BaTiO3-ZnNb2O6陶瓷介电及储能性能研究

采用固相法制备(1-x)BaTiO₃-xZnNb₂O₆ (x=0.5mol%, 1mol%, 1.5mol%, 2mol%, 3mol%, 4mol%) (简称BTZN)陶瓷, 研究了BTZN陶瓷的烧结温度、结构、介电性能和铁电性能。BTZN陶瓷烧结温度随着ZnNb₂O₆含量增加逐渐降低。XRD结果表明当ZnNb₂O₆含量达到3mol%时出现第二相Ba₂Ti₅O₁₂。介电测试结果表明随ZnNb₂O₆含量的增加, BTZN陶瓷介电常数逐渐减小, 而介电常数的频率稳定性逐渐增强。介电温谱表明所有BTZN陶瓷均符合X8R电容器标准。BTZN陶瓷的极化强度值随着ZnNb₂O₆含量的增加逐渐降低。当x=4mol%时, BTZN陶瓷获得240 kV/cm的击穿电场和1.22 J/cm ³的可释放能量密度。     

氧化气氛对CaCu3Ti4O12陶瓷显微结构及介电性能的影响

采用固相法合成了CaCu₃Ti₄O₁₂陶瓷, 研究了氧化气氛热处理对其显微结构和介电性能的影响。结果表明, 氧化气氛热处理后, CaCu₃Ti₄O₁₂陶瓷的介电常数略微下降, 介电损耗角正切值得到有效抑制, 降至0.03~0.04。在183~273 K温度范围内, CaCu₃Ti₄O₁₂陶瓷总的介电损耗可以分解成低频电导损耗和高频的两个弛豫损耗峰, 氧化气氛热处理后低频电导损耗的贡献下降较为明显。对CaCu₃Ti₄O₁₂陶瓷的晶粒、晶界进行阻抗分析, 发现在393 K时晶界电阻值从1.8×10⁴ Ω增大到8.6×10⁴ Ω。伏安特性(J-E)结果表明氧化气氛热处理使CaCu₃Ti₄O₁₂陶瓷的击穿场强和非线性系数分别从226 V/mm、3.52上升到397 V/mm、4.51, 晶界势垒高度从0.56 eV增大到0.63 eV。     

尖晶石型CuAl2O4掺杂对CaCu3Ti4O12陶瓷介电性能的影响

研究了尖晶石型CuAl₂O₄掺杂对CaCu₃Ti₄O₁₂陶瓷显微结构、介电性能以及松弛特征和缺陷结构的影响。在频率为10^-1~10⁷ Hz、温度为153~453 K的条件下测量了样品的介电性能。研究表明, 适量添加CuAl₂O₄, 使样品晶粒尺寸减小并趋于均匀, 击穿场强从CaCu₃Ti₄O₁₂陶瓷样品的3.0 kV/cm提高到13.0 kV/cm, 低频介电损耗减小。介电松弛中的高频松弛过程起源于晶粒本征缺陷的电子松弛过程, 其活化能~0.10 eV基本不变; 随着CuAl₂O₄含量增加, 与界面相关的松弛活化能从0.50 eV减小到0.22 eV, 可能与CuAl₂O₄在样品中引入杂质及更复杂的界面有关; 电导活化能从0.66 eV增至0.86 eV, 归因于CuAl₂O₄第二相抑制了晶界处的载流子跳跃, 提高了Schottky势垒高度。CuAl₂O₄掺杂量大于100mol%, 过量CuAl₂O₄会导致样品晶界势垒崩塌, 样品失去非欧姆特性和巨介电性能。     

SrSc0.5Nb0.5O3改性BNT基无铅陶瓷的储能特性研究

采用SrSc_0.5Nb_0.5O₃与(Bi_0.5Na_0.5)(Ti_0.95Al_0.025Nb_0.025)O₃固溶构建了无铅陶瓷体系材料(1-x)(Bi_0.5Na_0.5Ti_0.95Al_0.025-Nb_0.025O₃)-x(SrSc_0.5Nb_0.5O₃)(简记为(1-x)BNTA-x SSN,x=5%、10%、15%、20%,摩尔分数)。通过传统固相反应法制备陶瓷,研究了SrSc_0.5Nb_0.5O₃的引入对其结构、相变、储能和介电性能的影响。研究结果表明,(1-x)BNTA-x SSN样品为钙钛矿结构。其最大介电常数对应温度T_m...     

