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Low oxygen partial pressure processing was utilized in analyzing the precipitation characteristics of second phases from Gd1+xBa2-xCu3O7 solid solutions. The precipitation of CuO and Gd2BaCuO5 from the solid solution led to an increase of the superconducting transition temperature and critical current density. Starting composition, oxygen partial pressure and processing temperature were found to control the size and amount of second phases.

The phase transitions that occur in melt-spun YBa2Cu3O7 bulk superconductors at high temperatures of 1,400-1,650 degrees Celsius were studied. In addition, the crystallization sequence of the as quenched material while undergoing isothermal annealing in oxygen was examined. From measurements, it was found that the 'phase composition of the solidified melt' is directly proportional to the oxygen concentration of the melt.

An experimental study on the viability of neutron irradiation for raising flux pinning in high-temperature ceramic superconductors has been carried out on c-axis aligned Bi2Sr2CaCu2O8 textured samples. Conducted under varying fluences, it quantified the magnetization parallel and normal to the nominal c-axis. Its results revealed an inversely proportional relationship between fluence strength and the critical current density's dependency on temperature and magnetic field.

The superconducting properties and flux creep in Nd(1+x)Ba(2-x)Cu3O(7-delta) samples have been quantified to determine the effect of replacing Ba(+2) with Nd(+3). The samples, whose x composition ranged from 0.0 to 0.1, were subjected to critical current density, magnetic relaxation and hysteresis measurements at varying temperatures. The results did not reveal any impact of the Nd substitution on the flux pinning energy.

The microstructure characterization of amorphous and nanocrystalline NdBa2Cu3O(7-x) and GdBa2Cu3O(7-x) superconductors is presented. The melt-spun bulk materials, which used as Nd123 and Gd 123 as starting materials, respectively, were subjected to recrystallization experiments as well as magnetic and image analysis. The results reveal the disappearance of superconductivity despite a recovery to an orthorhombic structure for the recrystallized samples.

During normal digestion, ingested materials are propelled into the stomach by a wave of muscular contraction, passing through the cardiac (gastroesophageal) sphincter, which momentarily relaxes to allow passage. The highly acidic contents of the stomach are then prevented from entering the esophagus, where they would cause inflammation (esophagitis), by closure of the cardiac sphincter. In some cases, acid does manage to enter the esophagus from the stomach (gastroesophageal reflux), causing heartburn or, in more severe cases, physical damage to the esophageal mucosa. It is generally held that gastroesophageal reflux is more frequent when one is in a supine (as opposed to upright) position, resulting from the lack of opposing gravitational force. It is known that transient relaxation of the cardiac sphincter is the predominant cause of gastroesophageal reflux in the supine position. Recent evidence suggests that gastroesophageal reflux in the upright posture may be quite common, especially among patients suffering from reflux disease; the mechanism underlying this is not known. To investigate this issue, simultaneous determinations of esophageal acidity (pH) and pressure levels were performed in eight patients (equal numbers of men and women; average age 43 years) who had experienced daily heartburn for at least six months. Four of the patients had evidence of esophageal damage on endoscopy; two had normal esophageal mucosa, but had heightened sensitivity to esophageal acid. In this group of patients, the incidence of reflux was higher when patients were in the upright (compared with supine) position. In both positions, the predominant mechanism for allowing acid to enter the esophagus was transient relaxation of the cardiac sphincter. There were no differences in total reflux time (the time required to clear the acid from the esophagus) or number of episodes of greater than five minutes duration between the two positions. (Consumer Summary produced by Reliance Medical Information, Inc.)

The thermal expansion and magnetostriction of polycrystalline and single-crystal [Pr.sub.5] [Ni.sub.2] [Si.sub.3] were investigated over the temperature range 5-300 K. The results show two magnetic phase transitions, one corresponding to the Curie temperature and the other at a lower temperature exhibiting characteristics of a spin reorientation transition. In the temperature range below the Curie temperature, the thermal expansion in single-crystal samples exhibited a temperature dependent anisotropy. Specifically negative and positive magnetic contributions to the thermal expansion were observed along the directions parallel and perpendicular to the c axis respectively. Index Terms--Magnetostriction, rare earth, spin reorientation, single crystal, thermal expansion.

The effect of Nd substitution on microstructure and magnetic properties in [[Nd.sub.x][(YDy).sub.0.5(1-x)[??]2.2][Fe.sub.14]B ribbons melt-spun at 22 m/s has been systematically studied. As-spun ribbons with low Nd content consist of 2 : 17 and 2 : 14 : 1 phases in an amorphous matrix, while as-spun ribbons with high Nd contain 2 : 14 : 1 and Fe phases in the amorphous matrix. After annealing at 700 [degrees]C for 15 min, all of the ribbons exhibit only a single 2 : 14 : 1 phase in their X-ray diffraction patterns. Nd substitution can improve the maximum energy product of annealed ribbons but deteriorate the temperature stability of the ribbons. Increasing Nd (x) from 0 to 0.8, decreases coercivity from 22 to 13.5 kOe, but increases the maximum energy product from 5.87 to 11.2 MGOe. The temperature coefficients for remanence and coercivity increase from -0.045 [degrees]C to -0.106 % /[degrees]C, and -0.306 to -0.38 %/[degrees]C, respectively for the same substitution range. Transmission electron microscope microstructures show that the samples with less Nd content exhibit a more uniform distribution of grains. Their average grain size is about 40 nm. The studied results show that the YDy-based [R.sub.2][Fe.sub.14]B magnets are very promising for high-temperature performance. Index Terms--Magnetocrystalline anisotropy, melting spinning, permanent magnets, rare earth materials and compounds.

Modified high-pressure gas atomization (HPGA) produces spherical, rapidly solidified powder, which is more suitable for bonded magnet processing. He atomization produced powder in the dia. < 45 [micro]m size that has a glassy fraction comparable to melt-spun ribbon quenched from about 16 m/s. Differences in magnetic properties are attributed to differences in solidification microstructures. Index Terms--Bonded magnets, gas atomization, melt spinning.

The corrosion behavior of bonded NdFeB permanent magnet materials produced by melt spinning with and without TiC additions has been investigated. Typical anodic polarization experiments in 0.9 M [Na.sub.2]S[O.sub.4] showed that the addition of 6 a/o TiC resulted in lower corrosion currents and reduced iron dissolution at fixed potential. The role of hydrogen was also investigated by means of galvanostatic charging and discharging experiments (hydrogen absorption and desorption) in 6M KOH which showed that the addition of TiC resulted in a reduction of absorbed hydrogen.

Three techniques for rapid thermal processing of superconducting bulk materials have been evaluated. The drop tube melting, laser surface treatment and explosive compaction methods were applied to single-phase RE123 material to produce REBa2Cu3O(7-delta). These were investigated in terms of phase distributions and microstructures to show the influence of process parameters such as temperature and heating rates.