中日高纯CaCO3的质量评价

研究了中日两国BaTiO3系PTC热敏电阻器用高纯CaCO3的生产能力、生产方法。技术标准与质量水平等。其中着重对其化学特性（纯度或含量;杂质）、物理特性（粒子形状、粒度分布、平均粒径、密度、晶系及热特性）与工艺试验进行了评价。结果表明：国产CaCO3（山东益达;四川攀枝花）的理化指标,已拉近或达到日本石灰工业（株）的水平,仅一次粒子粒径有时尚粗。     

Ca对BaTiO_3 PTCR热敏电阻性能的影响

用 Ba0 .93- x (Sr0 .0 7Cax) Ti1 .0 0 6 O3系材料制备了常温电阻率小于 9Ω· cm的 PTCR热敏电阻。通过 Ca引入量的变化发现 :Ca含量对 PTCR热敏电阻的 R-θ性能影响较大 ;当 x (Ca) <8.0 %时 ,随 Ca含量的增加 ,常温电阻率下降 ,Rmax/Rmin降低 ,居里温区拓宽 ;若 x (Ca) >8.0 %后 ,PTC常温电阻率迅速增大。     

BaCO_3和TiO_2的物化特性对PTC热敏电阻器性能的影响

探讨了ＢａＣＯ３与ＴｉＯ２的物化特性，诸如纯度、杂质含量、晶型、热特性、颗粒形状、粒度分布及平均粒径等对ＰＴＣ热敏电阻器性能的影响。并据此提出了ＢａＣＯ３与ＴｉＯ２的技术标准。     

高纯CaCO3匠合成及其对PTCR电性能的影响

高纯ＣａＣｏ３的合成方式对ＣａＣＯ３粒子形貌有较大影响，对ＰＴＣ陶瓷的电性能也存在一定的作用，其中以气液反应合成方式所得ＣａＣｏ３对ＰＴＣＲ较适宜。     

BaTiO_3系PTCR热敏电阻器用烧结助剂的研究

研究了烧结助剂的作用，实验结果表明：如只引入半导化元素，不引入烧结助剂，则室温电阻率ρ２５很大，甚至是绝缘体。由于烧结助剂的加入，既改善了ＰＴＣＲ热敏电阻陶瓷的烧结性，又改善了其ρ２５、耐电压Ｖｂ、ＰＴＣ效应等特性，从而使产品的各种特性易于重复。烧结助剂昔日多用ＡＳＴ，现在常用ＳｉＯ２，其加入量ｘ宜小于２％。ＳｉＯ２的纯度、杂质等化学特性，与粒子形状、粒度分布、晶系等物理特性，对ＰＴＣＲ热敏电阻器的电性能有很大的影响。据此提出了ＢａＴｉＯ３系ＰＴＣＲ热敏电阻器用ＳｉＯ２的技术标准。     

PTC陶瓷用钛酸钡粉体材料的质量要求──《电子陶瓷用钛酸钡粉体材料规范》评述

根据我国最近制定的《电子陶瓷用钛酸钡粉体材料规范》规定的钛酸钡粉体材料预定用途和理化性能指标，评述了各类质量等级的钛酸钡粉体材料在ＰＴＣ陶瓷方面的应用范围，解释了某些理化性能指标在ＰＴＣ陶瓷配方设计和工艺中的实用意义。     

PTC热敏电阻移峰加入物的研究

探讨了移峰加入物的移动效率及其引入时工艺上应注意的问题。研究了常用的移峰加入物的化学特性、物理特性对ＰＴＣ热敏电阻器性能的影响。并据此提出了常用的移峰加入物的技术标准。     

碳酸钙对BaTiO_3系PTC热敏电阻电性能的影响

研究了碳酸钙对ＢａＴｉＯ３ 系ＰＴＣ热敏电阻电性能的影响。结果表明,随着钙加入量的增加,ＢａＴｉＯ３ 的低温相变点, 移向更低的温度; 促进烧成时芯片的致密化; 使ＢａＴｉＯ３ 晶粒尺寸几乎呈线性下降; 使晶粒、晶界电阻下降; α、Ｒｍ ａｘ／Ｒｍ ｉｎ 无大的变化, ρ２５增大, Ｖｂ 提高。碳酸钙的理化指标, 对ＰＴＣ热敏电阻电性能也有很大影响, 据此推荐了ＢａＴｉＯ３ 系ＰＴＣ热敏电阻用ＣａＣＯ３ 的技术标准     

PTC热敏电阻的现状与发展趋势(待续)

基于对1995年以来,国内外PTC热敏电阻的研究,介绍了PTC热敏电阻用原料(BaCO3、TiO2、BaTiO3、SrCO3、PbO、Pb3O4、SrTiO3、PbTiO3、Y2O3、Nb2O5、CaCO3、SiO2等);材料(BaTiO3系、V2O3系及高分子);生产技术(瓷粉制造、烧成、芯片制造、质量评定、理化分析、片式PTC生产);重点产品(消磁、马达启动、限流及加热等用)以及基础研究(相变应力模型、表面势垒模型)等方面的现状及今后的发展趋势.     

