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The current study demonstrates the effect of Ni-substitution on the structural, dielectric and ferroelectric properties of Ba0.90Sr0.10Ti1-xNixO3 (where x = 0.000, 0.005, 0.015 and 0.025) ceramics, synthesized by solid-state reaction approach. A pure perovskite phase with tetragonal structure has been confirmed by X-ray diffraction (XRD) analysis. Scanning electron microscope (SEM) images revealed change in microstructure. The dielectric behavior of the prepared ceramics was investigated as a function of temperature (30–150°C) at different frequencies. The results indicate that there is an increase in dielectric constant (ϵRT) and low dielectric loss (tanδRT) were obtained at room temperature by substitution of Ni2+ ions in BST ceramics, offering a promising material for capacitor applications at room temperature. Room temperature P-E loops were recorded at different applied electric fields and typical hysteresis loops were obtained. Improvement in the values of Pr and Pmax was observed by substitution of Ni2+ ions. [ABSTRACT FROM AUTHOR]

Polycrystalline ceramic samples with compositional formula Ba(1-x)PbxTi(1-x) ZrxO3 (x = 0, 0.05, 0.075, 0.10, 0.15, 0.20) were prepared by the conventional solid-state reaction route (SSR). All the samples were sintered at 1300°C for 4 h in closed high-density alumina crucibles with the lead-rich environment. Sintered samples were subjected to X-ray diffraction (XRD) analysis and scanning electron microscope (SEM) for structural analysis. XRD analysis confirmed tetragonal to orthorhombic phase transition for samples with x ≥ 0.10. The relative permittivity and loss were measured as a function of temperature at 1, 10, 100 and 1000 kHz frequencies. The value of relative permittivity at room temperature was found to be increased with an increase in x. PE hysteresis loops were recorded for all the samples (at 30°C and 50 Hz). It was found that the sample with x = 0.05 shows the maximum value of remanent polarization 'Pr' = 18.51 µC/cm2. [ABSTRACT FROM AUTHOR]

The effect of simultaneous substitution of La3+ and Fe3+ ions on structural, dielectric, ferroelectric and piezoelectric properties of BaTiO3 was studied. Polycrystalline ceramic samples with composition Ba1-xLaxTi1-xFexO3 with x = 0, 0.005, 0.015 and 0.020 were prepared by the solid-state route and sintered at 1325°C. X-ray diffraction (XRD) analysis confirmed the single phase with tetragonal perovskite structure in all the prepared ceramics. Dielectric constant 'ϵ' and tangent loss 'tanδ' was measured as a function of temperature (25–200°C). The value of ϵ increases with an increase in La and Fe contents. A very small value of tanδ (<4%) was observed. The temperature coefficient of capacitance 'Tcc' was found to be around 10% for all the samples. PE hysteresis loops were recorded at room temperature for all samples. The maximum value of ϵ and piezoelectric coefficient 'd33' was found to be 3735 (at 30°C, 100 kHz) and 140pC/N, respectively for x = 0.020. [ABSTRACT FROM AUTHOR]

High-density polycrystalline ferroelectric ceramics having compositional formula Ba0.70Ca0.30Ti1−xFexO3, BCTF (with x = 0.000, 0.010 and 0.015) were prepared by solid-state reaction route. The samples were sintered at 1325 °C for 4 h. The samples were investigated for structural, dielectric, ferroelectric and magnetic properties. Raman and X-ray diffraction analysis confirms the tetragonal phase in all the samples. It can be observed from the dielectric versus temperature curves that all the prepared compositions showed a diffused phase transition. The Curie temperature was observed to be decreasing from 93 °C to 72 °C with the increase in Fe content. PE hysteresis loops were recorded at different electric fields. Pinched hysteresis loops were observed for all the samples, wherein, the pinching increased with the increase in Fe content. The energy density 'Ed' and efficiency 'η' were calculated from the PE loops. A high value of Ed = 0.15 J/cm3 with an efficiency of 67% was observed for the sample with x = 0.015 at 35 kV/cm. MH hysteresis loops were recorded at room temperature for all the prepared samples. The simultaneous observations of PE and MH hysteresis loops confirm the multiferroicity in the prepared samples. [ABSTRACT FROM AUTHOR]

Highlights: [•] BPZT ceramics were prepared by normal and two-stage sintering technology. [•] Comparative study of impedance of BPZT was done. [•] Enhancement in the grain and grain boundary resistivity is observed. [Copyright &y& Elsevier]

Highlights: [•] Maximum relative density (95.64%) and Pr (52μC/cm2) can be observed for x =0.02. [•] P r/P s ratio indicating squareness of the PE loop found to be maximum for x =0.015. [•] P r/P s =0.83 is not reported in the literature for the PZT ceramics. [Copyright &y& Elsevier]

