The Effect of PVA Binder Solvent Composition on the Microstructure and Electrical Properties of 0.98BaTiO3-0.02(Ba0.5Ca0.5)SiO3 Doped with Dy2O3

In this study, the effect of the polyvinyl alcohol (PVA) binder solvent composition on the electrical properties of sintered 0.98BaTiO3-0.02(Ba0.5Ca0.5)SiO3 ceramics doped with x wt.% Dy2O3 (0.0 ≤ x ≤ 0.3) was investigated. In the absence of the PVA binder, the specimens sintered at 1260 and 1320 °C for 1 h in a reducing atmosphere showed a single BaTiO3 phase with the perovskite structure. The relative densities of the specimens were higher than 90%, and the grain morphologies were uniform for all the solvent compositions. At 1 kHz, the dielectric constant of the specimens depended not only on their crystal structural characteristics, but also on their microstructural characteristics. The microstructural characteristics of the specimens with the PVA binder were affected by the ethyl alcohol:water ratio of the 10 wt.% PVA-111 solution. A homogeneous microstructure was observed for the 0.1 wt.% Dy2O3-doped specimens sintered at 1320 °C for 1 h when the ethyl alcohol/water ratio of the binder solution was 40/60. These specimens showed the maximum dielectric constant (εr = 2723.3) and an insulation resistance of 270 GΩ. The relationships between the microstructural characteristics and dissipation factor (tanδ) of the specimens were also investigated.

Dielectric Properties of BaTiO3–Epoxy Nanocomposites in the Microwave Regime

We synthesized BaTiO3–epoxy nanocomposites (particle size < 100 nm) with volume fractions up to 25 vol. %, whose high-frequency complex permittivity was characterized from 8.2 to 12.5 GHz. The maximum dielectric constant approaches 9.499 with an acceptable loss tangent of 0.113. The dielectric loss gradually saturates when the particle concentration is higher than 15 vol. %. This special feature is an important key to realizing high-k and low-loss nanocomposites. By comparing the theoretical predictions and the experimental data, four applicable effective-medium models are suggested. The retrieved dielectric constant (loss tangent) of 100-nm BaTiO3 nanopowder is in the range of 50–90 (0.1–0.15) at 8.2–12.5 GHz, exhibiting weak frequency dispersion. Two multilayer microwave devices—total reflection and antireflection coatings—are designed based on the fabricated nanocomposites. Both devices show good performance and allow broadband operation.

Sintesis Ferroelektrik BaZrxTi1-xO3 Dengan Variasi Zirkonium Terhadap Struktur Kristal dan Konstanta Dielektrik

This study aims to determine influence addition Zr against the crystal structure and dielectric constant; and to know the influence of variations temperature sintering on addition mole Zr. Barium Zirconium Titanate (BaZrxTi1-xO3) have been made with variation zirconium (Zr) 1%, 5%, 10%, and 20% by solid state reaction method, that is blanded BaTiO3, TiO2 and ZrO2 powder. BaZrxTi1-xO3 powder is printed with die pressing and press hidrolik, then the samples were sintered by furnace at 900oC and 1000oC with holding time 2 hours. Characterization of samples use X-Ray Diffraction and Resistance Capacitance Inductance (RCL meter). Based on result obtained, the larger Zr content cause dielectric constant decreasing because crystal structure have been change from tetragonal (Zr = 1% and 5%) to cubic (Zr = 10% and 20%). The result from X-Ray Diffraction already match with data base ICDD no#360019. Measurement of dielectric constant (K) performed in the frequency range 1 kHz to 100 kHz and the highest value at Zr content 1%, because The dielectric constant decreasing with the larger Zr content. The maximum dielectric constant is obtained at mol Zr 5% and sintering temperature 1000oC, that is 150. The minimum dielectric constant is obtained at mol Zr 20% and sintering temperature 900oC, that is 62.

