Influence of Mn on dielectric and piezoelectric properties of A-site and B-site modified PLZT nano-ceramics for sensor and actuator applications

[Pb_0.961La_0.012Ba_0.015Sr_0.012][Zr_0.53Ti_0.47]_0.967-(h/2)Nb_0.02Zn_0.01Mn_hO₃ (PLBSZZMNT) nano-ceramics where h = 0, 0.5. 1 and 1.5 mol% fabricated through solid state reaction method has been investigated for phase formation, microstructure, density, dielectric and piezoelectric properties. X-ray diffraction studies indicated that all the samples exhibited a single-phase perovskite tetragonal structure which had strongly intensified due to the acceptor Mn content increment in the series. Our investigation with reference to isovalent (Ba²⁺ and Sr²⁺) on the A-site, pentavalent donor (Nb⁵⁺) and acceptor (Zn²⁺ and Mn⁴⁺) dopants on the B-site in PLZT perovskite with the stoichiometric compositional formulation tailored for dielectric and piezoelectric properties has been clearly explained. As Mn concentration increased, the grain growth enhanced, and the inter-diffusion between multiple ions promoted densification in the PLBSZZMNT nano-ceramics. TEM studies revealed an average particle size ranging from 20 to 72 nm. Dielectric characterization revealed that the ε_RT enhanced till 1.5 mol% Mn (2946) while the Curie temperature and dielectric loss at room temperature (T_c and Tanδ_RT) decreased, respectively. Mn doping in PLBSZZNT induced the piezoelectric parameters (k_p = 0.567) and (d₃₃ = 486 pC/N) till 1.5 mol% Mn. Thus, 1.5 mol% Mn modified PLBSZZNT exhibits optimum dielectric and piezoelectric properties, which are suitable for possible sensor and actuator applications.     

Influence of Ce3+ on dielectric properties of tungsten bronze structured PBN ceramics

The effect of A-site substitution of Ce³⁺ in tungsten bronze structured PBN ceramics with the general formula, Pb_{(x − 3y/2)}Ce _y Ba_(1 − x)Nb₂O₆ and the stoichiometric chemical formula, Pb_{(0.65 − 3y/2)}Ce _y Ba_0.35Nb₂O₆, where y = 0, 2, 4, 6, 8 and 10 mol% ceramic compositions synthesized through solid state reaction method are reported. The X-ray diffraction studies exhibited the presence of an orthorhombic phase, and its intensity increased with the increasing Ce³⁺ content up to y = 6 mol% or A₃ composition. The lattice parameters, unit cell volume and density as a function of Ce³⁺ concentration are discussed. It is observed that increasing Ce³⁺ content in A-site influenced the dielectric properties. The optimum dielectric properties of room temperature dielectric constant (ε_RT) and dielectric maximum () are observed in y = 6 mol% or A₃ composition while Curie temperature (T _c) and dielectric loss (tan δ) constantly decreased from undoped to y = 10 mol%, and thus A₃ composition or 6 mol% Ce modified tungsten bronze structured-PBN could be suitable for capacitor applications.     

Structure and piezoelectric properties of new (Bi0.5Na0.5)1?x?yBax(Yb0.5Na0.5)yTiO3 lead-free ceramics

New lead-free ceramics (Bi_0.5Na_0.5)_1−x−yBa_x(Yb_0.5Na_0.5)_yTiO₃ (x = 0.02–0.10 and y = 0–0.04) have been prepared by an ordinary sintering technique and their structure and piezoelectric properties have been studied. X-ray diffraction shows that Ba²⁺ and Yb³⁺ diffuse into the Bi_0.5Na_0.5TiO₃ lattices to form a solid solution with a pure perovskite structure and a morphotropic phase boundary (MPB) between rhombohedral and tetragonal phases is formed at 0.04 < x < 0.10. The partial substitutions of Ba²⁺ and Yb³⁺ for A-site ions of Bi_0.5Na_0.5TiO₃ decrease effectively the coercive field E _c and improve significantly the remanent polarization P _r. The ceramics with x = 0.06 and y = 0–0.02 situate within the MPB and possess the lower E _c and larger P _r, and thus exhibit optimum piezoelectric properties: d ₃₃ = 155–171 pC/N and k _p = 29.2–36.7%. The temperature dependences of the dielectric and ferroelectric properties suggest that the ceramics may contain both the polar and non-polar regions at temperatures near/above T _d.     

