La2O3掺杂对BaTiO3-Nb2O5-Fe2O3陶瓷的晶体结构和介电性能的影响

研究了La2O3 掺杂对BaTiO3-Nb2O5-Fe2O3(BTNF)基陶瓷的晶体结构和介电性能的影响.XRD分析表明:La2O3掺杂陶瓷的(200)和(002)晶面衍射峰都发生了明显分裂,说明陶瓷均以四方相为主晶相.随着La2O3含量的增加,四方率先增大后减小.用SEM研究La2O3对BTNF基陶瓷微观结构的影响,结果表明:随着La2O3掺杂量的增加,试样的晶粒明显变小,La2O3显著的抑制了晶粒的生长.当La2O3掺杂量为0.15 mol;时,陶瓷晶粒生长比较均匀.陶瓷的室温介电常数大体上呈现出先增大后减小的趋势,当La2O3掺杂量为0.15 mol;时,有最大介电常数4562.     

Nb2O5掺杂对Pb(Mg1/3Nb2/3)O3-PbZrO3-PbTiO3陶瓷组织与性能的影响

采用固相烧结法制备Nb2O5掺杂的Pb(Mg1/3Nb2/3) O3-PbZrO3-PbTiO3+ 0.5mol; ZnO(PMN-PZT)压电陶瓷,研究了不同Nb2O5掺杂量对材料结构及压电介电性能的影响.实验结果表明,随着Nb2O5掺杂量的增加(0～1 mol;),PMN-PZT陶瓷的晶界强度提高,断裂模式由沿晶断裂逐渐转变为穿晶断裂,而且陶瓷的压电介电性能升高.当Nb2O5掺杂量为1mol;时,1250℃烧结的陶瓷样品性能参数为:d33=430 pC/N,Qm=60,kp=0.52,kt=0.38,εr=3620,tanδ=0.017.     

Nb2O5/Co2O3加入量对(Ba,Sr)TiO3基电容器陶瓷介电性能的影响

研究了Nb2O5/Co2O3加入量[质量分数,Nb/Co(摩尔比)=0.8]不同对(Ba,Sr)TiO3(Barium strontiumtitanate,BST)铁电电容器陶瓷介电性能的影响,得到不同Nb2O5/Co2O3加入量与BST陶瓷性能的关系。借助扫描电镜(SEM)和X射线衍射仪(XRD)研究不同Nb2O5/Co2O3加入量对BST陶瓷显微结构和物相的影响,探讨了Nb2O5/Co2O3加入量对BST陶瓷性能影响机理。结果表明:当Nb2O5/Co2O3加入量为1.0%时,可得到满足Y5V特性、介电常数为3934、介质损耗为2.6%综合性能好的BST陶瓷。Nb2O5/Co2O3加入量对BST陶瓷性能的影响是通过细晶化、压抑展宽居里峰、改善介电常数温度特性、减少介电常数、形成杂相、形成“晶核-晶壳”结构等进行。     

Nb掺杂BaTiO%_3-Bi_(0.5)K_(0.5)TiO_3陶瓷系统PTCR性能的研究

采用固相反应法制备了Nb2O5掺杂的(1-x)BaTiO3-xBi0.5K0.5TiO3(BT-BKT,0≤x≤0.02)系统陶瓷,研究了Nb2O5和BKT掺杂量对该系统陶瓷显微结构和电性能的影响。结果表明:BaTiO3陶瓷的晶格轴率c/a值随着BKT含量的增加而变大,陶瓷具有良好的晶粒和明显的晶界。BT-BKT陶瓷的居里温度(Tc)也随着BKT的加入向高温移动,当x=0.01时,Tc提高到150℃,但室温电阻率(ρRT)随着BKT含量的增加也快速增大。     

(Nb2O5)1-x(TiO2)x陶瓷的制备及其介电性能的研究

我们采用传统固态反应方法烧结制备(Nb2O5)1-x(TiO2)x陶瓷,给出了掺杂量x从0.01到0.13陶瓷的介电性能.在本工艺条件下,所有样品的介电系数均大于120.当样品中TiO2的掺杂量为5mol;时,陶瓷的介电性能最佳:介电系数和损耗分别为217和0.078.XRD测试实验给出,当x≤0.05时,陶瓷的主要相结构为Nb2O5;当x≥0.07时,主相为TiNb24O62.     

