In this study, lead-free Ba 0.85 Ca 0.15 Ti 0.95 (Nb 0.5 Yb 0.5 ) 0.05 O 3 (BC15TYN5) ceramic has been successfully obtained through the conventional solid-state reaction. It has been found the multifunctionality of the BC15TYN5 ceramic. It exhibits ferroelectric properties, with a significant remanent polarization value of about P r = 9.36 mu C/cm 2 , and a recoverable energy storage density value of about W rec = 42.21 mJ/cm 3 . Additionally, it displays a dielectric permittivity of about epsilon ' r = 7230 around T C = 80 degrees C, and an electro-caloric strength value of about xi = 0.12 K mm/kV. It ' s worth noting that these values surpass those typically found in BaTiO 3 ceramics elaborated with similar experimental conditions. Electrical study (impedance, modulus, and conductivity characteristics) is essential for characterizing the BC15TYN5 material, determining its suitability for various technological applications, and optimizing manufacturing processes. The Cole -Cole plots exhibited two relaxations associated with the contribution of the grains and grain boundaries. The relaxation times for both grains and grain boundaries showed temperature -dependent variation following Arrhenius relation. The measured AC conductivity was evaluated by applying the Jonsher power law. Based on the thermal evolution of the exponent S , it was confirmed that the conduction mechanism follows the Correlated Barrier Hopping (CBH) model. These properties make BC15TYN5 ceramic suitable for applications such as dielectric capacitors, ferroelectric random-access memories, electrical energy storage units, and electro-caloric refrigeration systems.

Environment-friendly Ba0.95Ca0.05Ti0.91Sn0.09-xZrxO3 ceramics, with x = 0.00 and 0.01 (BCTSZx) were prepared through a standard solid-state sintering process. The diffusion coefficient estimated from the Santos-Eiras fit of ε_r -T plot implies that the ferroelectric-paraelectric transition is a diffuse type. Well-saturated and fatigue resistant P-E hysteresis loops were obtained at room temperature (RT). The energy-storage density (Wrec) and the associated efficiency (η) were obtained from P-E loops data. When applying a relatively losw electric field of 30 kV/cm, a large value of adiabatic temperature change (∆T = 0.73 K), high values of electrocaloric responsivity (ξ = 0.247*10−6 K·m·V−1) and coefficient of performance (COP = 12.26) were obtained in BCTSZ ceramic. In addition, the pyroelectric figures of merit (FOMs) were calculated. The density of pyroelectric energy harvesting increased from 206 to 237 kJ/m3 when the Olsen cycle was operated at temperatures between 25 and 100 °C and an electric field between 0 and 30 kV/cm. The results indicate that the increase in the grain size significantly enhances the dielectric, electrocaloric and pyroelectric properties. This research not only presents a novel technique for generating high-performance ceramic for refrigeration devices, but also expands the field of applications for BaTiO3-based lead-free ferroelectrics for energy storage applications.

In this study, lead-free Ba0.85Ca0.15Ti0.95(Nb0.5Yb0.5)0.05O3 (BC15TYN5) ceramic has been successfully obtained through the conventional solid-state reaction. It has been found the multifunctionality of the BC15TYN5 ceramic. It exhibits ferroelectric properties, with a significant remanent polarization value of about Pr = 9.36 μC/cm2, and a recoverable energy storage density value of about Wrec = 42.21 mJ/cm3. Additionally, it displays a dielectric permittivity of about ε′r = 7230 around TC = 80 °C, and an electro-caloric strength value of about ξ = 0.12 K mm/kV. It's worth noting that these values surpass those typically found in BaTiO3 ceramics elaborated with similar experimental conditions. Electrical study (impedance, modulus, and conductivity characteristics) is essential for characterizing the BC15TYN5 material, determining its suitability for various technological applications, and optimizing manufacturing processes. The Cole-Cole plots exhibited two relaxations associated with the contribution of the grains and grain boundaries. The relaxation times for both grains and grain boundaries showed temperature-dependent variation following Arrhenius relation. The measured AC conductivity was evaluated by applying the Jonsher power law. Based on the thermal evolution of the exponent S, it was confirmed that the conduction mechanism follows the Correlated Barrier Hopping (CBH) model. These properties make BC15TYN5 ceramic suitable for applications such as dielectric capacitors, ferroelectric random-access memories, electrical energy storage units, and electro-caloric refrigeration systems.