Tantalum influence on electrical properties of lead-free (K0.4425Na0.52Li0.0375)(Nb0.93?xTaxSb0.07) O3 piezoelectric ceramics

Lead-free (K_0.4425Na_0.52Li_0.0375)(Nb_0.93−x Sb_0.07Ta _x )O₃ (abbreviated as KNLNST _x ) piezoelectric ceramics with x = 0.045–0.075 have been prepared by an ordinary sintering technique with sintering temperature at 1,120 °C. The results of X-ray diffraction reveal that Ta⁵⁺ has diffused into the perovskite lattice to form a solid solution. The grain growth of the ceramics was inhibited by substituting Ta⁵⁺ for Nb⁵⁺. It has been shown that the substitution of Ta decreases Curie temperature T _C and orthorhombic-tetragonal phase transition temperature T _O-T. Besides, the dependence of the ceramics with different Ta content on the dielectric, piezoelectric and ferroelectric properties has been investigated. The results indicate that Ta substitution provides “soft” piezoelectric characteristics, owing to improvements in d ₃₃, k _p and ε _r and a decease in Q _m. For the ceramics with x = 0.06, the piezoelectric coefficient d ₃₃ becomes maximum at a value of 270 pC/N, while the other electrical properties remain reasonably high: dielectric constant ε _r = 1,577, planar mode electromechanical coupling factors k _p = 0.4, Curie temperature T _C = 252 °C and the remanent polarization P _r = 16.03 μC/cm². These results show that (K, Na, Li) (Nb, Sb)O₃ ceramics with small amount of Ta (x <8 mol%) are good lead-free piezoelectric ceramic.     

Extraordinary role of Ce–Ni elements on the electrical and magnetic properties of Sr–Ba M-type hexaferrites

The structural, electrical and magnetic behavior of Sr_0.5Ba_0.5−xCe_xFe_12−yNi_yO₁₉ (where x = 0.00–0.10; y = 0.00–1.00) hexaferrite nanomaterials are reported in this paper. The structural analysis indicates that the Ce–Ni doped Sr–Ba M-type hexaferrite samples synthesized by the co-precipitation method are stoichiometric, single magnetoplumbite phase with crystallite sizes in the range of 35–48 nm. The dc-electrical resistivity of the pure Sr–Ba hexaferrite is enhanced to almost 10² times by doping with Ce–Ni contents of x = 0.06; y = 0.60. The dielectric constant and dielectric loss tangent decrease to values 14 and <0.2, respectively, by increasing the frequency up to 1 MHz. Small relaxation peaks at frequencies >10⁵ Hz are observed for the samples with Ce content of x > 0.06. The values of saturation magnetization increase from 66.32 to 84.33 emu/g and remanance magnetization from 42.64 to 56.01 emu/g but coercivity decreases from 2.85 to 1.59 kOe by substitution of Ce–Ni. Sharp ferri-paramagnetic transition is observed in the samples, which is confirmed by DSC results. Ce–Ni substitution acts to reduce the electron-hopping between Fe²⁺/Fe³⁺ ions and also improves the magnetic properties. These characteristics are desirable for their possible use in microwave and chip devices.     

