Phase Stability And Low Temperature Sintering Properties Of ZnTiO₃

In recent years,the requirements of electronic components are getting higher and higher with the rapid development of communication industry,and also put forward higher requirements on the performance of microwave dielectric materials,which accelerates the innovation and development of microwave dielectric ceramic materials and related processing technologies.LTCC technology,as the mainstream technology of passive integration,is a trend of components manufacturing technology nowadays and in the future.ZnO-TiO₂ based ceramic,which has a relatively low sintering temperature and excellent microwave dielectric properties,is a promising candidate material for LTCC.In the ZnO-TiO₂ system,zinc titanate?ZnTiO₃?with hexagonal ilmenite structure has a higher Q?f,but it is difficult to obtain the ZnTiO₃ with single-phase structure because it decomposes to Zn₂TiO₄ and TiO₂ at temperatures higher than 945°C,which will deteriorate the material's performance.In this paper,the phase composition,microwave dielectric properties of ZnTiO₃ were investigated on the base of ion substitution.The effects of glass as sintering aids on the sintering temperature and properties of the materials were studied.The tape casting properties and co-firing compatibility with silver were also explored.First,the effect of substitution of Zn²⁺by Mg²⁺at A-site on the phase stability and microwave dielectric properties of(Zn_1-xMg_x)TiO₃ was studied.The research showed that in the proper sintering temperature range,Mg²⁺and Zn²⁺could form?Zn,Mg?TiO₃ solid solution,which can improve the temperature stability and microwave dielectric properties of ZnTiO₃.With the increase of x value,the structure of ZnTiO₃ phase became more stable,the dielectric constant decreased gradually,and?_f gradually changed from positive value to negative value.Multi-phase ceramic at x=0.2 sintered at 1075?possessed microwave dielectric properties of?_f=-7.7 ppm/?,?_r=25.2 and Q?f=40586 GHz,but a single phase structure of ZnTiO₃ with properties of?_r=22.7,Q?f=100749 GHz,?_f=-78.2 ppm/?can be obtained when(Zn_1-xMg_x)TiO₃?x=0.3?was sintered at 1100?Based on the ZnTiO₃ single phase obtained through the substitution of Zn²⁺by Mg²⁺,the low temperature sintering properties and microwave dielectric properties of ZnTiO₃were investigated using zinc-boron glass as sintering aids.The results show that adding appropriate amount of zinc-boron glass can effectively reduce the sintering temperature of ZnTiO₃ from 1100?to 925?and maintain the single-phase structure of ZnTiO₃.The dielectric constant and quality factor of the material decreased slightly after the addition of zinc-boron glass.As the content of zinc-boron glass increased,the dielectric constant and quality factor decreased gradually.Samples sintered at 925?with 5wt%zinc-boron glass had properties of?_r=21.7,Q×f=76069 GHz,?_f=-53.0 ppm/?with the highest bulk density.The temperature coefficient of resonant frequency of the material can be adjusted to near zero by adding 15wt%TiO₂,however,the dielectric constant of the material increased and Q×f value decreased:?_r=27.2,Q×f=49772 GHz,?_f=5.4 ppm/?.Uniform and dense casting tapes with good flexibility were achieved by adding appropriate organic additives.The tapes combined closely after the stack and exhibited good co-firing compatibility with silver,which could be a promising LTCC material.