Lanthanum nickelate layers have been deposited onto 100 mm diameter silicon/silicon dioxide and (0001) sapphire substrates by liquid-delivery metal±organic (MO) CVD using the precursors La(thd) 3 and Ni(thd) 2 (thd = 2,2,6,6-tetramethyl-3,5-heptanedionato) dissolved in tetrahydrofuran and heptane. The LaNiO 3 (LNO) was deposited at 630 C in an oxidizing atmosphere, and the as-grown layers were highly crystalline and highly (110)-oriented on Si/SiO 2 . Electrical resistivity studies were performed and showed a dependence on the La/Ni ratio, the substrate used, and the post-deposition annealing conditions. A minimum electrical resistivity value of 300 lX cm was measured for LNO deposited on (0001) sapphire and rapidly annealed at 750 C. The resistivity values of the LNO layers deposited onto silicon/silicon dioxide were higher, with a minimum value of 1 mX cm. The rapid annealing at 750 C resulted in cracking of some of the LNO layers deposited onto the silicon substrates. However, the layers that were nickel-rich withstood the annealing treatment better and showed little evidence of cracking.

No abstract

The specific heat of two twinned and one detwinned single-crystal samples of YBa 2 Cu 3 O 7Ϫ␦ have been measured with magnetic fields up to 8 T applied parallel to the c axes of the crystals. The crystals have zero-field transition widths of 0.3, 1.0, and 1.5 K. The zero-field data are analyzed in terms of the critical and Gaussian fluctuation models and the in-field data are analyzed in terms of critical and lowest-Landau-level ͑LLL͒ scaling. The data scale using the three-dimensional X-Y model in magnetic fields up to 8 T ͑the highest field we used͒. We also find LLL scaling to work, but only above 6 T. The implication is that there may be a crossover from three-dimensional XY to LLL scaling at some sample-dependent field of the order of 10 T. The results agree with recent measurements of the penetration depth and provide strong evidence for the existence of a critical regime within which there is scaling behavior characteristic of the three-dimensional X-Y model with critical exponents consistent with those observed in superfluid 4 He. We then perform the same analysis on previously published specific-heat data on YBa 2 Cu 3 O 7Ϫ␦ and LuBa 2 Cu 3 O 7Ϫ␦ in order to demonstrate the universality of the scaling functions.

This review summarizes recent progress in the use of X-ray diffraction for microstructural investigations. Advances in both detector architecture and computational power have led to the development of powerful yet relatively straight forward methods of analysis. Several case studies are presented.

No abstract