Dielectric Peak Temperature Research Articles

Preparation and dielectric properties of co-contained unfilled tungsten bronze ceramics Ba4RCo0.5Nb9.5O30

In this study, Ba4RCo0.5Nb9.5O30 (R = La, Nd, Sm, Eu) (BRCN) ceramics were synthesized using a high-temperature solid-state reaction. The XRD refinement results show that ceramic samples are tetragonal tungsten bronze (TTB). As the radius of rare-earth ions decreases, the unit cell volume of BRCN ceramics decreases, and the radius difference between Ba2+ and R ions increase, which results in BO6 octahedral distortion and the Raman peaks shift to high frequency. In addition, as the radius of rare-earth ions decreases, the ionic displacements increase and thus the dielectric constant peak temperature goes up. The high-temperature impedance results show that there exists n-type electronic conduction in the samples. The remanent polarization of the P–E curve at low frequencies increases from 0.470 to 1.038 μC cm−2 as the rare-earth ion radius decreases.

Dielectric relaxation and local domain structures of ferroelectric PIMNT and PMNT single crystals

AbstractDielectric relaxation properties of ternary Pb(In1/2Nb1/2)O3‐0.49Pb(Mg1/3Nb2/3)O3‐0.27PbTiO3 (PIMNT27) and binary Pb(Mg1/3Nb2/3)O3‐0.27PbTiO3 (PMNT27) single crystals have been investigated. The dielectric constant peak temperature Tm with frequency obeys the Vogel‐Fulcher (V‐F) law. The dielectric constants at temperatures above Tm can be described by the Lorenz‐type relationship. The fitting parameter δA and ΔTm of PIMNT27 are higher than those of PMNT27, indicating stronger relaxation in ternary PIMNT system. Local nanodomain structures were measured by the piezoelectric force microscopy (PFM). The average autocorrelation function technique was applied to quantify these nanoscale domain patterns. The PIMNT27 exhibits smaller size nanodomains and shorter mean local short‐range correlation length compared to PMNT27. The enhanced local disorder in PIMNT is related to the introduction of In3+ in PMNT system, which can enhance the disorder of B‐site ions. In addition, the evolution of local polarization rotation under a step‐increased tip dc voltage and the mean local short‐range correlation length <ξ> as a function of dc voltage were obtained for both PIMNT27 and PMNT27 single crystals, which are crucial parameters for the understanding of the relationship between dielectric relaxation and local domain structures in relaxor‐PbTiO3 systems.

Electrocaloric effect and pyroelectric energy harvesting in diffuse ferroelectric Ba(Ti1-xCex)O3 ceramics

In the present work Ba(Ti1-xCex)O3 ceramics are prepared through a standard solid-state sintering process. Crystal structures, dielectric properties, ferroelectric properties and electrocaloric effects are exactly studied. Ce4+ ions cannot entirely enter the position of Ti4+, so some impure phases are generated. The diffusivity of phase transition is strengthened by substituting Ti4+ with Ce4+ cations. The maximal pyroelectric coefficient decreases, and the extent of corresponding temperature deviating from the dielectric peak temperature to higher temperature increases with increasing the content of cerium cations. The adiabatic temperature change and isothermal entropy change display the same tendency as that of the pyroelectric coefficient. The Ba(Ti0.9Ce0.1)O3 ceramic shows the largest adiabatic temperature change of 0.41 K and the largest isothermal entropy change of 0.45 J/(kg·K) among the ceramics. Accordingly, the adiabatic temperature change responsivity is 0.090 × 10−6 K·m/V, and the isothermal entropy change responsivity is 0.100 × 10−6 J·m/(kg·K·V). For individual composition, the absolute value of pyroelectric coefficient decreases with increasing the magnitude of applied electric field, and the temperature of maximal pyroelectric coefficient deviates from the dielectric peak temperature shifts to higher temperature. Ba(Ti0.9Ce0.1)O3 ceramics show the largest pyroelectric energy density of 0.14 J/cm3 among all compositions.

