The Sol-gel Preparation and Electric Properties of MnO_2-doped PbTiO_3 Ceramics

MnO_2doped PbTiO_3 ceramics was prepared by means of solgel method, its density and some electric properties were investigated. The results showed that it was feasible to prepare multicomponent PbTiO_3 solgel series with the aid of solgel method, the obtained MnO_2doped PbTiO_3 ceramics showed a highpurity, uniform component, better dense structure, hardly crack, and had good dielectric, piezoelectric, ferroelectric and pyroelectric properties.

Physics-embedded machine learning search for Sm-doped PMN-PT piezoelectric ceramics with high performance

Pb(Mg_(1/3)Nb_(2/3))O_(3)–PbTiO_(3)(PMN-PT)piezoelectric ceramics have excellent piezoelectric properties and are used in a wide range of applications.Adjusting the solid solution ratios of PMN/PT and different concentrations of elemental doping are the main methods to modulate their piezoelectric coefficients.The combination of these controllable conditions leads to an exponential increase of possible compositions in ceramics,which makes it not easy to extend the sample data by additional experimental or theoretical calculations.In this paper,a physics-embedded machine learning method is proposed to overcome the difficulties in obtaining piezoelectric coefficients and Curie temperatures of Sm-doped PMN-PT ceramics with different components.In contrast to all-data-driven model,physics-embedded machine learning is able to learn nonlinear variation rules based on small datasets through potential correlation between ferroelectric properties.Based on the model outputs,the positions of morphotropic phase boundary(MPB)with different Sm doping amounts are explored.We also find the components with the best piezoelectric property and comprehensive performance.Moreover,we set up a database according to the obtained results,through which we can quickly find the optimal components of Sm-doped PMN-PT ceramics according to our specific needs.

Electric characteristics of Nd_2O_3 doped BaTiO_3 ceramics

Nd2O3 doped BaTiO3ceramics（the additive content was respectively 0.001, 0.002, 0.003, 0.005, 0.01 molar ratio）were prepared by Sol-Gel method to study their dielectric characteristics and electric conductivities through X-ray photoelectron spectrum （XPS）. The results showed that the dielectric characteristics of Nd2O3 doped BaTiO3 ceramics were improved by doping. When Nd2O3 content was 0.003 mol, the results were even better, the dielectric constant was increased, the dielectric loss was decreased, the Curie-temperature （Tc） was 110 ℃, and the frequency characteristic was also good. The resistivity of Nd2O3 doped BaTiO3 ceramics was lower than that of pure BaTiO3 ceramics, when Nd2O3 content was 0.001 mol,the resistivity was （2.364×）108 Ω·m, the smallest. The grain resistance of Nd2O3 doped BaTiO3 ceramics exhibited NTC effect, but the grain boundary resistance showed PTC effect, and the grain boundary resistance was larger than that of the grain resistance, so the PTC effect originated from the grain boundary. The analysis of the element binding energy through X-ray photoelectron spectrum were indicated that the quantivalence of Ba2+and Ti4+in Nd2O3 doped BaTiO3 ceramics was variable, and resulted in the improvement of the conductibility of BaTiO3 ceramics.

Rare earth doped CaCu_3Ti_4O_(12) electronic ceramics for high frequency applications

Ca1-xRxCu3Ti4O12(R=La,Y,Gd;x=0,0.1,0.2,0.3) electronic ceramics were fabricated by conventional solid-state reaction method.The microstructure and dielectric properties as well as impedance behavior were carefully investigated.XRD results showed that the secondary phases with the general formula R2Ti2O7 existed at grain boundaries of rare earth doped ceramics,which inhibited abnormal grain growth.The dielectric constant decreased from 4×105 in pure CaCu3Ti4O12(CCTO) ceramics to 2×103 with rare earth doping....

