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Phase structure analysis and pyroelectric energy harvesting performance of Ba(Hf <sub/><i>x</i> </sub> Ti <sub/> 1 <i>-x</i> </sub> )O <sub/>3</sub> ceramics
摘要： Ba(Ti1-xHfx)O3 ceramics were synthesized by a solid-state reaction process. The evolution of the phase structure was identified by XRD spectrum, dielectric spectroscopy and temperature-dependent Raman spectroscopy for the Ba(Ti1-xHfx)O3 ceramics. In addition, pyroelectric energy harvesting properties based on the Olsen cycle were investigated for the first time. A maximum pyroelectric energy harvesting density value of ND=491.30 kJ/m3 (ΔT=120 °C, EH=50 kV/cm) was achieved in the Ba(Hf0.05Ti0.95)O3 ceramic. Compared with those of BT, the values of ND more than doubled in the temperature range from ΔT=60 °C to ΔT=100 °C in the Ba(Hf0.05Ti0.95)O3 ceramic and even increased 3.2 times at ΔT=80 °C near the Curie temperature (TC) of the Ba(Hf0.05Ti0.95)O3 sample. In addition, a larger pyroelectric energy harvesting density value of ND=367.10 kJ/m3 (ΔT=120 °C, EH=50 kV/cm) was acquired in the Ba(Hf0.12Ti0.88)O3 ceramic. Values of ND-BHT5/ND-BT and ND-BHT12/ND-BT were analyzed in the Ba(Ti1-xHfx)O3 ceramics. The optimal pyroelectric properties can be obtained in the vicinity of the ferroelectric to paraelectric phase-transition region.
关键词： Phase transition,Lead-free ceramics,Raman spectra,Ferroelectric materials,Energy harvesting
更新于2025-09-09 09:28:46
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[Ceramic Transactions Series] Proceedings of the 12th Pacific Rim Conference on Ceramic and Glass Technology (Ceramic Transactions) || Recent Topics in the Field of Ferroelectric Materials for BME-MLCCs
摘要： The present paper focuses on the recent direction of materials technology for Base Metal Electrode (BME)-Multilayer Ceramic Capacitors (MLCCs). Recently, technologies are accelerating in the area of miniaturization, high capacitance, and reduction of production cost of MLCCs, in order to meet the requirements of the electronics market. In order to maintain high capacitance values with smaller case sizes, reduction in thickness and the multiplication of the dielectric layers have been advancing. Thinning dielectric layers, however, has a deleterious effect on the dielectric performance and it is considered getting closer to dimensional limit. So far, temperature stable MLCCs of high capacitance such as X7R, X7S, and X7T specifications in EIA-STD have been employing BaTiO3 based ferroelectric materials. In the case of BaTiO3 based ferroelectrics, X8R characteristics may be a limit for temperature stable MLCCs, because Curie temperature of BaTiO3 is around 120-130oC. Under these circumstances, numerous studies have been devoted to ferroelectric materials such as giant dielectric constant (K) materials, high TC materials of high K, and high withstanding voltage materials. In this paper, these challenges in the field of dielectric materials for MLCCs are reviewed, and a potential of filled tungsten-bronze-type ferroelectrics for high capacitance BME-MLCCs of X9R specification (ΔC/C25 ±15%, -55~200oC) are proposed.
关键词： BME-MLCCs,X9R specification,ferroelectric materials,tungsten-bronze-type ferroelectrics,BaTiO3
更新于2025-09-04 15:30:14
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Influence of uniaxial pressure on dielectric properties of (1- <i>x</i> )Na <sub/>0.5</sub> Bi <sub/>0.5</sub> TiO <sub/>3–</sub><i>x</i> SrTiO <sub/>3</sub> for <i>x</i> = 0.01, 0.04, and 0.1 ceramics
摘要： The conventional solid-state sintering was applied to synthesized (1-x)Na0.5Bi0.5TiO3–xSrTiO3 (x = 0.01, 0.04, and 0.1) ceramics. Dielectric measurements of these ceramics were taken in the temperature range from 20 to 600 °C, in the frequency range from 1 kHz to 2 MHz and under uniaxial pressure ranging from 10 to 1100 bar. The study of the dielectric behaviour showed that the influence of uniaxial pressure on the investigated properties was considerable. The peaks ?m gradually decreased and shifted towards lower temperatures with an increase of uniaxial pressure for all samples. The first effect developed with an increase of the strontium ion concentration. Experimental results revealed most interesting properties of the material in the context of its potential applications.
关键词： perovskite,uniaxial pressure,ferroelectric materials,dielectric spectroscopy
更新于2025-09-04 15:30:14
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Preparation and Characterization of Ba1-xSrxTiO3 by Sol-Gel Method
摘要： Barium strontium titanate (BST) with formula (Ba1-xSrxTiO3) has been synthesized by sol-gel method with different stoichiometric compositions (x = 0.3, 0.4, 0.5, 0.6). The raw materials which used to prepare compounds are (Ba,Sr) acetate as a source (Ba,Sr) and titanate isopropoxide source. The FE-SEM images showed that the particles size reduced from 464 to 13 nm when strontium concentration increased from 0.3 to 0.6. The X-ray diffraction studies have confirmed that Ba0.7Sr0.3TiO3 sample have the tetragonal phase while remaining samples have a cubic phase. The intensity of the major peaks were decreased and shifted toward higher 2θ angles when Sr2+ ions increases.
关键词： Barium strontium titanate,Curie Temperature,Ferroelectric materials,Perovskite structure
更新于2025-09-04 15:30:14