TiO2对Nb2O5低膨胀陶瓷的烧结性、力学强度和抗热震性能的影响

以TiO2和Nb2O5微粉为主要原料,通过高温固相反应烧结制备了TiO2掺杂改性的Nb2O5陶瓷,研究了TiO2含量对Nb2O5陶瓷的晶相组成、烧结性能、热膨胀性能、抗弯强度和抗热震性能的影响.研究表明,2; ～ 8; TiO2掺杂未改变Nb2O5陶瓷的单斜晶系结构,而TiO2含量为12;时,除Nb2O5主晶相外,还生成了少量Ti2Nb10O29晶相.通过加入适量TiO2改性,可明显抑制Nb2O5陶瓷烧成过程晶粒异常生长,改善烧结性能,避免开裂现象,获得较为均匀致密的显微结构,有效提高样品的抗弯强度.Nb2O5陶瓷的热膨胀系数和抗弯强度都随着TiO2含量增加而表现出先增大后减小的变化趋势,其中TiO2含量为4;时,样品具有最高的抗弯强度(75.6 MPa)和低的热膨胀系数(1.42×10-6/℃).添加4; ～12;的TiO2都可明显改善Nb2O5陶瓷的抗热震性能.     

共沉淀法制备Sr(Fe0.5Nb0.5)O3纳米粉体及其介电性能研究

采用共沉淀法制备Sr(Fe0.5Nb0.5) O3纳米粉体,两步烧结工艺制备Sr(Fe0.5 Nb0.5) O3陶瓷.用X射线衍射仪(XRD)分析烧结温度、煅烧时间、体系温度、pH值和初始溶液浓度对前驱体粉体物相的影响,用扫描电子显微镜(SEM)分析Sr(Fe0.5 Nb0.5) O3纳米粉体和陶瓷的微观形貌,用阻抗分析仪研究陶瓷的介电性能.结果表明:当体系温度为25℃,pH值为9,初始溶液浓度为0.25 mol/L,在950℃煅烧2h后可获得颗粒分布均匀(～ 50 nm)的Sr(Fe0.5Nb05)O3纳米粉体,用该纳米粉体获得的Sr(Fe0.5Nb0.5)O3陶瓷有优异的频率和温度稳定性及高的介电常数(ε'＞2×103)和较低的介电损耗(1 kHz,tanδ=0.086).高的介电常数与陶瓷晶粒和晶界间阻挡层的形成有关,低的介电损耗来源于陶瓷致密的微观结构.     

Fe2O3掺杂(Ba0.7Ca0.3)TiO3-Ba(Zr0.2Ti0.8)O3无铅压电陶瓷的制备与性能

采用固相合成法制备了Fe2O3掺杂(Ba0.7Ca0.3)TiO3-Ba(Zr0.2Ti0.8)O3(简称BCZT)无铅压电陶瓷。借助XRD、SEM、阻抗分析仪等对该陶瓷的相组成、显微结构以及压电和介电性能进行了研究。结果表明,Fe2O3掺杂降低了BCZT无铅压电陶瓷的烧结温度并使居里温度Tc从85℃提高到95℃;当Fe2O3掺杂为0.02wt%～0.1wt%时,陶瓷样品均为ABO3型钙钛矿结构;少量Fe2O3掺杂促进了陶瓷晶粒的生长,但随着Fe2O3掺杂量进一步增加,陶瓷晶粒随之细化;当Fe2O3掺杂量为0.04wt%时,陶瓷样品具有最优综合电性能,其压电常数d33、机电耦合系数kp、机械品质因数Qm、介电损耗tanδ和介电常数εr分别为400 pC/N,0.40,51,0.023和3482。     