PTC热敏电阻的现状与发展趋势(续二)

基于对1995年以来,国内外PTC热敏电阻的研究,介绍了PTC热敏电阻用原料(BaCO3、TiO2、BaTiO3、SrCO3、PbO、Pb3O4、SrTiO3、PbTiO3、Y2O3、Nb2O5、CaCO3、SiO2等);材料(BaTiO3系、V2O3系及高分子);生产技术(瓷粉制造、烧成、芯片制造、质量评定、理化分析、片式PTC生产);重点产品(消磁、马达启动、限流及加热等用)以及基础研究(相变应力模型、表面势垒模型)等方面的现状及今后的发展趋势。     

碳酸锰和纳米钛酸钡的添加对钛酸钡陶瓷的影响

以钛酸丁酯和乙酸钡为起始原料,采用液相法制备了纳米钛酸钡。研究了纳米钛酸钡和碳酸锰的掺杂对普通亚微米级钛酸钡的形貌及介电性能的影响。结果表明,在普通钛酸钡中加入一定量的纳米钛酸钡可以促进晶粒的生长,同时提高陶瓷的介电常数。而在普通钛酸钡中加入一定量的碳酸锰则可以抑制晶粒的生长。但同时添加碳酸锰和纳米钛酸钡,碳酸锰对晶粒生长的抑制作用将居于主导地位,并且此时钛酸钡陶瓷的介电常数温度特性曲线与单独添加锰离子时的走势基本相同,室温附近的介电常数峰将由于钛酸钡陶瓷的细晶效应而弥散。     

Magnetic properties of Co- and Mn-implanted BaTiO3, SrTiO3 and KTaO3

Implantation of Co or Mn into single-crystal BaTiO₃(K), SrTiO₃ or KTaO₃(Ca), followed by annealing at 700 °C, produced ferromagnetic behavior over a broad range of transition metal concentrations. For BaTiO₃, both Co and Mn implantation produced magnetic ordering temperatures near 300 K with coercivities 70 Oe. The M–T plots showed either a near-linear decrease of magnetization with increasing temperature for Co and a non-Brillouin shaped curve for Mn. No secondary phases were detected by high-resolution X-ray diffraction. The same basic trends were observed for both SrTiO₃ and KTaO₃, with the exception that at high Mn concentrations (5 at.%) the SrTiO₃ was no longer ferromagnetic. Our results are consistent with recent reports of room temperature ferromagnetism in other perovskite systems (e.g. LaBaMnO₃) and theoretical predictions for transition metal doping of BaTiO₃ [Nakayama et al., Jap. J. Appl. Phys. 40 (2001) L1355].     

日本3D电视机的高画质化竞争动向

1前言2010年,在3D数字电影兴起的推动下,国外电视广播界的3D立体电视热也有飞腾升空之势。目前,国外3D电视机仍是沿用3D电影的双眼式,即利用特殊眼镜观看的制式,虽然它还存在左右画面串扰和亮度的缺欠问题,但市场仍旧看好。目前,日本3D业界正在开展着以开拓市场为目的的高画质化竞争。为供国内同行     

Dielectric properties of single crystals of Al2O3, LaAlO3, NdGaO3, SrTiO3, and MgOat cryogenic temperatures

A dielectric resonator technique has been used for measurements of the permittivity and dielectric loss tangent of single-crystal dielectric substrates in the temperature range 20-300 K at microwave frequencies. Application of superconducting films made it possible to determine dielectric loss tangents of about 5×10^-7 at 20 K. Two permittivity tensor components for uniaxially anisotropic samples were measured. Generally, single-crystal samples made of the same material by different manufacturers or by different processes save significantly different losses, although they have essentially the same permittivities. The permittivity of one crystalline ferroelectric substrate, SrTiO₃, strongly depends on temperature. This temperature dependence can affect the performance of ferroelectric thin-film microwave devices, such as electronically tunable phase shifters, mixers, delay lines and filters     

