The Effect of Bi2O3 on the Structure and Microwave Dielectric Properties of Ba6-3xNd8＋2xTi18O54 System（x=2/3）

The structures and dielectric properties of Ba6-3xNd8＋2xTi18O54 system（x=2/3） doped with different contents of Bi2O3, whose final molecular formula is Ba6-3x（Nd1-yBiy）8＋2xTi18O54 were investigated. It is indicated that the dielectric constant increases greatly whereas Q value（f0=4 GHz） decreases with the increase of Bi2O3 content. However, the temperature coefficient could be controlled below 0±30×10^-6/℃ in the experiment. These phenomena are related to the appearance of a new phase, Bi4Ti3O12, which has high dielectric constant. Also, that Bi^3＋（0.13 nm） substitutes for Nd^3＋（0.099 5 nm） will increase the unit cell volume, which will lead to the enlargement of the octahedron B site occupied by Ti^4＋. So the spontaneous polarization of Ti^4＋ ions will be strengthened. Besides, Bi^3＋ will fill up some vacancies which Ba^2＋ or Nd^3＋ ions leave in two A1 sites and four A2 sites. More positive ions polarize, which also contributes to higher dielectric constant. The samples got with the optimium properties are sintered at 1 200 ℃ for 4 h, when y=0.25, ε≈110, Q≈5 400（f0=4 GHz）, TCC=-4.7×10^-6/℃; When y=0.3, ε≈120, Q≈5 000（f0=4 GHz）, TCC=-24×10^-6/℃.     

Y_2O_3-ZrO_2陶瓷的电导特性研究

对Ｙ２Ｏ３摩尔分数为６％的Ｙ２Ｏ３－ＺｒＯ２陶瓷的电导特性进行了实验研究．利用扫描电子显微镜、Ｘ光衍射仪、Ｖ氏硬度仪和交流阻抗法等研究测定了氧化钇部分稳定氧化锆在不同烧结温度下的显微组织、相比例、断裂韧性与电导率．实验证明,在温度为１６００℃时烧结的Ｙ２Ｏ３－ＺｒＯ２陶瓷材料,组织致密,其电导率达到１０－２Ｓ／ｃｍ,而四方相含量的降低可能是导致断裂韧性降低的重要原因．     

Corrosion resistance of plasma sprayed NiCrAl (ZrO_2 Y_2O_3) thermal barrier coating on 18-8 steel surface

1INTRODUCTION Austeniticstainlesssteelisdevelopedtocom pensateforpoorcorrosionresistanceofmartensite stainlesssteelandoverlargebrittlenessofferrite stainlesssteel.Basicconstituentsofitstypicalal loyare18%Crand8%Ni(massfraction),which isusuallycalledas188s…     

Properties of plasma sprayed NiCrAlY (ZrO_2 Y_2O_3) coating on refractory steel surface

1INTRODUCTION1Cr18Ni9Ti,i.e.188austeniticstainless steel,isakindofausteniticrefractorysteelwidely appliedinmanyfields,containingahighcontentofCrthatcanimproveheatandoxidationresistances,andalsoNicapableofformingastableaustenitic structure.However,suchstee…     

纳米粉掺杂的Y2O3-ZrO2陶瓷的制备

采用纳米粉掺杂烧结制备了Y2O3-ZrO2陶瓷。测试发现，纳米粉的掺入在一定程度上可以使烧结体的密度和硬度得到提高。SEM和EDS分析表明，烧结体表面比较平滑，元素分布比较均匀，有较小的气孔存在。     

Manufacture Process of 8Y_2O_3 Stabilized ZrO_2 from Nano Powders

1　IntroductionTheapplicationanddevelopmentofnewmaterials ,areveryimportant .Thesizeofnano materialsisintherangeof 1 1 0 0nm .Theatomarrangesofnanocrystallinearedifferentfrombothcrystalstructurewithlong distanceorderandnon crystalstructurewithlong dista…     

ZrO2/Al2O3复合载体中ZrO2的晶相和晶粒尺寸对Ni基催化剂性能的影响

用沉积-沉淀和溶胶-凝胶等法在扩孔后的Al2O3基载体上分别制备了不同ZrO2晶相和品粒尺寸的负载型纳米ZrO2／Al2O3复合载体，并用浸渍法制备了Ni／ZrO2／Al2O3．考察了纳米ZrO2品型结构和品粒尺寸对CO2重整CH4催化剂Ni／ZrO2／Al2O3的性能影响．结果表明，四方相ZrO2（t—ZrO2）有利于提高催化剂的表面吸附性能和催化剂的稳定性，同时t-ZrO2晶粒尺寸越小，活性物种的分散度越高，催化剂的活性好．     

CeO2 的加入对(ZrO2)0.86(MgO)0.14陶瓷电导率的影响

对（ＺｒＯ２）０．８６ＭｇＯ０．１４外加２～１２ｍｏｌ％ＣｅＯ２陶瓷材料的电导率进行了研究,对此类材料的电导率、活化能与强度、结构的关系进行了分析。实验发现,当外加ＣｅＯ２含量在６～８ｍｏｌ％时,电导率、活化能发生反常变化,此变化可能与点缺陷行为有关;随热处理时间的增加,电导率下降,电导活化能出现极小值,而弯曲强度出现极大值,出现极值的区域具有较好的对应关系。     

Pt／TiO2氧敏元件工艺和氧敏机制的研究

此文主要阐述了通过热分解氯铂酸工艺对TiO_2元件进行第二次铂催化能大幅度提高氧敏特性,并使元件呈现许多新特点。在总结实验的基础上,发展了肖特基势垒氧敏机制,较好地解释了实验现象。     

SO42-/ZrO2-Nd2O3固体酸的制备及其催化活性

以皮胶原纤维为模板剂,硫酸锆为锆源,掺杂稀土Nd元素制备SO42-/ZrO2-Nd2O3固体酸。通过TG、XRD、FT-IR、SEM以及N2吸附脱附分析等表征了制备条件对SO42-/ZrO2-Nd2O3固体酸结构的影响。结果表明,SO42-/ZrO2-Nd2O3固体酸较好地保持了模板的纤维结构,添加稀土Nd元素能有效抑制晶粒增长,ZrO2-Nd2O3晶粒尺寸为5.1~11.6 nm,比表面积为63.96 m2/g;以乙酸和正丁醇的酯化反应为模型反应考察SO42-/ZrO2-Nd2O3固体酸的催化活性,催化剂活性较高,重复使用5次,乙酸的转化率仍可达到85%,表现出较好的重复使用性,具有一定的工业应用前景。     

Effect of junction potential on the EMF of bielectrolyte solid-state sensors

The EMF (electromotive force) expressions of bielectrolyte solid-state sensors derived from classical thermodynamics are not rigorous. They are only applicable in some special situations. In order to expand their applicable scope, they should be derived from irreversible thermodynamics theory. There is a junction potential term in the EMF equations of double solid electrolyte sensors derived from irreversible thermodynamics. The junction potential involves the ion transference numbers and the electron transference numbers of two kinds of solid electrolytes. When the transference numbers of reaction ions in the two solid electrolytes equal 1 only,the junction potential term is zero and two types of EMF equations become the same.