Evidence for Antiferroelectric Behavior in KNbO3/KTaO3 Superlattices

2002 ◽  
Vol 720 ◽  
Author(s):  
J. Sigman ◽  
H. M. Christen ◽  
P. H. Fleming ◽  
L. A. Boatner ◽  
D. P. Norton
Keyword(s):  
Phase Transition ◽  
Dielectric Constant ◽  
Temperature Region ◽  
Dielectric Response ◽  
Nonlinear Response ◽  
Structural Phase ◽  
Dielectric Behavior ◽  
Ferroelectric Materials ◽  
Dc Bias ◽  
Superlattice Structures

AbstractThe dielectric response in artificially layered 1x1 KTaO3/KNbO3 perovskite superlattice structures is reported. While KTaO3 and KNbO3 are ferroelectric or paraelectric, respectively, superlattices appear antiferroelectric based on an increase in dielectric constant with applied dc bias. This “positive tunability” in dielectric response occurs at the same temperature region where a structural phase transition is observed. This dielectric behavior is inconsistent with the nonlinear response for either paraelectric or ferroelectric materials. However, an increase in the dielectric constant with applied electric field is consistent with antiferroelectric behavior. The antiferroelectric ordering correlates with cation modulation imposed by the superlattice.

Dielectric Properties of Pulsed Excimer Laser Ablated BaBi2Nb2O9 Thin Films

2002 ◽  
Vol 748 ◽  
Author(s):  
Apurba Laha ◽  
S. B. Krupanidhi ◽  
S. Saha
Keyword(s):  
Thin Films ◽  
Phase Transition ◽  
Dielectric Constant ◽  
Temperature Dependence ◽  
Loss Tangent ◽  
Dielectric Response ◽  
Room Temperature ◽  
Dielectric Constant And Loss ◽  
Wide Range ◽  
Room Temperature Dielectric Constant

ABSTRACTThe dielectric response of BaBi2Nb2O9 (BBN) thin films has been studied as a function of frequency over a wide range of temperatures. Both dielectric constant and loss tangent of BBN thin films showed a ‘power law’ dependence with frequency, which was analyzed using the Jonscher's universal dielectric response model. Theoretical fits were utilized to compare the experimental results and also to estimate the value of temperature dependence parameters such as n(T) and a(T) used in the Jonscher's model. The room temperature dielectric constant (ε') of the BBN thin films was 214 with a loss tangent (tanδ) of 0.04 at a frequency of 100 kHz. The films exhibited the second order dielectric phase transition from ferroelectric to paraelectric state at a temperature of 220 °C. The nature of phase transition was confirmed from the temperature dependence of dielectric constant and sponteneous polarization,respectively. The calculated Currie constant for BBN thin films was 4 × 105°C.

The cation-dependent structural phase transition and dielectric response in a family of cyano-bridged perovskite-like coordination polymers

2016 ◽  
Vol 45 (10) ◽  
pp. 4224-4229 ◽  
Author(s):  
Wei-Jian Xu ◽  
Shao-Li Chen ◽  
Zhi-Tao Hu ◽  
Rui-Biao Lin ◽  
Yu-Jun Su ◽  
...  
Keyword(s):  
Phase Transition ◽  
Structural Phase Transition ◽  
Coordination Polymers ◽  
Dielectric Response ◽  
Structural Phase

The cation-dependent phase transition and the relevant dielectric response were demonstrated in a family of cyano-bridged perovskite-like coordination polymers, [(CH3)nNH4−n]2[KFe(CN)6] (n = 1–4).

scholarly journals Dielectric behavior and phase transition in [111]-oriented PIN–PMN–PT single crystals under dc bias

2014 ◽  
Vol 04 (01) ◽  
pp. 1450004 ◽  
Author(s):  
Yuhui Wan ◽  
Zhenrong Li ◽  
Ming Ma ◽  
Fei Li ◽  
Zhuo Xu ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Single Crystals ◽  
Phase Region ◽  
Dielectric Behavior ◽  
Temperature Decrease ◽  
Dielectric Measurements ◽  
Phase Transition Temperatures ◽  
Dc Bias ◽  
Lower Temperature

Temperature and electric field dependences of the dielectric behavior and phase transition for [111]-oriented 0.23PIN–0.52PMN–0.25PT (PIN-PMN–0.25PT) and 0.24PIN–0.43PMN–0.33PT (PIN–PMN–0.33PT) single crystals were investigated over a temperature range from -100°C to 250°C using field-heating (FH) dielectric measurements. The transition phenomenon from ferroelectric microdomain to macrodomain was found in rhombohedra (R) phase region in the single crystals under dc bias. This transition temperature Tf of micro-to-macrodomain is sensitive to dc bias and move quickly to lower temperature with increasing dc bias. The phase transition temperatures in the two single crystals shift toward high temperature and the dielectric permittivities at the phase transition temperature decrease with increasing dc bias. Especially, the phase transition peaks are gradually broad in PIN–PMN–0.33PT single crystal with the increasing dc bias. Effects of dc bias on the dielectric behavior and phase transition in PIN–PMN–PT single crystals are discussed.

