Electron microscopy investigation of the ZrO2-ZrN system—I. Formation of an incommensurate superstructure ZrON

Abstract The ZrO 2 -ZrN system has been investigated in the ZrO 2 rich field using electron microscopy and diffraction. When 2.5 mol% or more ZrN is added to ZrO 2 the monoclinic transformation is partially avoided and a new long period modulated zirconium oxynitride is formed. The modulated structure has a rhombohedral (trigonal) symmetry and is based upon the Zr 7 O 11 N 2 structure which is isostructural with Zr 2 Sc 2 O 13 . The structure is closely related to the cubic fluorite phase but the vacancies, introduced by replacing oxygen with nitrogen, are ordered along one of the threefold axes, lowering the symmetry and giving rise to slight distortions of the original cubic lattice. The modulations with a 3 nm wavelength are most probably due to pseudo-periodic composition fluctuations in order to incorporate a deficiency of nitrogen necessary to form the Zr 7 O 11 N 2 structure. The final incommensurate modulated structure can be regarded as a completely coherent mixture of pure Zr 7 O 14 layers alternating with Zr 7 O 11 N 2 layers perpendicular to the threefold axis. The non-commensurability arises from local deviations in spacing and/or orientation of these layers.

[1]  F. H. Brown,et al.  Stabilization of Zirconia with Calcia and Magnesia , 1952 .

[2]  O. J. Whittemore,et al.  Thermal Expansion of Various Ceramic Materials to 1500°C , 1956 .

[3]  G. Tendeloo,et al.  Microstructural study of copper‐intercalated niobium disulphide and tantalum disulphide CuxNbS2 and CuxTaS2. I. Phase Transitions in Cu0.5NbS2 and Cu0.5TaS2 , 1976 .

[4]  A. Heuer,et al.  On a martensitic phase transformation in zirconia (ZrO2)—I. Metallographic evidence , 1972 .

[5]  D. K. Smith,et al.  The crystal structure of baddeleyite (monoclinic ZrO2) and its relation to the polymorphism of ZrO2 , 1965 .

[6]  G. Tendeloo,et al.  Incommensurate superstructures in MnSi2‐x , 1975 .

[7]  G. Tendeloo,et al.  Electron microscopic study of the chimney ladder structures MnSi2−x and MoGe2−x , 1976 .

[8]  S. Amelinckx,et al.  Diffraction effects associated with shear structures and related structures , 1972 .

[9]  G. Teufer,et al.  The crystal structure of tetragonal ZrO2 , 1962 .

[10]  S. Amelinckx,et al.  Diffraction effects due to shear structures: A new method for determining the shear vector , 1970 .

[11]  M. Perez,et al.  Recherches sur les oxynitrures metalliques , 1967 .

[12]  P. T. Moseley,et al.  On the extent of ordering in stabilized zirconia , 1976 .

[13]  A. Prodan,et al.  Electron diffraction study of the structures of NbS2 and order—disorder in Cu‐intercalated NbS2 , 1976 .

[14]  T. Komoda.  The Direct Observation of the Long Period of the Ordered Alloy CuAu(II) by Means of Electron Microscope , 1958 .

[15]  P. Okamoto,et al.  On short range order and micro-domains in the Ni4Mo system , 1971 .

[16]  L. Gauckler,et al.  Nitride‐Stabilized Cubic Zirconia , 1978 .

[17]  A. Heuer,et al.  On a martensitic phase transformation in zirconia (ZrO2)—II. Crystallographic aspects , 1973 .

[18]  K. Trueblood,et al.  The crystal structure of baddeleyite (monoclinic ZrO2) , 1959 .

[19]  M. Thornber,et al.  Mixed oxides of the type MO2 (fluorite)-M2O3. IV. Crystal structures of the high- and low-temperature forms of Zr3Yb4O12☆☆☆ , 1970 .

[20]  M. Thornber,et al.  Mixed oxides of the type MO2(fluorite)–M2O3. III. Crystal structures of the intermediate phases Zr5Sc2O13 and Zr3Sc4O12 , 1968 .

[21]  A. Heuer,et al.  Microstructural Development in MgO‐Partially Stabilized Zirconia (Mg‐PSZ) , 1979 .