Y2O3添加对Nb2O5低膨胀陶瓷结构与性能的影响

采用高温固相烧结法制备了Y2O3改性Nb2O5低膨胀陶瓷材料.研究了Y2O3添加量对Nb2O5陶瓷的物相组成、微观结构、气孔率、热膨胀性能、抗弯强度和抗热震性能等的影响.结果表明,经1390℃保温2h烧成,纯Nb2O5陶瓷样品存在开裂现象,表现出低的抗弯强度和差的抗热震性能.添加2～ 10;Y2O3后,样品主晶相为单斜相Nb2O5,还生成了YNbO4晶相.通过添加适量Y2O3改性,可抑制Nb2O5陶瓷烧成过程中的晶粒增长和避免开裂现象,形成致密的微观结构,样品的抗弯强度和抗热震性能显著提高.Nb2O5陶瓷的热膨胀系数随Y2O3添加量的增加而逐渐增大.Y2O3添加量为6;时,样品的热膨胀系数和抗弯强度分别为1.9×10-6/℃和103.4 MPa,表现出良好的抗热震性能.     

不同离子掺杂的钛酸铋钠基陶瓷结构与性能表征

采用传统固相反应法制备了0.94(Na0.5 Bi0.) TiO3-0.06BaTiO3-3wt; Bi2 O3-xwt; Nd2O3(x=0,1.5)陶瓷.研究了Bi3+和Nd3+掺杂对0.94 (Na0.5 Bi05)TiO3-0.06BaTiO3陶瓷结构和电学性能的影响.结果表明,Bi2O3和Nd2O3掺杂不影响0.94(Na0.5 Bi0.5) TiO3-0.06BaTiO3的钙钛矿结构.3wt; Bi2O3添加使得铁电陶瓷0.94(Na0.5Bi05) TiO3-0.06BaTiO3转变为反铁电陶瓷.反铁电陶瓷0.94(Na0.5Bi0.5)TiO3-0.06BaTiO3-3wt; Bi2O3具有更高的相转变温度Tm(～320℃).Nd2O3添加不改变0.94(Na0.5 Bi0.5) TiO3-0.06BaTiO3-3wt; Bi2O3陶瓷的反铁电态,但增强了陶瓷的介电性能和弛豫性能.     

CaO-MgO-Al2O3-Fe2O3-B2O3-SiO2系微晶釉的制备

通过引入B2O3以降低烧成温度,利用赤泥中的Fe2O3为着色剂,在1150℃左右低温烧成制备了CaO-MgO-Al2O3-Fe2O3-B2O3-SiO2系微晶釉.赤泥的加入量为20;左右时,釉面具有良好的装饰效果和显微硬度.利用XRD、SEM研究了釉的物相及显微组织.结果表明,釉中析出的微晶是普通辉石,微晶的含量随MgO及CaO的含量增加而增加,而提高Al2O3含量则抑制微晶的析出.     

Pr2O3对含Cr2O3辉石系矿渣微晶玻璃晶化行为的影响

以白云鄂博西尾矿和粉煤灰为主要原料,分别制备了添加0,2.0wt;,4.0wt;和6.0wt; Pr2O3的辉石系矿渣微晶玻璃;综合采用基于DSC/DTA结果的析晶活化能Ek、Avrami指数以及粘流活化能Eη和背散射电子SEM显微形貌分析研究了Pr2O3对析晶的影响.结果表明在所研究范围内,Pr2O3含量的提高在整体上抑制了辉石相的析出.其原因除了与富Pr颗粒相对辉石相在析晶过程中的“钉扎”有关外,还与Pr2O3含量提高后使基础玻璃网络聚合程度加大,从而增大了辉石相形成所需离子扩散的阻力有关.     

Fe2O3-CO3O4共掺杂MgO-Al2O3-SiO2体系的红外辐射性能研究

采用固相反应法制备Fe2O3-Co3O4共掺杂MgO-Al2O3-SiO2体系的复合陶瓷材料,并通过XRD、SEM、XPS以及红外辐射测试等方法研究了样品的结晶行为与红外辐射性能.结果表明:Fe2 O3和Co3 O4共掺杂MgO-Al2 O3-SiO2体系后离子分布改变并生成混合尖晶石,从而引起品格畸变,从而有效提高材料的红外辐射性能.材料的红外发射率与其晶格畸变程度具有相同的变化趋势,并随Fe2 O3与Co3O4质量之比(R)的增加呈非线性变化.当R=3∶2时,材料在8 ～ 14 μm波段的辐射率可达0.92.     

