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电镜在BaTiO3晶相转化机理研究中的应用 总被引:1,自引:0,他引:1
钛酸钡是重要的铁电、压电陶瓷材料,主要用来生产高介电的陶瓷电容器等电子元件.近年来人们对该材料的合成方法及物理性质进行了较为详细的研究,出现了一些新的合成方法,如水热法等[1].目前由水热法合成电性能优异的四方相钛酸钡最引人注目,先后有人报导了在较为温和的水热条件下用不同的钡源与钛源制备出四方相BaTiO3[2,3].也有人研究了原料的钛钡比对产物晶相的影响.但关于钛酸钡从立方相到四方相转化机理方面的研究还较少见,而该方面的研究对产物电学性质的控制及工艺条件的选择具有非常重要的意义.本工作以Ba(OH)2和 Ti(OC4H9) 为原料,辅以无机矿化剂OH-,用水热法制得含量较高的四方相钛酸钡,采用电子显微方法结合其它必要的手段,初步探讨了水热条件对产物晶相的影响及晶相转化机理. 相似文献
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采用传统固相法制备Ba-B-Al-Si无碱玻璃改性0.8BaTiO_3-0.2BiYO_3(0.8BT-0.2BiY)的介电陶瓷。研究了无碱玻璃含量对0.8BT-0.2BiY陶瓷微结构和介电性能的影响,无碱玻璃的质量分数分别为x=0,0.01,0.03,0.05,0.07。研究结果表明,玻璃改性后的陶瓷,烧结温度降低,X线衍射(XRD)图谱中均出现第二相,主晶相均仍维持钛酸钡钙钛矿伪立方结构,掺杂玻璃组分的质量分数为3%时,第二相的衍射峰的强度最弱。陶瓷经无碱玻璃改性后,介电常数均减小,居里峰展宽效应减弱,铁电性增强。在玻璃的质量分数低于3%时,极化强度增大,在玻璃的质量分数为3%时最大。 相似文献
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PTC陶瓷用钛酸钡粉体材料的质量要求:《电子陶瓷用钛酸钡粉体材料规范〉… 总被引:1,自引:0,他引:1
根据我国最近制定的《电子陶瓷用钛酸钡粉体材料规范》规定的钛酸钡粉体材料预定用途和理化性能指标,评述了各种质量等级的钛酸钡粉体材料在PTC陶瓷方面的应用范围,解释了某些理化性能指标的PTC陶瓷配方设计和工艺中的实用意义。 相似文献
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根据我国最近制定的《电子陶瓷用钛酸钡粉体材料规范》规定的钛酸钡粉体材料预定用途和理化性能指标,评述了各类质量等级的钛酸钡粉体材料在PTC陶瓷方面的应用范围,解释了某些理化性能指标在PTC陶瓷配方设计和工艺中的实用意义。 相似文献
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报道了采用激光烧结技术制备锆钛酸钡(BZT)压电陶瓷的研究。用常规方法制备了锆钛酸钡粉料,采用CO2激光直接烧结锆钛酸钡坯材,最大激光功率150 W,扫描转速1440 rad/min,烧结时间10 min;对陶瓷样品介电频谱与谐振频谱的测量显示了锆钛酸钡的压电特征;比较了传统高温炉烧结与激光烧结陶瓷样品的高温介电谱线,激光烧结陶瓷样品居里温度有所提高;测得介电常数和压电常数分别为1563 pC/N和45pC/N;X射线衍射(XRD)谱图显示(111),(002)衍射峰相对强度增强;陶瓷样品表面的显微照片显示了晶粒生长的形貌。激光烧结可以作为功能陶瓷烧结的方法之一。 相似文献
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《Electron Devices, IEEE Transactions on》1969,16(6):594-597
Ferroelectric domain boundaries in "Remeika" single crystals of tetragonal barium titanate were observed by transmission electron microscopy. Both 180 and 90° walls were observed and are described with regard to appearance and motion. The 90° boundaries are discussed in greater detail with respect to their interactions and nucleation. 相似文献
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Sb掺杂BaTiO_3的电磁及微波吸收特性研究 总被引:1,自引:0,他引:1
以BaCO3、TiO2、Sb2O3为原料,采用固相法制备了Sb掺杂BaTiO3样品,借助XRD、Raman光谱以及矢量网络分析仪等分析测试手段对所制样品的晶相、晶格常数、电磁性能及微波吸收特性进行了表征。结果表明:低掺杂Sb的样品均为单一四方相BaTiO3晶体,结晶良好;随着w(Sb2O3)的增大,晶格常数减小;与未掺杂的BaTiO3相比,Sb掺杂BaTiO3的反射损耗明显提高,且反射峰向低频方向偏移;当w(Sb2O3)为0.6%时,制得BaTiO3的反射损耗在3.7 GHz处达到最大值–28.2 dB。 相似文献
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采用TiCl4和BaCl2·2H2O原料,以正丁醇为分散剂,NH4HCO3和NH3·H2O作为沉淀剂合成钛酸钡前驱体,在900 ℃煅烧制备分散性良好的钛酸钡纳米粉体.利用XRD、透射电镜(TEM)和 SEM等手段分析了反应温度、TiCl4浓度、分散剂掺杂量等反应参数对粉体的晶相组成、晶粒度、形貌等的影响,并且测试了相应陶瓷烧结体的介电常数.结果表明,反应温度为900 ℃,TiCl4浓度为0.6 mol/L,分散剂用量为3‰条件下,保温2 h可制备高分散性的纳米级粉体.用以上方法制备的粉体烧结而成的陶瓷片介电常数约为3 400. 相似文献
