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We report the effect of partial substitution of Dy3+ rare earth ion in NBT-BT lead free ceramics on its structural, microstructural, ferroelectric and dielectric phase transitions. The Rietveld refined X-ray diffraction analysis revealed a coexistence of dual phase with major monoclinic (Cc) along with minor tetragonal (P4mm) in all Dy-NBT-BT ceramics. The T-dependent dielectric broad band spectroscopic study revealed that Dy-substituted NBT-BT ceramics exhibits two diffuse dielectric anomalies renowned as Ferro (FE) to anti Ferro (AFE) i.e., depolarization phase transition ( $$T_{d}$$ ) and Antiferro (AFE) to paraelectric (PE) i.e., curie phase transition ( $$T_{C}$$ ), below 150 °C and well above 300 °C temperature regions respectively. The complex frequency dependent dielectric and modulus spectroscopy analysis supports the Non-Debye type dielectric relaxation process was dominated for all the measured ceramics. T-dependent AC-conductivity study revealed, thermally activated charge carries and single ionized oxygen vacancies are found to contribute conduction process at different temperature regions. Room temperature polarization hysteresis (P–E) loops analysis exposed a slim asymmetric shape with Dy substitution increasing that indicates conversion of hard to soft ferroelectric character. Remnant polarisation ( $$P_{r}$$ ) and coercive field ( $$E_{c}$$ ) decreases with dopant concentration shows the tetragonality dominance with Dy substitution. Furthermore, an optimum recoverable energy density 1.477 J/cm3 was obtained in NBT-BT at Dy = 0.03 compositions that designate the materials could be useful for future high energy storage density applications.

The microstructure, dielectric and piezoelectric properties of Zr doped BaTiO3 ceramics sintered at optimum temperature, are investigated. High energy ball milling technique is adopted to realize nano-sized powders of Ba(Zr0.15Ti0.85)O3 ceramics. Increased boundary mobility of fine powders aided to obtain a relative density of >98.8% of theoretical density corresponding to ceramics under study. Internal stresses in these ceramics are found to be relieved by grain-boundary sliding. The Ba(Zr0.15Ti0.85)O3 ceramics synthesized at relatively low sintering temperatures exhibit remarkable, enhanced dielectric properties viz. improved polarization, high unipolar strain values comparable to Zr doped BaTiO3 single crystals of same composition, at relatively lower electric fields and also exhibit better fatigue tolerant properties. The underlying mechanisms responsible for superior dielectric, ferroelectric and piezoelectric properties are discussed.

In this report, the effect of rare-earth (RE

Nano-sized ferroelectric Ba(Zr0.15Ti0.85)O3 (BZT) thin films were deposited on Pt/Ti/SiO2/Si substrates using pulsed LASER deposition technique. X-ray diffraction results highlighted the formation of single phase perovskite structure and Atomic Force Microscopy analyses revealed the uniform distribution of the nanometer sized grains. Enhanced properties were observed by in situ annealing of deposited BZT thin films in oxygen rich environment. The observed values of saturation polarization, remanent polarization are several orders higher than those reported in literature. The possible mechanisms for enhanced properties were discussed. Annealing in oxygen rich atmosphere decreased oxygen vacancies which in turn helped in realizing high dielectric constant and better tunability. A low leakage current density was observed in 125 nm thick BZT films. The underlying transport mechanism of leakage current was found to be of Poole–Frenkel type, an interface related phenomenon. Tunability as high as 62 % was observed corresponding to in situ annealed thin films.

Nano-sized zirconium substituted barium titanate, Ba(Zr0.15Ti0.85)O3, hereinafter referred to as BZT was synthesised using high energy ball milling. Calcined powders were compacted using cold-isostatic pressing. Phase pure perovskite BZT, free from any secondary peaks was observed for sintered samples with a relative density ∼98%. High permittivity of ∼14,000 coupled with a dielectric loss of

Barium bismuth titanate (BaBi 4 Ti 4 O 15 ) ceramics prepared by conventional solid-state reaction method have been characterized, and influence of sintering temperature is shown to greatly affect the electrical properties. Formation of a single phase composition with orthorhombic structure and a randomly oriented plate-like microstructure is confirmed. Raman spectroscopy reveals broad over-damped low frequency modes indicating structural disorder. Room temperature dielectric response in the low frequency range (10 −2 –10 Hz) reveals the influence of dc conductivity on dielectric dispersion. Analysis in terms of Lorentz type relation describes well the diffuseness in the dielectric data, and indicates only one polarization process in the system. The well fitting of frequency dependent maximum temperature ( T m ) in e ′( T ) to the non-linear Vogel–Fulcher equation and a similar trend in temperature dependent ac conductivity imply a relaxor-like nature of the material. Sintering at 1050 °C for 5 h is found to be favorable and yields ceramics with high density, high resistivity (4.6 × 10 12 Ω cm), low dielectric loss (tan δ ∼ 0.05), remnant polarization ( P r = 3.63 μC/cm 2 ) and a high piezoelectric charge coefficient, d 33 = 24 pC/N.

Zirconium-doped barium titanate Ba(Zr0.15Ti0.85)O3 lead-free ceramics (hereinafter referred to as BZT) were synthesized using the solid-state reaction method by adopting the high-energy ball milling technique. Nanosized BZT powders resulted from high-energy ball milling, which in turn enhanced the dielectric and piezoelectric properties of the ceramics. A single-phase perovskite structure free from secondary phase peaks was observed for sintered BZT samples, and a relative density of ∼94% of the theoretical density was achieved. The electric-field-induced polarization-current data indicate the ferroelectric nature of the samples. Unipolar strain as high as 0.12% was realized for the ceramics sintered at 1350°C, indicating their potential for use in actuator applications. Very high tunability of >70% for these ceramics is also reported.

Lead-free Ba(Zr0.15Ti0.85)O3 (BZT15) ceramics were synthesized by adopting the solid-state synthesis method. The effect of increasing sintering temperature (Ts) in the range of 1,350–1,450 °C on the microstructure, dielectric, polarization, and electric field induced strain of the ceramics was studied. Fine grained (~260 nm) BZT15 ceramics displayed single phase perovskite structure with relative densities >94 % of the theoretical density. Both grain size and shape were influenced by the sintering parameters. With increase in Ts, not only the maximum dielectric constant decreased from 11,412 to 8,734 along with an increase in the degree of diffuseness, but also interestingly the Curie temperatures were found to vary within an interval of 61–73 °C. Optimum sintering temperature has been found resulting in high remnant polarisation and strain in these ceramics. The properties observed are attributed to a contribution from all polar vectors present in coexistent phases.

Barium zirconium titanate, Ba(Zr0.15Ti0.85)O3 nano-crystalline powders were synthesized using high energy ball milling. The calcined powders were compacted adopting two different approaches viz. the conventional uniaxial pressing and cold-isostatic pressing (CIP) and the compacts were sintered at 1350 °C. A single phase perovskite structure was observed in both cases. BZT ceramics compacted using CIP technique exhibited enhanced dielectric and ferroelectric properties compared to ceramics compacted by uniaxial pressing. The polarization current peaks have been used in this paper as an experimental evidence to prove the existence of ferroelectricity in the BZT ceramics under study. The peak polarization current was found to be ~700% higher in case of cold iso-statically compacted ceramics. Similarly electric field induces strain showed a maximum strain (S max) of 0.08% at an electric field of 28 kV/cm. The dielectric and ferroelectric properties observed are comparable to single crystals of the same material.