PhD Thesis Arne Lüker final version V4 - Cranfield University

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B Site Doping of PST 40/60 6.2 Enhanced Tunability and Ferroelectricity in Mn doped PST 118 Fig. 6.5 confirms the rule of thumb for tunable ferroelectrics “a high dielectric constant gives a high tunability”. It shows the tunability and loss vs. electric field at 150 kHz of (Pb0.4,Sr0.6)(Mnx,Ti1-x)O3 thin films with different Mn content. The overall loss remains under 7.5% for x = 0, 0.01, and 0.03 and increases for x = 0.05. The increase is attributed to the hopping conduction due to the hopping of the charge carriers between Mn sites which begins to occur at x = 0.02. The tunability seems to reach a maximum of 78% for x = 0.03 and an applied field of 350 kV/cm (10.5 V). (a) (c) Fig. 6.5: Tuanability and loss vs electric field at 150 kHz of (Pb0.4,Sr0.6)(Ti1-x,Mnx)O3. (a) x=0, (b) x=0.01, (c) x=0,03 and (d) x=0.05 (b) (d)
Tunability [%] 100 90 80 70 60 50 40 30 20 10 0 Sol-Gel derived Ferroelectric Thin Films for Voltage Tunable Applications Unfortunately the Cr/Au top electrodes of the four samples blistered away at different fields, making a direct comparison of the shown data in Fig. 6.5 rather complicated. The blistering could be a result of different adhesion strengths due to contaminations of the surface of the ferroelectric thin films prior to the deposition of the electrodes or an insufficient vacuum during the evaporation. To get a clearer picture the formula developed in section 2.1.2 was fitted to the measured data. The result is plotted in Fig. 6.6 -20 -15 -10 -5 0 5 10 15 20 Bias Voltage [V] The result shows that the tunability of Pb0.4Sr0.6Mn0.01Ti0.99O3 is slightly higher than that of Pb0.4Sr0.6Mn0.03Ti0.97O3. Actually no surprise as we discovered in the last section that the hopping of the charge carriers between the Mn sites begins to occur in 2 mol% pure calc. 1% Mn calc. 3% Mn calc. 5% Mn calc. pure meas. Fig. 6.6: Comparison of the measured and calculated tunability of (Pb0.4,Sr0.6)(Ti1-x,Mnx)O3. 1% Mn meas. 3% Mn meas. 5% Mn meas. The fitting parameters Cmax[nF]/V2[V] are: pure 9.5/5.1; 1% 15/3.5;3% 13.8/4.5; 5% 5.7/8.5 119
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Sol-Gel derived Ferroelectric Thin
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Abstract Ferroelectric perovskite t
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Acknowledgements I want to take thi
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Table of Content Introduction and M
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Page 69 and 70: Sol-Gel derived Ferroelectric Thin
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Internships: Sol-Gel derived Ferroe
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PhD Thesis Arne Lüker final version V4 - Cranfield University

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