Composition-Dependent Dielectric Properties of Poly(vinylidene fluoride-trifluoroethylene)s Near the Morphotropic Phase Boundary

The discovery of relaxor behavior in poly(vinylidene fluoride-trifluoroethylene) [P(VDF-TrFE)] copolymers plays a crucial role in driving the formation of a morphotropic phase boundary (MPB) near which large enhancements of dielectric and piezoelectric responses are achieved. Here we study the dielectric spectra of P(VDF-TrFE)s near MPB and analyze the relaxor behavior using two different theoretical models. We observe the largest dielectric constant of ∼76 at 1 kHz in morphotropic composition P(VDF-TrFE) 50/50 mol % at around 69 °C. We show that the compositional dependence of dielectric peak temperature changes dramatically in the vicinity of VDF = 49 mol %. Moreover, we find that the parameters (i.e., dielectric relaxation strength) deduced from the fit of the experimental data by different models also changes abruptly at VDF = 49 mol %. These findings clearly signify the destabilization of normal ferroelectric phase occurring at the critical VDF content of 49 mol % and explicitly mark one boundary of ...

Dielectric, impedance and piezoelectric properties of (K0.5Nd0.5)TiO3-doped 0.67BiFeO3-0.33BaTiO3 ceramics

A novel (0.67-x)BiFeO3-0.33BaTiO3-x(K0.5Nd0.5)TiO3 (KNT100x, x = 0.0, 0.02, 0.04, 0.06, 0.08 mol%) ceramics were fabricated and their microstructure and electrical properties were studied. All samples displayed a pseudo-cubic symmetry, and adding of KNT had little effect on grain size. The dielectric analysis displayed the dispersion increases with the addition of KNT compositions, showing strong relaxor properties. Besides, high dielectric constant (ε’) of 23000 and dielectric peak temperature (Tm) of 390 °C remain at 1 kHz in the x = 0.02 sample while the dielectric loss (tanδ) dropped below 0.5 in the range of 30–400 °C, showing excellent electrical insulation performance. In addition, doping of KNT had obvious influence on the strain, and a large strain (Smax) of 0.26% was obtained at x = 0.02 due to the increase of electrical insulation. More importantly, the strain at 50 kV cm−1 enhanced significantly with temperature increasing, reaching a maximum strain of 0.75% with a small hysteresis coefficient of 30% at 110 °C. Particularly, KNT02 exhibited excellent fatigue resistance within 105 fatigue cycles. Presumably these results are attributed to the coexistence of ferroelectric and non-ergodic relaxor domains and the thermally activated domain wall motion.

Evolution of depolarization temperature of PLZT from normal to relaxor ferroelectrics

Lead lanthanum zirconate titanate (PLZT x/59/41) ceramics with x from 0 to 6.5 mol. % are synthesized by the traditional solid-state reaction method. The temperature dependences of dielectric and resonant responses are used to characterize the depolarization processes of poled samples. It is found that the temperature of anti-resonance frequency minima (Tmin-a) accords completely with dielectric loss peak temperature (Tloss). The Tloss instead of anomalous dielectric peak temperature (Td*) can be regarded as depolarization temperature (Td). The Td* deviated from the Tloss suggests that the depolarization process in all the samples includes two stages: domain decoupling and polarization disorientation. With La content increasing, the Tloss decreases and the temperature difference ΔT between Tloss and dielectric peak temperature (Tm) increases nearly linearly. Since all studied samples have similar depolarization and freezing processes and the 0 mol. % La sample behaves like a normal ferroelectric, here we suggest that there may be no essential difference in depolarization process between relaxor and normal ferroelectrics.Lead lanthanum zirconate titanate (PLZT x/59/41) ceramics with x from 0 to 6.5 mol. % are synthesized by the traditional solid-state reaction method. The temperature dependences of dielectric and resonant responses are used to characterize the depolarization processes of poled samples. It is found that the temperature of anti-resonance frequency minima (Tmin-a) accords completely with dielectric loss peak temperature (Tloss). The Tloss instead of anomalous dielectric peak temperature (Td*) can be regarded as depolarization temperature (Td). The Td* deviated from the Tloss suggests that the depolarization process in all the samples includes two stages: domain decoupling and polarization disorientation. With La content increasing, the Tloss decreases and the temperature difference ΔT between Tloss and dielectric peak temperature (Tm) increases nearly linearly. Since all studied samples have similar depolarization and freezing processes and the 0 mol. % La sample behaves like a normal ferroelectric, here we ...

