TiO₂-(Zn_1/3Nb_2/3)O₂-ZrO₂ Microwave Dielectric Ceramics With Near-zero Temperature Coefficient Of Resonant Frequency

In the past several decades,microwave dielectric ceramics had received a lot of social attention among many electronic devices such as resonators and filters.As mobile electrocommunication become more and more convenient,higher performance microwave dielectric ceramics have been strongly needed.In order to satisfy the application in resonators and filters,microwave dielectric ceramics must meet the following three requirements:（1）moderate relative permittivity（25<?_r<50）,（2）high quality factor（Q?f>40000 GHz）,（3）near zero temperature coefficient of resonant frequency（–10≤?_f≤10 ppm/°C）.This paper concentrates on ternary system microwave dielectric ceramics xTiO₂-y(Zn_1/3Nb_2/3)O₂-（100–x–y）ZrO₂ with 0.5%wt CuO addition.With the help of vector network analyzer（VNA）,scanning electron microscope（SEM）,X-ray diffractometer（XRD）and other devices,this paper have make a research on the relationships among composition,sintering temperature,phase composition and microwave dielectric properties.In this paper,the microwave dielectric ceramic of xTiO₂-y(Zn_1/3Nb_2/3)O₂-（100–x–y）ZrO₂（y=14-28;3（x–40）=8（y–20））was studied firstly.The results showed that in the case of 0.5wt%CuO doping,the optimum sintering temperature was between 1260 and 1300°C for all ceramics samples and with the increasing of y,the maximum density of ceramics decreased from 5.10 to 4.56 g/cm³;when y between 18 and 24,the temperature coefficient of resonant frequency of all ceramic samples were near zero（–10≤?_f≤10 ppm/°C）after sintering at 1260-1300°C,and other microwave dielectric properties were excellent at the same time:?_r=37-43,Q?f=21000-28000 GHz@⁴.8-5.8 GHz.In this paper,the research then studied the microwave dielectric ceramic of xTiO₂-y(Zn_1/3Nb_2/3)O₂-（100–x–y）ZrO₂（y=29.56-66.67;20（x–44.17）=–8.13（y–40））.The results showed that in the case of 0.5 wt%CuO doping,the optimum sinteri-ng temperature of ceramic samples was different for different y values.With the increasing of y,the optimum sintering temperature decreased from 1340 to 1160°C,the maximum density of ceramic samples increased from 4.35 to 5.10 g/cm³,the relative permittivity?_r increased from 37 to46;The temperature coefficient of resonant frequency of the ceramic samples were near zero（8≤?_f≤13 ppm/°C）,and Q?f=12500-17500 GHz@⁵.1-5.4 GHz.