High-Performance BaTiO3 Film Based on Aqueous Tape Casting for Ultrathin MLCC Applications

Environment-friendly aqueous tape-casting are proposed as an inevitable tendency for producing a high-quality BaTiO3-based film in the development of ultra-thin multilayer ceramic capacitors. In this study, aqueous BaTiO3 suspension with high solids loading produced by using polycarboxylate ammonium salt APC (dispersant), proprietary acrylic formulation binder solution WB4101 (binder), and acrylic resin PL002 (plasticizer), respectively. It is demonstrated that the green density, tensile strength, and strain at failure of the 9.5-μm-thin BaTiO3 tape achieves 3.65 g/cm3, 7.65 MPa, and 11%, respectively. In particular, the capacitance and dielectric loss of BaTiO3-based MLCC chips at room temperature are found to be approximately 28 nF and 0.02 compatible with Pt electrodes. Additionally, the TCC, ferroelectric hysteresis loops, change of dielectric constants versus DC-BIAS field, and evolution of electrical resistivity under accelerated DC stressing of BaTiO3-based MLCC are studied. The results provide an effective method for the future improvement in aqueous MLCC applications.

Perovskite Ferroelectric

The spectrums of properties exhibited by ferroelectric materials are dielectric, ferroelectric, piezoelectric and pyroelectric effect. This is the makes these materials to have a wide range of useful application. Infrared detectors are used pyroelectric effect of ferroelectric materials. It is used in nonvolatile memories due to have ferroelectric hysteresis. Its piezoelectric properties make them useful for actuator, radio frequency filter, sensor, and transducer. Ferroelectric capacitors are used, their good dielectric behavior. According to the necessity of the system they are available in different form such as single crystals, ceramics, thin film, and polymer, composite. The diversity of properties ferroelectric materials always attracted the attention of engineers and researchers. Size reduction of this material from micro to nanoscale established an enormous consideration to develop nanotechnology. Its vast use of different filed imposed the in detail research in adding to the development of processing and characterization method. This chapter will put some light on some fundamental principle of ferroelectricity, the list of perovskite materials and their application.

Pure PZT95/5 ceramics and its phase transition behavior under external fields

Background: Compositionally modified Pb(Zr0.95Ti0.05)O3 (PZT 95/5) ferroelectric materials are extensively investigated in past decades for many important applications. However, few pure PZT95/5 ceramics were reported. Objective: Herein, pure PZT95/5 ceramics were successfully prepared and their microstructure, phase transition behaviors under external fields were studied. Method: Pure PZT95/5 ceramics were prepared by conventional solid state reaction using a mixed oxide route. The microstructure and its properties under different external fields were measured. Results: The X-ray diffraction patterns indicate that the virgin pure PZT95/5 ceramics exhibit an orthorhombic antiferroelectric phase, also evidenced by the superlattice reflections in SAED pattern. While a rhombohedral ferroelectric symmetry crystal structure was observed in the pooled samples suggesting that an electric field induced antiferroelectric to ferroelectric phase transition occured. Pure PZT95/5 ceramics exhibited a quenched ferroelectric hysteresis loop with a remnant polarization of ~8μC/cm2 under 3.5kV/mm. Temperature dependence dielectric response indicated that orthorhombic antiferroelectric to cubic paraelectric phase transition occured at 225oC, corresponding to its Curie temperature. A shard depolarization behavior and dielectric anomalies were observed under ~240 MPa hydrostatic pressure. Conclusions: The depolarization mechanism of pure PZT95/5 ceramics under hydrostatic pressure is attributed to the hydrostatic pressure induced FE-AFE phase transition. These results will offer fundamental insights into PZT95/5 ceramics for pulsed power supply applications.

