PZT95/5铁电陶瓷脉冲源用于nF电容器充电

采用简化的物理模型 ,分析了以电容为负载的PZT95 /5铁电陶瓷在冲击波加载下的电响应规律以及极化能的释放和转移特性 ,并运用爆炸平面冲击波垂直加载技术 ,对其在nF电容器下的输出特性进行了试验研究。     

Raman,X-ray and electrical properties of MOD PZT/PLZT thin films

Abstract

Ferroelectric PZT/PLZT thin films have been fabricated using the metallo-organic precursor compounds. The structural development, spectroscopic and dielectric properties of these films have been investigated using atomic force microscopy (AFM), X-ray diffraction, Raman scattering and dielectric measurements. Experimental results show that Raman spectroscopy is an effective tool of monitoring the structural development of the small sized PZT films in the tetragonal phase field. Dielectric characteristics have been improved by the rapid thermal processing approach. A rosette growth model is proposed to explain the observation of the tri-intersection of the perovskite phase in PZT films.     

P_2O_5-Co_2O_3-Bi_2O_3掺杂NiCuZn/PZT复合材料的电磁性能

首先用sol-gel法制得Pb_(0.95)Sr_(0.05)(Zr_(0.52)Ti_(0.48))O_3(PZT)纳米粉料,然后采用固相反应法制备NiCuZn/PZT铁氧体/陶瓷复合材料,研究了P_2O_5-Co_2O_3-Bi_2O_3组合掺杂对复合材料性能的影响.结果表明,当固定质量分数w(Bi_2O_3)=2.5 %,w(P_2O_5)=0.5 %,适量的Co_2O_3掺杂可同时提高复合材料品质因数Q、起始磁导率和介电常数,并降低材料的介电损耗.当w(Co_2O_3)=0.3%时,材料的综合电磁性能最佳.所制备的材料满足叠层片式电容器和电感器件的性能要求,有望成为用于叠片式滤波器的电感、电容复合双性材料.     

Effects of Al2O3 on the piezoelectric properties of Pb(Mn1/3Nb2/3)O3-PbZrO3-PbTiO3 ceramics

Piezoelectric properties of Al₂O₃-doped Pb(Mn_1/3Nb_2/3)O₃-PbZrO₃-PbTiO₃ ceramics were investigated. The constituent phases, microstructure, electromechanical coupling factor, dielectric constant, piezoelectric charge and voltage constants were analyzed. Diffraction peaks for (002) and (200) planes were identified by X-ray diffractometer for all the specimens doped with Al₂O₃. The highest sintered density of 7.8 g/cm³ was obtained for 0.2 wt% Al₂O₃-doped specimen. Grain size increased by doping Al₂O₃ up to 0.3 wt%, and it decreased by more doping. Electromechanical coupling factor, dielectric constant, piezoelectric charge and voltage constants increased by doping Al₂O₃ up to 0.2 wt%, and it decreased by more doping. This might result from the formation of oxygen vacancies due to defects in O^{2 −} ion sites and the substitution of Al³⁺ ions.     

Sintering and dielectric properties of Al2O3 ceramics doped by TiO2 and CuO

The effects of CuO and TiO₂ additives on the microstructure and microwave dielectric properties of Al₂O₃ ceramics were investigated. Al₂O₃ ceramics with CuO and TiO₂ additions can be well sintered to achieve 93∼98% theoretical densities below 1,360 °C due to Ti₄Cu₂O liquid phase sintering effect. The Qf values decreased with increasing CuO and TiO₂ content, due to the formation of the second phase Ti₄Cu₂O. However, the varying behaviors of the dielectric constant (ɛ _r ) and temperature coefficients (τ _f ) were associated with phase constitutions, as a result of the change of CuO and TiO₂content. The τ _f can be shifted close to 0 ppm/°C by controlling the content of CuO and TiO₂. The specimens with 0.5 wt.% CuO and 7 wt.% TiO₂ sintered at 1,360 °C for 4 h showed ɛ _r of 11.8, Qf value of 30,000 GHz, and τ _f of −7 ppm/°C.     

MOCVD of Pb(Zr x Ti1-x )O3 thin films on MgTiO3/Si substrates and their electrical properties

Abstract

Pb(Zh _x , Ti_1-x )O₃(PZT) thin films were deposited on Si substrates using MgTiO₃ as the buffer layer and the electrical properties of those MFIS structures were investigated. PZT and MgTiO₃ films were made by MOCVD using ultrasonic spraying technique. Perovskite PZT films have been succesfully made at the substrate temperature of 550 to 600°C only when using MgTiO₃ buffer layer. AES depth profile analysis and RBS analysis revealed that there is no remarkable interdiffusion and no formation of reaction layer between PZT and MgTiO₃ and/or between MgTiO₃ and Si substrate. The capacitance-voltage (C-V) curves of the MFIS structure which were made with PZT and MgTiO₃buffer layer have shown the hysteresis resulted from the ferroelectric switching of the PZT films.     

