A systematic investigation of the Li2Ti1-x(Mg_(1/3)Nb_(2/3))xO_(3)(0.1≤x≤0.35)solid solutions synthesized by traditional solid-state reaction method is reported in this work.In the composition range of 0.1≤x≤0.25,...A systematic investigation of the Li2Ti1-x(Mg_(1/3)Nb_(2/3))xO_(3)(0.1≤x≤0.35)solid solutions synthesized by traditional solid-state reaction method is reported in this work.In the composition range of 0.1≤x≤0.25,a monoclinic rock salt structured solid solution was formed.When x increased to 0.3,a phase transition from monoclinic to cubic phase,along with an order-disorder phase transition,was observed.With x increased from 0.1 to 0.35,the microwave permittivity(εr)and temperature coefficient of resonant frequency(TCF)of the Li2Ti1-x(Mg_(1/3)Nb_(2/3))xO_(3)ceramics decreased linearly from 21.0 to 18.6,+27.1 to-19.4 ppm/℃,respectively.The Li_(2)Ti_(0.75)(Mg_(1/3)Nb_(2/3))0.25O_(3)ceramic sintered at 1170℃shows high performance of microwave dielectric properties with aεr~19.6,a Qf(Q=quality factor=1/dielectric loss;f=resonant frequency)~109,770 GHz(at 7.7 GHz)and a near zero TCF~t 1.2 ppm/℃.Moreover,the burying sintering process can reduce the volatilization of lithium so that the porosity of Li_(2)Ti_(0.75)(Mg_(1/3)Nb_(2/3))0.25O_(3)ceramic was reduced effectively,which made Li_(2)Ti_(0.75)(Mg_(1/3)Nb_(2/3))0.25O_(3)ceramic promising for future applications.Selected area electron diffraction patterns,high-resolution transmission electron microscopy,Raman and far-infrared spectra were employed to study the relation between crystal structure and microwave dielectric properties in detail.展开更多
In the present work,a novel low temperature-ring Bi_(3)FeMo_(2)O_(12) ceramic was synthesized via the solid-state reaction method.The monoclinic Bi_(3)FeMo_(2)O_(12) phase can be formed at a low temperature 670℃.A re...In the present work,a novel low temperature-ring Bi_(3)FeMo_(2)O_(12) ceramic was synthesized via the solid-state reaction method.The monoclinic Bi_(3)FeMo_(2)O_(12) phase can be formed at a low temperature 670℃.A relative density above 96%can be obtained when sintering temperature is above 800℃.The Bi_(3)FeMo_(2)O_(12) ceramic sintered at 845℃ for 2 h shows high microwave dielectric performance with a permittivity-27.2,a Qf value of 14,500GHz and a temperature coefficient of-80 ppm/℃.It might be a candidate for low temperature co-fired ceramics technology.展开更多
基金the National Key Research and Development Program of China(2017YFB0406301)the Young Star Project of Science and Technology of Shaanxi Province(2016KJXX-34)+1 种基金the Fundamental Research Funds for the Central University,and the 111 Project of China(B14040)The SEM and TEM work was done at the International Center for Dielectric Research(ICDR),Xi'an Jiaotong University,Xi'an,China and the authors thank Ms.Yan-Zhu Dai and Mr Chuan-Sheng Ma for their help in using SEM and TEM.
文摘A systematic investigation of the Li2Ti1-x(Mg_(1/3)Nb_(2/3))xO_(3)(0.1≤x≤0.35)solid solutions synthesized by traditional solid-state reaction method is reported in this work.In the composition range of 0.1≤x≤0.25,a monoclinic rock salt structured solid solution was formed.When x increased to 0.3,a phase transition from monoclinic to cubic phase,along with an order-disorder phase transition,was observed.With x increased from 0.1 to 0.35,the microwave permittivity(εr)and temperature coefficient of resonant frequency(TCF)of the Li2Ti1-x(Mg_(1/3)Nb_(2/3))xO_(3)ceramics decreased linearly from 21.0 to 18.6,+27.1 to-19.4 ppm/℃,respectively.The Li_(2)Ti_(0.75)(Mg_(1/3)Nb_(2/3))0.25O_(3)ceramic sintered at 1170℃shows high performance of microwave dielectric properties with aεr~19.6,a Qf(Q=quality factor=1/dielectric loss;f=resonant frequency)~109,770 GHz(at 7.7 GHz)and a near zero TCF~t 1.2 ppm/℃.Moreover,the burying sintering process can reduce the volatilization of lithium so that the porosity of Li_(2)Ti_(0.75)(Mg_(1/3)Nb_(2/3))0.25O_(3)ceramic was reduced effectively,which made Li_(2)Ti_(0.75)(Mg_(1/3)Nb_(2/3))0.25O_(3)ceramic promising for future applications.Selected area electron diffraction patterns,high-resolution transmission electron microscopy,Raman and far-infrared spectra were employed to study the relation between crystal structure and microwave dielectric properties in detail.
基金supported by the National 973-Project of China(2009CB623302)NationalProject of International Science and Technology Collaboration(2009DFA51820)also the NSFC projects of China(109790365,60871044,and 50835007).
文摘In the present work,a novel low temperature-ring Bi_(3)FeMo_(2)O_(12) ceramic was synthesized via the solid-state reaction method.The monoclinic Bi_(3)FeMo_(2)O_(12) phase can be formed at a low temperature 670℃.A relative density above 96%can be obtained when sintering temperature is above 800℃.The Bi_(3)FeMo_(2)O_(12) ceramic sintered at 845℃ for 2 h shows high microwave dielectric performance with a permittivity-27.2,a Qf value of 14,500GHz and a temperature coefficient of-80 ppm/℃.It might be a candidate for low temperature co-fired ceramics technology.