Structure, infrared and Raman spectroscopic studies of new Sr0.50SbFe(PO4)3 and SrSb0.50Fe1.50(PO4)3 Nasicon phases

Two newly synthesised Sr_0.50SbFe(PO₄)₃ [Sr_0.5.] and SrSb_0.50Fe_1.50(PO₄)₃ [Sr.] phases were obtained by conventional solid-state reaction techniques at 1000 °C in air atmosphere. Their crystallographic structures were determined at room temperature from X-ray powder diffraction (XRPD) data using the Rietveld analysis. Both compounds belong to the Nasicon structural family. [Sr_0.5.] and [Sr.] crystallise in rhombohedral system with \textR[`3] {\text{R}}\overline{3} and \textR[`3] \textc {\text{R}}\overline{3} {\text{c}} space group, respectively. Hexagonal cell parameters for [Sr_0.5.] and [Sr.] are: a = 8.227(1) ?, c = 22.767(2) ? and a = 8.339(1) ?, c = 22.704(2) ?, respectively. Sr²⁺ and vacancies in {[Sr_0.50]_3a[□_0.50]_3b}_M1SbFe(PO₄)₃ are practically ordered within the two positions, 3a and 3b, of M1 sites. Structure refinements show also an ordered distribution of Sb⁵⁺ and Fe³⁺ ions within the Nasicon framework. Within the structure, each Sr_(3a)O₆ octahedron shares two faces with two Fe³⁺O₆ octahedra and each vacancy (□_(3b)O₆) site is located between two Sb⁵⁺O₆ octahedra. In [Sr]_M1Sb_0.50Fe_1.50(PO₄)₃ compound, all M1 sites are occupied by Sr²⁺ and the Sb⁵⁺ and Fe³⁺ ions are randomly distributed within the Nasicon framework. A Raman and infrared spectroscopic study was used to obtain further structural information about the nature of bonding in both selected compositions.     

Saturation magnetization and structural analysis of Ni0.6Zn0.4NdyFe2?yO4 by XRD, IR and SEM techniques

Compositions having general formula Ni_0.6Zn_0.4Nd _y Fe_2−y O₄ (where y = 0, 0.01, 0.02 and 0.03) were prepared by oxalate co-precipitation method from high purity sulphates. The samples were characterized by XRD, IR and SEM techniques. X-ray diffraction measurements confirmed the formation of single phase cubic spinel structure. Lattice constant increases with rise in Nd³⁺ content and obeys Vegard’s law. Crystallite size of the samples lies in the range 29.98–31.15 nm. The IR spectra shows two strong absorption bands in the frequency range 400–600 cm⁻¹. Further, it shows that Nd³⁺ occupies B-site. SEM studies show that the grain size of the samples decreases with increase in Nd³⁺ content. Saturation magnetization of Nd³⁺ substituted Ni–Zn ferrites is higher than unsubstituted ferrite.     

Microstructures formed during devitrification of Na2O·Al2O3·B2O3·SiO2·Fe2O3 glasses

Soda alumina borosilicate glasses of composition (24-y)Na₂O·yAl₂O₃·14B₂O₃·37SiO₂·25Fe₂O₃, y = 8, 12, 14, 16 mol%, were melted using Fe₂O₃ as raw material. Besides, samples with y = 12 and Fe₂O₃ concentrations of 14.32, 17.8, and 25.0 mol% were prepared from FeC₂O₄·2H₂O as raw material. The X-ray diffraction analyses showed the presence of magnetite for the samples from all the investigated compositions. Transmission electron microscopy (TEM) evidenced that all the samples are phase separated and droplets in the diameter range 100–1000 nm, enriched in iron, are formed. Inside these droplets, numerous small magnetite particles, with size in the 25–40 nm interval, are crystallized.     