V2O5-WO3/TiO2基催化剂SCR法脱硝试验研究

以工业级锐钛型TiO2为载体制备了V2O5-WO3/TiO2脱硝催化剂,通过BET、XRD、SEM等方法对微观结构进行表征.并在SCR反应器中测试其脱硝性能.自制催化剂比表面积较小,晶相仍为锐钛型,温度为330-4000℃、O2浓度大于1%、NH3/NO为0.9～1、空速比为24 000 h-1,脱硝效率达到80%以上,N2O生成率,NH3逃逸率及SO2氧化率均能够满足电厂脱硝的要求,并且因工业级TiO2粉体价格较低可降低催化剂成本.     

Piezoelectric properties of the Pb(Sc1/2Nb1/2) O3-Pb(Mg1/3Nb2/3) O3-PbTiO3 ternary ceramic materials near the morphotropic phase boundary

Abstract

The physical and electrical properties of xPb(Sc_1/2Nb_1/2)O₃-yPb(Mg_1/3Nb_2/3)O₃-zPbTiO₃(PSMNT 100x/100y/100z) ternary ceramic materials near the morphotropic phase boundary (MPB) were investigated. The MPB follows on almost linear region between the PSMNT 58/00/42 and PSMNT 00/68/32 MPB compositions of the binary systems. The maximum piezoelectric constant, d ₃₃ = 680 pC/N, were found at PSMNT 29/33/38, where ε^T ₃₃/ε₀ = 3,800, and electromechanical coupling factors, (k _p = 70%, k₃₁ = 43%, and k ₃₃ = 76%) and T _c = 207°C were obtained. The maximum electromechanical coupling factors, (k _p = 72%, k ₃₁ = 45%, and k ₃₃ = 77%) were found at PSMNT 29/34/37, where ε^T ₃₃/ε₀ = 3,000, d ₃₃ = 640 pC/N, and T _c = 205°C were obtained. These values are better than those of PZT.     

蜂窝状V2O5-WO3/TiO2催化剂脱硝性能研究

实验室制备了蜂窝状V2O5-WO3/TiO2的脱硝催化剂，通过BET、XRD、SEM等方法对微观结构进行表征。在自制SCR活性试验台上测试各种运行工况（温度、空速比等）和烟气组成（NH3/NO、水蒸汽等）对催化剂的脱硝活性、选择性、SO2的氧化率和氨逃逸量的影响。发现自制蜂窝状催化剂在空速比（SV）小于3500h-1、NH3/NO在 0.9~1.0、温度320~420℃范围内的NO脱除率较高、SO2氧化率和氨逃逸量较低，基本达到工业应用的要求，低含量（低于2％）水蒸汽可以提高高温段NO脱除率，而高含量的水蒸汽对催化剂NO脱除具有明显的抑制作用，但水蒸汽的加入会使NO脱除温度窗口拓宽；由于催化剂自身含有较多的硫酸盐，未观察到SO2对脱硝反应有促进作用。     

Piezoelectric ceramics of (Bi1/2Na1/2)TiO3-PbTiO3-BaTiO3 system

Piezoelectric and ferroelectric properties of bismuth sodium titanate, (Bi_1/2Na_1/2)TiO₃(BNT)-based solid solution, that is, (Bi_1/2Na_1/2)(_1-x)(Pb_a Ba_b)_xTiO₃(a + b = 1) [BNPB(100x-100a/100b)], are studied from the viewpoint of a new group of lead-free or low-lead content piezo-electric ceramics with a rhombohedral(F_a-tetragonal (F_β) morphotropic phase boundary (MPB). It is evident that the MPB seems to be remarkably efficacious in promoting piezoelectric and pyroelectric activities by electrical poling. X-ray diffraction data, dielectric properties and D-E hysteresis loops show that the MPB exist near (Bi_1/2Na_1/2)TiO₃[BNT] at x = 0.13–0.14, 0.08–0.09 and 0.06–0.07 in the case of b = 0, b = 0.5 and b = 1, respectively. BNPB ceramics are superior for piezoelectric ceramics in high-frequency ultrasonic uses, or special piezoelectric actuator materials with a lower free permittivity ε₃₃Tε₀, and a high electromechanical coupling factor k₃₃, along with a high mechanical strength.     

