Abstract:Oxygen-vacancy-related dielectric relaxations in SrTiO3 at high temperatures J. Appl. Phys. 113, 094103 (2013); 10.1063/1.4794349 Structure, magnetic and dielectric properties in Mn-substituted Sm1.5Sr0.5NiO4 ceramics J. Appl. Phys. 110, 064110 (2011); 10.1063/1.3639282Oxygen-vacancy-related dielectric relaxation in SrBi 2 Ta 1.8 V 0.2 O 9 ferroelectrics Quantum paraelectric SrTiO 3 has resulted in many investigations because of the anomalous properties. Here, using the conventional solid-state reaction method… Show more
“…For PLT20 and PLT32 ceramic, activation energies are about 1.73 and 1.75 eV respectively. For all compositions, values of activation energies are very close to OVs related high temperature dielectric relaxations in perovskite systems, such as: SrTiO 3
44 , (PbLa)(Zr 0.9 Ti 0.1 )O 3
45 , and (Pb,Cd,La)TiO 3 ceramics 42 .Figure 4Normalized imaginary parts Z ″ /Z ″ max of impedance as a function of frequencies for ( a ) PLT20, ( b ) PLT24, ( c ) PLT28 and ( d ) PLT32 ceramics.Figure 5ln ω versus 1000/T curves for PLT ceramics, straight lines are used to fit the Arrhenius law.
…”
The unique properties and great variety of relaxer ferroelectrics make them highly attractive in energy-storage and solid-state refrigeration technologies. In this work, lanthanum modified lead titanate ceramics are prepared and studied. The giant electrocaloric effect in lanthanum modified lead titanate ceramics is revealed for the first time. Large refrigeration efficiency (27.4) and high adiabatic temperature change (1.67 K) are achieved by indirect analysis. Direct measurements of electrocaloric effect show that reversible adiabatic temperature change is also about 1.67 K, which exceeds many electrocaloric effect values in current direct measured electrocaloric studies. Both theoretical calculated and direct measured electrocaloric effects are in good agreements in high temperatures. Temperature and electric field related energy storage properties are also analyzed, maximum energy-storage density and energy-storage efficiency are about 0.31 J/cm3 and 91.2%, respectively.
“…For PLT20 and PLT32 ceramic, activation energies are about 1.73 and 1.75 eV respectively. For all compositions, values of activation energies are very close to OVs related high temperature dielectric relaxations in perovskite systems, such as: SrTiO 3
44 , (PbLa)(Zr 0.9 Ti 0.1 )O 3
45 , and (Pb,Cd,La)TiO 3 ceramics 42 .Figure 4Normalized imaginary parts Z ″ /Z ″ max of impedance as a function of frequencies for ( a ) PLT20, ( b ) PLT24, ( c ) PLT28 and ( d ) PLT32 ceramics.Figure 5ln ω versus 1000/T curves for PLT ceramics, straight lines are used to fit the Arrhenius law.
…”
The unique properties and great variety of relaxer ferroelectrics make them highly attractive in energy-storage and solid-state refrigeration technologies. In this work, lanthanum modified lead titanate ceramics are prepared and studied. The giant electrocaloric effect in lanthanum modified lead titanate ceramics is revealed for the first time. Large refrigeration efficiency (27.4) and high adiabatic temperature change (1.67 K) are achieved by indirect analysis. Direct measurements of electrocaloric effect show that reversible adiabatic temperature change is also about 1.67 K, which exceeds many electrocaloric effect values in current direct measured electrocaloric studies. Both theoretical calculated and direct measured electrocaloric effects are in good agreements in high temperatures. Temperature and electric field related energy storage properties are also analyzed, maximum energy-storage density and energy-storage efficiency are about 0.31 J/cm3 and 91.2%, respectively.
“…reported that a large electro-shape-memory effect (up to 0.23% under the electric field of 5 kV/mm) in Mn-doped (Pb,Sr)TiO 3 ceramics10. SrTiO 3 is a quantum paraelectric and shows dielectric relaxation at high temperatures due to oxygen vacancies20212223. While in this work, both dielectric relaxations and pinning/depinning phenomenons were observed in (Sr,Pb)TiO 3 ceramics.…”
mentioning
confidence: 48%
“…Recently, the research about oxygen vacancies in materials has been done from theory and experiment451215213536373839404142. Li et al .…”
Section: Resultsmentioning
confidence: 99%
“…9. Annealing in oxygen can reduce oxygen vacancies21. When the concentration of oxygen vacancies is low, the restoring force from oxygen vacancies is insufficient to reverse the domain to original state, resulting in a slightly contractive loop.…”
The behavior of ferroelectric domain under applied electric field is very sensitive to point defects, which can lead to high temperature dielectric relaxation behaviors. In this work, the phases, dielectric properties and ferroelectric switching behavior of strontium lead titanate ceramics were investigated. The structural characterization is confirmed by X-ray diffraction. The high dielectric tunability and high figure of merit of ceramics, especially Sr0.7Pb0.3TiO3 (SPT), imply that SPT ceramics are promising materials for tunable capacitor applications. Oxygen vacancies induced dielectric relaxation phenomenon is observed. Pinched shape hysteresis loops appeared in low temperature, low electric field or high frequency, whereas these pinched hysteresis loops also can become normal by rising temperature, enhancing electric field or lowering frequency. The pinning and depinning effect can be ascribed to the interaction between oxygen vacancies and domain switching. A qualitative model and a quantitative model are used to explain this phenomenon. Besides, polarization and oxygen treated experiment can exert an enormous influence on pinning effect and the machanisms are also discussed in this work.
“…It is widely accepted that dielectric relaxation in oxide materials in high temperature region are usually related to OVs, and oxygen-vacancy-related dielectric relaxation appears typically in the low-frequency region. [22][23][24] Obviously, OVs are a key factor to understand many properties in the high temperature region, and understanding the dynamic mechanism of OVs is of vital importance. Previous work on PZT95/5 based materials mainly focused on depolarization mechanisms, 14 electrocaloric effect, 11 etc.…”
Failure behavior of Pb(Zr0.95Ti0.05)O3 ferroelectric ceramics under shock compression J. Appl. Phys. 113, 183501 (2013); 10.1063/1.4803052 Room-temperature magnetoelectric properties of Fe doped BaZr0.05Ti0.95O3 J. Appl. Phys. 113, 17D918 (2013); 10.1063/1.4795425Thermal stability of piezoelectric coefficients in (Ba1−xCax)(Zr0.05Ti0.95)O3: A lead-free piezoelectric ceramic Appl.(Pb 1-x Ba x )(Zr 0.95 Ti 0.05 )O 3 (x=0, 0.025, 0.05, 0.075 and 0.1) ceramics were prepared via a solid-state reaction route. Low-frequency (20 ∼ 2×10 7 Hz) dielectric properties were investigated in the temperature region of 25-650 • C. Ba 2+ doping can slightly reduce the phase transition temperature of ferroelectric to paraelectric. The dielectric diffuse anomaly in the dielectric relaxation was found in the high temperature region of 400-650 • C. Activation energy, calculated from the impedance and conductivity data of samples, suggests that the dielectric relaxation is due to oxygen vacancies generated during the sintering process. Ba 2+ doping can reduce significantly the concentration of oxygen vacancies, and slightly enhance activation energy for the migration of oxygen vacancies. Results of activation energy calculated from impedance and conductance suggest that the dielectric relaxation is due to the short-range hopping of oxygen vacancies, and the conduction due to the movement of doubly-ionized oxygen vacancies. C 2014 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License. [http://dx.
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