In response to the growing interest in materials exhibiting magneto-dielectric coupling across diverse application domains, we present a detailed study on the electrical behavior of Ba0.1Bi0.9(Ti0.9Zr0.1)0.1Fe0.9O3 (BBTZF) ceramic. This study includes a comprehensive analysis of temperature- and frequency-dependent dielectric behavior, along with ac impedance properties. The thermo-dielectric study in the temperature range of 300–650 K suggests the presence of an anomaly near the Neel temperature (TN = 603 K), supporting the strong magneto-dielectric coupling in BBTZF. The differential thermal study also revealed an anomaly around TN, characterized by an exothermic peak. Furthermore, the well-described experimental dielectric data as a function of frequency (100 Hz–1 MHz), by the Cole–Cole relaxation equation modified by introducing complex conductivity, demonstrated a remarkable change in the frequency of relaxation (fr) as a function of temperature in the vicinity of TN. This change is attributed to the coupling between magnetic and electric order parameters. Through the complex impedance analysis recorded at different temperatures, it was found that both the capacitance and resistance of the grain showed a change in behavior around TN, suggesting that the magneto-electric coupling is predominantly of intrinsic origin in our material. Furthermore, the intrinsic magneto-capacitance grain value is approximately − 0.36

Correction for ‘Enhanced electrocaloric effect, energy storage density and pyroelectric response from a domain-engineered lead-free BaTi 0.91 Sn 0.08 Zr 0.01 O 3 ferroelectric ceramic’ by Hend Kacem et al. , RSC Adv. , 2022, 12 , 30771–30784, https://doi.org/10.1039/D2RA04914G.

We report the impact of dysprosium (Dy, with y = 0.01, 0.02, 0.05 and 0.08) substitution in (Na0.5 Bi0.5)0.94 Ba0.06TiO3 (NBT-6BT) lead-free ceramics. The structural, vibrational dielectric, ferroelectric and electrocaloric (EC) properties of all samples were systematically investigated. X-ray diffraction analysis revealed the coexistence of tetragonal (P4mm) and rhombohedral (R3c) structural phases at low content of Dy (y = 0.01, 0.02 and 0.05). The structural changes with the introduction of Dy were confirmed by Raman spectroscopy at room temperature. The evolution of the Raman spectra with temperature was found to be strongly correlated with the dielectric measurements. Higher stability of the ferroelectric (FE) phase was obtained at room temperature for the compositions y = 0.01, 0.02 and 0.05, with optimum values for y = 0.02 as remanent polarization Pr = 32µC/cm2, as well as piezoelectric coefficients d33 = 137 pC/N, kp = 0.27 and kt = 0.16, whereas a higher content of Dy (y = 0.08) induced a remarkable decrease of the ferroelectric and piezoelectric properties. Using the direct EC measurement, the ceramic corresponding to y = 0.02 exhibited a significant EC response, where ΔT = 1.2 K under 5 kV/mm. The incorporation of Dy was found to enhance the EC responsivity coefficient ζ = iT/ΔE), with a best value of ζ = 0.24 K.mm/kV for y = 0.02.

The present paper reports the effect of Yttrium substitution on the structural, microstructure, dielectric, ferroelectric, and electrocaloric (EC) properties of the lead-free (Na 0.5 Bi 0.5 ) 0.94 Ba 0.06 TiO 3 (abbreviated as NBT-6BT) ceramics. For a small quantity of Yttrium ( x = 0.01 and 0.05), the X-ray diffraction and Raman spectra exhibit the coexistence of rhombohedral and tetragonal phases at room temperature. However, with x = 0.08 composition, a structural change to pseudo-cubic phase was identified. By adding a small amount of Yttrium, the ferroelectric properties were improved by increasing the remnant polarization from ( P r = 27µC/cm 2 ) for x = 0 up to ( P r = 36µC/cm 2 ) for x = 0.01. This resulted in an improvement of 30% in the estimated ferroelectric parameters as well as an improvement in the piezoelectric properties, as measured by the value of d 33 of 130 pC/N. The electrocaloric temperature change (ΔT) is calculated by a direct method using Differential Scanning Calorimetry (DSC) to be at more than 1 K at 5 kV/mm for x = 0.01. Despite the minimal amount employed, our observations lead us to say that the introduction of Yttrium into the NBT-6BT ceramic has directly affected the properties of this material. Nevertheless, with a higher content of Yttrium ( x = 0.08), a sudden decrease of both ferroelectric and EC effect was observed. The declined properties at higher contents may originate from the structural change which can influence the polar distribution in the structure.