Zirconium substituted strontium modified barium titanate ceramics with compositional formula Ba0.9Sr0.1Ti1-xZrxTiO3 (0 ≤ x ≤ 0.16 in steps of 0.04) were prepared by the solid state reaction route. Effects of substitution of Zr4+ on the physical and ferroelectric properties were studied. Decrease in relative density with increase in Zr content was observed. Ceramic sample with 4 mol% Zr showed maximum remnant polarization (11.5 μC/cm2) and coercive field (3.2 kV/cm). Microstructural information collected from scanning electron microscopy (SEM) was found helpful to explain ferroelectric properties. [ABSTRACT FROM AUTHOR]

Due to its important applications, there has been a great deal of interest in the fabrication as well as in the electrical and ferroelectric properties of barium titanate (BT)-based ceramics. The dielectric and ferroelectric properties of BT depends on the fabrication techniques and compositional modifications. In conventional solid state reaction technique, the main problem in fabrication of ceramics includes contamination from the tearing and wearing of balls and walls of the milling container, time and power consumption. Various attempts has been made in reducing the time and power consumption. Ultrasonic mixing of raw materials to prepare desired material is a method to reduce contamination and time & power consumption. X-ray diffraction confirms the existence of single phase. Comparative study of the dielectric properties shows the better stability of dielectric constant with frequency and temperature in case of barium titanate prepared using ultrasonically mixing. [ABSTRACT FROM AUTHOR]

Abstract: Barium titanate is one of the most studied ferroelectric materials which has been used in various forms, e.g. bulk, thin and thick films, powder, in a number of applications. In order to achieve a material with desired properties, it is modified with suitable substituents. Most common substituents have been strontium, calcium and zirconium. Here, we report studies on lead and zirconium substituted barium titanate. The material series with compositional formula Ba0.80Pb0.20Ti1−x Zr x O3, with x varying from 0 to 0.1, was chosen for investigations. The material was synthesized by solid-state reaction method. Reacted powders compacted in the form of circular discs were sintered at 1300°C. All the samples were subjected to X-ray diffraction (XRD) analysis and found to have single phase perovskite structure. Dielectric behavior was studied as a function of frequency and temperature. Curie temperature (T c) was found to decrease with increasing x. [Copyright &y& Elsevier]

In this paper we report samarium substituted Ba0.80Pb0.20Ti0.90Zr0.10O3 (BPZT) ceramics. The material series with compositional formula Ba0.80-xSmxPb0.20Ti0.90Zr0.10O3 with x varying from 0 to 0.01 in the steps of 0.0025 was chosen for investigations. The material was synthesized by solid state reaction method. Reacted powders compacted in the form of circular discs were sintered at 1325°C. All the samples were subjected to X-ray analysis and found to be single phase. Dielectric behavior was studied as a function of frequency and temperature and Curie temperature (Tc) was determined. Tc was found to decrease with increasing x. The details are discussed and presented here. [ABSTRACT FROM AUTHOR]

Polycrystalline ceramic samples with compositional formula Ba 0 · 90 Sr 0 · 10 Ti 1-3x/4 Fe x O 3 (x = 0, 0.01 and 0.015) 'BTSF' were prepared by the conventional solid state reaction method. The phase confirmation was done by using X-ray diffraction 'XRD' technique. Tetragonality 'c/a' was found to be decreased with Fe3+ substitution. Dielectric constant 'ε' and tangent loss 'tanδ' was measured as a function of temperature at different frequencies (1, 10, 40, 80 and 100 kHz). The value of ε and tanδ at 30 °C for BTSF0 sample was found to be 2300 and 4.5% (at 100 kHz), whereas for BTSF2 sample it was 3170 and 2.3% (at 100 kHz). The dielectric results indicate the prepared samples can be the potential candidates for capacitive applications. The P-E hysteresis loops for all samples were recorded at different temperature. The remnant polarization 'P r ' and coercive field 'E c ' was found to be decreased with an increase in temperature for all the samples. Electrocaloric effect 'ECE' was observed in BTSF2 sample. The value of ΔT max was found to be 1.06 K at 25 kV/cm, and the value of the electrocaloric coefficient § max was found to be 0.0424 K cm kV−1. The high value of § max implies that BTSF2 ceramics can be used in potential applications like future solid-state refrigeration technologies. • Tetragonality of BST ceramics decreases with increase in Fe-content. • Dielectric constant and tangent loss improves with an increase in Fe-content. • A large value of adiabatic ΔT = 1.06 K was observed in BTSF2 sample. • The electrocaloric strength is very large (0. 0424 K cm kV-1) in BTSF2 sample. [ABSTRACT FROM AUTHOR]

