本研究利用CO2低溫雷射退火製程，將鋯鈦酸鉛(PZT)鐵電薄膜與錳酸鍶鑭(LSMO)氧化物電極鍍製於316型不鏽鋼線與薄板基板上，以改善傳統爐內退火常導致線狀或薄板型鐵電元件產生界面擴散與氧化等問題，用以開發相關的可撓性元件。
研究結果顯示PZT/LSMO/SUS316鐵電結構元件，經過高溫長時間的傳統爐內退火熱處理，表面易生成氧化物，破壞了LSMO鍍層之結構性，導致PZT鍍膜品質劣化、漏電流過大，並影響鐵電特性，無法得到飽和的電滯曲線。在不鏽鋼薄板基材方面，傳統爐內退火試片之殘留極化值(Pr)為4.3μC/cm2，矯頑電場值(Ec)為288.3kV/cm，漏電流密度約為10-6A/cm2。使用CO2雷射退火取代爐內退火，在雷射功率95W/cm2_95s照射下，可使其Pr值提升至17.9μC/cm2， Ec值下降至126.3kV/cm，漏電流密度降為10-9A/cm2。另在不鏽鋼線基材方面，使用傳統爐內退火之其PE0值為2.9μC/cm2， EP0值為290kV/cm，漏電流密度約為10-5A/cm2；使用CO2雷射退火取代爐內退火，在雷射功率59W/cm2_45s照射下，可使其PE0值提升至9.8μC/cm2，EP0值下降至165kV/cm，漏電流密度降為10-7A/cm2。
再者，本文亦利用電解拋光方式來改善不鏽鋼線表面狀況，電解拋光後之PZT/LSMO/SUS316線狀結構，再使用雷射功率59W/cm2_45s照射下，其PE0值可提升至12.9μC/cm2，EP0值下降至146.5kV/cm，漏電流密度降為10-8A/cm2，已十分接近於光滑SUS316薄板上鍍製LSMO、PZT薄膜元件的鐵電性，可見基材的表面狀況影響鐵電特性甚大。
最後，將上述PZT/LSMO/SUS316 線狀試片彎曲成不同曲率半徑(r)測試其可撓性，發現當r值小於0.7mm以下，易使PZT/LSMO界面發生膜裂情形；在r值為20mm以上，則可避免PZT與LSMO界面發生膜裂情形，並且滿足一般撓曲應用之需求。因此，本研究所開發之線材結構大幅提升鐵電可撓性元件製作的可能性。

In this study, Pb(Zr0.52Ti0.48)O3(PZT) and La0.7Sr0.3MnO3 (LSMO) ferroelectric thin films were coated on stainless steel substrates of planar and micro wire shaped using sol-gel process, spin coating and sputtering technques. The phase structure of the films was successfully transformed from pyrochlore to perovskite phase using low temperature CO2 laser annealing. The interfacial property between different components was significantly improved using laser annealing process in order to develop flexible components.

Microstructural analysis reveals that the furnace annealed films causes to generate oxide elements on the surface due to high temperature annealing. The growth of oxide elements started from the surface of the substrate and grown upto the surface of LSMO by which the adhesion between LSMO and PZT is reduced. Hence the leakage current increased to maximum. This resulted in degrading the film quality and ferroelectric property.

Furnace annealed PZT film coating on planar stainless steel substrate showed ferroelectric remanent polarization of 4.3μC/cm2 and coercive field of 288.3kV/cm. The remanent polarization and coercive fields were improved significantly to 17.9μC/cm2 and 126.3kV/cm by using low temperature CO2 laser annealing. This might be due to decrease in leakage current from 10-6 to 10-9 A/cm2 and enhanced interfacial property between different components.

Similar behavior is observed in the case of PZT films coated on wire shaped stainless steel substrate. The remanent polarization increased from 2.9 to 9.8μC/cm2 and coercive field decreased from 290 to 165kV/cm. Moreover, the improvement in leakage current density is from 10-5 to 10-7 A/cm2. The microstructure of the wire shaped stainless steel substrate surface showed the pores, grown oxides and defects. Hence, a new process was used to overcome the defects and surface property. Electropolishing technique was carried out to improve the surface property as well as interfacial property between substrate and buffer layer. The surface condition was enhanced by applying voltage of 2V for 150 sec in electropolishing process. The ferroelectric hysteresis loop of PZT films with wire shaped stainless steel substrates after electropolishing show remanent polarization of 12.9μC/cm2 and coercive field of 146.5kV/cm. In addition the leakage current also decreased to 10-8A/cm2. This result is closer to the ferroelectric property obtained for the films with planar shaped stainless steel substrates. Hence it can be concluded that the surface property and interfacial condition has a major role in increasing the property.

Finally, the flexible characteristic was tested using the bending property of the wire. When the wire is bent into the curve of radius 20mm, the surface structure is found stable without any macro cracks. But, cracks were observed by increasing the bending strength upto the radius of curvature to 0.7mm. This indicates that the bending upto the radius of curvature 20mm is an appropriate condition to meet the requirements for flexible device.

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