The lead-free $$\left( {{\text{Na}}_{0.5} {\text{Bi}}_{0.5} } \right)_{0.94} {\text{Ba}}_{0.06} {\text{TiO}}_{3}$$ (NBT–6BT) ceramics was fabricated at various sintering temperatures using a conventional solid-state reaction method. The effect of calcination temperature was systematically investigated on the structural properties. The XRD results show that the 850 °C is the best calcination temperature, where the NBT–6BT ceramic had the largest crystallite size with a dense sample, 96% of the theoretical value. However, the density decreased significantly with increasing the calcination temperature above 850 °C due to the secondary phase formation. On the other hand, the effect of sintering temperature was studied on the piezoelectric and ferroelectric properties evolutions. It is found that the optimal ferroelectric and piezoelectric values were obtained at 1150 °C (Pr = 27 µC/cm2, Ec = 3.89 kV/mm and d33 = 110 pC/N). According to these results, we suggest that 850 °C and 1150 °C can be considered as optimal calcination and sintering temperature in NBT–6BT ceramic, respectively.

A BaTi0.91Sn0.08Zr0.01O3 (BTSZ) ceramic was prepared by a conventional solid-state reaction method. Its structural, dielectric, ferroelectric, and pyroelectric properties were carefully studied. The Rietveld refinement was used to characterize the structural proprieties of the synthesized ceramic. The microstructure was observed by scanning electron microscopy. Phase transitions observed in the temperature dependent dielectric permittivity (epsilon(r)-T and tan delta-T) showed a transition close to room temperature, resulting in improved piezoelectric, pyroelectric and electrocaloric performance. In addition, it was found that an electric field poling process changed the character of epsilon(r)-T and tan delta-T plots. Resonance modes in the polarized state, where maximum power transmission was achieved, were observed in the impedance spectrum. The extra-slim hysteresis loops revealed a relatively low coercive field and hysteresis loss related to the diffuse phase transition, which can significantly improve energy storage efficiency up to 75% at 100 degrees C. To characterize the electrocaloric effect (ECE), indirect and direct methods based on the thermodynamic approach were used. Both methods results showed good consistency and revealed a large ECE peak evolving along the phase diagram. Furthermore, pyroelectric figures of merit (FOMs) for voltage responsivity (F-v), current responsivity (F-i), energy harvesting (F-E), new energy harvesting (F-e*) and detectivity (F-d) were calculated. Finally, thermal energy harvesting (N-D) was determined by using the Olsen cycle. The obtained maximum N-D was 233.7 kJ m(-3) when the Olsen cycle operated at 25-100 degrees C and 0-30 kV cm(-1). This study introduces not only a technique to produce a high performance ceramic for refrigeration devices, but also broadens the range of applications for BT-based lead-free ferroelectrics beyond actuators, sensors, and energy harvesting to solid-state cooling.

BaTiO3 (BT) ceramic has been prepared by the solid-state reaction method. The Rietveld refinement and the Raman spectroscopy have been employed to characterize the structural information of the BT ceramic based on the analysis of dielectric at room temperature (RT). Detailed microstructure has been observed by scanning electron microscopy. The dielectric properties of our ceramic have been investigated over wide frequency (10(2)-10(6) Hz) and temperature (-100-600 degrees C) ranges. At high temperature region (250-600 degrees C), a dielectric relaxation phenomenon has been observed. To better understand the physical mechanisms at high temperature, a macroscopic and phenomenological statistical model has been used. The calculated activation energy for relaxation and conduction was approximated to 1 eV. This suggests that relaxation in our studied sample at high temperature region is associated with the short-range hopping of ions. This is caused by oxygen vacancies in the bulk of the material. The BT ceramic demonstrated optimum electrical properties: epsilon(r) = 1105, tan delta = 0.079, T-C = 130 degrees C, epsilon(max) = 4050, P-max= 18.35 mu C/cm(2), Pr = 7.93 mu C/cm(2), E-C = 2.65 kV/cm, vertical bar Y vertical bar = 1.86*10(11) N/m(2), d(33) = 197 pC/N, kp = 14%, and Q(m) = 196. In addition, the evolution of energy storage performance with an increase in the applied electric field has been investigated. The energy storage efficiently has achieved 40 % at RT, under an electrical field of 30 kV/cm.