Preparation and magnetic properties of Ni–Zr doped barium strontium hexaferrite

M-type Hexaferrites B_0.5Sr_0.5Fe_12−2x Ni _x Zr _x O₁₉ were synthesized and investigated. The XRD patterns show single phase of the magnetoplumbite barium strontium ferrite and no other phases were present. The samples exhibit well defined crystallization; all of them are hexagonal platelet grains. As the substitution level increased from x = 0.2 to 0.8 mol%, the grains are agglomerated and the average diameter increased. This suggests that Ni–Zr substitution increases the grain size, as observed in the FE-SEM micrographs. The results of magnetic measurement revealed that M_s of barium strontium hexaferrite increased when the value of x increased from 0 to 0.4 mol% and then decreased with the increasing Ni–Zr content. The H_c decreases remarkably with increasing Ni and Zr ions content. Hard magnetic material is converted into soft magnetic material when the substitution level is increased from 0.2 to 0.8 mol%. In particular, Ba_0.5Sr_0.5Fe_12−2x Ni _x Zr _x O₁₉ with x = 0.2, 0.4, 0.6, 0.8 mol% has suitable magnetic characteristics with particle size small enough for high-density magnetic recording applications.     

Structural and dielectric properties of nanocrystalline Nd<Superscript>3+</Superscript> substituted nickel–zinc ferrites

Ferrite samples with general formula Ni_1−xZn_xNd_yFe_2−yO₄ (x = 0, 0.2, 0.4, 0.6, 0.8 and 1; y = 0.01, 0.02 and 0.03) were synthesized by oxalate co-precipitation technique. The X-ray diffraction study confirms the formation of single-phase cubic spinel structure. The lattice constant of the samples increases with increase in zinc content and obeys Vegard’s law. On Nd³⁺ substitution lattice constant of the samples slightly increases except zinc ferrite. The frequency dependence of the dielectric constant, dielectric loss and AC conductivity of the samples were determined in the frequency range from 20 Hz to 1 MHz at room temperature. The experimental results reveal that the dielectric constant and dielectric loss decreases where as AC electrical conductivity increases with increase in frequency. The dielectric loss increases with increase in zinc content whereas it decreases with increase in Nd³⁺ content. There is no appreciable change in permittivity of the samples with increase in Nd³⁺ content. Permeability of all the samples increases with increase in Nd³⁺ content. Because of lower dielectric loss, Nd³⁺ substituted Ni–Zn ferrites are useful in electronic devices.     

Magnetic properties of YIG doped with cerium and gadolinium ions

Nanoparticles Y_3−x−y Ce _x Gd _y Fe₅O₁₂ (x = 0–0.1, y = 0–1.0) were fabricated by a sol–gel method. The crystalline structures and magnetic properties of samples were investigated by X-ray diffraction (XRD), scanning probe microscopy (SPM), X-ray photoelectron spectroscopy (XPS), and vibrating sample magnetometer (VSM). The XRD patterns of Y_3−x−y Ce _x Dy _y Fe₅O₁₂ have only peaks of the garnet structure and the mean size range from 42 nm to 65 nm. The particle’s size observed for all the samples analyzed by SPM are in good agreement with these data from XRD. The particle’s size ranged from 50 nm to 70 nm, at the same time, there are small amount of reunited particles can be observed. XPS for Y_2.9Ce_0.1Fe₅O₁₂ gives two peaks at 885.15 and 905.15 eV attributing to Ce³⁺ 3d^5/2 and 3d^3/2, respectively. The results confirm the valence state of Ce atoms being +3. Results of VSM show that the saturation magnetization is increased with increasing Ce content (x) and is decreased with increasing the Gd concentration (y) in a linear manner. The saturation magnetization is increased with increasing the particle’s size.

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Structural and Physical Properties of Ca1?xSrxFe2As2 (0≤x≤1.0) and Ca0.5Sr0.5Fe2?yCoyAs2 (0≤y≤0.6)