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微波液相合成钛酸锶钡纳米粉体 总被引:1,自引:0,他引:1
以BaCl2、TiCl4为原料,以NaOH为沉淀剂,利用微波加热技术在低温下快速制备出了Ba0.8Sr0.2TiO3纳米粉体.应用X衍射、透投射电镜、X-射线荧光分析等对粉体的结构、形貌进行了分析.研究表明,在约80 ℃,5~10 min内即制备出颗粒大小分布均匀、粒径在50 nm的高纯BST纳米粉体,该方法合成粉体属于立方相钙钛矿晶体结构,粒子形状近似为球形.粉体的杂质含量小于电子工业行业标准. 相似文献
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A powder-filled rectangular groove in the surface of a plastic substrate has been demonstrated as a dielectric waveguide at 94 GHz. Propagation losses as low as 0.09 dB/cm were measured by direct transmission with nickel-aluminum titanate powder in a polypropylene substrate and with barium tetratitanate powder in a polytetrafluoroethylene (PTFE) substrate; values as low as 0.06 dB/cm were deduced from ring resonator measurements. Guide wavelengths measured for various combinations of guide dimensions, powders, and substrates agree within 10% with values predicted by the approximate theory of Marcatili for the E11y mode. Effective loss tangents for the powders at 94 GHz were calculated from waveguide attenuation measurements, using Marcatili's field solutions. Ring resonators fabricated by filling a groove in a polypropylene substrate with nickel-aluminum titanate powder exhibit Q's as high as 2400 at 94 GHz in an 8 cm diameter ring. Coupling to the resonators was achieved with adjacent straight powder core channel guides as directional couplers 相似文献
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The electronic and optical properties of tetragonal barium titanate (BaTiO3) have been investigated by use of first-principles density functional theory on a plane wave basis, by use of norm-conserving pseudopotentials in the localized density approximation. For accuracy, experimental lattice parameters reported in the literature were used. The band structure, total and partial density of states (DOS), and Born effective charges of tetragonal BaTiO3 were obtained from first-principles calculations. The partial DOS and Born effective charges indicate that the Ti–O bonds are partially covalent and the Ba–O bonds are partially ionic. The complex dielectric functions for ordinary and extraordinary optical polarization were calculated, and were in reasonable agreement with those from previous first-principles calculations. The refractive index, extinction coefficient, reflectivity, and energy-loss spectrum for both types pf polarization were calculated from the complex dielectric function; the results obtained were an improvement on other published results. 相似文献