Polycrystalline ferroelectric ceramics with compositional formula Pb (1-1.5x) Sm x Zr 0.588 Ti 0.392 Fe 0.01 Nb 0.01 O 3 'PSZTFN', with x = 0.02 in steps of 0.005 were prepared by the conventional solid state route. The prepared samples were investigated for their structural, dielectric and ferroelectric properties. A direct relation was noticed between grain size and maximum dielectric constant 'ε max '. Remnant polarization 'P r ' to saturation polarization 'P s ' ratio 'P r /P s ' as recorded from the P-E hysteresis loops was found to be improved. The maximum value of the P r /P s ratio and P r was 0.877 and 47.41 μC/cm2, respectively, for 2% of Sm3+ content. The maximum value of piezoelectric coefficient 'd 33 ' is 356 for 2% of Sm3+ content. The enhancement in the P r and remnant to polarization ratio suggests that the prepared materials are suitable for memory applications. Image 1 • The maximum value of the P r /P s ratio is 0.877 for 2% of Sm3+ content. • The maximum value of the P r is 47.41 μC/cm2 for 2% of Sm3+ content. • The prepared materials can be suitable for memory applications. [ABSTRACT FROM AUTHOR]

In this study, we investigated the impact of Chromium substitution on the structural, dielectric and ferroelectric characteristics of Ba 0·90 Sr 0·10 Ti 1-3x/4 Cr x O 3 (x = 0, 0.005, 0.010, 0.015 and 0.020) ceramics fabricated by solid state reaction method. Rietveld refinement of X-ray diffraction pattern confirmed tetragonal perovskite structure for all the samples. Based on the crystal structure and the lattice parameter obtained through XRD measurement, the Madelung energy of each sample was computed. SEM images revealed a reduction in grain size with rising Cr concentration. TEM, HRTEM, SAED and EDS analysis was carried out for BST-Cr3 sample. Diffused rings observed in Selective Area Electron Diffraction (SAED) patterns indicate the crystallinity of the sample. EDS analysis indicated the presence of Ba, Sr, Ti, O and Cr elements. In the temperature range of 30 °C–150 °C, dielectric measurements (dielectric constant 'ε' and tangent loss 'tanδ') have been made at different frequencies (1, 10, 50, 100 and 1000 kHz). The samples displayed a diffused phase transition, with noticeable reduction in Curie temperature 'T c ' and tangent loss 'tanδ' with the substitution of Cr. Polarization versus electric field loops were recorded at different electric fields (5, 10, 15, 20 and 25 kV/cm) and improved values of remnant polarization 'P r ' and coercive field 'E c ' were observed. A lower E c value facilitates easier domain movement within the unit cell, leading to enhanced ferroelectric properties. Temperature dependent P-E loops indicated that as the temperature increased, the material became softer accompanied by simultaneous reduction in P r and E c values. [ABSTRACT FROM AUTHOR]

A comparative study is reported on the ferroelectric ceramics with compostional formula Ba 0 · 98 La 0 · 02 Ti 0 · 98 Fe 0 · 02 O 3 (BLTF1) and Ba 0 · 97 La 0 · 02 Ti 0 · 98 Fe 0 · 02 O 3 (BLTF2; valency compensated). The samples were prepared by solid state route and sintered in air at 1325 °C for 4 h. The X-ray diffraction analysis confirmed the formation of tetragonal perovskite phase. The prepared samples were characterized for their dielectric and ferroelectric properties at different temperatures at 1, 5, 10 and 100 kHz. Enhancement in ferroelectric properties (P r = 11.25 μC/cm2, E c = 9.05 kV/cm) was observed in BLTF2 ceramics as compared to BLTF1 ceramics (P r = 6.53 μC/cm2, E c = 9.35 kV/cm) along with the observation of electrocaloric effect. The value of piezoelectric coefficient 'd 33 ' was found to be 140 pC/N and 163 pC/N for BLTF1 and BLTF2 samples respectively. The present investigations show that the valency compensation method can improve the ferroelectric properties of the ferroelectric ceramics thereby making them more suitable for different applications. [ABSTRACT FROM AUTHOR]