Rock/water interaction in dielectric properties: Experiments with hydrophobic sandstones

Geophysics ◽  
1995 ◽  
Vol 60 (2) ◽  
pp. 431-436 ◽  
Author(s):  
Rosemary Knight ◽  
Ana Abad
Keyword(s):  
Dielectric Constant ◽  
Dielectric Response ◽  
Water Saturation ◽  
Dielectric Behavior ◽  
Partially Saturated ◽  
Water Interaction ◽  
Water Wetting ◽  
Rock Water Interaction ◽  
Air System ◽  
Air Mixing

The dielectric constant of a partially saturated sandstone varies as a function of the level of water saturation. Experimental data indicate that rock/water interaction, at low saturations, has a large effect on the measured dielectric response. To theoretically predict the dielectric constant of the rock/water/air system, this rock/water interaction must be accounted for by including the effect of the water wetting the rock solid. Alternatively, if the rock/water interaction can be eliminated, a three‐component (dry rock, water, and air) mixing law can be used to model the dielectric behavior. In this laboratory study, a chemical treatment is used to change four water‐wet sandstones into hydrophobic sandstones. In three hydrophobic samples the rock/water interaction, seen in the data for the water‐wet samples, is eliminated and the dielectric constant of the partially saturated sandstones can be simply modeled as a dry rock/water/air system. This experimental study illustrates the importance of the chemical state of the rock surfaces in determining the dielectric behavior of sandstones.

scholarly journals The Study of Dielectric Behavior and Phase Transition of Mixed Compound of Lead Tantalate Sintered with Silver Oxide with Temperature Variation

2021 ◽  
Vol 04 (06) ◽  
Author(s):  
Shri Prakash Dubey ◽  
Keyword(s):  
Phase Transition ◽  
Dielectric Constant ◽  
Temperature Variation ◽  
Smart Materials ◽  
Silver Oxide ◽  
Dielectric Behavior ◽  
Heating Cycle ◽  
Cooling Cycle ◽  
Bridge Model ◽  
Mixed Compound

The dielectric constant of mixed compound of Lead Tantalate(PbTa2O6) sintered with Silver oxide has been measured between the temperatures 40°C to 300°C using the capacitance bridge model ZENITH M 92A at the frequency of 1000 Hz. During the measurement, it is found that the properly annealed sample have three peaks at the temperature 90°C (ε = 1000), 220°C (ε =800) and 230°C (ε = 623) respectively and a high peak at the temperature of 130°C (ε = 1600) in the heating cycle curve with some intermediate fluctuations. When the variation of dielectric constant was studied in cooling cycle the peak was observed at 240ºC, above and below this temperature, dielectric constant decreases with some intermediate fluctuations showing shows a first order phase transition. The variation in heating cycle is explained on the basis of activated polarization process. When the behavior of compound is studied in cooling cycle, then pronounced hysteresis is found with certain intermediate fluctuations. The cooling cycle curve does not follow heating curve because of the temperature relaxation of the compound. The occurrence of peak at the Curie temperature is explained by the latent heat type properties of the mixed compound. The temperature variation of the mixed compound suggests for its valuable applications as active and smart materials and its applications in the ceramics.

The Influence of DC Bias on the Dielectric Response of Sr1-xCaxTiO3 Ceramics

2006 ◽  
Vol 514-516 ◽  
pp. 240-244
Author(s):  
Alexander Tkach ◽  
Branca Araújo ◽  
Paula M. Vilarinho
Keyword(s):  
Dielectric Constant ◽  
Electric Field ◽  
Dielectric Response ◽  
Lattice Parameter ◽  
X Ray Diffraction ◽  
Average Grain Size ◽  
Electron Microscopy Analysis ◽  
Microscopy Analysis ◽  
Dc Bias ◽  
Microstructural Studies

The effect of the electric field on the dielectric response of the Sr1-xCaxTiO3 ceramic system was analysed and complemented by structural and microstructural studies. A monotonic decrease of the lattice parameter and an increase of the average grain size from 11 to 23 μm with increasing x were observed by X-ray diffraction and scanning electron microscopy analysis respectively. Samples with x = 0.003 and 0.01 reveal a monotonous increase of low-temperature dielectric constant, corresponding to an enhancement of the tunability and a reduction of the driving electric field at 10-30 K for x = 0.01. For Sr1-xCaxTiO3 ceramic samples with x = 0.04 and 0.10 the ferroelectric phase transition of around 20 K was observed together with the enhanced tunability of the dielectric constant at 30-85 K for x = 0.10.

The High DC Electric Field Effects on the Dielectric Behavior of Barium Strontium Titanate Ceramics

2013 ◽  
Vol 547 ◽  
pp. 125-132
Author(s):  
Qi Wei Zhang ◽  
Ji Wei Zhai ◽  
Xi Yao
Keyword(s):  
Phase Transition ◽  
Dielectric Constant ◽  
Electric Field ◽  
Paraelectric Phase ◽  
Dielectric Behavior ◽  
Solid State Reactions ◽  
Electric Field Effects ◽  
Temperature Dependences ◽  
Dc Electric Field ◽  
Titanate Ceramics

BaxSr1-xTiO3 (x=0.4, 0.5, 0.6) ceramics were fabricated by the conventional solid-state reactions method. The temperature dependences of the dielectric constant and tunability were investigated under high DC electric field. It was found that the change of dielectric constant and tunability under the applied electric field were closely related to ferroelectric phase, phase transition region and paraelectric phase states. The Curie temperature (Tc) was gradually shifted to higher temperature and were broadened and depressed with increasing of DC electric field. The tunability dependence of temperature exhibits different trends in a wide temperature range and reaches a maximum value near the ferroelectric-paraelectric phase transition. These results may be helpful in understanding the mechanism of dielectric response under higher electric field.

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