| As an important component in electronic equipment,capacitors are widely used in coupling,bypassing,filtering,tuning loops,etc.With the improvement of people's living standards,the demands for the performance of electronic products are getting higher and higher.PbTiO3-based ceramics are widely used in capacitors because of their excellent performance.Due to the harm to people and the environment caused by the preparation,the PbTiO3-based ceramic capacitors are gradually being replaced by lead-free materials.BaTiO3-based ceramics are widely used due to their high dielectric constant,low loss,and no pollution.However,the dielectric peak of barium titanate ceramic changes suddenly at 120?,which restricts their further appication.Although the properties of modified barium titanate-based ceramic material has been improved,it is still subject to certain restrictions at high temperatures.In this paper,potassium sodium niobate?KNN?ceramics with high Curie temperature?TC?were chose as the research objec to obtain the ceramics with high dielectric constant and temperature stability of ceramics at high temperature.Firslt,using the idea of doping modification,the ceramics were prepared by the conventinal solid state reaction method.Furthermore,the phase structure,microstructure and electrical properties of?1-x?KNLN-xBNLT,?1-x?KNLN-xBNT,?1-x?KNLLN-xBNZ,?1-x?KNLLN-xSNN ceramics were systematically studied.Finally,serials of materials with high temperature stablity.?1??1-x?0.99KNLN-xBNLT ceramics have a single perovskite structure at low composition.The relative permittivity??r?1100?of 0.99KNLN-0.01BNLT ceramic has good thermal stability in the range of 70?375?(??/?70??±12%),low dielectric loss?tan??3.8%?.?2?The main phase of?1-x?KNLN-xBNT ceramics is perovskite-type structure.The average grain size of ceramics firstly increases and then decreases with increasing the BNT content.0.995KNLN-0.005BNT ceramic samples have a high relative permittivity??r?1237?,low dielectric loss?tan??4%?and good temperature stability(??/?60??±10%)in the range of 60?350?.?3?The phase structure of?1-x?KNLLN-xBNZ ceramics is a perovskite structure.The ceramics gradually change to the tetragonal phase and the grain size gradually decreases with increasing the BNZ content.When x=0.015,the ceramics have a high elative permittivity??r=1655?,low dielectric loss?tan??3.4%?,and good thermal tability(??/?100?=±12%)in a wide temperature range of 100? to 447?.?4?The phase structure of?1-x?KNLLN-xSNN ceramics is perovskite phase.The average grain size of ceramic decreases gradually with the increase of SNN doping composition.When x=0.005,the samples have optimized dielectric properties with igh relative permittivity??r?1461?,low dielectric loss?tan??3.6%?and good thermal stability(??/?127??±13%)over a wide temperature range of 127?470?. |
PDF Full Text Request