EPR and magnetic susceptibility studies of B2O3–Bi2O3–Gd2O3 glasses

Glasses of the xGd₂O₃ · (100 − x)[B₂O₃ · Bi₂O₃] system with 0.5 ⩽ x ⩽ 10 mol% were studied by electron paramagnetic resonance (EPR) and magnetic susceptibility measurements. Data obtained show that for low gadolinium oxide contents of the samples (x ⩽ 3 mol%) the Gd³⁺ ions are randomly distributed in the host glass matrix and are present as isolated and dipole–dipole coupled species. For higher gadolinium oxide contents of the samples (x > 3 mol%) the Gd³⁺ ions appear as both isolated and antiferromagnetically coupled species. The EPR spectra of the glasses reveal resonance sites with an unexpected high crystalline field in addition to the ‘U’ spectrum, typical for Gd³⁺ ions in disordered systems. This absorption line is due to Gd³⁺ ions that replace Bi³⁺ ions from the host glass matrix and could play the network unconventional former role in the studied glasses.     

Yb2O3-Y2O3-Gd2O3-ZrO2热障涂层制备及性能研究

以Yb2O3、Y2O3 、Gd2O3稀土氧化物粉末和ZrOCl2·8H2O粉末为原料,采用化学共沉淀法制备了Yb2O3-Y2O3-Gd2O3-ZrO2 (YYGZO)热喷涂用粉末,采用大气等离子喷涂技术制备了YYGZO涂层,利用场发射扫描电镜(FESEM)、X射线衍射(XRD)研究了YYGZO粉末及涂层的微观组织形貌、相结构.结果表明,制备的热喷涂YYGZO粉末大部分呈规则实心球体状,且球形度良好,颗粒粒径均匀,大部分颗粒粒径分布为30～60μm,流动性能较好,满足大气等离子喷涂的要求.YYGZO涂层具有较好的高温相结构稳定性.所制备YYGZO热障涂层组织结构比较致密,涂层各个界面结合紧密,孔隙率约为9.23;,结合强度为35.2 MPa.     

R2O-RO-SiO2-Al2O3-Fe2O3-P2O5系分相釉的研究

针对铁红分相釉的配方特点,采用L8(4 ×24)正交实验研究了钠长石、牛骨灰、滑石、方解石、石英加入量对R2O-RO-SiO2-Al2O3-Fe2O3-P2O5系统分相釉釉面效果的影响,采用扫描电子显微镜(SEM)和能谱分析(EDS)对釉层的微观结构进行了表征.研究发现:牛骨灰对釉面是否出现“柿红”效果影响最显著,而方解石影响最不明显.Si/P摩尔比对铁红色釉面的产生起关键作用,当Si/P摩尔比小于2O,出现铁红釉面效果的概率极高.随着滑石加入量从9份变化到18份,出现铁红色釉面的趋势反而降低.经SEM和EDS分析发现,“柿红色”、“酒红色”釉面效果的产生很大程度上是由于釉层液液分相促进Fe2O3富集或偏析造成,且特别容易在高钠、低镁、低铝处聚集,最终连成雪花状结晶.     

Thermal expansion and transition temperature of glasses in the systems BeO–Al2O3–B2O3 and MgO–Al2O3–B2O3

Researches were conducted for glasses in the systems BeO–Al₂O₃–B₂O₃ and MgO–Al₂O₃–B₂O. The following characteristics have been determined: thermal expansion coefficient within 20–300 °C, structural thermal expansion coefficient (STEC) and glass transition temperature. The discussed properties of Be-aluminoborate and Mg-aluminoborate glasses have been compared with those of Ca-, Sr- and Ba-aluminoborate glasses. TEC of studied glasses gets higher going from Be-aluminoborate glasses to Ba-aluminoborate ones, but T_g decreases under the same succession. The dependence of STEC on the nature of a given cation is more complicated. The pattern of dependence of the properties on composition is due to changing the boron coordination number with respect to oxygen, which is the main network-former, and to competition between the aluminium and boron for the oxygen brought by an ion-modifier. The difference between the effect of one ion-modifier and that of another is determined by decreasing the radius of an ion and increasing its electric field strength in the succession from Ba²⁺ to Be²⁺. The ions of Be and Mg can also act as network-former to some extent.     

