Pyro, Ferro and Dielectric Properties of Ba_0.8Sr_0.2TiO₃ Films Deposited by Sol-Gel on Platinized Silicon Substrates

Abstract

We report on the deposition by a sol-gel process of Ba 0.8 Sr 0.2 TiO 3 films on platinum coated silicon substrates. X-Ray diffraction patterns show that the films are (111) preferentially oriented. The surface morphology is smooth, without cracks and the grain size is about 50 nm as determined by AFM and SEM. The dielectric constant measured from 10 2 to 10 6 Hz decreases slightly and is around 400 at 10 4 Hz. The losses are constant in a first approximation for a 1.5 μm thick film with a value of 0.03 at 10 kHz. The existence of an hysteresis cycle attests that the films, whatever their thickness, are in a ferroelectric state. Pyroelectric coefficients have been determined and the best figure of merit obtained at 293 K and 10 kHz is 40 μC/m 3 /K.

Electrical Characterizations of Lead Free Sr and Sn Doped BaTiO3 Ferroelectric Films Deposited by Sol-Gel

“…It is in agreement with results obtained on barium titanate ceramics (Arlt et al, 1985;Frey et al, 1998). Previously, we have measured similar values of the dielectric constant for Ba 0.8 Sr 0.2 TiO 3 films annealed at 750 °C (Mascot et al, 2008). As concerns the loss tangent presented figure 3.b, for the three samples the curves are very close and merge at 1 MHz towards a value inferior to 0.01.…”

“…The presence of a remnant polarization confirms that our films are in a ferroelectric state. However our results are not as good as those for PZT films, P r = 22 µC/cm 2 (Arlt et al, 1985) but they are similar to those for Ba 0.8 Sr 0.2 TiO 3 films, P r = 5 µC/cm 2 (Mascot et al, 2008;Pontes et al, 2001). Figure 11 shows the evolution at 1 kHz of respectively the capacitance (a) and polarization (b) as a function of a DC field for 3 annealing duration at the optimum temperature of 950°C.…”

High pyroelectric response of lead zirconate stannate titanate based antiferroelectric ceramics with low Curie temperature

“…(1). Recently, in order to improve the pyroelectric response of BST materials, various technologies have been done such as dopant [11][12][13], porous BST [14] and BST film [8,[15][16][17][18][19][20][21][22]. However, there are still many problems.…”

High tunability in lead-free Ba0.85Sr0.15TiO3thick films for microwave tunable applications

“…Our research is focusedon lead-free Ba0.85Sr0.15TiO3(BST), a good candidate to replace PZT in several uses [4].This composition (BST85/15) is a good trade-off to have very good ferroelectric and dielectric properties for applications at temperatures close to room temperature. So, BaxSr1-xTiO3is the most extensively investigated material to date thanks to the high dielectric permittivity, small dielectric losses,low leakage-current density and other excellent physical properties.For applications in electronic devices,BaxSr1-xTiO3 has been investigated in varied material forms, including thin films (t< 1μm), thick films 1μm<t<500 μm) and ceramics t>500 μm) [5,6]. At present, the majority oftheworks on ferroelectric oxides is oriented towards the form of thin films and/orceramics.…”