Gaseous Penetration of Pr into PbTiO_3 Ceramics and Their Electric Properties

The gaseous Pr-penetration is a new method to modify ceramics, which is expected to be a promising method for producing new conductor ceramic materials. The gaseous penetration of Pr into PbTiO_3 ceramics and their improved electric properties were reported. Through XRD, EPMA and SEM analysis,it is confirmed that the gaseous penetration makes Pr enter into PbTiO_3 ceramics, and the new compound of Pr_2Ti_2O_7 is formed by the penetration of Pr in the gaseous state. The formed new Pr_2Ti_2O_7-PbTiO_3 ceramic materials have a significant change in electric properties. The room temperature resistivity decreases from 2.0×10^(10) Ω·m to 9.487 Ω·m. The grain resistance and the grain boundary resistance decrease with increase in temperature, and the PTCR effect disappears. The tendency of transition to a conductive body is manifest.

Optical temperature sensor based on up-conversion fluorescence emission in Yb^(3+):Er^(3+) co-doped ceramics glass

yb^3＋：Er^3＋ co-doped oxy-fluoride ceramics glass has been prepared. The mechanism of up-conversion emissions about Er^3＋ was discussed, and the temperature properties of green up-conversion fluorescence between 303 and 823 K were investigated. The results show that the sensitivity of this sample reaches its maximum value, about 0.0047 K^-1, when the temperature is 383 K, indicating that this kind of sample can be used as high temperature and high sensitivity optical temperature sensor.

Influence of doped Ag^+ on multifunction characteristics in SrTiO_3 ceramics

SrTiO 3 capacitor varistor multifunction ceramics is fabricated by a single sintering process. The research is carried out, mainly aimed at the influence of the doped Ag + on multifunction characteristics in SrTiO 3 ceramics and its mechanism. The results show that the density of grain boundary acceptor state increases effectively due to the fact that Sr 2+ on grain surface is substituted by doped Ag distributing at grain boundary in form of Ag + during the course of oxidizing annealing, which is proposed to be the fundamental reason for understanding the significant difference of both the dielectric properties and varistor properties in SrTiO 3 ceramics samples with various Ag + contents.

Study on Mg PSZ Ceramics Doped with Y_2O_3 and CeO_2

Mg PSZ ceramics doped with Y 2O 3 and CeO 2 was prepared using traditional processing method. The fine grain PSZ ceramics( d c10 μm) sintered at low temperature(1550 ℃) was obtained by means of composition design. The effects of co stabilization of Y 2O 3, CeO 2 and annealing at 1100 ℃ on material composition, microstructure and mechanical properties were studied. The results show that Y 2O 3 and CeO 2 during annealing at 1100 ℃ can inhibit subeutectoid decomposition reaction effectively, and optimize nucleation and growth of t ZrO 2 precipitates in c ZrO 2 matrix phase. The materials show transgranular and intergranular fracture characteristics, and exhibit better mechanical properties owing to the cooperative effect of stress induced transformation toughening and microcrack toughening.

Spectral properties of Ce^(3+) doped yttrium lanthanum oxide transparent ceramics

Ce3＋-doped yttrium lanthanum oxide （Y0.9La0.1）2O3 transparent ceramics is fabricated with nanopowders and sintered in H2 atmosphere. The spectral properties of Ce：（Y0.9La0.1）2O3 transparent ceramics are investigated. There appear two characteristic absorption peaks of Ce3＋ ions at 230~nm and 400~nm, separately. It is found that Ce3＋ ions can efficiently produce emission at 384~nm from （Y0.9La0.1）2O3 transparent ceramic host, while the emission is completely quenched in Re2O3 （Re=Y, Lu, La） host materials.

