"Nickel oxide is an antiferromagnetic material, below a NBel temperature, T of 523 OK, with a spin structure such that one family of (111) planes has a ferromagnetic arrangement of spins, and adjacent sheets have antiparallel spins. Above TN, NiO has the sodium chloride structure, but in the ordered state the lattice contracts slightly along the [ill] axis normal to the ferromagnetic sheets and the crystal structure becomes rhombohedral. As a result of this rhombohedral distortion, single crystals of NiO at room temperature are multiply twinned such that each twin domain has a different (111) contraction axis. Although it has been widely assumed that this crystallographic distortion is closely associated with the magnetic ordering there has been some controversy over whether the distortion actually disappears at TN o r some lower temperature (e. g. (1)).The X-ray topographic study of the domains in epitaxially grown NiO crystals, previously confined to room temperature (2). has been extended to cover a temperature range including TN, and the misorientation between adjacent domains has been measured using the Schulz technique. The specimens were mounted in a small furnace and topographs were taken at 20 C intervals (closer near the transition temperature) until well after the domains had disappeared, and then at similar intervals back to room temperature. 0The angular misorientation decreased continuously with increasing temperature and disappeared completely at (517 f 3) K; this value for the transition temperature agrees excellently with a T 0 of (516 2)'K obtained from magnetic susceptibility N

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We report on the influence of various plasma species on the growth and structural properties of indium nitride in plasma-assisted metalorganic chemical vapor deposition. Atomic emission spectroscopy was used to quantify the molecular, neutral, and ionized nitrogen species concentrations above the growth surface. Reflectance and Raman spectroscopy and X-ray diffraction techniques were used to characterize the grown InN films. It has been found that ionized rather than molecular or neutral nitrogen species is positively correlated with the InN growth rate. We conclude that InN formation in the present case is due to the chemical combination of atomic nitrogen ions with indium.

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