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Microwave dielectric ceramics as a new type of electronic materials, modern communication is used as resonators, filters, dielectric substrate, dielectric antenna, medium wave guide loop, microwave technology is widely used in many fields, such as mobile phones, cars phones, cordless phones, TV, satellite receiver, satellite radio, military radar, radio remote control, more and more extensive attention. The microwave dielectric ceramic performance requirements for: (1) material at microwave frequencies relative permittivity should be large in order to facilitate the miniaturization of the device; (2) at microwave frequencies, the dielectric loss should be small, i.e., the quality factor of the medium to be ; (3) close to the zero frequency-temperature coefficient. Bi 2 (Zn 1/3 Nb 2/3 ) 2 O 7 ceramics with low sintering temperature, high dielectric constant, wide adjustment range of the temperature coefficient of frequency characteristics, these factors are in LTCC technology possible. \sub> ceramic is the object of study, through the study of different preparation methods, the optimization of the sintering process and the dielectric properties of the ceramic; on this basis, by ion substituted and add a sintering additive to study the structure of the ceramic phase, microstructure and dielectric The variation of the electrical properties. First, the study of the solid-phase synthesis method, semi-chemical and molten salt prepared Bi 2 (the Zn 1/3 Nb 2/3 The) 2 O 7 ceramics, experimental results show that: the solid-phase synthesis method, semi-chemical and molten salt method can obtain pure monoclinic pyrochlore phase, while derived the reaction mechanism of the three preparation methods; solid-phase method and semi-chemical powder prepared granular distribution of molten salt prepared powder morphology was unique sheet; using three methods Preparation the ceramic concrete performance: ρ = 7.79g/cm The , the ε r = 83, tanδ = 0.0022 (solid-phase method); ρ = 7. 61g/cm 3 the ε r = 84, tnaδ = 0.0029 (semi-chemical method); ρ = 7.64g/cm 3 , ε r = 81, tanδ = 0.0051 (the molten salts Act). Visible, prepared by solid Bi 2 (Zn 1/3 Nb 2/3 ) 2 O < sub> 7 more dense ceramic dielectric properties. Thus, the solid-phase method is a more appropriate method. Second, determine the solid-phase method for the basic experimental methods, in order to improve of Bi 2 (the Zn 1/3 Nb 2/3 ) < sub> 2 O 7 ceramic dielectric properties of to replace Bi 2 (Zn 1/3, Nd 3 Nb 2/3 ) 2 O 7 the the ceramic A bit Bi 3 to Ta 5 -substituted Bi 2 (Zn 1/3 Nb 2/3 ) 2 O 7 of ceramic B bit Nb 5 , the experimental results show that: the (Bi 2-x the Nd x ) (Zn 1/3 Nb 2/3 ) 2 O 7 ceramics when Nd 3 to replace the amount of x lt; 0.3, the ceramic remains monoclinic pyrochlore structure, x gt; 0.3, ceramics, cubic pyrochlore phase ceramics show monoclinic phase and the cubic phase coexistence when x ≥ 1.0, the ceramic Bi 2 Nd 4 O 9 phase, showing the three-phase coexistence of the structure; With Nd 3 to replace the amount of the increase, the dielectric constant first increases and then decreases, and the dielectric loss first decreases and then increases. Sintered at 1000 ℃ substitution x = 0.2 Chu ceramic to achieve the best performance: ρ = 7.76g/cm 3 ε r = 79, tan δ = 0 .002 (1MHz). Of Bi 2 (the Zn 1/3 Nb (2/3-y/3) of Ta y / 3 ) 2 O , 7 ceramics Add to Ta 5 replace the B bit Nb 5 , ceramic main crystalline phase in addition to single outside oblique pyrochlore phase also appeared the second phase Bi 3 of TaO 7 In phase as the Ta 5 replace the gradual increase in the amount of Bi 3 TaO 7 phase ratio begins to decrease, When Ta 5 replace the amount increased to 2.0, ie Nb 5 completely the Ta 5 replace, ceramic presents pure monoclinic pyrochlore structure, Bi 3 TaO 7 phase disappeared completely; With Ta 5 to replace the amount of the increase, the dielectric constant was gradually reduced, and the dielectric loss was reduced gradually. Visible, Nd 3 replace A bit Bi 3 and did not significantly improve the dielectric properties of the ceramic, Ta 5 to replace the B-site Nb 5 worsened the dielectric properties of the ceramic. Finally, in order to lower the sintering temperature of the ceramic, and maintain its good dielectric properties, as dopant respectively LiSbO 3 and BiFeO 3 , a detailed study of the Bi 2 (the Zn 1/3 the Nb 2/3 ) 2 O 7 ceramic sintering temperature, phase structure, microstructure and dielectric properties. The experimental results show that: LiSbO 3 and BiFeO 3 doped not of Bi 2 (the Zn 1/3 the nb 2/3 ) 2 O 7 ceramic phase structure impact; When LiSbO 3 content 0 .1 wt. %, The sintering temperature from 1000 ℃ to 920 ℃, compactness, has a better performance at the same time: ρ = 8.04g/cm 3 the ε r = 79, tanδ = 0.002 (1MHz); When the content of the BiFeO 3 0.15wt. %, Bi 2 (Zn 1/3 Nb 2/3 ) 2 O 7 < / sub> ceramic sintering temperature from 1000 ℃ to 920 ℃, while maintaining excellent performance: ρ = 7.87g/cm 3 , ε r = 79 , tanδ = 0.00086 (1MHz), in particular is the dielectric loss greatly reduced, very beneficial application of the LTCC.
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