Bismuth layered ceramic materials Na0.5Bi8.5Ti7-xMnxO27(0≤x≤0.1)with inter-growth structure were prepared by the solid-state method.The effects of oxygen vacancy migration and oxygen vacancy concentration on the electrical properties of Na0.5Bi8.5Ti7-xMnxO27 ceramic materials were studied by regulating the migration of oxygen vacancies and the concentration of oxygen vacancies in the Na0.5Bi8.5Ti7-xMnxO27 system through Mn ion doping.The study found that all samples possessed a single inter-growth bismuth layered structure without any phase impurities.In the ceramic samples doped with Mn,Mn ions occupy the position of Ti ions in the perovskite structure.When x ≤ 0.06,the oxygen vacancy migration rate decreases,and the influence of oxygen vacancy migration on the electrical properties of ceramics predominates.As a result,dielectric loss and leakage current decreased,while the piezoelectric constant continuously increased.With the gradual increase in Mn content,when x＞0.06,the influence of oxygen vacancy concentration on the electrical properties became the main advantage.Consequently,the oxygen vacancy concentration increased,leading to an increase in dielectric loss and leakage current and a decrease in the piezoelectric constant.The maximum piezoelectric constant d33 value of 19.8 pC/N was obtained at x=0.06.At this time,the dielectric loss is low and the comprehensive electrical properties are optimal.
Li(Al1-xLix)SiO4-x (x = 0.005, 0.01, 0.015, and 0.02) ceramics were synthesized via a traditional solid phase reaction method with different sintering temperatures. To determine the positions occupied by Li+ in the lattice, the defect formation energies and total energies of various sites of LiAlSiO4 (LAS) occupied by Li+ were examined, and the energy of LAS systems were calculated using density functional theory of first-principle with the CASTEP module. The results demonstrated that the Al-sites occupied by Li+ had the lowest formation energies and total energy, so Li + should substitute Al3+. The impacts of replacing Al3+ with Li+ on the bulk density, sintering properties, phase composition, microstructure, and microwave dielectric properties of Li(Al1-xLix)SiO4-x (0 = x <= 0.02) ceramics were thoroughly studied. With Li+-doping, the sintering temperature decreased from 1300 degrees C (x = 0) to 1175 degrees C (x = 0.02), while the Q x f and tau f values of LAS ceramics significantly increased. The Li(Al0.99Li0.01)SiO3.99 ceramic was fully sintered at 1250 degrees C for 10 h to obtain excellent microwave dielectric properties: epsilon r = 3.49, Q x f = 51,358 GHz, and tau f = -51.48 x 10-6 degrees C- 1.
以清朝官款画珐琅器款识的装饰颜色为研究对象,将现存的画珐琅器与史料找到对应,得出蓝色款在日常生活中使用,红色款和黑色款分别在喜事和丧事中使用,黄色款和金色款只在紫砂胎和深色胎体上使用,是审美功能的体现和皇权的象征.蓝色款最多,与"景泰蓝"的认同感和釉料工艺相关.款识装饰的背后体现着皇权等级制度和汉文化传统内容.
在SiO2-Al2O3-CaO-Na2O-B2O3多元釉系统中以氧化铁作为变量,研究不同氧化铁添加量对于硼硅酸盐系统的釉层显微结构、釉色等的影响.结果表明:氧化铁的加入使得釉层结构改变,进而形成了釉面颜色变化.在没有氧化铁加入时,硼硅酸盐釉系统形成分相,产生200 nm左右的富B球形液滴和富Si连续相,在米氏散射作用下釉面呈现乳浊白色;少量氧化铁的加入导致釉熔体分相结构改变,富B相球形液滴尺寸减小,入射光在釉层被散射,在离子着色的作用下釉面呈现棕黄色;随着氧化铁的增加,球形液滴的尺寸继续减小,铁离子浓度在釉层不断聚集增大,入射光在釉层被大量的消耗,最终使得釉面呈黑色;当氧化铁添加量过多时,大量六边形赤铁矿α-Fe2O3晶体从釉层析出且呈不规则取向排列,形成"金星闪耀"的釉面效果.
文化融合是丝绸之路艺术的基本特征,其中可见中外多元文化艺术的交流和互鉴,唐代三彩狮子是丝绸之路艺术中别具一格的陶瓷艺术作品,其造型特征不仅呈现拟犬化的趋势,更凸显出拟拂菻狗(猧子)化的特征,最终形成具有唐代艺术风格的多元化、本土化、世俗化的文化特征.本文通过物种的传入与形象考证,参与佛教活动源流及拟犬化造型特征的演变几个方面,结合文献查阅考证和案例对比分析研究,阐释了三彩陶瓷狮子在丝绸之路佛教艺术中的文化内涵,以此揭示其造型演变规律,同时也反映了唐代文化在兼收并蓄、创新发展方面达到前所未有的高度.