Electrooptic coefficient measurements in LiTaO3 andLiNbO3 waveguides

The magnitudes of linear electrooptic coefficients r₁₃ and r₃₃ in Zn:LiTaO₃ repoled channel waveguides are reported. The measurements were made at 0.633-μm wavelength using a Fabry-Perot interferometer. The waveguides were produced by diffusion from the vapor phase at a temperature above the Curie temperature. For full recovery of the Pockels effect, an electric field of 200 V/cm is needed during repoling. The measured values of r₁₃ and r₃₃ at 32-MHz modulation frequency are 7.2 and 30.3 pm/V, respectively. The difference between unclamped and clamped coefficients is comparable to that from bulk crystals. Measurements were also made on Ti:LiNbO₃ waveguides that did not require repoling, and good agreement with bulk crystal values was obtained     

Sensor effect in YBa2 Cu3 Oy

The high-T_c superconducting material YBa₂ Cu₃ O_y, well known as a 1–2–3 compound, shows other very interesting properties. One of them is very strong conductivity-oxygen content dependence. On the basis of our previous measurements, an investigation of dilatation synthesis, X-ray diffraction (XRD) analysis and conductivity measurements were performed. The results on quenched and slowly cooled samples show a phase transition region and an obvious interdependence between conductivity, unit cell volume and oxygen content.     

First-principle study of ferroelectricity in PbTiO3/SrTiO3 superlattices

We performed the first-principles calculation to investigate the electronic structure and polarization behaviors in PbTiO₃/SrTiO₃ (PST) superlattices. The DOS (density of state) profiles show that there are strong hybridizations of atom Ti–O and Pb–O which play very important roles on ferroelectricity of the PbTiO₃/SrTiO₃ superlattices. Comparing to the corresponding paraelectric phase, we find the electrons of the PT (PbTiO₃) layers occupy lower energy states and electrons of the ST (SrTiO₃) layer occupy higher energy states. It is shown that the polarizations of the superlattices decrease with proportion of SrTiO₃ increasing. The constant polarization of local layer indicates that PST superlattices with small modulation lengthen can be approximately considered as a single ferroelectric material. Furthermore, according to electrostatic model, we find that directions of internal electric fields in PT and ST layers are opposite. In PST superlattices, internal electric field in PT layer leads to the loss of polarization of this layer, but the polarization of ST layer is induced by internal electric field of this layer. Compared to the value of the polarization in bulk PbTiO₃, polarization of PST is smaller.     

硫酸铝铵制高纯氧化铝粉的性能表征

通过XRD衍射分析和SEM扫描电镜、差热失重、BET比表面仪等分析手段,对硫酸铵盐制取高纯氧化铝粉的热解过程进行了详细分析,提出了其热解相变过程为:Al2(SO4)3950～1000 ℃→δ-Al2O31100℃→纳米级α-Al2O3 δ-Al2O31200～1220 ℃→亚微米级α-Al2O3通过采用无压分段式热解工艺,可获得分散性良好的类球性高纯度氧化铝粉.通过实际产品烧结证明,其活性明显高于其它同类原理制备的氧化铝粉.     

Red, Green, and Blue Light Through Cooperative Up-Conversion in Sol-Gel Thin Films Made With Yb0.80La0.15Tb0.05F3 and Yb0.80La0.15Eu0.05F3 Nanoparticles

Silica and zirconium dioxide sol-gel thin films made with Yb_0.80La_0.15Tb_0.05F₃ or Yb _0.80La_0.15Eu_0.05F₃ nanoparticles are reported. Bright blue (413 and 435 nm), green (545 nm), and red (585 and 625 nm) emissions are produced from Tb³⁺ ions through cooperative up-conversion of 980 nm light. Similarly, red (591 and 612 nm) emission is generated from Eu³⁺ ions. These up-convertors may find use in white light sources. The cooperative up-conversion of Yb³⁺-Tb³⁺ ions is more efficient than of Yb³⁺-Eu³⁺ ions because the efficiency of energy transfer from excited Yb³⁺ ions to a Tb ³⁺ ion (0.37) is more than two-times higher than of excited Yb³⁺ ions to a Eu³⁺ ion (0.15), as estimated from the lifetime of excited Yb³⁺ ion. The estimated quantum yields of both Tb³⁺ ion and Eu³⁺ ion emissions are on the order of 40%, and hence are not the cause of the difference in efficiency. This approach does not work for Sm³⁺, Pr³⁺ , and Dy³⁺. Incorporation of the respective Ln³⁺ ions in nanoparticles is crucial, as controls, in which the various Ln³⁺ ions are incorporated directly into the sol-gel, that do not show cooperative up-conversion