The Ca_1−x Sr _x Fe₂As₂ (0≤x≤1) and Ca_0.5Sr_0.5 Fe_2−y Co _y As₂ (0≤y≤0.6) materials were prepared by a solid state reaction method. X-ray diffraction analysis shows that the lattice parameters of Ca_1−x Sr _x Fe₂As₂ decrease continuously with increasing Ca content. Resistivity measurements reveal that the Ca/Sr ratio has a visible influence on the resistivity anomaly associated with the spin-density-wave (SDW) instability. Experimental measurements on Ca_0.5Sr_0.5Fe_2−y Co _y As₂ show clear superconducting transitions for Co in range of 0.26≤y≤0.43; the highest critical transition temperature is found to be at about 17 K. Transmission electron microscopy (TEM) investigations on the superconducting Ca_0.5Sr_0.5Fe_2−y Co _y As₂ samples reveal visible inhomogeneous distribution of Sr and Ca elements, which could result in structural distortions and broaden superconducting transitions as observed in our experiments.     

Structural, magnetic and dielectric properties of Bi1−ySryFe(1−y)(1−x)Sc(1−y)xTiyO3 (x = 0-0.2, y = 0.1-0.3) ceramics

In this study, bulk ceramics with general formula Bi_1−ySr_yFe_{(1−y)(1−x)}Sc_(1−y)xTi_yO₃ (x = 0-0.2, y = 0.1-0.3 mol%) were prepared by traditional solid-state reaction method. As a comparison, bulk BiFeO₃ (BF) was also sintered by rapid sintering method. Their structural, magnetic, dielectric properties were investigated. X-ray diffraction analysis indicated that apart from a small amount of secondary phase detected in BF, all other samples crystallized in pure perovskite structure and maintained original R3c space group. The room temperature M-H curves were obtained. While BF had a coercive magnetic field (H_c) of 150 Oe, Bi_1−ySr_yFe_1−yTi_yO₃ solid solutions had a much larger value (for y = 0.1, 0.2, 0.3, H_c were 4537, 5230 and 3578 Oe, respectively). Sc³⁺ substitution decreased the H_c values of these solid solutions remarkably, and resulted in soft magnetic properties, as well as a decrease of the dielectric loss. At 1 MHz, the tan δ of Bi_0.7Sr_0.3Fe_0.7(1−x)Sc_0.7xTi_0.3O₃ with x = 0.05, 0.1, 0.15, 0.2 were 0.1545, 0.1078, 0.1046 and 0.1701, respectively.     

Low dielectric loss and enhanced tunable properties of Cr-doped barium strontium titanate solid solution

The dielectric response and tunable properties of Cr-doped Ba_0.6Sr_0.4TiO₃ solid solution were investigated. The XRD patterns revealed that all of the doped specimens are cubic perovskite phase, and the SEM micrographs showed that the grain size increases with the increase of Cr content below 0.6 mol%. The dielectric frequency spectra of the doped BST solid solution showed that an additional relaxation of the doped specimens is observed at frequencies above 10 MHz. Both of the tunability and dissipation factor were improved by doping with Cr concentration lower than 1.0 mol% compared with undoped material. The 0.6 mol% Cr-doped specimen reveals a maximum tunability and figure of merit of 23.3% and 518.3, respectively. Extremely low dissipation factor in order of 5 × 10⁻⁴ is found for 0.4–0.6 mol% Cr-doped BST solid solution. The dramatically low dissipation factor of the specimen is explained by the reducing of Cr³⁺ to Cr²⁺ and the acceptor action of Cr³⁺ and Cr²⁺ which neutralized the donor action of oxygen vacancies.     

Effect of ZnO on the microstructure and electrical properties of (K<Subscript>0.5</Subscript>Na<Subscript>0.5</Subscript>)NbO<Subscript>3</Subscript> lead-free piezoelectric ceramics

K_0.5Na_0.5NbO₃–x ZnO (KNN–xZn) lead-free ceramics have been prepared using the conventional sintering technique and the effects of ZnO addition on the phase structure and piezoelectric properties of the ceramics have been studied. Our results reveal that a small amount of ZnO can improve the density of the ceramics effectively. Because of the high density and ZnO doping effects, the piezoelectric and dielectric properties of the ceramics are improved considerably. The good piezoelectric and dielectric properties of d ₃₃ = 114 pC/N, k _p = 0.36, ε _r = 395, and Q _m = 68 were obtained for the KNN ceramics doped with 1 mol% ZnO. Therefore, the KNN-1.0 mol%Zn ceramics is a good candidate for lead-free piezoelectric application.     

