Dielectric and Pyroelectric Properties of Compositionally Graded Pb(Zr1-xTix)O3 Thin Films Prepared by Sol-gel Process

Abstract

Compositionally graded ferroelectric lead zirconate titanate Pb(Zr1-xTix)O3 (PZT) thin films were grown on Pt/Ti/SiO2/Si substrates by using a sol-gel process. The final structure consists of six layers, up-graded graded films starting from PbZrO3 on the Pt electrode to the top PZT(50) layer, it consists of no Ti, 10%Ti, 20%Ti, 30%Ti, 40%Ti, and 50%Ti respectively. Whereas films with opposite gradient are called down-graded graded films. Structure and dielectric properties of the graded films was investigated by X-ray diffraction, Auger electron spectroscopy and by impedance analysis. The up-graded and down-graded PZT films annealed at 600C, exhibited the remanent polarization values of 18.0 and 24.2 C/cm2, respectively. The typical small signal dielectric constants and loss tan at a frequency of 100 Hz were 523 and 0.018, 544, and 0.020, respectively, for up-graded and down-graded PZT thin films. The temperature dependence of pyroelectric coefficients of the graded PZT films was measured by a dynamic technique. From 20C to 82C, the pyroelectric coefficients of the up-graded and down-graded PZT films up to 374 and 407 C/m2K, respectively.

Switching Characteristics and High-Temperature Dielectric Relaxation Behaviours of Pb(Zn1/3Nb2/3)0.91Ti0.09O3 Single Crystal

“…The imaginary part of the pyroelectric coefficients are pyroelectric losses. At a room temperature of 25 °C, the value of the pyroelectric coefficient was −463.3 μC/m 2 K, and the absolute value of the pyroelectric coefficient (463.3 μC/m 2 K) was higher than that of the graded PZT films on Pt-coated silicon substrates (202–250 μC/m 2 K) and Ba 3 Nb 2 O 8 ceramic (103 μC/m 2 K) [32,54]. A useful comparative figure of merit ( FOM ) used in comparing pyroelectric materials is defined as F D = | P |/ c ( ε r ε 0 tan δ ) 1/2 , where c is the heat capacity per unit volume ( c = 2.5 J/cm 3 K) [55], ε r is the relative permittivity, ε 0 is the permittivity of the vacuum and tan δ is the dissipation factor.…”

“…Furthermore, the temperature dependence of pyroelectric coefficient was measured by a dynamic technique [ 32 , 33 ]. At a certain temperature T 0 , the sample temperature was sinusoidally modulated T ( t ) = T 0 + T ~ sin 2π ft ] with frequency f = 5 mHz and amplitude T ~ = 1 K using a Peltier element.…”

Ferroelectric, Dielectric and Pyroelectric Properties of Highly C-Axis -Oriented Nanostructured (<i>Pb,Sr</i>)(<i>Zr,Ti</i>)O₃ Thin Films

“…287-290 phenomena of PLZT thin films by transmission electron microscopy with energy dispersive X-ray analysis, field emission scanning electron microscopy, and AFM. During RTA the PSZT perovskite nuclei form on the Pt and crystallize on the bottom electrode and then growth proceeds from the interface uniformly to the surface in columnar grains that push excess Pb and inclusions to the film surface [10,22]. From the XRD and AFM results, we know that the heterogeneous nucleation is considered to play a dominant role in the nucleation of the perovskite phase.…”

“…A dynamic method was used to measure the pyroelectric coefficient (p) for PSZT films at room temperature [22]. At room temperature T 0 (26 °C) the sample temperature was sinusoidally modulated [T (t) =T 0 +T ~sin2πft] with frequency f=5 mHz and amplitude T ~=1K using a Peltier element [12].…”

“…At room temperature T 0 (26 °C) the sample temperature was sinusoidally modulated [T (t) =T 0 +T ~sin2πft] with frequency f=5 mHz and amplitude T ~=1K using a Peltier element [12]. The pyroelectric current signal was amplified with an electrometer and the 90° out of phase component of the current with respect to the temperature modulation was measured with a lock-in amplifier [12,22]. A PSZT film was first poled at room temperature by applying a dc voltage of 6 V for 10 min then short circuited at room temperature overnight.…”