2016
D.O. Charkin et al. / Materials Research Bulletin 45 (2010) 2012–2016
perovskites. With calcium, we succeeded as yet in preparation of
only FeIII compounds, and this oxidation state is not directly
transferable to pnictides due to redox incompatibility of FeIII and
PnꢀIII [20]. Further studies of calcium compounds involving cations
stable to reduction, e.g. GaIII, are evidently necessary before we see
whether isostructural Ca oxide pnictides can exist.
under the State contracts P-279 (D.O.C. and S.M.K.), P2306 and
02.552.11.7093 (A.V.S. and O.E.O.). A.V.S. would like to thank LPI
Educational Research Center for the support. The support of the
Russian Foundation for Basic Research is acknowledged (Grants
Nos. 10-03-00681-a, 09-02-01370).
Unfortunately, the direct relationships between composition
and structures are yet unknown as evidenced by the fact that the
suggested Ca3Ch2Fe2O5Ch2 compounds were not obtained. Though
the differences in the a cell parameters between Ca2FeO3Cl and
Ca3Fe2O5Cl2 are marginal, the double anionic layers in the former
compound may be stuffed with Cu+ while in the latter, not as yet.
Unless proper synthetic conditions have not been found, there
seems to be a rather delicate interplay between the ‘‘42262’’
(Sr2CuGaO3S) and ‘‘32252’’ (Sr3Cu2Fe2O5S2) structures both in the
oxide chalcogenide and oxide pnictide families, the possibility of
formation depending on the nature of both perovskite and anti-
fluorite layers. Among compounds of Sr and Ba, for instance, the
‘‘42622’’ structure was observed with trivalent cations of Ga (CuS),
In (CuS), Sc (FeAs, CrAs), V (FeAs), Cr (CuS, FeAs), Mn (CuS), and Fe
(CuS) while the 32522 structure has been found for Sc (CuS, FeP,
FeAs) and Fe (CuS, CuSe, AgS, and AgSe) [3,4,14,18,20–25]. In cases
where both structures are formed, the differences in the a cell
parameters are not so great as to suggest that the anti-fluorite
layers should be strained too much to contribute to one structure
but not to the other. Evidently, more thorough investigations of
both structure types are necessary to discover the trends in relative
stability of the structures in question. However, Ca2+ (and probably
Eu2+) can be employed more widely to partially substitute for Sr2+
in the structures of existing FeAs superconductors as a ‘‘chemical
press’’, to increase the transition temperature.
References
[1] Y. Kamihara, T. Watanabe, M. Hirano, H. Hosono, J. Am. Chem. Soc. 130 (2008)
3296.
[2] S.J. Clarke, P. Adamson, S.J.C. Herkelrath, O.J. Rutt, D.R. Parker, M.J. Pitcher, C.F.
Smura, Inorg. Chem. 47 (2008) 8473.
[3] X. Zhu, F. Han, G. Mu, P. Cheng, B. Shen, B. Zeng, H.-H. Wen, Phys. Rev. B 79 (2009)
220512(R).
[4] X. Zhu, F. Han, G. Mu, B. Zeng, P. Cheng, B. Shen, H.H. Wen, Phys. Rev. B 79 (2009)
024516.
[5] V. Johnson, W. Jeitschko, J. Solid State Chem. 11 (1974) 161.
[6] D.O. Charkin, X.N. Zolotova, Cryst. Rev. 13 (2007) 201.
´
[7] E. Parthe, S. Hu, J. Solid State Chem. 174 (2003) 165.
[8] C.S. Knee, M.A.L. Field, M.T. Weller, Solid State Sci. 6 (2004) 443.
[9] Z. Hiroi, N. Kobayashi, M. Takano, Physica C 266 (1996) 191.
[10] T. Sowa, M. Hiratani, K. Miyauchi, J. Solid State Chem. 84 (1990) 178.
[11] Y. Shimizu, H. Ogino, N. Kawaguchi, K. Kishio, J. Shimoyama, arXiv:1006.3769,
unpublished.
[12] H. Ogino, S. Sato, K. Kishio, J. Shimoyama, T. Tohei, Y. Ikuhara, Appl. Phys. Lett 97
(2010) 072506.
[13] H. Ogino, Y. Shimizu, K. Ushiyama, N. Kawaguchi, K. Kishio, J. Shimoyama, Appl.
Phys. Expr 3 (2010) 063103.
[14] W.J. Zhu, P.H. Hor, Inorg. Chem. 36 (1997) 3576.
[15] W.J. Zhu, P.H. Hor, J. Solid State Chem. 134 (1997) 128.
[16] TOPAS, Version 3; Bruker AXS: Karlsruhe, Germany, 2005.
[17] J.M. Delgado, G. Diaz de Delgado, M. Quintero, J.C. Woolley, Mater. Res. Bull. 27
(1992) 367.
[18] W.J. Zhu, P.H. Hor, J. Solid State Chem. 153 (2000) 26.
[19] P. Quebe, L.J. Terbu¨ chte, W. Jeitschko, J. Alloys Compd. 302 (2000) 70.
[20] L. Cario, A. Lafond, T. Morvan, H. Kabbour, G. Andre, P. Palvadeau, Solid State Sci. 7
´
(2005) 936.
[21] K. Otzschi, H. Ogino, J.-I. Shimoyama, K. Kishio, J. Low Temp. Phys. 117 (1999) 729.
[22] Y.L. Xie, R.H. Liu, T. Wu, G. Wu, Y.A. Song, D. Tan, X.F. Wang, H. Chen, J.J. Ying, Y.J.
Yan, Q.J. Li, X.H. Chen, EPL 86 (2009) 57007.
[23] M. Tegel, F. Hummel, S. Lackner, I. Schellenberg, R. Poettgen, D. Johrendt, Z. Anorg.
Allg. Chem. 635 (2009) 2242.
Acknowledgements
[24] H. Ogino, Y. Matsumura, Y. Katsura, K. Ushiyama, S. Horii, K. Kishio, J. Shimoyama,
Supercond. Sci. Technol. 22 (2009) 075008.
[25] H. Ogino, Y. Katsura, S. Horii, K. Kishio, J. Shimoyama, Supercond. Sci. Technol. 22
(2009) 085001.
The authors would like to thank Prof. V.M. Pudalov and Prof. E.V.
Antipov for helpful discussion. This work was partially supported
by the Ministry of Science and Education of Russian Federation