Dielectric,ferroelectric, and piezoelectric properties of lead-free Ba0.95Ca0.05Ti1-xZrxO3 ceramics

Abstract

Ba_0.95Ca_0.05Ti_1-xZr_xO₃ (BCTZO) ceramics were prepared by a solid state reaction method. The samples were characterized by X-ray diffraction (XRD), Scanning electron microscopy (SEM) and X-ray absorption near edge structure (XANES). The ceramics exhibit a pure perovskite structure. The average grain size gradually decreases with increasing Zr concentration. XANES results indicate that the intensities of pre-edge peaks dropped with increasing Zr concentration. The BCTZO ceramic of x?=?0.05 has the optimum electrical properties with the maximum dielectric constant (ε'_m), remanent polarization (2P_r), coercive electric field (2E_c) and piezoelectric charge constant (d₃₃) of 7,244, 12.54 (μC/cm²), 5.29 (kV/cm) and 288 (pC/N), respectively.     

BaxSr（1—x）TiO3多层膜椭偏光谱研究

用溶胶－凝胶技术在Bi(100）衬底上制备了单层和渐变型多层的BaxSr(1-X)TiO3薄膜，其膜层组分分别为：Ba0.7Sr0.3TiO3,Ba0.8Sr0.2TiO,Ba0.9Sr0.1TiO3,BaTiO3，对生长制备出的多层BaxSr(1-X)TiO3薄膜进行了变角度椭偏光谱测量，通过椭偏光谱解谱分析研究，首次得到了BaxSr(1-X)TiO3多层膜结构不同膜层的膜厚和光学常数，其结果显示：椭偏光谱分析得到的不同膜层的膜厚与卢瑟福背向散射测量得到的结果基本相符；渐变型多层膜中BaTiO3薄膜的折射率比单层BaTiO3薄膜折射率大许多，与体BaTiO3的折射率相接近，这说明渐变型多层膜中BaTiO3薄膜的光学性质与体材料的光学性质接近。     

含钡合金的生产及其对钢液脱氧行为的研究

介绍了含钡合金的生产状况。在MoSi2炉上对钢管钢进行了含钡合金脱氧行为的研究，然后在150tLF／VD精炼设备上进行了使用含钡合金的工业试验。研究中主要选取SiAlBa、SiCaBa、SiAlBaCa、SiAlBaCaSr及用于钙处理的SiCa包芯线，并选用Al和FeSiAl作为对比脱氧剂，分别考察了实验室条件下和实际生产过程中，采用钡系合金对钢液脱氧的全氧含量，脱氧产物的分布、尺寸和形貌，探讨了钡系合金脱氧和对夹杂物的变质作用的机理。     

ICP-AES法测定硅铝钡合金中的钡

介绍ICP—AES法测定硅铝钡中的钡的分析方法，用氢氟酸一硝酸一高氯酸混合酸溶解试样，用钡的233．527nm谱线测定钡．该方法简便快速，精密度好，准确度高，加标试验回收率为99％～100％，相对标准偏差为0．25％～0．56％．     

含钡合金在钢液中的脱氧行为研究

在MoSi2炉上采用MgO质坩蜗对钢管进行了含钡合金脱氧行为的研究。实验中钡系合金主要选取SiAUBa、SiCaBa、SiAlBaCa、SiAlBeCaSr及用于钙处理的SiCa包芯线，选用Al作为对比脱氧剂，考察了钡系合金脱氧的全氧含量，脱氧产物的分布、尺寸和形貌，探讨了钡系合金脱氧和对夹杂物变性作用的机理。     

高Q Ba(Zn_(1/3)Ta_(2/3))O_3介质谐振器材料及其在毫米波系统中的应用

叙述了Ｂａ（Ｚｎ１／３Ｔａ２／３）Ｏ３介质谐振器材料的制备、结构、微波性能及典型应用。Ｂａ（Ｚｎ１／３Ｔａ２／３）Ｏ３介质材料介电常数εｒ为２９．５，频率温度系数τ≈０（－５５～＋８５℃），１０ＧＨｚ下最大无载Ｑ值１４７００，在２８ＧＨｚ测得Ｑ值约为４８００。这种材料具有高Ｑ值，特别适用于Ｘ以上波段作为振荡器电路中频率稳定元件。用这种介质谐振器已研制出８ｍｍ介质稳频微带耿氏振荡器，频率稳定度小于１０×１０－６／℃，最大输出功率达１８０ｍＷ。     