We reported the effect of Erbium (Er with x = 0.005, 0.01, 0.015, 0.02, 0.025 and 0.03)-substituted Ba0.8Ca0.2Ti0.975(Nb0.5Yb0.5)0.025O3 lead-free ceramics. Structural, dielectric, piezoelectric, ferroelectric and photoluminescence properties of all ceramics were systematically explored. At room temperature, X-ray diffraction (XRD) analysis showed that (Ba0.8Ca0.2)1-xEr2x/3 $$\square$$ x/3Ti0.975(Nb0.5Yb0.5)0.025O3 samples (Abbreviated as BCTYN-xEr) exhibited a pure tetragonal phase for x ≤ 0.025. However, the composition (x = 0.03) showed the formation of an additional phase. The vibrational study was found to correlate strongly with XRD analysis. The dielectric properties were improved in the composition x = 0.01, where the dielectric constant was increased from 5824 for x = 0 up to 6150 for x = 0.01. The composition (x = 0.005) revealed the optimum properties with a d33 piezoelectric coefficient of 88 pC/N, a kp planar electromechanical coupling factor of 16.9% and a Pr remanent polarization of 9.25 μC/cm2. The photoluminescence (PL) results showed, at 525 nm and 550 nm, two strong green bands. As multifunctional materials, BCTYN-xEr samples represent a great potential in the applications of mechanical–electro-optical coupling and integration devices.

The present paper reports the effect of Yttrium substitution on the structural, microstructure, dielectric, ferroelectric, and electrocaloric (EC) properties of the lead-free (Na0.5 Bi0.5)0.94 Ba0.06TiO3 (abbreviated as NBT-6BT) ceramics. For a small quantity of Yttrium (x = 0.01 and 0.05), the X-ray diffraction and Raman spectra exhibit the coexistence of rhombohedral and tetragonal phases at room temperature. However, with x = 0.08 composition, a structural change to pseudo-cubic phase was identified. By adding a small amount of Yttrium, the ferroelectric properties were improved by increasing the remnant polarization from (Pr = 27µC/cm2) for x = 0 up to (Pr = 36µC/cm2) for x = 0.01. This resulted in an improvement of 30% in the estimated ferroelectric parameters as well as an improvement in the piezoelectric properties, as measured by the value of d33 of 130 pC/N. The electrocaloric temperature change (ΔT) is calculated by a direct method using Differential Scanning Calorimetry (DSC) to be at more than 1 K at 5 kV/mm for x = 0.01. Despite the minimal amount employed, our observations lead us to say that the introduction of Yttrium into the NBT-6BT ceramic has directly affected the properties of this material. Nevertheless, with a higher content of Yttrium (x = 0.08), a sudden decrease of both ferroelectric and EC effect was observed. The declined properties at higher contents may originate from the structural change which can influence the polar distribution in the structure.

In this work, (Na0.5Bi0.5)(0.94)Ba0.06TiO3 ceramic doped with three lanthanides La3+, Gd3+, Ho3+ were prepared and investigated the corresponding structural, vibrational, ferroelectric and energy storage properties. The X-ray diffraction and Raman spectra reveal a pure perovskite with the coexistence of rhombohedral and tetragonal phases at room temperature for all samples. The thermal dependence of the dielectric constant shows a ferroelectric/antiferroelectric phase transition around Td, confirmed by the change in the shape of P-E hysteresis loops for all samples. We found that the optimal piezoelectric and ferroelectric properties were obtained in the ceramic doped with Ho-3+(.) Furthermore, the later sample revealed relatively remarkable features of energy storage density with temperature, reaching a maximum of 0.63 J/cm(3) around 100 degrees C. The results discussed in this work highlight the great potential of the doped NBT-6BT based lead-free ceramics.

