Articles you may be interested inEnergy-storage performance and electrocaloric effect in (100)-oriented Pb0.97La0.02(Zr0.95Ti0.05)O3 antiferroelectric thick films J. Appl. Phys. 110, 064109 (2011); 10.1063/1.3641983 Dielectric properties of (110) oriented Pb Zr O 3 and La-modified Pb Zr O 3 thin films grown by sol-gel process on Pt ( 111 ) ∕ Ti ∕ Si O 2 ∕ Si substrate J. Appl. Phys. 100, 044102 (2006); 10.1063/1.2234819 ( Pb , La ) ( Zr , Sn , Ti ) O 3 antiferroelectric thin films grown on La Ni O 3 -buffered and Pt-buffered silicon substrates by sol-gel processing J. Appl. Phys. 97, 024102 (2005); 10.1063/1.1834730 Dielectric enhancement and ferroelectric anomaly of compositionally graded (Pb,Ca)TiO 3 thin films derived by a modified sol-gel technique Appl.
The electrocaloric effect is calculated for PMN-PT relaxor ferroelectric thin film near morphotropic phase boundary composition. Thin film of thickness, ∼ 240 nm, has been deposited using pulsed laser deposition technique on a highly (111) oriented platinized silicon substrate at 700°C and at 100 mtorr oxygen partial pressure. Prior to the deposition of PMN-PT, a template layer of LSCO of thickness, ∼ 60 nm, is deposited on the platinized silicon substrate to hinder the pyrochlore phase formation. The temperature dependent P-E loops were measured at 200 Hz triangular wave operating at the virtual ground mode. Maximum reversible adiabatic temperature change, ΔT = 31 K, was calculated at 140°C for an external applied voltage of 18 V.
In recent years, alternative cooling devices have become essential for the present threat of global warming. Two major reasons of increasing temperature of this planet are the production of green house gases due to domestic and industrial activities and the heat generation due to high current densities in integrated circuits. In recent studies by Mischenko et al. [1,2] it has been seen that the electrocaloric effect of perovskite thin film materials can provide a better solution than bulk to reduce the heat generation in integrated circuits. The possible change of temperature on the application or withdrawal of electric field under adiabatic condition, which is known as the electrocaloric effect (EC effect), has been seen maximum ( 6 1 0.155 10 K mV --¥ at 226 °C) in antiferroelectric PbZr 0.95 Ti 0.05 O 3 thin films [1]. A similar study on relaxor ferroelectric 0.9 PbMg 1/3 Nb 2/3 O 3 -0.1 PbTiO 3 (0.9PMN-0.1PT) shows an electrocaloric effect of 6 1 0.056 10 K mV --¥ at 75 °C [2]. However, nowadays, instead of EC effect in thin films, the effect in bulk and the understanding of electrocaloric effect by theoretical insights have become cutting edge research [3][4][5]. Therefore, the investigation of EC effect in ferroelectric and antiferroelectric thin films is of high significance.Among the various antiferroelectric materials PbZrO 3 (PZ) is one of the most studied materials since 1951 [6]. Though the EC effect of PZ bulk ceramic was studied at 4.36 K [7], the temperature dependent EC effect of PZ thin films is hardly studied.According to Tuttle and Payne [8], the reversible adiabatic temperature change (Δ ) T in a material of density ρ and heat capacity C depends on the applied electric field, E, and the temperature dependent polarization at that particular E. Moreover, according to several reports [1,2,4], the assumption of Maxwell relation ( ) ( ) E T P T S E ∂ ∂ = ∂ ∂ describes the EC effect as follows:Recent reports by Mischenko et al. [1,2] have shown that for a ferroelectric material 1 0, E = whereas for an antiferroelectric material 1 E is such a lower limit that above 1 E the antiferroelectric regime can be avoided.In our present study, we have looked into the temperature dependent EC effect of PZ thin films deposited on Pt(111)/Ti/SiO 2 /Si substrate by sol-gel route. According to the earlier report on C of PZ, it has been noticed that there is a large heat capacity anomaly at the Curie point [9]. Hence, we have measured the heat capacity (C) of PZ by Differential Scanning Calorimetry (DSC) and incorporated the effect of temperature dependent C in the present investigation.The preparation method of PZ thin films and primary characterizations like XRD, thickness measurement and dielectric phase transition are similar to our earlier report Antiferroelectric PbZrO 3 thin films have been deposited on Pt(111)/Ti/SiO 2 /Si substrate by polymer modified sol -gel route. Temperature dependent P -E hysteresis loops have been measured at 51 MV/m within a temperature range of 40 °C to 330 °C. The maximum electro...
Highly (110) preferred orientated antiferroelectric PbZrO3 (PZ) and La-modified PZ thin films have been fabricated on Pt∕Ti∕SiO2∕Si substrates using sol-gel process. Dielectric properties, electric field induced ferroelectric polarization, and the temperature dependence of the dielectric response have been explored as a function of composition. The Tc has been observed to decrease by ∼ 17°C per 1mol% of La doping. Double hysteresis loops were seen with zero remnant polarization and with coercive fields in between 176 and 193kV∕cm at 80°C for antiferroelectric to ferroelectric phase transformation. These slim loops have been explained by the high orientation of the films along the polar direction of the antiparallel dipoles of a tetragonal primitive cell and by the strong electrostatic interaction between La ions and oxygen ions in an ABO3 perovskite unit cell. High quality films exhibited very low loss factor less than 0.015 at room temperature and pure PZ; 1 and 2mol% La doped PZs have shown the room temperature dielectric constant of 135, 219, and 142 at the frequency of 10kHz. The passive layer effects in these films have been explained by Curie constants and Curie temperatures. The ac conductivity and the corresponding Arrhenius plots have been shown and explained in terms of doping effect and electrode resistance.
Barium zirconium titanate [Ba(Zr0.05Ti0.95)O3, BZT] thin films were prepared by pulsed laser ablation technique and dc leakage current conduction behavior was extensively studied. The dc leakage behavior study is essential, as it leads to degradation of the data storage devices. The current-voltage (I-V) of the thin films showed an Ohmic behavior for the electric field strength lower than 7.5MV∕m. Nonlinearity in the current density-voltage (J-V) behavior has been observed at an electric field above 7.5MV∕m. Different conduction mechanisms have been thought to be responsible for the overall I-V characteristics of BZT thin films. The J-V behavior of BZT thin films was found to follow Lampert’s theory of space charge limited conduction similar to what is observed in an insulator with charge trapping moiety. The Ohmic and trap filled limited regions have been explicitly observed in the J-V curves, where the saturation prevailed after a voltage of 6.5V referring the onset of a trap-free square region. Two different activation energy values of 1.155 and 0.325eV corresponding to two different regions have been observed in the Arrhenius plot, which was attributed to two different types of trap levels present in the film, namely, deep and shallow traps.
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