Articles

All articles  |  Recent articles

Solid Solution in LnTiO₂N and MTaO₂N Oxynitrides, Ln = La,Nd; M = Ca, Sr, Ba

J. Ahchawarattaworn, D.P. Thompson

School of Chemical Engineering and Advanced Materials, University of Newcastle, Newcastle upon Tyne, NE1 7RU, U.K.

received February 12, 2014, received in revised form April 04, 2014, accepted May 09, 2014

Vol. 5, No. 3, Pages 173-183   DOI: 10.4416/JCST2014-00003

Abstract

The last fifty years have witnessed a considerable level of interest in the field of oxynitrides. This has mainly been because of their thermal and mechanical properties, but certain members of this group have the perovskite atomic arrangement, and as such might be expected to have interesting electrical and electronic properties. Foremost among these are the rare earth titanium oxynitrides, LnTiO₂N, with Ln = La and Nd the two rare earths most commonly investigated, and also the Group II tantalum oxynitrides of the type MTaO₂N where M = Ca, Sr and Ba. The present paper explores the changes in structure which occur in solid solutions between end-members of these two series. In the (La_pNd_1-p)O₂N series, the Pnma space group of the Nd end-member is retained up to p = 0.8 in the above formula; in the (Ba_pSr_1-p)TaO₂N series, the cubic structure of BaTaO₂N is retained up to p ∼ 0.5 before transforming into the tetragonal modification of SrTaO₂N; in the (Ca_pSr_1-p)TaO₂N series, the tetragonal structure of SrTaO₂N is stable up to p ∼ 0.65 before changing into the orthorhombic form of CaTaO₂N. No evidence was found for solid solutions between CaTaO₂N and BaTaO₂N.

Keywords

Oxynitrides, perovskites, synthesis, crystal structure, dielectric properties

References

¹ Thompson, D.P.: Oxynitride research in the nano era, Mater. Sci. Forum, 554, 1 – 10, (2007).

² Marchand, R., Pors, F., Laurent, Y.: Preparation and characterization of new oxynitrides with a perovskite structure, (in French), Rev. Int. Hautes Tempér. Réfract. Fr., 23, 11 – 15, (1986).

³ Gouin, X., Marchand, R., Laurent, Y., Gervais, F.: Infrared dielectric response of BaTaO₂N, Sol. State Comms., 93, 857 – 9, (1995).

⁴ Kim, Y.-I., Woodward, P.M., Baba-Kishi, K.Z., Tai, C.W.: Characterization of the structural, optical and dielectric properties of oxynitride perovskites AMO₂N (A = Ba, Sr, Ca; M=Ta,Nb), Chem. Mater., 16, 1267 – 76, (2004).

⁵ Marchand, R., Laurent, Y., Guyader, J., L'Haridon, P., Verdier, P.: Nitrides and oxynitrides: preparation, crystal chemistry and properties, J. Eur. Ceram. Soc., 8, 197 – 213, (1991).

⁶ Clarke, S.J., Guinot, B.P., Michie, C.W., Calmont, M.J.C., Rosseinsky, M.J.: Oxynitride perovskites: synthesis and structures of LaZrO₂N, NdTiO₂N and LaTiO₂N and comparison with oxide perovskites, Chem. Mater., 14, 288 – 94, (2002).

⁷ Pors, F., Bacher, P., Marchand, R., Laurent, Y., Roult, G.: Structural study of the oxynitride perovskite SrTaO₂N and the solid solution Ba_1-xSr_xTaO₂N by neutron diffusion, Rev. Int. Hautes Tempér. Réfract. Fr., 24, 239 – 46, (1988).

⁸ Günther, E., Hagenmayer, R., Jansen, M.: Structural studies of the oxynitrides SrTaO₂N, CaTaO₂N and LaTaON₂ by means of neutron and X-ray diffraction, (in German), Z. Anorg. Allg. Chem., 626, 1519 – 25, (2000).

⁹ Yashima, M., Saito, M., Nakano, H., Takata, T., Ogisu, K., Domen, K.: Imma perovskite-type oxynitride LaTiO₂N: structure and electron density, Chem. Comm., 46, 4704 – 6, (2010).

¹⁰ Jansen, M., Letschert, H. P.: Inorganic yellow-red pigments without toxic metals, Nature, 404, 980 – 82, (2000).

Copyright

Göller Verlag GmbH