Y系掺杂的TiO2压敏陶瓷性能研究

通过在TiO2压敏陶瓷制备过程中引入Y系作为受主掺杂,讨论了以Y取代Bi受主掺杂对双功能TiO2压敏陶瓷性能的影响.实验结果表明:以Y系掺杂的Ti-Nb基压敏陶瓷可获得较好的低的压敏电压与高的电容双功能特性.其中,以Y+Cu为受主掺杂剂,SiO2为烧结助剂的配方,在1300℃温度下烧结,获得压敏电压V1mA＝9.4V/mm,非线性系数α＝4.8,介电常数ε＝21300,介电损耗tanδ＝0.09较优异的压敏介电性能.同时Y系掺杂也避免了掺杂Bi的高温挥发性.     

TiO2陶瓷的复合功能特性

本文研究了Ｎｂ２Ｏ５和Ｓｂ２Ｏ３施主掺杂对ＴｉＯ２瓷的半导化和电容－压敏复合功能特性的影响，施主掺杂的最佳量是０．５ｍｏｌ％。结果表明，Ｎｂ２Ｏ５掺杂能较大的降低ＴｉＯ２瓷的电阻率和提高其介电常数。掺杂Ｎｂ２Ｏ５和Ｓｂ２Ｏ３的ＴｉＯ２瓷，均呈现优异的电压－电流的非线性关系，具有较低的初始电压，低的泄漏电流和较大和非线性系数。     

双施主掺杂对PTC陶瓷性能的影响

为了提高PTC陶瓷整体性能,本文用正交法对高温PTC进行了双施主Nb2O5和La2O3掺杂配比的实验,优选了配方,其中La2O3的摩尔分数应该控制在0.0006～0.0008之间,Nb2O5控制在0.0005～0.0007之间较好。同时研究了双施主掺杂与单施主掺杂分别对高居里点PTC陶瓷性能的影响。     

Sb2O3掺杂对ZnO压敏陶瓷晶界特性和电性能的影响

制备了掺有Sb2O3不同掺杂量ZnO压敏陶瓷样品,采用扫描电镜对样品进行显微结构分析,研究了Sb2O3掺杂浓度对ZnO压缩电阻显微结构和性能的影响,测量了样品的电性能,由样品C－V特性的测量计算出晶界参数,并由此讨论了陶瓷性能与晶界特性的相关性。研究发现,在ZnO压敏陶瓷样品中掺杂适量的Sb2O3可以提高ZnO压敏陶瓷样品的非线性性能,但当Sb2O3的摩尔分数超过0．088％时,电性能反而优化,这是因为Sb2O3掺杂浓度不同会引起晶界势垒高度、施主浓度与陷阱密度的变化,因此Sb2O3掺杂量要控制在适当的范围内。     

TiO2压敏陶瓷的研究

本文研究了Nb2O5和Sb2O3施主掺杂对TiO2瓷的半导化和电客一压敏复合功能特性的影响。施主掺杂的最佳量是0．5mol％。结果表明，Nb2O5掺染能较大的降低TiO2瓷的电阻率和提高其介吃常数。掺杂Nb2O5或Sb2O3的TiO2瓷，均呈现优升的吃工一屯流的非域性失系，具有较低的初始电压，低的泄漏屯流和校大的非线性系数。     

SrTiO3压敏陶瓷一次烧成工艺的研究

研究了一次烧成法的温度、还原和氧化条件、施主和受主掺杂等对ＳｒＴｉＯ３陶瓷压敏和介电性能的影响。借助于ＳＥＭ，ＥＤＡＸ和ＷＤＡＸ等分析技术，阐述了这种陶瓷的显微结构、杂质分布和电性能之间的关系。     

氧化铟对ZnO压敏陶瓷压敏特性及微观结构的影响

用粘度为0．1～0．3mm的氧化锌粉末为原料，制得了氧化锌压敏陶瓷片，研究了In_2O_3掺杂对其压敏特性和微观结构的影响、结果表明：这种氧化锌粉末具有很高的烧结活性，适合作低压压敏电阻器。当烧结温度一定（1240℃）时。阀值电压Vc随着In_2O_3含量的增高而增加，其原自是由于In_2O_3含量的增加，在高温时烧结体内In_2O_3的分解量增加，从而使烧结体中的孔隙率增加。导电性降低。     