无铅压电陶瓷K0.5Na0.5NbO3-BiFeO3的烧结工艺与压电性能研究

采用传统常压固相烧结工艺制备了掺杂0.8at%BiFeO₃(BF)的K_0.5Na_0.5NbO₃(KNN) 无铅压电陶瓷,着重研究了烧结温度与保温时间对陶瓷的晶体结构、相转变、致密度与压电、介电性能的影响. 研究结果表明, 所有陶瓷样品都为单一的钙钛矿结构, 烧结温度与保温时间对陶瓷样品的室温晶体结构与相转变温度几乎没有影响, 但对陶瓷的表面形貌、密度和压电性能有较大的影响. 当保温时间为3h,在1100℃至1150℃范围内, 随烧结温度的升高,陶瓷的压电常数d33、平面机电耦合系数Kp及机械品质因数Qm均一直升高, 介电损耗tanδ则显著降低. 当烧结温度为1150℃时, 随保温时间的增加, 陶瓷的压电性能先显著提高后基本保持不变. 1150℃保温2h烧结的陶瓷获得良好的性能：密度ρ=4.50g/cm³（致密度为95.63%）, d₃₃=132pC/N, K_p=45%, Q_m=333.73, tanδ=2.39%.     

PrBi4Fe0.5Co0.5Ti3O15多铁陶瓷的性能研究

采用传统固相反应法与两步合成法制备了PrBi₄Fe_0.5Co_0.5Ti₃O₁₅陶瓷, 研究了Pr与Co共掺杂对Bi₅FeTi₃O₁₅陶瓷的结构、磁性能以及介电性能的影响。X射线衍射分析显示, 传统固相反应法制备的样品比两步法制备的样品更容易形成单相结构。铁电和磁性测量证明样品具有多铁性, 并且Pr与Co共掺杂能大幅提高材料的磁性能, 固相反应法与两步合成法制备的样品在室温下的剩余磁化强度(2M_r)分别为0.315, 0.576 Am²/kg, 比文献报道的Bi₅FeTi₃O₁₅陶瓷的2M_r ( 2.7 Am²/kg ) 高5个数量级, 比掺Co的Bi₅Fe_0.5Co_0.5Ti₃O₁₅陶瓷2M_r ( 7.8×10^-3 Am²/kg ) 高2个数量级。     

高Q值(1-x)(Sr0.2Nd0.208Ca0.488)TiO3-xNd(Ti0.5Mg0.5)O3微波陶瓷的微结构及介电性能研究

采用固相法制备了(1-x)(Sr_0.2Nd_0.208Ca_0.488)TiO₃-xNd(Ti_0.5Mg_0.5)O₃(0.3≤x≤0.4, SNCT-NTMx)系微波介质陶瓷材料, 并研究了该体系的相组成、显微结构、烧结性能和微波介电性能之间的关系。结果表明: 在x = 0.3~0.35范围内, SNCT-NTMx陶瓷形成了正交钙钛矿固溶体, 并伴随有少量未知第二相; 当x增至0.4时, 第二相含量有所增加。介电性能研究结果显示: 随着x的增加, 体系介电常数(ε_r)减小, 但品质因子(Q×f)得到改善; 此外, 体系谐振频率温度系数(τ_f)随NTM含量的增加逐渐向负值方向移动。当x = 0.35, 陶瓷样品在1520℃烧结4 h 得到的微波介电性能较优: ε_r=50.1, Q×f =44910 GHz, τ_f= -1.7×10^-6/℃。     

反应烧结制备Li2Zn2Mo3O12微波介质陶瓷及其微波介电性能研究

采用反应烧结法制备了具有超低烧结温度的Li₂Zn₂Mo₃O₁₂微波介质陶瓷,研究了烧结温度对Li₂Zn₂Mo₃O₁₂陶瓷的烧结特性、物相组成、微观结构以及微波介电性能的影响。XRD表明：在550～650℃范围内,温度对陶瓷的物相组成影响不大;随着烧结温度的升高,Li₂Zn₂Mo₃O₁₂陶瓷的体积密度、相对密度、介电常数(ε_r)和品质因数(Q×f)均呈先增大后减小的趋势,谐振频率温度系数(τ_f)在-(70～90)×10^-6/℃波动。在625℃烧结2 h获得最大体积密度和相对密度：4.25 g/cm³和96.4%,以及优异的微波介电性能ε_r=10.9,Q×f=69 459 GHz,τ_f=-84×10<...     

p型多晶Bi0.5Sb1.5Te3合金类施主效应与热电性能

晶粒细化是提高Bi_0.5Sb_1.5Te₃合金力学性能的有效途径,但是粉末冶金过程中晶粒细化导致的类施主效应会严重劣化材料热电性能,制约了Bi_0.5Sb_1.5Te₃基合金在微型热电器件中的应用。本研究围绕p型Bi_0.5Sb_1.5Te₃基合金,采用实验结合理论计算系统研究了粉末冶金制备过程中研磨和脱附气氛对烧结样品中类施主效应和电热输运性能的影响规律和机制。Bi_0.5Sb_1.5Te₃基合金破碎研磨过程中粉体表面产生缺陷V_Te^··和V_S’’_b并物理吸附空气中的O₂,在烧结过程中与吸附的O₂发生缺陷化学反应,产生大量V_Te^··空位和自由电子,导致类施主效应,使空...     