Structural evolution and dielectric properties of Nd and Mn co-doped BaTiO3 ceramics

(Ba1−xNdx) (Ti0.97Mn0.03)O3 (BNTM) (x = 0.01, 0.02, 0.04, 0.06) ceramics were prepared using a conventional cold-pressing ceramic technique. The structure, valence state and dielectric properties were investigated using XRD, RS, SEM, TEM, EPR, and dielectric temperature and frequency measurements. XRD, RS analysis coupled with SEM and TEM observations indicate that the samples have a coexistence of tetragonal and hexagonal phase at room temperature as x ≤ 0.02 and become a single phase in the tetragonal as x = 0.04 and in the cubic as x = 0.06 (air-sintered, 1400 °C/12 h). It reveals that Nd3+ ions can suppress hexagonal phase effectively and benefit the formation of single-phase ceramics. Improvement of dielectric properties is accompanied by the structural evolution. Particularly a cubic ceramic with x = 0.06, the dielectric-peak temperature is found to shift to room temperature, meeting the EIA Y5V specification with tan δ < 0.04. Up to x = 0.04, the phase transition remains first order. The valence state of Mn ions was analyzed by EPR. It is found that Mn ions transform from high valence (+3 and + 4) to low valence (+2) with the increase of Nd concentration, and all of the Mn ions exist as Mn2+ when x = 0.06. The unit cell volume and dielectric-peak temperature of BNTM decrease nonlinearly with increasing x, which can be ascribed to the incorporation of Nd ions and the formation of 2NdBa·−MnTi″ donor-acceptor defect complexes.

A high-permittivity and low-loss (Ba1−xNdx)(Ti1−y−x/4Cey)O3 ceramic

(Ba1−xNdx)(Ti1−y−x/4Cey)O3 (BNTC) ceramics with a pseudo-cubic structure were prepared using the mixed oxide method. The dielectric-peak temperature decreased rapidly at a rate of −27 °C/at.% Nd for BNTC with y = 0.05. BNTC with x = y = 0.05 (BN5TC5) exhibited a high-permittivity diffuse phase transition behavior but had a higher dielectric loss (tan δ = 0.219). A high-permittivity (ε′RT = 14100) and low-loss (tan δ = 0.014) X7V ceramic was achieved by means of the addition of 1% Ce in BN5TC5. A g = 2.509 electron spin resonance (ESR) signal associated with Ce3+ Kramers ions confirmed the existence of mixed valence states of Ce3+/Ce4+. A g = 2.151 ESR signal of Nd3+ can be detected at room temperature after these ceramics were preserved over a long period of time.

Strongly enhanced dielectric and energy storage properties in lead-free perovskite titanate thin films by alloying

Lead-free perovskite oxide thin films prepared by alloying of titanates and materials with lower melting points are shown to have enhanced ferroelectric and dielectric properties. BaTiO3 (or SrTiO3) with 25% addition of BiFeO3 has much improved crystalline perfection because of the lower melting point of the BiFeO3 giving enhanced growth kinetics. The maximum dielectric peak temperature of BaTiO3 is increased by ~ 200°C and leakage currents are reduced by up to a factor of ~ 100. The loss tangent reduces up to 300°C, with a factor of > 14 reduction at room temperature. The dielectric breakdown strength is higher by a factor of ~ 3 (> 2200kVcm−1) and from room temperature up to 500°C the dielectric constant is > 1000. Also, a low variation of dielectric constant of ~ 9% from room temperature to 330°C is obtained, compared to ~ 110% for BaTiO3. The maximum polarization (Pmax) is double that of BaTiO3, at 125.3μCcm−2. The film has high energy storage densities of > 52Jcm−3 at 2050kVcm−1, matching Pb-based ferroelectric films. The strongly improved performance is important for applications in energy storage and in high temperature (up to 300°C) capacitors as well as wider application in other electronic and energy technologies.

Multiplicity of photoluminescence in Raman spectroscopy and defect chemistry of (Ba1−xRx)(Ti1−xHox)O3 (R = La, Pr, Nd, Sm) dielectric ceramics