掺杂对BaTiO3基PTC陶瓷材料性能的影响

概述了BaTiO3基PTC陶瓷半导化的掺杂种类和机理,综述了掺杂物的添加量和加入方式对BaTiO3基PTC陶瓷材料性能的影响,并展望了其发展趋势。通常BaTiO3陶瓷的电阻率在开始时都随施主掺杂浓度的增加而降低,当施主掺杂浓度达到某一值时,电阻率降至最低,而后随着施主掺杂浓度的提高,电阻率则迅速上升。随着受主掺杂含量的增加,材料的室温电阻率和升阻比逐渐增大,PTC性能逐步提高,当含量超过某一值时,升阻比又呈降低趋势,PTC效应有所降低,室温电阻率依然增大。由于各掺杂物的优缺点不同,近几年研究发现,双施主掺杂和施受主共掺能够很好的改善材料的性能。     

掺杂Fe2O3对氧化锌压敏陶瓷压敏特性的影响

本文研究了分别掺杂微量Fe2O3杂质对ZnO压敏陶瓷的压敏特性的影响。研究结果表明:随Fe2O3掺杂量的增加,ZnO压敏陶瓷的压敏电压V1 mA和非线性系数先下降,后升高,最小值出现在Fe2O3摩尔掺杂量为1.00%;并从理论上详细地探讨了产生这些影响的原因。     

Er2O3掺杂ZnO压敏陶瓷的制备及其电学性能

研究了Er₂O₃掺杂对ZnO–Bi₂O₃–Sb₂O₃–Co₂O₃–MnO₂–Cr₂O₃–SiO₂压敏陶瓷微观结构和电学性能的影响。Er₂O₃掺杂后，部分Er固溶于富Bi相中，对ZnO压敏陶瓷的晶界特性和电学性能产生了较大影响。随着Er₂O₃掺杂量从0.09%(质量分数)增大到0.35%，样品晶界电阻率不断减小，漏电流密度不断增大，双Schottky晶界势垒高度和非线性系数先增大后减小，击穿场强不断增大；当Er₂O₃掺杂量为0.27%时，所得ZnO压敏陶瓷非线性系数达到54.4±1.5，击穿场强为(470.1±2.8) V·mm^–1，漏电流密度为(1.9±0.1)μA·cm     

镧锶铋钛陶瓷的介电性能与缺陷机构

研究了镧锶铋钛系陶瓷的介电性能与缺陷机构。结果表明,镧含量低时,材料中存在复合缺陷,且材料的介电常数随镧含量增加呈现峰值;当镧含量较高时,镧在锶铋钛系中的替代位置由A位向B位移动,呈现施-受主补偿,使得材料中复合缺陷解体,材料的介电常数下降。在缺陷机构发生改变的过程中,材料的电子密度变化不大。此外.根据正电子湮没寿命谱的结果,对材料中缺陷机构的进一步分析证实了上述缺陷模型的合理性。     

施、受主掺杂对高居里点BaTiO3基PTCR陶瓷材料性能的影响

以合成的(Ba_(0.6)Pb_(0.4))TO_3为主要原料,通过电性能测试、SEM、XRD等手段分析研究了施主Nb~(5 )掺杂以及施主Nb~(5 )、受主Mn~(2 )共掺对高居里点BaTiO_3基PTCR陶瓷材料性能的影响。结果表明,施受主掺杂不影响材料基体的晶体结构,适量的施主Nb~(5 )掺杂可降低材料的室温电阻率从而改善其性能,受主Mn~(2 )掺杂提高了施主Nb~(5 )掺杂的高居里点BaTiO_3基PTCR陶瓷材料的室温电阻率且只有极少量的Mn~(2 )掺杂才使材料的PTC效应稍有提高。     

Positive Temperature Coefficient of Resistivity Effect in Highly Donor–Doped Barium Titanate

