Normal state electrical measurements near the ferroelastic phase transformation in single crystal YBa/sub 2/Cu/sub 3/O/sub 7- delta /

Normal state electrical resistance measurements were made on single crystal YBa/sub 2/Cu/sub 3/O/sub 7- delta / over the temperature range 200-800 degrees C in oxygen and argon atmospheres, and the twin structure was observed simultaneously by hot-stage optical microscopy. The resistance of the crystal maintained a linear metallic-type behavior to higher temperatures (500 degrees C) than reported for bulk ceramic specimens. Anomalous resistance behavior was observed in the vicinity of the ferroelastic orthorhombic-to-tetragonal phase transformation under certain probe configurations and measuring conditions. Correlations between observed in situ twinning and resistance characteristics are discussed.<
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