Preparation and Spectral Properties of Er,Na∶CaF_(2) Transparent Ceramics

Er^(3+),Na^(+)co-doped CaF_(2) transparent ceramics with Er^(3+)dopant concentration of 3% and Na^(+) of 0%,0.5%,1.0%,1.5% and 2.0% were fabricated by the vacuum hot pressing method with 16 mm in diameter and 3 mm in thickness.The average grain size of the obtained Er,Na∶CaF_(2) powders varied from 28 nm to 36 nm with the shape of sphere.The effects of Na^(+) doping on the transmittance,microstructure and spectral properties of Er^(3+)∶CaF_(2) transparent ceramics were investigated.The transmittance of all the obtained ceramic samples is above 84%in the wavelength of 1000 nm.The results show that after introducing Na^(+)into Er^(3+)∶CaF_(2) transparent ceramics,charge-neutralized Er^(3+)-Na^(+) structure formed which prevent Er^(3+) from clustering.The emission spectra of Er^(3+) in CaF_(2) transparent ceramics at around 1.5 and 2.7μm could be modulated by adjusting the concentration of Na^(+) and the near-infrared fluorescence lifetime at around 1.5μm increase with the increasing of Na^(+) concentration,reaching a maximum of 56.75 ms.

用于高温和高频领域的PbTiO_3基陶瓷的研究

主要研究用于高温和高频领域的 Pb Ti O3基陶瓷的制备工艺、主要性质、显微结构、电导机制及其应用。 Pb Ti O3基陶瓷的性质是与此种陶瓷的制备工艺 ,显微结构和电导机制紧密相关的。

砂磨固相法快速制备Ca掺杂的BaTiO_(3)陶瓷及其结构和电性能研究

Ca^(2+)可掺杂在BaTiO_(3)(BT)陶瓷的A及B位。本文中系统研究B位掺杂Ca元素对BaTiO_(3)陶瓷的相结构与微观形貌、介电性能、可靠性和铁电性能的影响。采用砂磨-固相反应-造粒-压片方法制备BaTi_(1-x)Ca_(x)O_(3)-x(BTC-x,其中x=0,0.01,0.02,0.03,0.04)陶瓷样品。随着Ca掺杂量的增加,陶瓷样品的晶粒尺寸先增大后减小,样品居里温度T_(c)持续降低,其中BTC-1样品具有较高和较宽的介电峰及极小的损耗。利用高温阻抗谱对样品进行了可靠性分析,可知BTC-2的电学失效的风险最分散。由P-E电滞回线可知:在掺杂样品中,BTC-2的P_(max)值最大,归因于其内部可供极化的空间电荷浓度高。综上所述,当Ca元素在BT的B位掺杂量较低时,BTC材料具有良好的介电性能及可靠性,能应用于片式多层陶瓷电容器(Multi-layer Ceramic Capacitors,MLCC)行业。

Spectral and laser properties of Yb and Ho co-doped(YLa)_2O_3 transparent ceramic

Highly transparent Yb,Ho doped（YLa）2O3 ceramic was fabricated by conventional ceramic processing with nanopowders.The absorption and emission spectra of the ceramic was investigated.The energy transfer mechanism between Yb3＋ and Ho3＋ was also discussed.The strong emission band around 2 μm indicated that the Yb-Ho：（Y 0.90 La 0.10）2O3 transparent ceramic is a promising gain medium for the generation of 2 μm laser emissions.The laser operation of Yb-Ho co-doped（YLa）2O3 ceramic at 2.1 μm is first reported.

Up-conversion luminescence properties and energy transfer of Er^(3+)/Yb^(3+)co-doped oxyfluoride glass ceramic containing CaF_2 nano-crystals

The Er^3＋/yb^3＋ co-doped transparent oxyfluoride glass-ceramics containing CaF2 nano-crystals were successfully prepared. After heat treatments, transmission electron microscopy （TEM） images showed that CaF2 nano-crystals of 20-30 nm in diameter precipitated uniformly in the glass matrix. luminescence of Er^3＋ at 540 nm and 658 nm was observed in Comparing with the host glass, high efficiency upconversion the glass ceramics under the excitation of 980 nm. Moreover, the size of the precipitated nano-crystals can be controlled by heat-treatment temperature and time. With the increase of the nano-crystal size, the intensity of the red emission increased more rapidly than that of the green emission. The energy transfer process of Er^3＋ and Yb^3＋ was convinced and the possible mechanism of Er^3＋ up-conversion was discussed.

