BSTO/RO铁电移相材料的介电性能及应用探讨

采用固相反应法制备了不同组分钛酸锶钡/轻金属或稀土氧化物(BSTO/RO)铁电移相材料。研究了该系材料的介电性能。结果表明:对于Ba0.6Sr0.4TiO3/质量分数为60%RO材料,1MHz下,εr为119,tanδ为0.001;3.37GHz下,εr为110,tanδ为0.004。3×103V/mm偏置场强下,介电调谐率η为12.8%。材料的介电性能基本上达到了相控阵移相器的使用要求。     

Fe_2O_3掺杂的BST/MgO铁电移相器材料

采用传统陶瓷工艺制备了Fe2O3掺杂BST/MgO铁电陶瓷材料。研究了Fe2O3掺杂量对该复合体系εr、tanδ等参数的影响。结果表明,适量的掺杂能有效改善体系的电性能。控制掺杂量x(Fe2O3)为0.1%,陶瓷介质在微波频段(S波段)的εr为100.5;tanδ约为5.3×10–3;4000V/mm偏压下的调谐性可达14.2%。采用极化理论对掺杂机理进行了探讨。     

BSTO移相器材料结构与温度特性的研究

为了改进BSTO/MgO系铁电移相材料的电学性能,研究了在同等掺杂条件下,调节Ba1–xSrxTiO3中各成分的配比,即改变x的取值对材料结构及温度特性的影响。实验表明:当x=0.45时,BSTO/MgO系统在10kHz下,εr=84.45;tanδ=3.4×10–3;可调率为11.01%(5kV/mm)。3.5GHz下,εr=87.01,tanδ=4×10–3,并具有相对较好的温度稳定性,在–20~+40℃下αεr=–0.482×10–2/℃,可调率温度系数为–0.836×10–2/℃。     

玻璃–氧化硅复合基板材料的制备及性能

以低相对介电常数的硼硅酸盐玻璃粉末和氧化硅粉末为原料,制备了玻璃–氧化硅复合材料。研究了烧结温度和氧化硅含量对复合材料的电学性能和力学性能的影响。结果表明,当氧化硅质量分数为45%时,玻璃–氧化硅复合材料经840℃、2h的烧结后,其εr为3.8,tanδ为4×10–4,ρv为9.8×1011?·cm,抗弯强度σ为30MPa。另外,该复合材料在100~500℃之间的热膨胀系数为(8.0~10.0)×10–6℃–1。     

ZnO对钙长石/莫来石复合材料性能的影响

以钙长石和莫来石等为主要原料,制备了与硅芯片相匹配的新型复合材料。研究了烧结助剂ZnO的加入量、烧结温度和显微结构等因素对材料性能的影响。结果表明:当w(ZnO)为8%时,该复合材料烧结温度为1000℃,其主要性能如下:在1MHz下εr为6.48,tanδ为4.00×10–3,抗折强度为76.29MPa,αl(25~500℃)为3.44×10–6℃–1。     

镁铝硅钛铈系微晶玻璃的显微结构及介电性能

选取工业纯原料,采用熔融法制备了镁铝硅钛铈系微晶玻璃,研究其在不同晶化温度下的显微结构及微波介电性能。结果表明:随着晶化温度的提高,微晶玻璃的εr先增大后减小,在1000℃时达到最大值;同时微晶玻璃中晶粒逐渐长大,残余玻璃相减少,tanδ降低;当晶化温度超过1200℃时,晶粒粗化,tanδ略有升高。所制微晶玻璃在微波频率(8GHz)下,其εr在8.55~14.61可调,tanδ小于8×10–4,是一种性能优良的微波介质材料。     

耐高温BNT-BT陶瓷电容器的制备及性能研究

采用氧化铋、碳酸钠、二氧化钛和钛酸钡为原料,制备了0.05Na0.5Bi0.5TiO3-0.95BaTiO3(BNT-BT)二元体系陶瓷。研究了BiNbO4和Nb2O5掺杂量对BNT-BT陶瓷的介电性能和容温变化率的影响。结果发现,对BNT-BT陶瓷掺杂摩尔分数为3.0%的BiNbO4和4.0%的Nb2O5时,获得了在–55~+200℃容温变化率都在±15%以内,且常温1 kHz下εr为1 297,tanδ为1.25×10–2的高稳定性、高性能MLCC。     

