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Preparation and Dielectric Properties of CaO-Li2O-Sm2O3-TiO2 Microwave Dielectric Ceramics

Author: HuJingChuan
Tutor: DengZhaoPing
School: Chengdu University of Technology
Course: Mineral materials science
Keywords: Microwave dielectric ceramics Permittivity Dielectric loss The temperature coefficient of resonant frequency
CLC: TQ174.1
Type: Master's thesis
Year: 2010
Downloads: 90
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Abstract


Microwave dielectric ceramic is a new kind of information materials. Prepared in this experiment CaO-Li2O-Sm2O 3 -TiO2 microwave dielectric ceramic expect the resonant frequency temperature coefficient material. Microscopic morphology by XRD and SEM analysis, dielectric constant, quality factor, resonance frequency temperature coefficient were measured in the microwave frequency of the phase composition of the material and section. In order to study the material composition, the relationship between the morphology, chemical composition, sintering process and dielectric properties. xCaTiO 3 - (1-x) (Li1/2Sm1/2) TiO 3 by solid-phase method. The department is pre-fired powder to form a perovskite structure. The ceramic cell volume was negatively correlated with the content of Li, Sm3. Li, the content of of Sm3 is more, the lower dielectric constant ceramic, experiments obtained permittivity ε: 81 to 149; the Li, Sm3 content increases, the dielectric loss increases, the quality factor QF: 2489 to 4895GHz; of Li, of Sm3 content increased, the resonance frequency temperature coefficient τ? by a positive value to the negative movement. Permittivity of the ceramics with the sintering temperature increases; dielectric loss with sintering temperature decreases and then increases, there is a great value of the quality factor in the sintering temperature range; increasing sintering temperature, the resonant frequency of temperature coefficient decreases. The optimization of the dielectric properties of the composition point study found that: when x = 0.26, for the better dielectric properties: Dielectric constant ε = 101, the quality factor QF = 3399GHz, the resonance frequency temperature coefficient τ of? = 8ppm / ° C. 0.3CaTiO 3 -0.7 [Li0.5 (Sm1-xNdx) 0.5] TiO 3 by the legal system in the precursor. Nd3 added successfully to improve the dielectric constant ε: 109 to 126; reduce the resonance frequency temperature coefficient, τ?: -14 To 16ppm / ° C; but the dielectric loss increases, i.e. the quality factor is reduced, Qf: 3530 ~ 2313GHz. With the sintering temperature, the lower the dielectric constant, the dielectric loss increases, the temperature coefficient of resonant frequency is reduced. When the sintering temperature is 1360 ℃, x = 0.4, the sample is the better performance can be obtained: dielectric constant of ε = 118, the quality factor Qf = 3068GHz, resonance frequency temperature coefficient τ? = 5ppm / ° C. The 16CaO-9Li2O-12Sm2O 3 -63TiO2 by solid-phase method. Its pre-burn powder XRD analysis showed that the phase composition Sm2Ti2O7 (pyrochlore phase); with the calcining temperature increases, ceramic density to improve; main crystalline phase of the sintered ceramic structure of perovskite, with pre-calcination temperature rise The impurity phase rutile TiO2 reduce to 1150 ℃, the ceramic tends to a single orthorhombic perovskite phase composition. Sintered at 1340 ℃ obtained the following dielectric properties: Dielectric constant ε = 112, the quality factor Qf = 2535GHz, the resonant frequency stability coefficient τ? = 52 ppm / ° C.

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