TiO2烧结助剂对纳米η-Al2 O3制备Al2 O3-Cr2 O3固溶体的影响研究

以纳米η-Al₂O₃粉和工业铬绿为原料,以摩尔比1:1配比制备Al₂O₃-Cr₂O₃固溶体,以TiO₂为烧结助剂,在还原气氛下经1400 ℃、1500 ℃和1600 ℃固相烧结.研究了TiO₂的加入对纳米η-Al₂O₃制备Al₂O₃-Cr₂O₃固溶体的致密度、线收缩率、相组成、晶胞参数、互扩散程度和微观结构的影响.结果表明:TiO₂的加入能促进Al₂O₃-Cr₂O₃固溶体的致密化;当温度为1600 ℃,TiO₂的添加量为2wt;时,试样的体积密度最大为4.57 g·cm^-3,线收缩率为19.8;;TiO₂的加入能使Al₂O₃-Cr₂O₃固溶体中Al³⁺和Cr³⁺的互扩散程度增加;微观结构表明,TiO₂的加入能使Al₂O₃-Cr₂O₃固溶体晶粒之间结合更紧密,实验温度范围内,随着TiO₂添加量的增加晶粒从沿晶断裂向穿晶断裂转变,只在晶间和晶内存在极少量气孔,当温度为1600 ℃,TiO₂的添加量为2wt;时,晶粒大小较均匀,平均晶粒尺寸约10μm.     

Structural properties of Cr2O3–Fe2O3–P2O5 glasses,Part I

The structural properties of xCr₂O₃–(40 − x)Fe₂O₃–60P₂O₅, 0 ⩽ x ⩽ 10 (mol%) glasses have been investigated by Raman and Mössbauer spectroscopies, X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The Raman spectra show that the addition of up to 5.3 mol% Cr₂O₃ does not produce any changes in the glass structure, which consists predominantly of pyrophosphate, Q¹, units. This is in accordance with O/P ≈ 3.5 for these glasses. The increase in glass density and T_g that occurs with increasing Cr₂O₃ suggests the strengthening of glass network. The Mössbauer spectra indicate that the Fe²⁺/Fe_tot ratio increases from 0.13 to 0.28 with increasing Cr₂O₃ content up to 5.3 mol%, which can be related to an increase in the melting temperature from 1423 to 1473 K. After annealing, the 10Cr₂O₃–30Fe₂O₃–60P₂O₅ (mol%) sample was partially crystallized and contained crystalline β-CrPO₄ and Fe₃(P₂O₇)₂. The SEM and AFM micrographs of the partially crystallized sample revealed randomly distributed crystals embedded in a homogeneous glass matrix. EDS analysis indicated that the glass matrix was rich in Fe₂O₃ (39.6 mol%) and P₂O₅ (54.9 mol%), but contained only 5.5 mol% of Cr₂O₃. These results suggest that the maximum solubility of chromium in these iron phosphate melts is 5.5 mol% Cr₂O₃.     

In2O3 and tin-doped In2O3 nanocrystals prepared by glass crystallization

Glasses in the system Na₂O/B₂O₃/Al₂O₃/In₂O₃/(SnO₂) were melted and subsequently tempered in the range from 540 to 700 °C. This led to the crystallization of In₂O₃, besides also NaBO₂ and Na₂Al₂B₂O₇ were formed. The crystallite sizes were in the range from 12 to 34 nm, depending on the temperature of thermal treatment, as calculated from XRD-line broadening. Crystal sizes determined by TEM were in the same range. Particle size histograms show a narrow crystal size distribution. After crystallization, the glass matrices and the non indium-containing crystalline phases were dissolved in diluted acetic acid. Spectra of the obtained suspensions containing tin-doped In₂O₃ nanocrystals exhibited a sharp UV-cut off, high transmission in the visible range and strongly decreasing transmission at wavelengths >1000 nm.