The sintering of LaFeO 3 has been studied in the temperature interval 1100 -1600°C in air. The effect of cation nonstoichiometry on densification, microstructure, and phase composition is emphasized. La 2 O 3 was observed to inhibit both sintering and grain growth. In Fe-excess materials, exaggerated grain growth occurred, particularly above 1430°C, where a liquid phase was formed. Postsintering swelling was observed in Fe-excess materials above 1430°C. The swelling mechanism is related to phase equilibria, which are reductive in nature and lead to the evolution of oxygen gas. The density in La-excess materials remains high up to 1600°C, but the ceramics might disintegrate in air.

The magnetic Aux noise generated by films and crystals of Bi2Sr2CaCu20&+y and YBa2Cu30& "up to 30 p, m thick and cooled in nominally zero magnetic field, has been measured at opposing surfaces by two dc superconducting quantum interference devices. For both materials, the noise sources at the two surfaces were highly correlated at specific temperatures in a given cooldown. This result suggests that the observed vortices moved as rigid rods. At other temperatures, the noise was mostly uncorrelated, suggesting that the relevant vortices were pinned at more than one point along their length.

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