BaTiO₃ ceramics doped with different La concentrations (0–12 mol%) were prepared by sintering under the reducing conditions of a nitrogen atmosphere containing 1% hydrogen. The critical donor concentration that causes blocking of the exaggerated grain growth was observed to be ∼10 mol% La. The samples, which were semiconducting after sintering under reducing conditions, were subsequently reoxidized by annealing in air to induce the positive temperature coefficient of resistivity (PTCR) effect. After reoxidation at 1150°C a noticeable PTCR effect was observed in the samples doped with La concentrations as high as 2.5 mol%. The room-temperature resistivity after reoxidation was found to increase with increasing donor concentration due to an increase in the thickness of the insulating layers at the grain boundaries. TEM analysis showed that reoxidation of the samples caused precipitation of the Ti-rich compound Ba₆Ti₁₇O₄₀ inside the doped BaTiO₃-matrix grains.     

用纳米粉制备Nd:Y1.84La0.16O3透明陶瓷

用碳酸盐共沉淀法制备一种新的掺钕氧化镧钇(Nd:Y1.84La0.16O3)纳米粉体,得到颗粒细小、均匀、分散性好、粒径为50～60nm的Nd:Y1.84La0.16O3纳米粉体.分别采用Nd:Y1.84La0.16O3纳米粉料和商业粉料,用传统陶瓷无压烧结工艺制备Nd:Y1.84La0.16O3透明陶瓷.Nd:Y1.8vLa0.16O3纳米粉制备的陶瓷样品的组分均匀、几乎不存在第二相,具有较高的透过率.商业粉制备的陶瓷样品因混料不均匀而在晶界处存在部分第二相,降低了陶瓷的透过率.此外,还运用体视学法预测了2种陶瓷透过率的相对高低,分析了三维结构参数对陶瓷光学性能的影响.     

La3+掺杂及载体类型对纳米TiO2薄膜光催化活性的影响

实验以钛酸四正丁酯及硝酸镧为原料,采用浸渍涂覆工艺,以溶胶-凝胶法在不同载体上制备纳米级二氧化钛薄膜,以甲基橙为模拟对象,研究了不同浓度的La3+掺杂对催化剂光活性的影响.结果表明降解效率随载体、掺杂浓度不同而变,最佳的离子掺杂浓度也有差别.釉面瓷砖、铝、不锈钢载体掺杂0.5%La 3+的二氧化钛薄膜对甲基橙有最高的降解效率,陶瓷载体掺杂0.05%La3+的降解效率最高,玻璃载体最佳La 3+掺杂浓度为5%,而钛片载体最佳La3+掺杂浓度为300%.     

Critical role of CuO doping on energy storage performance and electromechanical properties of Ba0.8Sr0.1Ca0.1Ti0.9Zr0.1O3 ceramics

CuO doped Ba_0.8Sr_0.1Ca_0.1Ti_0.95Zr_0.05O₃ (BSCTZ) ceramics were prepared by a modified mechano-chemical activation technique with the aim of improving energy storage properties for ceramic capacitor applications. CuO can effectively improve the microstructural characteristics along with a transformation of BSCTZ from classical ferroelectric to relaxor, which is the prime requirement for obtaining high discharge energy density and energy efficiency. The effect of CuO doping on the microstructural, ferroelectric, dielectric, and piezoelectric properties have been systematically studied. The study reveals that an appropriate amount of CuO doping can significantly enhance the morphological properties along with improvement in material density, which is very beneficial in a material for attaining improved energy storage performance. The BSCTZ sample with 3 mol% CuO doping has shown a highly dense microstructure, high saturation polarization (33.01 μC/cm²), low remnant polarization (6.74 μC/cm²), ultrahigh discharge energy density (1.81 J/cm³) and high energy efficiency (81.9%). The CuO doping in BSCTZ has also led to a slight improvement in breakdown strength and electromechanical properties compared to pure BSCTZ ceramics, which is mainly attributed to excellent density and optimum grain size of the material.     