(Bi0.5Na0.5)0.935Ba0.065TiO3-xBiScO3陶瓷储能及应变性能研究

本研究采用BiScO₃组分对固相烧结工艺制备的(1-x)(Bi_0.5Na_0.5)_0.935Ba_0.065TiO₃-xBiScO₃(BNBT-xBS)无铅陶瓷进行改性, 考察了BiScO₃掺杂含量对陶瓷的微观结构、储能、场致应变和介电等性能的影响。结果表明: 随着BiScO₃掺杂含量的增加, BNBT-xBS陶瓷的相结构由三方相与四方相共存演变为伪立方相, 无杂相形成, 且平均晶粒尺寸略有增大; BiScO₃组分的引入破坏了BNBT陶瓷铁电畴的长程有序, 表现出弱极化, 且伴随有铁电相到弛豫铁电相的相变过程。BiScO₃组分提高了储能和应变性能, 在70 kV/cm电场下其最大储能密度为0.46 J/cm³, 电致应变达到0.25%。介电常数随着掺杂含量的增加逐渐降低, 其介电行为也表明陶瓷具有弛豫铁电体特征; BNBT-xBS陶瓷表现出负温度系数效应, 且在450℃以下具有较好的绝缘性。     

Microwave dielectric characteristics of Ba(Mg1/3Ta2/3)O3 ceramics sintered at low-temperatures

The microwave dielectric properties and microstructures of Ba(Mg_1/3Ta_2/3)O₃ (BMT) ceramics sintered at low temperatures with 2–3 wt.% NaF additives were investigated. BMT ceramics sintered at 1340 °C for 3–12 h showed dielectric constants (_r) of 25.5–25.7, Qf values of 41 500–50 400 GHz and temperature coefficients of the resonator frequency (τ_f) of 10.9–21.4 ppm °C⁻¹. The variation of sintering time almost had no effect on the dielectric constant. The Qf value increased and the τ_f decreased with increasing sintering time. The ordering degree of Mg²⁺ and Ta⁵⁺ at B-sites increased with increasing sintering time.     

Effect of V2O5 on the Sintering Behavior, Microstructure, and Electrical Properties of (Na/sub 0.5/K/sub 0.5/)NbO/sub 3/Ceramics

Well-sintered (Na_0.5K_0.5)NbO_3-x mol% V₂O₅ ceramics (abbreviated as NKN-V) with fine electrical properties were successfully prepared by conventional solid-state reaction through the careful control of processing conditions. The sintering behavior, phase structure, and electrical properties of the V₂O₅-doped NKN ceramics were investigated. Results show that when the V₂O₅ content is 0.6 mol%, the NKN ceramics attained the maximum density of 4.46 g/cm³ (about 98.9% of the theoretical density) at 1060degC, and therefore possessed enhanced electrical properties. But when the V₂O₅ content continued increasing, the density decreased. The secondary phase (Na₂V₆O₁₆) could be detected by XRD analysis in all samples except x = 0 mol%. The Curie temperature of the NKN-based materials was found to decrease with the increase of V₂O₅. The dielectric properties of NKN ceramics doped with 0.6 and 0.9 mol% V₂O₅ were better than that of pure NKN ceramics. In addition, annealing treatment was proved to be an effective technique for improving dielectric properties and reducing the leakage current density.     

Ferroelectric, dielectric and piezoelectric properties of potassium lanthanum bismuth titanate K0.5La0.5Bi4Ti4O15 ceramics

The Aurivillius type bismuth layer-structured compound potassium lanthanum bismuth titanate (K_0.5La_0.5Bi₄Ti₄O₁₅) is synthesized using conventional solid-state processing. The phase analysis is performed by X-ray diffraction (XRD) and the microstructural morphology is conducted by scanning electron microscopy (SEM). The ferroelectric, dielectric and piezoelectric properties of K_0.5La_0.5Bi₄Ti₄O₁₅ (KLBT) ceramics are investigated in detail. The remnant polarization (P_r) and coercive field (E_c) are found to be 8.6 μC cm⁻² and 60 kV cm⁻¹, respectively. The Curie temperature T_c and piezoelectric coefficient d₃₃ are 413 °C and 18 pC N⁻¹, respectively.     

