La₂NiO₄-based Giant Dielectric Ceramics And Its Performance Improvement

Study on La2NiO4 ceramic and its composite ceramics with strontium titanate or barium titanate mainly through this thesis,understanding the relationship between the internal structure of the material and dielectric properties,the deepening of the nickelates giant dielectric constant intrinsic dielectric behavior understanding,explore the ways to optimize the performance of materials.The optimum sintering temperature of La2TiO4 powder in 900-1100 ℃,found in the air environment can be obtained with high purity and activity of the powder dispersion at 1000 v for 3 hours in La2NiO4 sintering;ceramic sintering temperature of 1300 ℃ for 3 hours can also be saturated grain shape and dense structure ceramic obtained,the relative density is about 98%.The frequency range of La2NiO4 ceramics at room temperature 1KHz-5MHz,dielectric constant in the above 30000,showing very good frequency stability,but the dielectric loss at low frequency is about 350;the La2NiO4 ceramic giant dielectric constant frequency stability and high dielectric loss in the range of 30-240 ℃ in(at 1KHz,εr = 40000,Tanσ= 100).This is mainly with the sample inside the polaron thermal activation,the reason may be that there are multiple polar regions for ceramics.La2NiO4-BaTiO3 and La2NiO4-SrTiO3 ceramics are at 1200 ℃ for 3 hours to get the highest density of sintered ceramics.Among them,0.85 BaTiO3-0.15 La2NiO4 composite ceramics in 100Hz-10MHz range showed the best dielectric properties(εr ≥ 4000,Tan ≤0.2).At 75-525 ℃,εr = 4000,0.05 ≤ Tanσ≤10;0.9La2NiO4-0.1SrTiO3 composite ceramics in the range of 10MHz dielectric constant is although not big(50-1400),but dielectric loss is very low(0 to 0.1),in 75-125 ℃ at 1MHz under the dielectric loss of less than 0.01.It can even be visible in the elemental material properties unable to meet the modern social requirements for components,composite materials with high performance have certain potential application value.