Influence of Heat Treatment Temperature and of Sb2O3 addition on Photoluminescence Properties of ZnO Ceramics Prepared by Sol-Gel Technique Preparation

To explore thin transparent electroluminescence and electric conductive films by sol-gel technique, Sb2O3 doped n-type ZnO ceramics powders were prepared by sol-gel technique and photoluminescence properties were measured. Then, the influences of composition and heat treatment temperature on photoluminescence properties were investigated in detail. With respect to the dopant concentration, about 1mol% addition of Sb2O3 was effective to increase photoluminescence intensity. With respect to heat treatment temperature, 800℃ was appropriate, and rather higher heat treatment temperature resulted in the formation of Zn7Sb2O12 and decrease the intensity. The excited ultraviolet wavelength of 200nm was proper to intense photoluminescence.

硬性BSPT基高温压电陶瓷温度稳定性研究

采用固相合成法在1125~1175℃烧结范围内制备了0.15BiScO_(3)-0.85(Pb_(0.88)Bi_(0.08))(Ti^(0.97)Mn_(0.03))O_(3)(BSPT-Mn)高温压电陶瓷。所有样品均为纯相,晶粒尺寸分布符合正态规律,掺杂元素均匀,未发现明显的富集现象。研究表明,在1150℃烧结制备的BSPT-Mn高温压电陶瓷的最大机械品质因数为1500.3,在484.4℃温度下压电常数为289.8 pC/N,压电性能良好。

掺杂Ba(Zr_(0.15)Ti_(0.85))O_(3)陶瓷的结构与电性能研究

采用固相烧结法制备了不同氧化钬掺杂量的Ba(Zr_(0.15)Ti_(0.85))O_(3)(BZT)陶瓷,对比分析了未掺杂和掺杂不同含量氧化钬的BZT陶瓷的物相组成、显微组织、介电性能和铁电性能。结果表明:未掺杂或氧化钬掺杂量较小(质量分数≤2%)的BZT陶瓷主要以单相固溶体形式存在;当氧化钬质量分数增加至3%及以上时,BZT陶瓷中形成新的Ho_(2)Ti_(2)O_(7)相;掺杂氧化钬的BZT陶瓷晶粒尺寸明显小于未掺杂氧化钬的BZT陶瓷,且随着氧化钬掺杂量的增加,BZT陶瓷的平均晶粒尺寸逐渐减小。此外,随着氧化钬掺杂量的增加,BZT陶瓷的ε_(r RT)和tan δ_(RT)先增加后减小,当氧化钬质量分数为2%时可以得到高ε_(r RT)、低tan δ_(RT)的BZT陶瓷。掺杂氧化钬的BZT陶瓷具有弛豫铁电陶瓷特征,氧化钬质量分数为2%~7%的BZT陶瓷的剩余极化强度均低于未掺杂氧化钬的BZT陶瓷,且剩余极化强度随着氧化钬掺杂量的增加逐渐减小;掺杂氧化钬的BZT陶瓷的矫顽电场均小于未掺杂氧化钬的BZT陶瓷,且矫顽电场随着氧化钬掺杂量的增加逐渐减小;BZT陶瓷剩余极化强度和矫顽电场的变化主要与BZT陶瓷内部相变、晶粒尺寸等有关。

