Crystallization regions of the La<sub>2</sub>Cu<sub>2</sub>O<sub>5</sub> and La<sub>1-x</sub>Sr<sub>x</sub>CuO<sub>2.5- delta </sub> phases in the La<sub>2</sub>O<sub>3</sub>-SrO-CuO system
A N Maljuk; G A Emel'chenko; I I Zver'kova; A V Kosenko; A N Maljuk; Inst. of Solid State Phys., Acad. of Sci., Chernogolovka, Russia; G A Emel'chenko; Inst. of Solid State Phys., Acad. of Sci., Chernogolovka, Russia; I I Zver'kova; Inst. of Solid State Phys., Acad. of Sci., Chernogolovka, Russia; A V Kosenko; Inst. of Solid State Phys., Acad. of Sci., Chernogolovka, Russia
Журнал:
Superconductor Science and Technology
Дата:
1994-08-01
Аннотация:
The La<sub>2</sub>Cu<sub>2</sub>O<sub>5</sub> and La<sub>1-x</sub>Sr<sub>x</sub>CuO<sub>2.5- delta </sub> crystallization regions have been investigated in the system La<sub>2</sub>O<sub>3</sub>SrO-CuO at fixed molar ratio La<sub>2</sub>O<sub>3</sub>:CuO=1:8 in the range of SrO concentrations from 0.0 to 5.5 mol%. It has been shown that Sr is non-soluble in La<sub>2</sub>Cu<sub>2</sub>O<sub>5</sub> and the crystallization region of this phase is limited by the SrO concentration in the melt approximately=1 mol%. When the SrO concentration in the melt exceeds approximately=1% mol%, the La<sub>1-x</sub>Sr<sub>x</sub>CuO<sub>2.5- delta </sub> phase crystallization takes place below 1050 degrees C. The Sr lower solubility limit in La<sub>1-x</sub>Sr<sub>x</sub>CuO<sub>2.5- delta </sub> is found to be x approximately=0.05 atoms/FU. This compound does not exist if the Sr content is lower. The tentative projections of the primary crystallization phase boundaries of CuO, La<sub>2</sub>Cu<sub>2</sub>O<sub>5</sub>, La<sub>1-x</sub>Sr<sub>x</sub>CuO<sub>2.5- delta </sub> and La<sub>2-x</sub>Sr<sub>x</sub>CuO<sub>4- delta </sub> phases on the La<sub>2</sub>O<sub>3</sub>SrO-CuO composition triangles have been constructed.
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