Structural, Phase Transition, Morphological, Optical and Dielectric Properties of Lead Free(1-x)(Na0.99K0.01)(Nb0.95Sb0.05)O3-xBaTiO3 Solid Solutions

In this work, lead free (1-x)(Na0.99K0.01)(Nb0.95Sb0.05)O3-xBaTiO3, where x=0.1, 0.2 ceramic solid solution systems were prepared via solid state sintering method. X-ray diffraction (XRD) reveals that the influence of Ba2+ on crystal structure of the NKNS-xBT (x=0.1, 0.2) solid solutions. PXRD analysis showed that Ba2+ addition into NKNS ceramics caused significant change in crystal symmetry from tetragonal to cubic. The surface morphology of the prepared ceramics were determined by scanning electron microscopic (SEM) measurements and revealed that the uniform distribution of grains. Energy band gap were determined by UV-visible absorption spectrophotometer. Dielectric measurements show the maximum dielectric constant (ε~3044) and temperature (Tm~120°C) at 1 kHz.

Investigation of Structural, Dielectric and Electrical Properties of Barium Titanate Ceramics Co-Doped with Bismuth and Yttrium

Bismuth and Yttrium co-doped Barium Titanate (BaTiO3) ceramics with the general formula (Ba[Formula: see text]BiX) (YxTi[Formula: see text]) O3 (where [Formula: see text], 0.01, 0.03, 0.05) have been synthesized at 1300∘C for 3[Formula: see text]h by the standard solid-state reaction method. The prepared samples were characterized by X-ray diffraction (XRD), Scanning Electron Microscope (SEM) and Impedance Analyzer. Temperature-dependent dielectric properties of the samples were also measured. The XRD result revealed perovskite structure for un-doped and co-doped BaTiO3 with tetragonal phase. However, with increasing doping concentration, a Pseudo cubic phase occurs also confirmed by the twin peaks (002) and (200) of XRD pattern. From SEM micrograph, submicron size particles were observed for all synthesized BaTiO3 samples and exhibit a narrow size distribution with quiet uniform morphology. The crystalline size for un-doped BaTiO3 found was 24.26[Formula: see text]nm, the size decreases (minimum 19.59[Formula: see text]nm for [Formula: see text]) for all compositions of co-doped BaTiO3. Dielectric constant values were apparently high and direct current (DC) resistivity follows a decreasing trend at higher doping concentration. The sample doped with [Formula: see text] shows minimum DC resistivity and maximum dielectric constant among the samples investigated.

Effect of Sintering Temperature on Mechanical and Electrical Properties of Lead-Free Bi0.5(Na0.4K0.1)Ti0.98Zr0.02O3 Piezoelectric Ceramics

Effect of sintering temperatures on phase formation, mechanical and electrical properties of lead-free Bi0.5(Na0.8K0.2)0.5Ti0.98Zr0.02O3 or BNKTZ piezoelectric ceramics were investigated. The BNKTZ ceramics were prepared via a conventional solid-state sintering technique under various sintering temperature range 1100-1150°C for 2 h. The phase formation and microstructure of the ceramics were examined using X-ray diffraction (XRD) and scanning electron microscopy (SEM) method, respectively. XRD analysis indicated that all samples exhibited a single perovskite structure and no secondary phase. SEM microscopy study revealed an increase in grain size with increasing sintering temperature. The maximum values of density and maximum dielectric constant of the ceramics sintered at 1125 °C were 5.79 g/cm3 and 3446, respectively. In addition, the ceramics sintered at 1125 °C showed highest mechanical properties (HV = 4.32 GPa, HK = 5.87 GPa, E = 143 GPa and KIC = 1.30 MPa.m1/2). The highest values of ferroelectric and piezoelectric were found at this sintering temperature.

Mechanical and Electrical Properties of La3+ Modified BNKZT Ceramics

In this work, Bi0.5-xLaxNa0.4K0.1Zr0.02Ti0.98O3(wherex= 0, 0.01, and 0.03 mol%) ceramics were prepared by conventional solid-state sintering method, sintered in air at l125°C for 2 h. The mechanical and electrical properties of the sintered ceramic with different La-doping were investigated. The crystalline structure of all ceramics was assessed by X-ray diffraction (XRD) method. Other physical and mechanical properties, i.e. density, porosity, shrinkage, Vickers (HV) and Knoop hardness (HK), and electrical properties were determined. XRD patterns for all samples exhibited a pure perovskite, where coexistence between tetragonal and rhombohedral phases was observed for some composition. The maximum dielectric constant at room temperature was obtained forx= 0.03 ceramic. In addition, the piezoelectric properties were improved and showed the highestd33,Smaxandd*33values of 189 pC/N, 0.28% and 560 pm/V, respectively forx= 0.01 composition. Furthermore, the optimum values of hardness were observed at this composition.