Mn^(2+)掺杂对YAG∶Ce^(3+)荧光陶瓷发光性能的影响

过渡族金属Mn^(2+)掺杂的石榴石荧光陶瓷被认为是实现高显色激光照明的候选材料。然而,由于Mn^(2+)在不同配位环境下离子半径的多样性,Mn^(2+)掺杂石榴石陶瓷体系设计方案尚不明确。本文采用真空烧结技术制备得到不同浓度Mn^(2+)掺杂的YAG∶Ce^(3+)荧光陶瓷,并将Mn^(2+)分别设计进入八面体(OC)和十二面体(DO)格位。通过表征样品物相和显微结构、光致发光、荧光寿命、量子效率等,并通过LD激光器激发对荧光陶瓷的发光性能进行研究。实验结果表明,在添加电荷与体积补偿剂SiO_(2)的前提下,相比Mn^(2+)进入十二面体格位,Mn^(2+)进入八面体后石榴石的晶体结构更加稳定。因此,当Mn^(2+)的浓度控制在0.5%^(6)%(at)范围内,OC系列样品的量子效率高于DO系列样品。此外,OC系列样品的PL谱中位于588 nm和725 nm处的发射峰分别对应于Mn^(2+)占据八面体和十二面体格位的^(4)T_(1)→^(6)A_(1)电子跃迁,而DO系列样品中位于572 nm处的发射峰则源于Mn^(2+)占据扭曲的十二面体格位产生的电子跃迁。得益于Ce^(3+)→Mn^(2+)间高效的能量传递,将浓度为6%(at)的Mn^(2+)设计进入YAG∶Ce^(3+)中八面体格位制得荧光陶瓷,封装得到的激光白光光源的显色指数为70.8,相对色温为5117 K。本文对于Mn^(2+)掺杂的石榴石发光材料的开发研究是有力补充,也为提升YAG∶Ce^(3+)荧光陶瓷光谱中的红光成分,进而提高医疗、显示等领域的激光光源的显色性能提供借鉴。

Bi_(2)(SnO_(3))3掺杂(Ba,Sr)TiO_(3)介电陶瓷介电性能的研究

通过传统固相法制备Bi_(2)(SnO_(3))_(3)(BSO)掺杂(Ba_(0.79)Sr_(0.21))TiO_(3)((Ba,Sr)TiO_(3),BST)陶瓷。采用XRD、SEM等研究了Bi_(2)(SnO_(3))_(3)(BSO)掺杂对BST陶瓷的物相和微观结构及介电的性能影响。实验结果表明:随着BSO掺杂量增加,BST基介电陶瓷的介电常数开始增大而后减小然后再增大随后再减小,陶瓷的介质损耗首先增大然后减小。当掺杂BSO的量是2 wt%的时候,BST基介电陶瓷具有较好的介电性能:介电常数是5430;介质损耗是0.0145,电容温度变化率是+20.64%,-45.58%。BSO掺杂的BST基介电陶瓷仍为钙钛矿结构。BSO的掺杂起到移峰和压峰的作用。

掺杂Al_(2)O_(3)对LiNbO_(3)压电陶瓷组织和性能的影响研究

通过真空热压烧结法在900℃、35 MPa下保温120 min制备铌酸锂(LiNbO_(3),简称LN)压电陶瓷,研究掺杂不同含量的Al_(2)O_(3)对其压电性能的影响。通过物相、密度、微观组织、压电性能和介电性能分析发现,在0.5%~3%(摩尔分数)Al_(2)O_(3)掺杂量范围内,所有LN压电陶瓷样品的主体衍射峰位置相同、峰形尖锐,均为类钙钛矿结构;随着Al_(2)O_(3)掺杂量的增加,LN压电陶瓷晶粒尺寸逐渐减小,气孔增大、增多,密度和压电常数d_(33)均呈先增大后减小的趋势,均在Al_(2)O_(3)掺杂量为1%时达到最大,分别为4.65 g/cm^(3)和11.3 pC/N,此压电常数相较于激光烧结法制备的LN压电陶瓷提高了88.3%。在1 MHz测试频率下,LN压电陶瓷的相对介电常数随着Al_(2)O_(3)掺杂量的增加而逐渐增大。