sodium iridates
AU - Baroudi, Kristen
AU - Yim, Cindi
AU - Wu, Hui
AU - Huang, Qingzhen
AU - Roudebush, John H.
AU - Vavilova, Eugenia
AU - Grafe, Hans Joachim
AU - Kataev, Vladislav
AU - Buechner, Bernd
AU - Ji, Huiwen
AU - Kuo, Changyang
AU - Hu, Zhiwei
AU - Pi, Tun Wen
AU - Pao, Chiwen
AU - Lee, Jyhfu
AU - Mikhailova, Daria
AU - Hao Tjeng, Liu
AU - Cava, R. J.
N1 - Funding Information:
The work at Princeton was supported by the NSF Solid state chemistry program , grant NSF-DMR-1005438 . The authors thank the 11-BM team at the Advanced Photon Source for their excellent synchrotron diffraction data. Use of the Advanced Photon Source at Argonne National Laboratory was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences , under Contract no. DE-AC02-06CH11357 . EV acknowledges support of RFBR through grant RFBR 14-02-01194. Jason Krizan is acknowledged for helpful discussions.
PY - 2014/2
Y1 - 2014/2
N2 - The synthesis, structure, and elementary magnetic and electronic properties are reported for layered compounds of the type Na3-xMIr 2O6 and Na3-xM2IrO6, where M is a transition metal from the 3d series (M=Zn, Cu, Ni, Co, Fe and Mn). The rhombohedral structures, in space group R-3m, were determined by refinement of neutron and synchrotron powder diffraction data. No clear evidence for long range 2:1 or 1:2 honeycomb-like M/Ir ordering was found in the neutron powder diffraction patterns except in the case of M=Zn, and thus in general the compounds are best designated as sodium deficient α-NaFeO2-type phases with formulas Na1-xM1/3Ir2/3O 2 or Na1-xM2/3Ir1/3O2. Synchrotron powder diffraction patterns indicate that several of the compounds likely have honeycomb in-plane metal-iridium ordering with disordered stacking of the layers. All the compounds are sodium deficient under our synthetic conditions and are black and insulating. Weiss constants derived from magnetic susceptibility measurements indicate that Na0.62Mn 0.61Ir0.39O2, Na0.80Fe 2/3Ir1/3O2, Na0.92Ni 1/3Ir2/3O2, Na0.86Cu 1/3Ir2/3O2, and Na0.89Zn 1/3Ir2/3O2 display dominant antiferromagnetic interactions. For Na0.90Co1/3Ir2/3O2 the dominant magnetic interactions at low temperature are ferromagnetic while at high temperatures they are antiferromagnetic; there is also a change in the effective moment. Low temperature specific heat measurements (to 2 K) on Na 0.92Ni1/3Ir2/3O2 indicate the presence of a broad magnetic ordering transition. X-ray absorption spectroscopy shows that iridium is at or close to the 4+ oxidation state in all compounds. 23Na nuclear magnetic resonance measurements comparing Na 2IrO3 to Na0.92Ni1/3Ir 2/3O2 and Na0.89Zn1/3Ir 2/3O2 provide strong indications that the electron spins are short-range ordered in the latter two materials. Na0.62Mn 0.61Ir0.39O2, Na0.80Fe 2/3Ir1/3O2, Na0.90Co 1/3Ir2/3O2, Na0.92Ni 1/3Ir2/3O2, Na0.86Cu 1/3Ir2/3O2 and Na0.89Zn 1/3Ir2/3O2 are spin glasses. (CSD-numbers: Na0.62Mn0.61Ir0.39O2: 426657, Na0.80Fe2/3Ir1/3O2: 426659, Na 0.90Co1/3Ir2/3O2: 426658, Na 0.92Ni1/3Ir2/3O2: 426656, Na 0.86Cu1/3Ir2/3O2: 426655, and Na2.8ZnIr2O6: 426660.)
AB - The synthesis, structure, and elementary magnetic and electronic properties are reported for layered compounds of the type Na3-xMIr 2O6 and Na3-xM2IrO6, where M is a transition metal from the 3d series (M=Zn, Cu, Ni, Co, Fe and Mn). The rhombohedral structures, in space group R-3m, were determined by refinement of neutron and synchrotron powder diffraction data. No clear evidence for long range 2:1 or 1:2 honeycomb-like M/Ir ordering was found in the neutron powder diffraction patterns except in the case of M=Zn, and thus in general the compounds are best designated as sodium deficient α-NaFeO2-type phases with formulas Na1-xM1/3Ir2/3O 2 or Na1-xM2/3Ir1/3O2. Synchrotron powder diffraction patterns indicate that several of the compounds likely have honeycomb in-plane metal-iridium ordering with disordered stacking of the layers. All the compounds are sodium deficient under our synthetic conditions and are black and insulating. Weiss constants derived from magnetic susceptibility measurements indicate that Na0.62Mn 0.61Ir0.39O2, Na0.80Fe 2/3Ir1/3O2, Na0.92Ni 1/3Ir2/3O2, Na0.86Cu 1/3Ir2/3O2, and Na0.89Zn 1/3Ir2/3O2 display dominant antiferromagnetic interactions. For Na0.90Co1/3Ir2/3O2 the dominant magnetic interactions at low temperature are ferromagnetic while at high temperatures they are antiferromagnetic; there is also a change in the effective moment. Low temperature specific heat measurements (to 2 K) on Na 0.92Ni1/3Ir2/3O2 indicate the presence of a broad magnetic ordering transition. X-ray absorption spectroscopy shows that iridium is at or close to the 4+ oxidation state in all compounds. 23Na nuclear magnetic resonance measurements comparing Na 2IrO3 to Na0.92Ni1/3Ir 2/3O2 and Na0.89Zn1/3Ir 2/3O2 provide strong indications that the electron spins are short-range ordered in the latter two materials. Na0.62Mn 0.61Ir0.39O2, Na0.80Fe 2/3Ir1/3O2, Na0.90Co 1/3Ir2/3O2, Na0.92Ni 1/3Ir2/3O2, Na0.86Cu 1/3Ir2/3O2 and Na0.89Zn 1/3Ir2/3O2 are spin glasses. (CSD-numbers: Na0.62Mn0.61Ir0.39O2: 426657, Na0.80Fe2/3Ir1/3O2: 426659, Na 0.90Co1/3Ir2/3O2: 426658, Na 0.92Ni1/3Ir2/3O2: 426656, Na 0.86Cu1/3Ir2/3O2: 426655, and Na2.8ZnIr2O6: 426660.)
KW - Honeycomb
KW - Iridate
KW - Oxide
KW - Spin Glass
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U2 - 10.1016/j.jssc.2013.11.017
DO - 10.1016/j.jssc.2013.11.017
M3 - Article
AN - SCOPUS:84890531749
SN - 0022-4596
VL - 210
SP - 195
EP - 205
JO - Journal of Solid State Chemistry
JF - Journal of Solid State Chemistry
IS - 1
ER -