(Ba1−xRx)(Ti1−xHox)O3 (R = La, Pr, Nd, Sm; x ≥ 0.04) (BRTH) ceramics were prepared using a mixed oxides method. The solubility limits in BRTH with R = La, Pr, Nd, Sm were determined by XRD to be x = 0.11, 0.12, 0.06, and 0.14, respectively. The ionic radius of R at Ti-site plays a decisive role in the solubility limit in BRTH. Only BRTH with R = La satisfied Vegard's law. The multiplicity of photoluminescence (PL) signals of Nd3+/Ho3+ and Sm3+/Ho3+ in Raman scattering under 532-nm excitation laser and the high-permittivity abnormality for the denser BRTH with R = Sm and at x = 0.07 were reported. The PL provided the evidence of a small number of Ho3+ at Ba-site in BRTH and it was determined that the number of Ba-site Ho3+ ions increased from 0.05at% at R = La to 0.19at% at R = Sm with increasing atomic number of light rare earth. BRTH exhibited a much broadened dielectric-temperature characteristics, marked by ×5T, ×6T, ×7T, and ×8S dielectric specifications for BRTH with R = La, Pr, Nd, Sm and at x = 0.06, respectively, and they exhibited lower dielectric loss (tan δ < 0.015) at room temperature. The dielectric-peak temperature (Tm) of BRTH decreased linearly at a rate of less than −21°C/%(R/Ho). The defect chemistry, solubility limit, lower dielectric loss, and dielectric abnormality are discussed.

Electrocaloric effect in relaxor ferroelectric Ba(Ti1-xYx)O3-x/2 ceramics over a broad temperature range

Crystal structures, dielectric, ferroelectric properties and electrocaloric effects of hetero-valent substituted Ba(Ti1-xYx)O3-x/2 ceramics were studied in the present work. The polar space group of P4mm was adopted based on the Rietveld refinement at room temperature. The diffusivity of phase transition and relaxor behavior are both strengthened by the yttrium substitution. The maximal pyroelectric coefficient decreases, and the extent of corresponding temperature deviated from the dielectric peak temperature to higher temperature increases with increasing the yttrium content. The adiabatic temperature changes and isothermal entropy changes display the same tendencies as those of the pyroelectric coefficients. The Ba(Ti0.944Y0.056)O2.972 ceramic shows the largest adiabatic temperature change and largest isothermal entropy change among all compositions over a broad temperature range of 50 K. For individual composition, the value of pyroelectric coefficient decreases with increasing the magnitude of applied electric field, and the temperature of maximal pyroelectric coefficient deviates from the dielectric peak temperature to higher temperature. Therefore, the optimal electrocaloric temperature can be adjusted by the magnitude of electric field in relaxor ferroelectricity.

Quantum phase transitions in Ba(1−x)CaxFe12O19 ( 0≤x≤0.10 )

The ground state of BaFe12O19 (BFO) is controversial as three different quantum states, namely quantum paraelectric, frustrated antiferroelectric and quantum electric dipole liquid (QEDL), have been proposed. We have investigated the quantum critical behavior of BFO as a function of chemical pressure (a non-thermal variable) generated by smaller isovalent ion Ca2+ at the Ba2+ site. Analysis of synchrotron x-ray diffraction data confirms that Ca2+ substitution generates positive chemical pressure. Our dielectric measurements reveal that Ca2+ substitution drives BFO away from its quantum critical point (QCP) and stabilizes a quantum electric dipolar glass state whose dielectric peak temperature (Tc) increases with increasing Ca2+ content as Tc ~ (x-xc)1/2, a canonical signature of quantum phase transitions. Our dielectric measurements reveal that pure BFO is slightly away from its QCP with a Tc of 2.91 K. Specific heat measurements reveal excess specific heat of non-Debye and non-magnetic origin with linear temperature dependence below Tc which could be due to QEDL state of BFO.

Electrocaloric response in a relaxor ferroelectric polymer at temperatures far below the dielectric maximum

ABSTRACTRelaxor ferroelectric polymer poly(vinylidene fluoride–trifluoroethylene–chlorofluoroethylene) (P(VDF-TrFE-CFE)) and its blends have been shown to exhibit a giant electrocaloric effect (ECE) over a broad temperature range, e.g. from 0 to 50 °C. Here, a special calorimeter was designed to directly characterize the heat absorbed QECE due to ECE cooling of the blend of P(VDF-TrFE-CFE) with P(VDF-TrFE) 65/35 mol% copolymer down to −15 °C, which covers the temperature range for many refrigeration applications. From QECE, the isothermal entropy change ΔS and adiabatic temperature change ΔT are deduced. The data reveal that at −15 °C the relaxor terpolymer/copolymer blend generates ΔS = 23.0J kg−1 K−1 and ΔT = 5.1K under 100 MV/m, which are still more than 65% of the ECE at room temperature. This temperature is far below the dielectric peak temperature of the relaxor blend and the results reveal the promise of the relaxor polymers for a broad range of EC cooling applications.