Surfactant assisted synthesis of nanostructured Mn-doped CuO: An efficient photocatalyst for environmental remediation

The nanostructured Mn-doped CuO material was hydrothermally synthesized using urea as a surfactant to control the shape and size of the material particles. Advanced physiochemical methods were used to look at the microstructure, texture, morphology, and chemistry of the Mn-doped and pristine CuO materials. I–V and UV/visible experiments were performed on doped and un-doped materials to investigate the effect of Mn-doping on electrical conductivity and bandgap. The antibacterial and photocatalytic characteristics of the hydrothermally prepared materials were evaluated and compared through the destruction of Escherichia coli (E.coli) and the photocatalytic mineralization of Rh–B dye. The Mn-doped CuO material has much better photocatalytic activity for the mineralization of Rh–B dye than pristine CuO, with 93.8% dye mineralization after 90 min of visible light illumination compared to 56.52% for pristine CuO. The Mn-doped CuO material mineralized the Rh–B dye at a rate constant (k) of 0.02152 min^?1, about three times faster than virgin CuO (k = 0.00802 min^?1). The Mn-doped CuO material has negligible electron-hole recombination aptitude but quicker charge transport characteristics than the un-doped comparable based on transient photocurrent and impedance testing. The current work shows how to make a doped semiconductive material that can be used to clean up the environment and is versatile, cheap, and very effective.     

氧供体醇对非水解溶胶-凝胶法低温合成钛酸铝的影响

以TiCl4和无水AlCl3为原料,以无水低碳醇为氧供体通过非水解溶胶-凝胶法低温合成了钛酸铝,研究了无水低碳醇种类及用量对钛酸铝合成反应的影响.结果表明:当氧供体按反应式化学计量比用量加入时,在750℃能合成出钛酸铝,其中以乙醇的合成效果最好,异丙醇次之,正丁醇的效果较差;采用甲醇和叔丁醇作氧供体,由于它们的化学活性过大而引发水解反应,不能低温(750 ℃)合成钛酸铝.当醇用量超过化学计量比时,则合成效果显著下降;当醇用量低于化学计量比时,改变乙醇的用量对合成效果影响不明显,而减少异丙醇和正丁醇用量可显著提高钛酸铝的合成效果.     

溶胶凝胶法制备的La_（2–x）M_xCuO_（4–δ）晶体的UV–Vis–NIR光学性质

采用溶胶–凝胶法制备了La2CuO4和La2–xMxCuO4–δ（M=Ca、Sr和Ba）晶体。通过X射线衍射、扫描电子显微镜和紫外–可见–近红外光谱对La2CuO4和La2–xMxCuO4–δ（x=0.1）粉体进行了测试和表征。结果表明,700℃煅烧2h,可以获得单相La2CuO4和La2–xMxCuO4–δ（M=Ca、Sr和Ba）,且均为正交晶型结构。光谱性质表明,La2CuO4和La2–xMxCuO4–δ系化合物在紫外–可见和近红外范围都有较宽的吸收。La2CuO4、La1.9Ca0.1CuO4–δ、La1.9Sr0.1CuO4–δ和La1.9Ba0.1CuO4–δ的带隙分别为1.44、1.57、1.40eV和1.37eV。带隙的变化是由于碱土金属离子的半径不同,造成对键的不匹配性的影响不同而引起的。     

PMN-PFN铁电陶瓷低温烧结技术研究

Pb(Mg1/3Nb2/3)O3(PMN)是一种典型的弛豫铁电体,它具有很大的介电常数,较小的介电损耗,良好的压电稳定性和电致伸缩效应,在叠层电容器、致动器等方面有重要的应用。PMN可以方便地与Pb(Fe1/2Nb1/2)O3(PFN)形成固溶体以移动介电常数峰值温度(Tm)。本文使用Swartz和Shrout提出的两步法,研究了基体掺杂不同物质对0.9PMN-0.1PFN和0.75PMN-0.25PFN二元体系的烧结性能及介电性能的影响。经研究发现:添加BiFeO3、Li2CO3、MnO2,都能使烧结温度降低。其中,当在0.9PMN-0.1PFN中掺入5wt%的Li2CO3时,介电常数为18120,大于纯组分的0.9PMN-0.1PFN的介电常数,当掺入BiFeO3和MnO2时,都使介电性能恶化。对不同掺杂对性能的影响进行了解释。