BaTiO_3粉体中Ti/Ba比分析方法的比较

提出了用ＫＯＨ熔融分解ＢａＴｉＯ３粉体〔１〕，再用浓ＨＣｌ酸化后，用感应耦合等离子体发射光谱法（ＩＣＰ—ＡＥＳ法）测定试样中的Ｔｉ／Ｂａ比，并与化学分析法的结果作了比较，显示出ＩＣＰ—ＡＥＳ法简便，快速，结果更好。     

Role and distribution of different Ba-containing phases in supported Pt–Ba NSR catalysts

Pt–Ba/MeO (where MeO = Al₂O₃, CeO₂, SiO₂ and ZrO₂) NO _x storage-reduction catalysts with Ba-loading varying from 0 wt.% to 28 wt.% were investigated concerning stability of Ba phases and NO _x storage-reduction efficiency. For Pt–Ba/Al₂O₃ three different Ba-containing phases with different thermal stability are distinguished based on their interaction with the support. The relative concentration of these phases varies with the Ba-loading and NO _x storage tests indicated that the BaCO₃ phase decomposing between 400 °C and 800 °C (LT-BaCO₃) is the most efficient Ba containing phase for NO _x storage. Similar investigations of Pt–Ba catalysts supported on CeO₂, SiO₂ and ZrO₂ showed that the relative amount of LT-BaCO₃ phase depends also on the support material. NO _x storage measurements confirmed a correlation between the concentration of LT-BaCO₃ and NO _x storage efficiency. Basicity and textural properties of the support are identified as crucial parameters for efficient NO _x storage catalysts.     

Comparison of ISO 14902:2001 with AOCS Ba 12a-2020 for determining trypsin inhibitor activity in protein products

For measuring trypsin inhibitor activity (TIA), there are two major official methods: American Oil Chemists Society (AOCS) method Ba 12a-2020 and International Organization for Standardization (ISO) 14902:2001. The former was recently approved. The two methods differ in sample preparation, extraction, colorimetric assay systems and TIA calculations. In this study, the two methods were symmetrically compared using three unique sets of samples: assorted protein products of soybeans, pulses, and grains; soybeans boiled for varied durations; and soy white flakes toasted for varied durations. For given samples, significant differences existed in TIA measured by the two methods, resulting from effects related to the assay systems and TIA calculations, not from the difference in sample preparation and extraction. When the same trypsin was used, TIA (in mg trypsin inhibited/g sample) measured by the two methods were highly correlated (r = 0.9973, n = 27), giving an equation of y = 0.5464x − 0.4887, where y represents ISO values and x for AOCS values. The line connecting ratios of ISO/AOCS in TIA and AOCS values remained relatively flat around 0.53 but started to curve down when TIA approached the lowest. Furthermore, for the same samples, TIA values measured by the ISO method decreased with increasing specific activity of trypsin used, while AOCS values remained consistent, leading to decreasing ratios of ISO/AOCS. Therefore, accurate and direct comparison of the two methods was impossible. It could not be resolved by simply changing ISO method's calculations as hypothesized earlier. Regardless, for most samples, ISO values were roughly about 55% of AOCS values.     

Effects of B2O3-SiO2 doping on electrical properties of Ba0. 65 Sr0. 35 TiO3 ceramics

Ba0. 65 Sr0. 35 TiOa ceramics doped with B2O3-SiO2 glass composition were prepared by using conventional solid-state reaction method. The effects of glass dopant on the dielectric and ferroelectric properties were investigated. The results show that the dielectric constant decreases while the dielectric loss increases after doping. And as the glass content increases the dielectric constant decreases while the dielectric loss changes slightly. From the complex impedance analysis the resistance and the relaxation time of the grain and the grain boundary can be calculated.Comparing the P--E hysteresis loop of undoped Ba0.65 Sr0.35 TiO3 ceramics with that of B2O3-SiO2 doped Ba0.65 Sr0.35 TiO3 ceramics, it can be seen that the remanent polarization decreases when the B2O3-SiO2 content is lower than 8% (molar fraction), and the coercive field increases with the increase of B2O3-SiO2 content.