Dielectric properties and defect chemistry of barium titanate ceramics co-doped R and Dy ions (R=Eu, Gd, Tb)

The structure, microstructure, dielectric behavior, point defects, mixed valence states, site occupations, and defect chemistry of nominal (Ba1−xRx)(Ti1−xDyx)O3 (x=0.06, R=Eu, Gd, Tb) (BRTD) ceramics were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, electron paramagnetic resonance (EPR), dielectric and resistivity measurements. BRTD exhibited a tetragonal perovskite structure, a higher ceramic density of ρr=91% of theoretical density, a diffuse phase transition (DPT) behavior, and a nonlinear shift in dielectric-peak temperature (Tm) with the kind of doping ions. The feature of mixed valence states associated with site occupation is responsible for this abnormal Tm-shift rate. BRTD with R=Tb exhibited a lowest dielectric loss of tan δ=0.025 at 1kHz and a nearly frequency-independent stability up to 107Hz at room temperature. A double-site compensation mode of GdBa•-DyTi' could be formed and led to a rapid Tm-shift rate of approximately −10°C/%(Gd-Dy). A symmetrical EPR signal at g=1.985 was designated as Gd3+ (4f7) Kramers ions. The mixed valence states of Ba-site Eu3+/Eu2+ (4f7) and Ba-site Tb3+/Ti-site Tb4+ (4f7) appeared in BRTD owing to the metastable nature of the 4f7 electron configuration. The Raman spectra in a high-wavenumber region of 1500–6700cm−1 were discovered and might be likely linked to the 4f7 doping ions, such as Eu2+, Gd3+, and Tb4+ ions. The defect chemistry is discussed.

Dielectric properties and defect chemistry of La and Tb co-doped BaTiO3 ceramics

(Ba1−xLax)(Ti1−xTbx)O3 (0.03 ≤ x ≤ 0.20) (BLTT) and (Ba1−xLax)(Ti1−xTbx)O3–0.03nTb (x = 0.03, n = 0, 1, 3, 5, 7) (BL3TT-nT) ceramics were prepared using a mixed oxides method. The structure, microstructure, dielectric properties, valence state, and defect chemistry of BLTT and BL3TT-nT were investigated using X-ray diffraction (XRD), Raman spectroscopy, scanning electron microscopy (SEM), electron paramagnetic resonance (EPR), X-ray photoelectron spectroscopy (XPS), and dielectric temperature and frequency measurements. The solid solution limits of Tb in BLTT and BL3TT-nT were determined by XRD to be x = 0.15 and n = 3, respectively. The incorporation of the extra Tb ions in BLTT enhanced the relative density of the ceramic from 84% to 96%, accompanied by an improvement in dielectric permittivity. The defect chemistry of BLTT is discussed. Tb ions coexist in mixed-valence states, at the Ba-site as Tb3+, and at the Ti-site as Tb3+/Tb4+. The dielectric-peak temperature (Tm) decreased linearly at a rate of −19 °C/%(LaTb) for BLTT. Due to its higher room-temperature permittivity (ε′ = 2450) and lower loss (tan δ = 0.029), BLTT with x = 0.07 can be considered as a promising dielectric for X7U applications. The existence of a small number of metastable Tb4+ ions at Ti-sites and the predominant presence of La3+Tb3+ complexes at double sites are both responsible for the lower tan δ of BLTT.

Study of the solubility of La3+–Dy3+ defect complexes and dielectric properties of (Ba1−xLax)(Ti1−xDyx)O3 ceramics

Based on the double-site compensation mode, the solubility of LaBa•–DyTi′ defect complexes and the dielectric properties of (Ba1−xLax)(Ti1−xDyx)O3 (0.03≤x≤0.20) ceramics (BLTD) were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), Raman spectroscopy, electron paramagnetic resonance (EPR), and dielectric measurements. The solid solubility of LaBa•–DyTi′ defect complexes in the BaTiO3 lattice was determined to be x=0.17. With an increase in x, the increase in the unit cell volume was linear and satisfied Vegard׳s law. The dielectric-peak temperature (Tm) decreased rapidly at a rate of −23°C/at% LaBa•–DyTi′. The BLTD ceramics with x=0.05 and 0.07 met the Y5V specification with a higher room-temperature permittivity (εRT′~4000 and ~3000) and a lower dielectric loss (tanδ<0.04). A weak g=2.004 EPR signal associated with ionized Ti-vacancy defects appeared in all of the BLTD ceramics. The exclusive occupations of La3+ ions at Ba sites and the preference for the self-compensation mode by Dy3+ ions are responsible for the formation of predominant LaBa•–DyTi′ defect complexes and the appearance of the minute concentration of Ti vacancies and DyBa•–DyTi′ defect complexes.