Nowadays, much attention is paid for developing lead-free ceramics, which can be utilized in the refrigeration domain. This communication provides a detailed description of the synthesis and characterization of a lead-free solid solution of BaTi0.91Sn0.09O3. The X-ray diffraction analysis showed that the compound exhibits a single phase of tetragonal symmetry (P4mm (99)). The average crystallite size estimated using Scherrer's technique was found to be 122 nm. The microstructure or surface morphology of the sintered sample was investigated by using scanning electron microscopy. Based on mapping image, the sensitivity and spatial resolution of the different elements in our sample were improved. Analytical and simulation data for the electrocaloric effect in our sample were reported. A good electrocaloric strength (ξ = ΔT/ΔE) of ξ = 0.171 K mm/kV near the ferroelectric-paraelectric phase transition temperature was obtained. These values are very interesting when compared to those for other materials and show the possibility of using such lead-free ceramics for refrigeration domain.

Ferroelectric materials are used in a number of applications such as sensors, transducers and health monitoring systems. The multi-physical coupling ability possessed by these materials has been established to be useful for energy harvesting applications. Lead-free BaTi0.91Sn0.09O3 ceramic has been successfully synthesized by the conventional solid-state method. The structural information of our sample has been determined by combining the Rietveld refinement using X-ray diffraction data and the Raman spectra. Based on the dielectric properties, the ferroelectric behavior of relaxor has been observed. Permittivity data have been fitted based on empirical laws describing the diffuse phase transition in the relaxor. A saturated hysteresis loop has been obtained at room temperature. The variation of remnant polarization, maximum polarization and squareness of the hysteresis loop as a function of temperature are in good accordance with phase transition deduced from dielectric properties. Based on Arrhenius' law, the link between the temperature and the back-switching polarization is estimated in order to assess the average activation energy. Our sample has shown a recovered energy density equal to 48.18 mJ/cm(3) at 110 degrees C under an electric field of 30 kV/cm, with an energy efficiency of 41%. Furthermore, the properties of pyroelectric energy harvesting according to Olsen cycle have been studied. The maximum density of pyroelectric energy harvesting per cycle for our studied ceramic has been calculated. It was found to be 210 kJ/m(3) for an electric field of 0-30 kV/cm and in temperature ranging from 20 degrees to 120 degrees C. This result leads to the ability to use our sample for energy conversion applications. (C) 2021 Elsevier B.V. All rights reserved.

The (Ba0.97Ca0.03)(1-3y/2)BiyZr0.18Ti0.82O3 ceramic system was prepared by the conventional solid-state sintering technique. The effect of bismuth substitution has been investigated via X-ray diffraction, Scanning electron microscopy, dielectric, electric and ferroelectric measurements. X-ray diffraction showed that these compounds crystallized, at room temperature, in tetragonal P4mm space group symmetry for BCTZ10 and BCTZ10-0.02Bi compounds and in cubic symmetry with space group Pm (3) over barm for y = 0.06; 0.08 and 0.1 compositions distorted perovskite structures. SEM images were used to observe the microstructure. The effect of the crystal structure change and microstructure features on the dielectric and ferroelectric properties of our new BCTZ10-yBi ceramic system has been discussed. The dependence of the permittivity on temperature indicated a crossover from a normal ferroelectric, for both BCTZ10 and BCTZ10-0.02 ceramics, to a relaxor state for 0.06 < y <= 0.1 composition compounds. The enhancement of the dielectric properties was marked by the shift of T-m to room temperature, the increase of the maxim of permittivity and the improvement of the relaxor behavior that characterizes optimal composition due to Be3+ substitution. BCTZ10-0.06Bi ceramic exhibit the highest epsilon(rm)', with a value of 11508 at 1 kHz, at T-m of 270 k near room temperature. Both BCZT10 and BCZT-0.02Bi ceramics exhibit a hysteresis loops signature of ferroelectric behavior at room temperature. While doped BCZT-0.02Bi show just a non linear evolution of P vs. E, the increase of the spontaneous and remnant polarizations: Ps from 0.063 mu C/mm(2) to 0.073 mu C/mm(2) and P-r from 0.028 mu C/mm(2) to 0.040 mu C/mm(2) for BCZT10 and BCZT10-0.02Bi compositions, respectively, is an evidence of the enhancement of ferroelectric properties as a result of bismuth substitution on BCZT10. The electrical properties of our new BCTZ10-yBi ceramic system may be largely tunable and could be attractive for non-volatile random access memory devices.