Differential Vaporization During Laser Ablation Deposition of Bi-Sr-Ca-Cu-O Superconducting Materials

Nanosecond and picosecond pulsed laser ablated materials from Bi-Sr-Ca-Cu-O superconducting targets are monitored by inductively coupled plasma-atomic emission spectrometry with a photodiode array detector. Differential vaporization was observed; elements of the lower-melting-point oxides (Bi₂O₃ and CuO) are enriched in the vapor phase, indicating a thermal vaporization mechanism. Melted droplets observed with SEM and enriched Ca and Sr content in the ablation crater measured with EDX support the hypothesis. A steady-state mass ablation composition after prolonged laser sampling is also observed; the ratios of intensity for Bi, Ca, and Sr to Cu are constant for power density 0.1 to 3.0 GW/cm²

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