[(Na_(0.97-x)K_xLi_(0.03))_(0.5)Bi_(0.5)]TiO_3无铅压电陶瓷的性能研究

采用传统电子陶瓷工艺,制备了多重离子A位复合的、具有钙钛矿结构的新型压电陶瓷材料[(Na0.97-xkxLi0.03)0.5Bi0.5]TiO3(其中x为0.10,0.15,0.20和0.25),研究了该陶瓷的相结构与介电铁电性能。结果表明,随着K+含量的增加,材料的晶粒尺寸明显细化,εr也随之增加,tanδ先降低后增加,其弥散性指数均介于1.7～1.9。在x为0.25时,材料为两相共存结构,其εr峰值达到2353.22,tanδ仅为0.058,d33达到80pC/N,Ec为1.71×103V/mm,表现出优异的介电和压电性能。     

TiO_2掺杂量对PTFE/SiO_2复合材料性能的影响

采用新型化学工艺,制备了SiO2与TiO2共同填充的PTFE复合材料,系统研究了TiO2掺杂量对所制复合材料显微结构、微波介电性能和热膨胀系数的影响。结果表明,复合材料的密度、介电常数和热膨胀系数都随着掺杂量的增大而增加,吸水率随着掺杂量的增大而减小,介电损耗随着掺杂量的增大先减小后增大。当TiO2掺杂量为质量分数7%时,PTFE很好地包覆在SiO2表面,复合材料结构致密,具有与铜箔较为匹配的线膨胀系数(17.76×10–6/℃),且介电性能优良(εr=2.94,tanδ=0.000 82)。     

常压水热法制备BTZ粉体及其在Y5V瓷粉中的应用

采用常压水热法制备锆钛酸钡粉体,研究了工艺参数对锆钛酸钡粉体颗粒大小的影响,以及粉体颗粒、Ba/(Ti+Zr)摩尔比对制成的Y5V瓷粉介电性能的影响。结果表明:选择改进的加料方式,再通过洗涤控制,可以得到粒度(D50)在0.4~0.5μm、Ba/(Ti+Zr)摩尔比为1.0的粉体;其能与抗还原剂、助熔剂很好匹配,获得性能优良(εr≥15000,tanδ<30×10–4,–80%≤?C/C20≤+30%)的镍内电极MLCC用Y5V瓷料。     

丙烯酸树脂/钛酸钡纳米复合材料的研究

采用原位聚合的方法制备了丙烯酸树脂/BaTiO_3纳米复合材料,用SEM分析其表面形貌。研究了该复合材料与聚对苯二甲酸乙二醇酯(PET)基膜复合的电性能,并探讨了PET基膜和涂层对复合薄膜整体电性能的影响。初步制备出了具备高介电常数、高击穿、低损耗的复合薄膜。为工业化低成本生产高储能密度电容器提供了新的思路。     

Synthesis of high tetragonality nanoparticle BaTiO3

New preparation methods for barium titanate powders that can be used for more compact/superior multilayer ceramic capacitors, embedded capacitors, and high capacitance plastic composite materials in microelectronics are described. The methods involve dissolution and precipitation of barium and titanium compounds followed by crystallization at near ambient condition. The particle morphology, tetragonality, and the corresponding dielectric constants are shown to be different for different preparation methods. The mean particle sizes are less than 100 nm and smaller for lower dielectric constant of the solvent medium and higher refluxing temperature. The tetragonality is high for the particles synthesized under totally water-free conditions at 180 °C followed by calcination at 600 °C. The dielectric constants of particles prepared under water-based ambient conditions were 490 and 900 after dehydroxylation treatment by N-methyl pyrrolidone.     

Enhanced Dielectric and Crystalline Properties in Ferroelectric Barium Titanate Thin Films

A chemical solution synthesis technique incorporating barium titanate and a high‐temperature liquid phase is developed. In a temperature range conventional to thin‐film growth, the presence of the liquid phase dramatically enhances grain growth, densification, and overall crystalline quality. By controlling the liquid‐phase stoichiometry and molar fraction, thin films with grain sizes greater than 10 μm that pronounce X‐ray peak splitting, low loss, and permittivity values in excess of 3000 at room temperature can be produced. These properties are comparable, and in some cases superior, to those observed in well‐prepared bulk barium titanate. As such, the historical difficulty in reproducing bulklike properties in polycrystalline barium titanate is overcome. These results have broad implications for the expanded use of ferroelectric thin films by demonstrating bulk properties in thin layers and by providing a means of achieving these properties with low thermal budgets.     