Influence of CuO addition on dielectric and piezoelectric properties of (Bi0.5Na0.5)TiO3–BaTiO3lead-free piezoceramics

Doping effects of CuO on the sintering behavior and electrical properties of 0.94(Bi[Formula: see text]Na[Formula: see text]TiO3–0.06(BaTiO[Formula: see text]–[Formula: see text]CuO (BNT–BT6–[Formula: see text]Cu) lead-free piezoceramic obtained by the conventional solid-state reaction method were investigated. Regarding the undoped system, it is already known that it presents the best densification values when it is sintered at 1150[Formula: see text]C, however, the doped system was sintered at 1150[Formula: see text]C, 1100[Formula: see text]C, 1050[Formula: see text]C, 1025[Formula: see text]C, and 975[Formula: see text]C to determine the effect of Cu on the densification process. Therefore, it was obtained that the CuO-doped samples sintered at 1050[Formula: see text]C presented the highest density values and therefore were the ones chosen to perform the characterization tests together with the undoped system. The samples were characterized using X-ray diffraction (XRD), Raman microspectroscopy, and scanning electron microscopy (SEM) analysis, whereas the ferroelectric and dielectric properties were evaluated by means of ferroelectric hysteresis loops and impedance spectroscopy studies. As a result, the addition of CuO allowed an improvement in sinterability and densification, with the subsequent grain growth, and the improvement of the piezoelectric coefficient ([Formula: see text].

Hafnium Zirconium Oxide Thin Films for CMOS Compatible Pyroelectric Infrared Sensors

Pyroelectric infrared sensors are often based on lead-containing materials, which are harmful to the environment and subject to governmental restrictions. Ferroelectric Hf1−xZrxO2 thin films offer an environmentally friendly alternative. Additionally, CMOS integration allows for integrated sensor circuits, enabling scalable and cost-effective applications. In this work, we demonstrate the deposition of pyroelectric thin films on area-enhanced structured substrates via thermal atomic layer deposition. Scanning electron microscopy indicates a conformal deposition of the pyroelectric film in the holes with a diameter of 500 nm and a depth of 8 μm. By using TiN electrodes and photolithography, capacitor structures are formed, which are contacted via the electrically conductive substrate. Ferroelectric hysteresis measurements indicate a sizable remanent polarization of up to 331 μC cm−2, which corresponds to an area increase of up to 15 by the nanostructured substrate. For pyroelectric analysis, a sinusoidal temperature oscillation is applied to the sample. Simultaneously, the pyroelectric current is monitored. By assessing the phase of the measured current profile, the pyroelectric origin of the signal is confirmed. The devices show sizable pyroelectric coefficients of −475 μC m−2 K−1, which is larger than that of lead zirconate titanate (PZT). Based on the experimental evidence, we propose Hf1−xZrxO2 as a promising material for future pyroelectric applications.

Humidity Effects on Domain Structure and Polarization Switching of Pb(Zn1/3Nb2/3)O3-x%PbTiO3 (PZN-x%PT) Single Crystals

The effect of relative humidity on the domain structure imaging and polarization switching process of Pb(Zn1/3Nb2/3)O3-x%PbTiO3 (PZN-x%PT) ferroelectric single crystals has been investigated by means of the piezoresponse force microscopy (PFM) and piezoresponse force spectroscopy (PFS) techniques. It was found that the PFM amplitude increases with the relative humidity, and that the ferroelectric hysteresis loops at different relative humidity levels show that the coercive bias decreases with the increase in relative humidity. These observed phenomena are attributed to the existence of the water layer between the probe tip and the sample surface in a humid atmosphere, which could affect the effect of the electric field distribution and screening properties at the ferroelectric sample surface. These results provide a better understanding of the water adsorption phenomena at the nanoscale in regard to the fundamental understanding of ferroelectrics’ properties.

Structural, Electrical, Magnetic and Optical Properties of BaTi1-x(Ni1/2Nb1/2)xO3 Ceramics

In this work, we have investigated the structural, electrical, magnetic and optical properties of Ni-Nb co-doped BaTiO3 ceramics. The compositions of BaTi1 − x(Ni1/2Nb1/2)xO3 were prepared through conventional solid-state reaction method. All the samples exhibit a gradual phase transition behavior from the tetragonal to a cubic structure with the increase of Ni-Nb co-doping concentration. The temperature dependence of the dielectric constant reveals that the transition temperature gradually decreased with an increase in Ni2+ and Nb5+ concentrations. The ferroelectric studies show these doping samples have relatively full ferroelectric hysteresis loops at room temperature, but exhibit a decreasing ferroelectric property with the increasing level of doping. The magnetic measurement suggests that these samples have ferromagnetic ordering at room temperature with an increase in the Ni-Nb doping. Moreover, band gaps of these samples are obviously reduced through the strategy of co-doping.