退火时间对FeGaB/Al2O3多层薄膜性能的影响

现代电子元器件的高速发展,以及磁性元器件小型化、集成化需求日益增长,推动了纳米级磁性功能薄膜材料的研究。以高饱和磁致伸缩系数、低矫顽力的FeGaB薄膜材料为研究基础,以提高薄膜软磁性能为目标,使用脉冲激光沉积系统制备了FeGaB/Al2O3复合多层薄膜,发现在350℃的生长环境下,未退火的样品成膜质量较好,但软磁性能一般。为了提高磁性能,进行一组不同退火时间下的退火实验,实验发现样品的铁磁共振线宽较大,且退火时间对吸收峰强度影响较大。     

形变与热处理对Y2O3/Al2O3/Cu复合材料组织和性能的影响

通过对0.3%Y2O3/0.3%Al2O3/Cu复合材料冷拉拔以及随后的退火工艺,研究了形变及热处理对材料力学性能、导电性能及其组织结构的影响规律。结果表明,随着冷拉拔变形量的增加,0.3%Y2O3/0.3%Al2O3/Cu复合材料的等轴晶粒逐渐沿其变形方向被拉长,材料的抗拉强度增加,导电率下降。变形量为70%时抗拉强度达到峰值,进一步形变后材料出现加工软化。随退火温度的升高,材料的导电率提高,显微硬度下降。显微组织中重新生成无畸变的等轴晶粒。退火后材料力学性能得到改善,断口形貌呈现出大而深的韧窝组织与撕裂棱。     

三元乙丙橡胶聚集态结构对其复合材料动态力学性能的影响

采用动态力学分析技术分别研究了两种不同聚集态结构三元乙丙橡胶(EPDM)对EPDM／Al(OH)2复合材料动态力学性能的影响。研究结果表明，在玻璃化转变过程中，结品性EPDM比非结晶的动态模量(E')大，而介质损耗因素(tanδ)、动态粘度(n’)值则小，且峰温移向高温；当Al(OH)2填料浓度相同时，结品性EPDM与Al(OH)3复合材料的E’大、tanδ峰值小，但在结晶性EPDM与Al(OH)3复合材料中Al(OH)3粒子与EPDM两相间的作用参数(B)较小。     

V2O5-WO3/TiO2烟气脱硝催化剂的载体选择

在选择性催化还原试验台上对4种不同TiO2为载体制备的催化剂的脱硝性能进行测试,采用BET、X射线衍射、傅里叶转换红外光谱、扫描电镜-能谱分析、X射线荧光分析和热重分析等技术进行微观表征,并与商业催化剂进行对比。以硫酸法制备的纳米级锐钛型TiO2适合作为选择性催化还原催化剂载体,制备的催化剂脱硝效率高,温度窗口宽,选择性好,其中硫酸盐质量分数为8%~10%时最为有利;以氯化法制备纳米TiO2过程中,生成了V3Ti6O17的聚合物导致NO脱除率较低,因此不适合作为催化剂载体。以工业级TiO2为载体制备的催化剂氨氮比为1.0时,在355~420 ℃的温度范围内NO脱除率为80%~85%,但由于成本很低,因此可以用于脱硝要求不高的场合。由钛酸丁酯溶胶法制备TiO2为载体制备的SCR催化剂性能不及硫酸法制备的纳米级锐钛型TiO2制备的催化剂,且操作复杂,技术难度大,不适宜推广。     

Effect of B2O3 and CuO on the sintering temperature and microwave dielectric properties of the BaTi4O9 ceramics

The effect of B₂O₃ and CuO on the sintering temperature and microwave dielectric properties of BaTi₄O₉ ceramics was investigated. The BaTi₄O₉ ceramics were able to be sintered at 975^∘C when B₂O₃ was added. This decrease in the sintering temperature of the BaTi₄O₉ ceramics upon the addition of B₂O₃ is attributed to the formation of BaB₂O₄ second phase whose melting temperature is around 900^∘C. The B₂O₃ added BaTi₄O₉ ceramics alone were not sintered below 975^∘C, but were sintered at 875^∘C when CuO was added. The formation of BaCu(B₂O₅) second phase could be responsible for the decrease in the sintering temperature of the CuO and B₂O₃ added BaTi₄O₉ ceramics. The BaTi₄O₉ ceramics containing 2.0 mol% B₂O₃ and 5.0 mol% CuO sintered at 900^∘C for 2 h have good microwave dielectric properties of ε_r = 36.3, Q× f = 30,500 GHz and τ_f = 28.1 ppm/^∘C     