Sb掺杂BaTiO_3的电磁及微波吸收特性研究

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。     

Co掺杂对BST薄膜介电性能的影响

用sol-gel法在Pt/Ti/SiO2/Si(100)衬底上制备了掺Co的钛酸锶钡(BST)薄膜,研究了Co的掺杂量x(Co)对BST薄膜的晶相结构和电学性能的影响。结果表明:随着x(Co)的增加,BST薄膜的介电常数εr,介质损耗tgδ和漏电流密度JL均降低;当x(Co)为5%时,BST薄膜的εr、tgδ、JL、可调性和品质因子分别为:228.3、0.013、3.69×10–7 A/cm2、15.4%、12.03。     

Current-voltage characteristics and capacitance of single grain boundaries in semiconducting BaTiO3 ceramics

Specimens were prepared of doped ceramic barium titanate in the form of bars which, between their metallized ends, contained only one high-resistance grain boundary running across the entire cross-section. The measurements covered the differential capacitance of these individual grain boundaries, under bias, and their d.c. current-voltage characteristics. The results can be described quite well by a model in which a layer of a second phase present between the barium titanate grains is assumed to possess, firstly, acceptor character and, secondly, a dependence of its permittivity on the temperature and the electric field strength.     

钛酸钡纳米粉体的共沉淀法合成与研究

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.     

Barium Titanate Inverted Opals—Synthesis,Characterization, and Optical Properties

Barium titanate inverted opals with powder and film morphologies were synthesized from barium ethoxide and titanium isopropoxide in the interstitial spaces of a polystyrene opal. This procedure involves infiltration of precursors into the interstices of the polystyrene opal template followed by hydrolytic polycondensation of the precursors to amorphous barium titanate and removal of the polystyrene opal by solvent extraction or calcination. In‐situ variable temperature powder X‐ray diffraction and micro‐Raman spectroscopy allow one to observe the thermally induced transformation of the as‐synthesized amorphous barium titanate inverted opal to the nanocrystalline form. In this way, a nanocrystalline barium titanate inverted opal can be engineered as either the cubic or tetragonal polymorph. Control of this process is key to the practical realization of a room‐temperature stable ferroelectric barium titanate inverted opal that can be thermally tuned through the ferroelectric–paraelectric transition around the Curie temperature. Optical characterization demonstrated photonic crystal behavior of the inverted barium titanate opals and results were in good agreement with photonic band structure calculations. The synthesis of optical quality ferroelectric barium titanate inverted opals provides an opportunity to electrically and optically engineer the photonic band structure and the possibility of developing tunable three‐dimensional photonic crystal devices.     

溶剂热法制备立方钛酸钡纳米晶

将钛酸丁酯和适量乙醇混匀后,与氯化钡水溶液在溶剂热条件下反应制备立方钛酸钡纳米晶。结果表明:以KOH为矿化剂,r(Ba:Ti)为1.1,φ(乙醇)为25.0%和150℃反应12h,可得平均粒径为60nm左右、分散性较好的钛酸钡纳米晶。当乙醇用量增大时,产物的粒径减小,分散性降低;随着r(Ba:Ti)的增大,产物粒径减小。当r(Ba:Ti)为1.6时,产物的平均粒径可减小至35nm左右;矿化剂的种类、反应温度和反应时间对产物的形貌及晶体结构没有影响。     

钛酸锶钡铁电陶瓷介电调谐性能研究进展

钛酸锶钡(B_a1-x_Sr_xTiO_3)铁电材料因其优异的介电可调谐性能而备受关注。该文介绍了B_a1-x_Sr_xTiO_3可调谐材料的发展现状,重点分析优化了B_a1-x_Sr_xTiO_3可调谐性能当前的研究趋势,包括粒子尺寸、掺杂改性及介质复合优化,在此基础上综述了铁电-铁氧复合对可调谐性能的影响,并对未来的发展方向提出了见解。