A comparative study on the influence of different 3d transition metal ions (Cr3+, Fe3+ and Ni2+) on the structural, dielectric, ferroelectric and electrocaloric response of BST ceramics is reported in the present work. Conventional solid-state reaction method was adopted for preparing the samples. A pure perovskite phase with tetragonal structure was confirmed by X-ray diffraction (XRD) analysis. Tetragonality was found to be decreased with the substitution of transition metal ions except in Cr3+ substituted sample. The dielectric behavior was investigated as a function of temperature (30 °C–150 °C) at different frequencies. Dielectric constant (ε) data was fitted with Power Law above T c and diffused phase behavior was observed in the samples. P-E loops were recorded at different applied electric fields and temperatures. Improvement in ferroelectric properties (P r = 10.56 μC/cm2, E c = 2.40 kV/cm and P r/ P max = 0.53) was observed for Cr-substituted sample. Indirect method based on Maxwell's entropy-polarization relationship was employed to evaluate the electrocaloric effect (ECE) for all the samples. The value of ΔT max was found to be maximum for (1.113K) for Cr substituted samples. The results show that Cr substituted BST are suitable for use in capacitor, memory devices and new generation solid-state cooling devices. [ABSTRACT FROM AUTHOR]

Lead free polycrystalline (1-x)BZT-xBSCT ceramics with x = 0.45, 0.50 and 0.55 were prepared by solid state reaction method. The samples were sintered at 1325 °C. XRD analysis confirms the perovskite structure in all the samples. The average grain size of ceramics decreases from 7.38 to 5.36 μm with the increase in the BSCT content. A maximum value of ε equal to 5715 at room temperature was found for sample with x = 0.50 and all the samples show diffused phase transition. PE loops were recorded at different temperatures to understand the ferroelectric nature. The polarization extension mechanism was found in sample with x = 0.50 through Arrott curves. The results show that the properties in solid solution of Sm3+ modified BCT ceramics with BZT, which makes the prepared ceramics as the potential candidates for several applications. • Lead free Sm3+ modified (1-x)BZT-xBSCT ceramics with x = 0.45, 0.50 and 0.55 were prepared by solid state reaction route. • Dielectric and ferroelectric properties near Morphotropic phase boundary 'MPB' in Sm3+ Modified BZT-BCT Ceramics. • Power law described the diffusiveness of phase transition in paraelectric phase. • The values of Power law fitted parameter γ at 10 kHz lie between 1.85 to 1.92, which shows a high degree diffused phase transitions. • Maximum value of room temperature dielectric constant (ε = 5715) was found for sample with x = 0.50. • Arrott curves between "P2 vs E/P" confirms the polarization extension mechanism in sample with x = 0.50. [ABSTRACT FROM AUTHOR]

• Fe3+ modification was done in BZT-BCT ceramics near MPB. • Diffused phase transition can be observed for all the samples. • The maximum value of ε was found to be 16,000 (at 30 °C, 100 kHz) for x = 0.45. • Maximum value of energy density efficiency was found to be 86% at 20 kV/cm for x = 0.50. Ceramic samples with compositional formula (1-x)BaTi 0.80 Zr 0.20 O 3 -xBa 0.70 Ca 0.30 Ti 0.99 Fe 0.01 O 3 with x = 0.45, 0.50 and 0.55 were prepared by conventional solid state reaction method. The structural analyses were done by X-ray diffraction and Scanning Electron Microscopy. A high value of dielectric constant at room temperature was found for all the samples. PE hysteresis loops were recorded and energy storage efficiency was determined for all the samples. The value of η was found to be around 80% at a small electric field of 20 kV/cm. The results show significant improvement in the properties of the prepared ceramics. [ABSTRACT FROM AUTHOR]

• Temperature coefficient (Tcc) is above 10%. • The value of tanδ is very small all over the temperature range. • The tetragonality decreases with Sm3+ and Fe3+ substitution. • Room temperature dielectric constant increases. Polycrystalline ferroelectric ceramics with compositional formula Ba 0.70−x Ca 0.30 Sm x Ti 1−x Fe x O 3 (BCSTF) with (0, 0.005, 0.010, 0.015 and 0.020) were prepared by solid state reaction route and sintered at 1325 °C for 4 h. Single perovskite phase with tetragonal structure was confirmed from X-ray diffraction (XRD) analysis. The dielectric constant 'ε' and tangent loss 'tanδ' were studied for all the samples as a function of frequency (100 Hz to 100 kHz) and temperature (30–200 °C). A very small low 'tanδ' (0.9% at 100 kHz) was observed. The high value of temperature coefficient of capacitance 'Tcc' (~10%) was observed for all the BCSTF samples. P-E hysteresis loops were recorded for sample with x = 0.020 at different temperature. Electrocaloric effect 'ECE' was investigated and the temperature change 'ΔT' was found to be 0.53 K at 35 kV/cm with a high value of electrocaloric coefficient (0.15 K m/MV). The results show that the prepared ceramics can be useful in applications such as capacitor, dielectric bolometers, electrocaloric applications. [ABSTRACT FROM AUTHOR]