Observation of an intrinsic nonlinearity in the electro-optic response of freezing relaxors ferroelectrics

We demonstrate an electro-optic response that is linear in the amplitude but independent of the sign of the applied electric field. The symmetry-preserving linear electro-optic effect emerges at low applied electric fields in freezing nanodisordered KNTN above the dielectric peak temperature, deep into the nominal paraelectric phase. Strong temperature dependence allows us to attribute the phenomenon to an anomalously reduced thermal agitation in the reorientational response of the underlying polar-nanoregions.

Structural and dielectric properties, electron paramagnetic resonance, and defect chemistry of Pr-doped BaTiO3 ceramics

Fine-grained Pr-doped BaTiO3 ceramics (BPT) were prepared according to the nominal formula (Ba1−xPrx)Ti1−x/4O3 (0.02⩽x⩽0.05) using a mixed oxide method. Structure, microstructure, dielectric properties, and defect chemistry were investigated by X-ray diffraction (XRD), Raman spectroscopy, electron paramagnetic resonance (EPR), scanning electron microscopy (SEM), and dielectric measurements. Crystal structure changed from tetragonal (0.02⩽x⩽0.04) to cubic (x=0.05), accompanied by a linear decline of the c/a axial ratio with x. BPT exhibited a slight diffuse phase transition behavior and its dielectric-peak temperature (Tm) decreased rapidly at a rate of −22°C/at.% Pr. Pr ions were substituted predominantly for Ba sites as Pr3+ and induced Ti-vacancy defects, which are evidenced by a change in unit cell volume, a rapid Tm – shifting rate, a new Raman band at ∼837cm−1, and an EPR signal at g=2.002. A very small number of Pr ions inevitably entered Ti sites as Pr4+, which is evidenced by a thermally accessible signal at g=3.77 related to the preservation history of the x=0.05 sample. The effect of electron free radicals on EPR signal is discussed. Another thermally accessible EPR signal associated with a rhombic g-tensor of the stronger g=2.002 signal was observed. This signal is also related to the preservation history of the sample.

Temperature-Dependent Structure of a High-k (Ba,La)(Ti,Ce)O&lt;sub&gt;3&lt;/sub&gt; Ceramic

The lattice structure of a high-k BL3TC5 [(Ba1-xLax)(Ti1-x/4-yCey)O3 (x = 0.03, y = 0.05)] ceramic with cubic structure at room temperature was investigated using temperature-dependent X-ray diffraction (XRD) and Raman spectroscopy. The XRD results indicated that with increasing temperature, the cubic lattice of BL3TC5 showed a lower coefficient of linear expansion (α = 7.7 × 10-6/°C) relative to the cubic BaTiO3 (9.3 × 10-6/°C), but no abnormal change in cell volume occurred around the dielectric peak temperature Tm (= 38 °C). The peak position of the ~835 cm-1 Raman band induced by the substitution of La3+ ions for Ba sites in BL3TC5 was nearly independent of temperature on each side of Tm, whereas a slight fall (3 cm-1) in the peak position around Tm was detectable. The link between the dielectric peak with DPT and the lattice change was discussed.

Enhanced dielectric, pyroelectric and ferroelectric properties of Mn-doped 0.15Pb(In1/2Nb1/2)O3–0.55Pb(Mg1/3Nb2/3)O3–0.30PbTiO3 single crystals

Mn-doped 0.15Pb(In1/2Nb1/2)O3–0.55Pb(Mg1/3Nb2/3)O3–0.30PbTiO3 single crystals were grown by modified Bridgman technique. High dielectric peak temperature of 161°C, low dielectric loss of 0.03% and enhanced pyroelectric coefficient of 10.1×10−4C/m2K are observed. Effects of oxygen vacancies related to annealing atmosphere have been investigated to explain enhanced dielectric and pyroelectric properties. Detectivity figure of merit of 34.1×10−5Pa−1/2 is achieved for oxygen-annealed crystals, which is the highest value among reported PIMNT crystals. Two different linear relationships between the coercive field and frequency are observed to obey Merz’s law, which reveals the domain and polarization switching mechanism.