No abstract

No abstract

No abstract

Enhancement of flux pinning and critical currents in YBa 2 Cu 3 O 7 − δ films by nanoscale iridium pretreatment of substrate surfaces

No abstract

No abstract

Fourier transform-infrared studies have been carried out on the non-stoichiometric Ni-Zr substituted barium hexaferrite synthesized through the citrate precursor method. We observed approximately 30 bands, almost twice as many as reported for stoichiometric samples. These are attributed to the shifting of the vibrational modes under lattice distortion, which produces significant reduction in anisotropy and coercive fields without affecting magnetization.

The corrosion and vaporization behavior of eight commercial refractories containing Cr 2 O 3 were investigated under simulated pressurized pulverized coal combustion (PPCC) conditions at 1723 K in the presence of liquid slag. The corrosion resistance of the refractory materials decreased with increased content of free Cr 2 O 3 , because bursting (reaction of Fe 3 O 4 with Cr 2 O 3 ) occurred. Refractories containing MgCr 2 O 4 with dissolved Al 2 O 3 showed the highest corrosion resistance. Thermodynamic calculations showed that CrO 3 and CrO 2 (OH) 2 were the most volatile species in air and in PPCC flue gas, whereas additions of A 2 O (A ‫؍‬ Na and K, minor slag component) increased the chromium vaporization significantly because of A 2 CrO 4 formation. Knudsen effusion mass spectrometry measurements showed that the chromium vaporization of refractories was directly correlated to the Cr 2 O 3 content of the material. In contrast, refractories containing MgCr 2 O 4 showed a significant decrease in chromium vaporization.