Nd3+:Lu2O3放电等离子烧结及光学性能

Lu₂O₃是具有高热导率而成为极具潜力的高功率激光介质材料。实验以商用氧化物粉体为原料, LiF为烧结助剂, 采用放电等离子烧结法制备了不同Nd³⁺掺杂浓度(C_Nd=0, 1at%, 3at%和5at%) Lu₂O₃透明陶瓷, 并研究了Nd³⁺掺杂浓度对Lu₂O₃陶瓷的物相、烧结性能、微观结构及光学性能的影响。结果表明：在高Nd³⁺浓度(5at%)掺杂后烧结样品仍为纯Lu₂O₃相;Nd³⁺掺杂对Lu₂O₃陶瓷烧结性能及微观形貌的影响有限;所有样品最终均表现出高致密性(99.5%以上)和优异的透光性能, 其中3at% Nd³⁺:Lu₂O₃的透过率最高, 在1064和2000 nm处的透过率分别为82.7和83.2%。Nd³⁺:Lu₂O₃透明陶瓷的最强发射峰位于1076和1080 nm;且随着Nd³⁺掺杂浓度的增加, 荧光强度降低, 寿命变短, 发生浓度淬灭。     

Dielectric Properties of Ba0.6Sr0.4TiO3-La(B0.5Ti0.5)O3 (B=Mg, Zn) Ceramics

Ba_0.6Sr_0.4TiO₃-La(B_0.5Ti_0.5)O₃ (B = Mg, Zn) ceramics were prepared by a solid-state reaction method, and their microwave dielectric characteristics and tunability were investigated. The ferroelectric-dielectric solid solutions with cubic perovskite structures were obtained for compositions of 10 to 60 mol% La(Mg_0.5Ti_0.5)O₃ and 10 to 50 mol% La(Zn_0.5Ti_0.5)O₃. With the increase of linear oxide dielectric content, the dielectric constant and tunability were decreased and Qf was increased. Ba_0.6Sr_0.4TiO₃-La(Mg_0.5Ti_0.5)O₃ has better dielectric properties than Ba_0.6Sr_0.4TiO₃-La(Zn_0.5Ti_0.5)O₃. 0.9Ba_0.6Sr_0.4TiO₃-0.1La(Mg_0.5Ti_0.5)O₃ has a dielectric constant ε = 338.2, Qf = 979 GHz and a tunability of was 3.7% at 100 kHz under 1.67 kV/mm. The Qf value of 0.5Ba_0.6Sr_0.4TiO₃- 0.5La(Mg_0.5Ti_0.5)O₃ reached 9367 GHz, but the tunable properties were lost.     

(Bi0.5Na0.5)TiO3:Sm3+无铅压电陶瓷的红光发射特性

采用传统的固相反应烧结方法制备了稀土Sm³⁺掺杂的(Bi_0.5Na_0.5)TiO₃无铅压电陶瓷。系统分析了掺杂浓度、烧结温度和离子补偿对发光特性的影响。稀土Sm³⁺离子的加入实现了(Bi_0.5Na_0.5)TiO₃陶瓷的红绿光发射, 其激发光波段位于400~500 nm范围内, 与已经成熟的蓝光LED芯片的发射光谱充分匹配。当烧结温度为1100℃, Sm³⁺离子的掺杂浓度为0.015 mol时, 陶瓷样品呈现最强的发光强度。同时, 通过Li⁺、Na⁺、K⁺离子进行电荷补偿, 有效提高了陶瓷样品的发光性能, 发光强度随离子半径增大而增强。可见, Sm³⁺掺杂的(Bi_0.5Na_0.5)TiO₃材料在光电集成器件中具有很好的应用前景。     

V_2O_5与Al_2O_3复合改性CaSiO_3陶瓷的烧结性能与微波介电性能

为降低CaSiO3陶瓷的烧结温度,通过在CaSiO3粉体中添加1wt%的Al2O3以及不同量的V2O5,探讨了V2O5添加量对CaSiO3陶瓷烧结性能、微观结构及微波介电性能的影响规律。结果表明:适量地添加V2O5除了能将V2O5-Al2O3/CaSiO3陶瓷的烧结温度从1 250℃降低至1 000℃外,还能抑制CaSiO3陶瓷晶粒异常长大并细化陶瓷晶粒。在烧结过程中,V2O5将熔化并以液相润湿作用促进CaSiO3陶瓷的致密化进程;同时,部分V2O5还会挥发,未挥发完全的V2O5将与基体材料反应生成第二相,第二相的出现将大幅降低陶瓷的品质因数。综合考虑陶瓷的烧结性能与微波介电性能,当V2O5添加量为6wt%时,V2O5-Al2O3/CaSiO3陶瓷在1 075℃下烧结2h后具有良好的综合性能,其介电常数为7.38,品质因数为21 218GHz。