(a) Generation of the pyroelectric charge in the electrodes around a ferroelectric nanorod with inhomogeneous spontaneous polarization under its temperature variation on . The lower plot schematically shows the charge profile across the rod at time moments and . (b) Pyroelectric electromotive force (EMF) and current generation by ferroelectric nanostructures: a single polarized rod and nanowires vertically aligned array in contact with the electrode plates. (c) Equivalent circuit of operating pyroelectric electromotive force: is the effective capacitance of the capacitor, is the diode (if any appeared due to the possible rectification effect at the ferroelectric-semiconductor-electrode interface), is the external load impedance, at that for small internal resistance of current source.
Pyroelectric coefficient vs nanowire radius for different surface tension coefficients and fixed length [curves 1–3 in plot (b)]; different length and fixed surface tension coefficients [curves 1–4 in plot (a)]. (c) Averaged pyroelectric coefficient vs the average radius for different relative halfwidth , 0.25, 0.5, 1, 2 (curves 0–4) of the size distribution function shown in plot (d). Surface tension coefficient , length . Horizontal lines indicate of bulk material . Material parameters of : , , , , , room temperature , and gradient term coefficient .
Pyroelectric current [(a) and (b)] and voltage [(c) and (d)] vs time for different nanowire radius and fixed fraction of nanowires [plots (a) and (c)]; different fraction of nanowires , , , 0.45 and fixed radius [plots (b) and (d)], small load resistance [(a) and (b)] and high resistance [(c) and (d)]. Central inset shows the temperature variation and its conversion into pyroelectric response. Wires length , electrode area , temperature variation amplitude , relaxation time , , , . Other parameters are the same as in Fig. 2.
[(a) and (b)] Efficiency of the power converter vs temperature and wire radius for parameters , , , and . (a) Contour map of values in coordinates temperature-thickness. Different curves correspond to the fixed efficiency values 1%, 5%, 10%, 20%, and 50%. (b) Efficiency vs radius for different temperatures (figures near the curves). (c) The current power spectrum at . Other parameters are the same as in Figs. 2 and 3(a).
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