纳米SiO2增强脲醛树脂机械性能的分子模拟研究

介电材料广泛应用于现代电网,但容易出现开裂现象,引起局部放电、电树枝等危害。将芯材为双环戊二烯,壁材为脲醛树脂(PUF)的自修复微胶囊掺杂进介电材料,可实现材料的自修复。但PUF微胶囊硬度不足,其机械性能需要增强。文中采用分子模拟方法建立3组模型,每组分别包括一个纯PUF模型和一个掺杂纳米SiO2的PUF模型,经过计算后分析其密度、自由体积分数、机械性能,建立PUF/SiO2界面相互作用模型以挖掘其内部机理。结果发现,掺杂纳米SiO2有利于增大PUF材料的密度,减小自由体积分数、增强其机械性能。原因是PUF链上的极性原子和纳米SiO2表面的羟基、O原子之间存在氢键相互作用。文中采用分子模拟技术揭示了纳米SiO2增强PUF机械性能的内部机理。     

钾盐对V2O5/TiO2催化剂NH3选择性催化还原NO反应的影响

钾在中国燃煤和生物质烟气中以钾盐--硫酸钾和氯化钾的形式存在。文中采用静态N2物理吸附、程序升温表面反应(temperature-programmed surface reaction,TPSR)、傅里叶变换红外(Fourier transform infrared,FT-IR)光谱和催化活性评价的方法,研究了钾盐对V2O5/TiO2催化剂上NH3选择性催化还原NO反应的影响。结果表明,钾盐使V2O5/TiO2催化剂活性降低。随着钾盐在催化剂上负载量的增加,稳定的NO脱除温度窗口逐渐变窄,当K与V物质的量之比达到3.0时,该窗口消失。钾盐的掺入使催化剂表面活性位数量明显减少,但是并没有显著改变催化剂的反应性。催化剂失活的主要原因是K优先配位在催化剂表面的Br￠nsted酸性位上,中和了Br￠nsted酸性位酸性,使Br￠nsted酸性位上吸附的氨减少。     

AIPO4包覆对LiNi1/3Co1/3Mn1/3O2性能的影响

采用共沉淀法在LiNi1/3Co1/3Mn1/3O2表面包覆AIPO4.利用X射线衍射仪、扫描电子显微镜和充放电测试技术研究AIPO4包覆对正极材料的晶体结构、微观形貌和电化学性能的影响.电化学性能测试结果表明:不同AIPO4包覆量对正极材料LiNi1/3Co1/3Mn1/3O2物理性质、结构及电化学性能有显著影响.当采用AIPO4包覆量为1％时,循环性能最好,50次循环后,放电比容量仅降到176 mAh/g,容量衰减最小,只有1.7％.表现出良好的电化学稳定性,同时材料的倍率性能也明显提高.     

Co2O3或/和V2O5掺杂对NiZn铁氧体磁性能的影响

一定量的V2O5掺杂有利于NiZn铁氧体烧结温度的降低，且在一定范围内起始磁导率升高；而Co2O3掺于Nizn铁氧体，起始磁导率降低，但损耗特性可得到改善。我们采用Co2O3-V2O5复合掺杂，发现选择适当的配比，在起始磁导率没有大的下降的情况下，烧结温度和损耗特性等其他磁特性可得到较好的改善。     

Effects of ZnO on the piezoelectric properties of Pb(Mn1/3Sb2/3)O3-Pb(Zr,Ti)O3 ceramics

Perovskite-type 0.05 Pb(Mn_1/3Sb_2/3)O₃-0.95 Pb(Zr_0.5Ti_0.5)O₃ (PMS-PZT) was synthesized by conventional bulk ceramic processing technique. ZnO as a dopant up to 0.5 mol% was incorporated into the PMS-PZT system, and the effects on piezoelectric properties were investigated. Pyrochlore phase was not detected to form during the synthesis of the PMS-PZT system with 0∼0.5 mol% ZnO addition. The highest density of 7.92 g/cm³ was obtained when sintered at 1200°C for 2 hrs. Piezoelectric properties as a function of ZnO content were evaluated using a gain phase analyzer. Piezoelectric charge constant (d₃₁) and piezoelectric voltage output coefficient (g₃₁) increased up to −130 pC/N and −24.9 × 10³Vm/N, respectively, with increasing ZnO content. Mechanical quality factor (Q _m) was shown to reduce considerably with increasing ZnO content. When 0.3 mol% of ZnO was added into the system, electromechanical coupling factor (k _p) and relative dielectric constant () reached to the maximum of 56% and 1,727, respectively.