Processing and dielectric properties of ZnTiO3 ceramics prepared from nanopowder synthesised by sol-gel technique

ZnTiO3 nanopowders were obtained by sol-gel method. The nanopowders were characterised by means of TGA/DTA analysis, X-ray diffraction, TMA analysis and SEM characterisation. The results show that the crystalline structure of the sol-gel powders was obtained at 600 °C, with crystallite sizes of 10 nm. SEM shows that most of the prepared ZnTiO3 nanopowders are agglomerated. Since agglomeration plays an important role in the sintering of the ZnTiO3 ceramics, different deagglomeration techniques (ultrasonication, pulverisation and attrition milling) were investigated. Dense ZnTiO3 structure was obtained from the attrition milled powder at 1050 °C and its dielectric characteristics were also investigated (εr =25, tε= -26 ppm/°C and tgδ < 10-3 at 1 MHz). The low sintering temperature and the good dielectric properties show promise for the manufacture of multilayered capacitors with internal copper electrodes

Sintering of stacked pellets for controlling the temperature coefficient of dielectrics

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Effects of the sintering atmosphere on the BaZn1/3Ta2/3O3 based Cu multilayer ceramic capacitors

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Low temperature sintering of ZnTiO3/TiO2 based dielectric with controlled temperature coefficient

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Disminución drástica de la temperatura de sinterización del Ba (Zn_1/3Ta_2/3) O₃ mediante la adición de una fase vítrea y sales de litio.

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Disminución drástica de la temperatura de sinterización del Ba (Zn_1/3Ta_2/3) O₃ mediante la adición de una fase vítrea y sales de litio.

The complex perovskite oxide Ba(Zn1/3Ta2/3)O3 (BZT) has been studied for its attractive dielectric properties which make this material interesting for applications such as multilayer ceramics capacitors or hyperfrequency resonators. Nevertheless, BZT ceramic requires high temperature to be correctly sintered (≅1450°C), that is too high to envisage a silver co-sintering (Tf(Ag) = 961°C). For this reason, the lowering of the sintering temperature of BZT by glass phase’s additions has been investigated. This material is sinterable at low temperature with combined glass phase –lithium salt additions, and exhibits, at 1MHz very low dielectric losses combined with relatively high dielectric constant and a good stability of this later versus temperature. The 5 wt% of ZnO-SiO2-B2O3 glass phase and 1 wt% of LiF added BZT sample sintered at 900°C exhibits a relative density higher than 95% and attractive dielectric properties: a dielectric constant εr of 32, low dielectrics losses (tan (δ)-3) and a temperature coefficient of permittivity τε of -10ppm/°C. Their good dielectric properties and their compatibility with silver electrodes, make these ceramics suitable for L.T.C.C applications.Se ha estudiado el óxido complejo con estructura tipo perovskita Ba (Zn1/3Ta2/3) O3 (BZT). Sus atractivas propiedades dieléctricas le hacen muy interesante para aplicaciones como condensadores cerámicos multicapa o resonadores de microondas. No obstante, los cerámicos de BZT requieren temperaturas de sinterización superiores a 1450 ° C, que es muy alta para abordar un proceso de co-sinterización con electrodos de plata (Tf (Ag) = 961 ° C). Para ello, se ha estudiado la bajada de la temperatura de sinterización del BZT mediante la adición de una fase vítrea. La suma combinada de la fase vítrea y la sal de litio lleva la sinterización de este material a temperaturas bajas. Las propiedades dieléctricas presentan pérdidas muy bajas, constante dieléctrica relativamente alta a 1MHz y buena estabilidad frente a la temperatura. La adición del 5% en peso de una fase vítrea de ZnO-B2O3-SiO2 y el 1% en peso de LiF disminuye la temperatura de sinterización del BZT hasta 900° C presentando una densidad relativamente alta ( > 95%) y las propiedades dieléctricas de interés: la constante dieléctrica de 32, bajas pérdidas dieléctricas (tan (δ) -3) y un coeficiente de temperatura de la permitividad τε de -10ppm / ° C. Las propiedades dieléctricas obtenidas y la compatibilidad con los electrodos de plata hacen esta cerámica adecuada para su aplicación como LTTC

Sintering of glass-added BaZn1/3Nb2/3O3 ceramics

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Low sintering temperature of (Zn0.65Mg0.35)TiO3–xCaTiO3-based dielectric with controlled temperature coefficient

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Low temperature sintered ZnTio3 dielectric ceramics with temperature coefficient of dielectric constant near zero

ZnTiO3 compound is an attractive dielectric ceramics owing to its interesting dielectric properties in high frequency range (εr= 19, QXf = 30,000GHz, τε ≈ +120 ppm/°C). The structure, microstructure and dielectric properties of sintered ZnTiO3, with a mixture of ZnO-B2O3 glass phase and CuO oxide as sintering aids, have been investigated. For all compounds, the sintering temperature becomes 850°C due to the glass addition. It is also shown that the addition of CuO oxide allows a control of the temperature coefficient of the permittivity (τε). This parameter varies from positive to negative values with increasing the CuO content. The ZnTiO3 composition sintered at 850°C with 5 wt.% ZnO-B2O3 glass phase and 2.2 wt.% CuO addition exhibits attractive dielectric properties (εr = 23, tan δ < 10-3 and a temperature coefficient of the dielectric constant near zero, τε= 3 ppm/°C) at 1 MHz. All these properties lead this system compatible for manufacturing Ag based electrodes multilayer dielectrics devices needed for LTCC application or other multilayer dielectric components

Investigation of some niobate-based dielectrics in view of base metal co-sintering

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