Piezoelectric properties and conductivity of Pb(Zr,Ti)O<Subscript>3</Subscript> with SrO–WO<Subscript>3</Subscript> additive

The influence of SrO–WO₃ additive on the piezoelectric properties and electric conductivity of lead zirconate–titanate (PZT) near the morphotropic phase boundary was investigated. Starting from the composition 0.995 Pb(Zr_0.525Ti_0.475)O₃ + 0.015 SrO + 0.005 WO₃ (corresponding to 0.5 mol% of Sr₃WO₆) the fraction of WO₃ was increased until Sr:W = 1:1. These samples were compared to a set of samples of PZT with WO₃ addition but without SrO. Sr₃WO₆ has pseudocubic K₂NaAlF₆ structure with part of the strontium being octahedrally coordinated. In a solid solution with PZT this opens the possibility of realizing Sr on a B-site adjacent to a B-site occupied by W. Piezoelectric properties were measured on sintered disc samples under high field conditions. Impedance spectroscopy was used to investigate the conductivity and dielectric properties of the ceramics at various temperatures. The combined addition of SrO and WO₃ increases the piezoelectric strain compared to samples of PZT with WO₃ addition only. The results in polarization and conductivity indicate that the donor effect of WO₃ is counteracted by the addition of SrO.     

A novel approach for synthesis of M-type hexaferrites nanopowders via the co-precipitation method

M-type hexaferrites; barium hexaferrite BaFe₁₂O₁₉ and strontium hexaferrite SrFe₁₂O₁₉ powders have been successfully prepared via the co-precipitation method using 5 M sodium carbonate solution as alkali. Effects of the molar ratio and the annealing temperature on the crystal structure, crystallite size, microstructure and the magnetic properties of the produced powders were systematically studied. The results indicated that a single phase of barium hexaferrite was obtained at Fe³⁺/Ba²⁺ molar ratio 12 annealed at 800–1,200 °C for 2 h whereas the orthorhombic barium iron oxide BaFe₂O₄ phase was formed as a impurity phase with barium M-type ferrite at Fe³⁺/Ba²⁺ molar ratio 8. On the other hand, a single phase of strontium hexaferrite was produced with the Fe³⁺/Sr²⁺ molar ratio to 12 at the different annealing temperatures from 800 to 1,200 °C for 2 h whereas the orthorhombic strontium iron oxide Sr₄Fe₆O₁₃ phase was formed as a secondary phase with SrFe₁₂O₁₉ phase at Fe³⁺/Sr²⁺ molar ratio of 9.23. The crystallite sizes of the produced nanopowders were increased with increasing the annealing temperature and the molar ratios. The microstructure of the produced single phase M-type ferrites powders displayed as a hexagonal-platelet like structure. A saturation magnetization (53.8 emu/g) was achieved for the pure barium hexaferrite phase formed at low temperature 800 °C for 2 h. On the other hand, a higher saturation magnetization value (M _s = 85.4 emu/g) was obtained for the strontium hexaferrite powders from the precipitated precursors synthesized at Fe³⁺/Sr²⁺ molar ratio 12 and thermally treated at 1,000 °C for 2 h.     