Structure, dielectric properties of low-temperature-sintering BaTiO3-based glass–ceramics for energy storage

The 0.85BaTiO3–0.15Bi(Mg[Formula: see text]Nb[Formula: see text])O3 (BTBMN) ceramics with low-melting-temperature B2O3–Na2B4O7–Na2SiO3 (BNN) glass addition were prepared by the solid state method. The composition of the glass–ceramics was BTBMN–[Formula: see text] wt.% BNN ([Formula: see text], 1, 3, 5, 7, 9, 12, 15; abbreviated as BG). The sintering characteristics, phase structure, microstructure, dielectric properties and energy storage properties were systematically investigated. The sintering temperature of BTBMN ceramics was greatly reduced by the addition of BNN glass. The second-phase BaTi(BO[Formula: see text] was observed in the BG system until the glass content reached 15[Formula: see text]wt.%. The addition of BNN glass significantly reduces the grain size of BTBMN ceramics. With the increase of BNN glass content, dielectric constant of BG glass–ceramics at 1[Formula: see text]kHz gradually decreased, the maximum dielectric constant ([Formula: see text] of BG glass–ceramics gradually decreased, while the temperature corresponding to the maximum dielectric constant ([Formula: see text] increased, the ferroelectric relaxation behavior decreased and the temperature stability of the dielectric constant gradually improved. As the BNN glass content increased, the breakdown electric field strength (BDS) of BG glass–ceramics increased first and then decreased, and the polarization values reduced gradually, while the trend of energy storage performance is similar to BDS. When the BNN glass content was 3[Formula: see text]wt.%, the energy storage properties of the BG glass–ceramics were optimal, and a recoverable energy storage density ([Formula: see text]) of 1.26[Formula: see text]J/cm3 and an energy storage efficiency ([Formula: see text]) of 80.9% were obtained at the electric field strength of 220[Formula: see text]kV/cm. The results showed that BG glass–ceramics were promising for energy storage capacitors.

Effects of Sintering Temperatures on Structural, Electrical and Mechanical Properties of BNKT Piezoelectric Ceramics

This research investigated the effects of sintering temperatures on the structural, dielectric, ferroelectric, piezoelectric and mechanical properties of lead-free Bismuth Sodium Potassium Titanate (BNKT) piezoelectric ceramics. The BNKT ceramics were prepared by solid-state mixed oxide method and sintering at temperature ranging from 1100 to 1150°C for 2 h. All ceramics sample showed highly density and reach a maximum at sintering temperature 1125°C of 5.81 g/cm3. X-ray diffraction patterns exhibited pure perovskite structure with coexisting of rhombohedral-tetragonal phases for all compositions. The microstructure was characterized by Scanning Electron Microscope (SEM), from SEM image the ceramics showed cubic-like grain shape. The average grain size increased with increasing sintering temperature. The dielectric permittivity showed the optimum sintering at 1125°C with reach a maximum dielectric constant of 4,194. Furthermore, at sintering temperature 1125°C present highest strain (Smax = 0.14%) with a large normalized strain coefficient (d*33 = Smax/Emax) of 233 pm/V.

Structural and electrical characterization of La3+ substituted PMS-PZT (Zr/Ti:60/40) ceramics

Pb(1-x)Lax [(Zr0.6Ti0.4)(1-x)(Mn1/3Sb2/3)x]O3 ceramics with x = 0.02, 0.03, 0.04, and 0.05 were synthesized by using a conventional solid state reaction route. The influence of La, Mn, and Sb contents on phase structure, microstructure, and electric properties were investigated. The results of X-ray diffraction (XRD) show that the phase structure of the ceramics transforms from rhombohedral phase to tetragonal phase. However, the minority pyrochlore phase appears on the micrographs of XRD and SEM if the doping concentration is greater than 2 mol%. The grain size of the ceramics gradually increases (from 1.36 μm to 1.57 μm) with increasing doping. The dielectric properties of the ceramics have been measured as a function of temperature in the range of 20 °C to 430 °C at 1 kHz. The results indicate that the transition temperature and the maximum dielectric constant decrease with increasing PL-PMS content in the system. These results clearly show the significance of PL-PMS in controlling the dielectric behavior of the PL-PMS-PZT system.