Structure and electrical properties of Bi0.5Na0.5TiO3–Bi0.5K0.5TiO3–BiCoO3 lead-free piezoelectric ceramics

Lead-free piezoelectric ceramics (1 − x − y)Bi_0.5Na_0.5TiO₃–xBi_0.5K_0.5TiO₃–yBiCoO₃ (x = 0.12–0.24, y = 0–0.04) have been fabricated by a conventional solid-state reaction method, and their structure and electrical properties have been investigated. The XRD analysis shows that samples with y ≤ 0.03 exhibit a pure perovskite phase and very weak impurity reflections can be detected in the sample with y = 0.04. With x increasing from 0.12 to 0.24 and y increasing from 0 to 0.04, the ceramics transform gradually from a rhombohedral phase to a tetragonal phase and rhombohedral–tetragonal phase coexistence to a pseudocubic phase, respectively. The morphotropic phase boundary (MPB) of the system between rhombohedral and tetragonal locates in the range of x = 0.18–0.21, y = 0–0.03. The ceramics near the composition of the MPB have good performances with piezoelectric constant d ₃₃ = 156 pC/N and electromechanical coupling factor k _p = 0.34 at x = 0.21 and y = 0.01, which attains a maximum value in this ternary system. Adding content of BiCoO₃ leads to a disappearance of the response in the curves of dielectric constant-temperature to the ferroelectric–antiferroelectric transition. The temperature dependence of dielectric properties suggests that the ceramics are relaxor ferroelectrics. The results show that (1 − x − y)Bi_0.5Na_0.5TiO₃–xBi_0.5K_0.5TiO₃–yBiCoO₃ ceramics are good candidate for use as lead-free ceramics.     

Effects of Bi2O3 and Cr2Ti3O9 Co-doping on dielectric properties in BaTiO3-based ceramics

A microwave ceramic with general composition (1-x-y) BaTiO₃ + x Cr₂Ti₃O₉ + y Bi₂O₃ has been prepared by solid state synthesis at 1300-1400 °C. The phase composition, perovskite structural parameters and dielectric properties have been obtained by X-ray diffraction and dielectric measurements as a function of chemical composition and temperature. At low doping levels the formation of BaTiO₃-based solid solution has been found. The precipitation of BaCrO₃ has been detected at x = y = 2.0 mol%. A model of the incorporation of Cr³⁺ and Bi³⁺ ions into BaTiO₃-based crystal lattice has been proposed. Diffused phase transition in the temperature range 100-140 °C have been revealed by dielectric measurements for different ceramic composition. As high dielectric constant as 7311 and as low dielectric loss as 0.02 have been found for the composition of 0.98BaTiO₃-0.01Cr₂Ti₃O₉-0.01Bi₂O₃.     

Dielectric and piezoelectric properties of (Bi,Na,Li)TiO<Subscript>3</Subscript>–Ba(Ti,Zr)O<Subscript>3</Subscript> lead-free ceramics

The lead free ceramics of two different stoichiometric 0.9(Bi_0.5Na_0.5)TiO₃-0.1Ba(Ti_1−x Zr _x )O₃ (abbreviated as BNBTZ-100x, x = 0, 0.045, 0.050, 0.055, 0.060) and 0.9(Bi_0.5Na_0.5−y Li _y )TiO₃-0.1Ba(Ti_0.945Zr_0.055)O₃ (abbreviated as BNLBTZ-100y, y = 0, 0.015, 0.025, 0.035, 0.05, 0.075, 0.10, 0.125) compositions were prepared by the conventional ceramic fabrication technique. The crystal structure, dielectric and piezoelectric properties of the ceramics were investigated. All the ceramics formed single-phase solid solutions with tetragonal pervoskite structure, which was affected obviously by the addition of Zr and Li. The T _m of the BNBZT-100x ceramics trends to increase whereas the T _d trends to decrease as Zr content increases. And the T _d of the BNLBZT-100y increases from 107 to 157 °C when y increases from 0 to 0.015, but decreases sharply as y increases further. The d ₃₃ and k _p of the BNBTZ-100x ceramics tend to increase with the addition of Zr. The maximum values of d ₃₃ and k _p, 156 pC/N and 18.9%, are obtained when x = 0.055. The d ₃₃ of the BNLBTZ-100y ceramics keep almost unchanged when y increases from 0 to 0.035. And maximum value of k _p, 16.3%, of the BNLBTZ-100y ceramics is obtained when y = 0.015.