scholarly journals Ceramic Materials. Preparation and Properties of ZrO2-Coated BaTiO3 Composite Particles by Sol-Gel Method with Zr-Alkoxide.

2001 ◽  
Vol 50 (6) ◽  
pp. 630-633 ◽  
Author(s):  
Takashi HAYASHI ◽  
Akihiro TANIMURA ◽  
Hiroshi SHINOZAKI ◽  
Kazuya TAKANASHI ◽  
Hideyuki AOKI ◽  
...  
2021 ◽  
pp. 61-73
Author(s):  
Yu.E. Lebedeva ◽  
◽  
N.E. Shchegoleva ◽  
V.A. Voronov ◽  
St.S. Solntcev ◽  
...  

The rheological properties, processes of structure and phase formation of the Al2O3–ZrO2 system compositions obtained by the sol-gel method have been investigated. The temperature range of crystallization of the compositions is 900–1100 °C. With an increase in the concentration of zirconium dioxide in the system, the temperature of the transition from the tetragonal to the monoclinic phase decreases. The effect of the ratio of the components in the initial solutions and the temperature regime of heat treatment of gels on the physicochemical properties of nanopowders and sintered materials has been studied. Ceramic materials of eutectic composition give the highest density and lower values of porosity and water absorption.


2008 ◽  
Vol 22 (18n19) ◽  
pp. 3216-3224
Author(s):  
E. MOHAMMADI ◽  
H. ABDIZADEH ◽  
H. R. BAHARVANDI ◽  
A. M. HADIAN

Ceramic materials based on zirconium titanate prepared by sol-gel method are used extensively in microwave, telecommunications and catalysis. In order to investigate the effects of concentration of TTIP, a series of ZrO 2– TiO 2 mixed oxides was prepared by a modified sol–gel method and varying mole fraction of TTIP from 0.002, to 0.1. The samples were characterized by XRD, TG/DTA, and SEM. The XRD pattern of 370°C calcined samples showed the formation of TiO 2 phase. The optimum concentration of TTIP in the zirconia-titania mixed oxide in the precipitation solution was 0.032 for obtaining complete coating. Each oxide was calcined between 250 and 620°C. The results showed that concentration of TTIP have a pronounced effect on particle size of the calcined zirconium titanate ( ZT ) powders. The results showed that the surface area of the composite powder increased proper to monolithic ZrO 2 powder.


2016 ◽  
Vol 61 (3) ◽  
pp. 1441-1446 ◽  
Author(s):  
K. Osińska ◽  
M. Płońska ◽  
A. Marzec

Abstract The aim of presented study was to obtain the PLZT:Yb3+ ceramics. Nanopowders of itterbium doped PLZT materials were synthesized by the sol-gel method from high quality metaloorganic precursors, as lead (II) acetate, lanthanum acetate, ytterbium acetate, zirconium (IV) propoxide and titanium (IV) propoxide. Anhydrous acetic acid and n-propyl alcohol were used as solvents, while acetyloacetone was added as stabilizer of hydrolysis reactions. Thermal evolution of the dried gels, before and after calcination, was studied by the simultaneous thermal analysis. The amorphous PLZT:Yb3+ gels were first calcined in the furnace at T = 850°C, and then mixed in the planetary ball mill. Additionally, the mean particle sizes were calculated by means of powder specific surface area measurements, based on the BET physical adsorption isotherm. Such obtained powders were subsequently pressed into pellets, and sintered by the free sintering method at temperature T = 1250°C / 6h. The morphology of fabricated PLZT:Yb3+ ceramic powders and samples was studied using Scanning Electron Microscopy. Chemical characterization of samples was carried on using the Energy-dispersive X-ray spectroscopy - EDS system. Studies provided detailed data concerning the relationships between doping and preparing conditions on the basic physical and chemical properties of obtained ceramic materials.


2014 ◽  
Vol 8 (2) ◽  
pp. 101-108
Author(s):  
Nouara Lamrani ◽  
Ahcène Chaouchi ◽  
Jerôme Bernard ◽  
Brahim Itaalit ◽  
David Houivet ◽  
...  

In this work, we have studied the influence of lithium carbonate (Li2CO3) associated with the vanadium oxide (V2O5) on sintering and dielectrics properties of Ca0.5Sr0.5TiO3 ceramic materials obtained from nanopowder synthesized by sol-gel method. The nanopowder was obtained by controlled mixing of titanium butoxide dissolved in butanol-2 and acetic acid with a saturated aqueous solution of calcium acetate and strontium carbonate and subsequent drying of the formed gel at 80 ?C and calcination at 1100?C. The synthesized nanopowder was mixed with different amount of additives, and then uniaxally pressed and sintered in air atmosphere at temperature determined by dilatomertic measurements. The pure Ca0.5Sr0.5TiO3 sample obtained by this process required a sintering temperature around 1500?C. The addition of Li2CO3 combined with V2O5 improved sinterability and caused a shift of dilatimeric shrinkage curve to much lower temperatures. Thus, dense ceramics (98% of theoretical density) were obtained at sintering temperature ? 1300?C. The effect of adding Li2CO3-V2O5 on the structure of ceramics and the dielectric properties is discussed and show that type I dielectric properties (linear variation of the permittivity) are conserved, but with an increase of dielectric loss.


Author(s):  
René Miguel Guillén Pineda ◽  
A. Borrell ◽  
M. Salvador ◽  
F. L. Penaranda-Foix ◽  
R. Moreno

At present, ZrTiO4 nanopowders are used as a dielectric in the electroceramic field, applications of catalysis, microwave telecommunications devices, pigments, composites, etc. One of the most interesting applications is the potential as structural material and similar applications that require a high thermal resistance. However, all the properties of zirconium titanate are still a subject of interest for the industrial field.12   There are several routes of synthesis of ZrTiO4; among them is the sol-gel method and lyophilization. These methods have been used to make powders or small pieces of zirconium titanate. However, structural applications require materials in large quantities, so it is necessary to identify the differences between the methods of synthesizing and allowing the preparation of powders suitable for the generation of green materials for subsequent sintering.3   To develop a new generation of nanomaterials with microstructural differences it is necessary to innovate in the sintering process. Years ago, the use of conventional oven for sintering material was the usual procedure. Nowadays, non-conventional methods as Microwave sintering (MW) are a bright way to produce high dense materials, using heating rates in reduce dwell times and lower consumption using 70%-80% less energy. 4   This reactive sintering technique achieves excellent mechanical properties, homogeneous microstructure employing lower sintering temperatures. All these energy and economic advantages generate a new vision for the future on ceramic materials and their industrial production. The main objective of this study is to make a comparison of the mechanical properties of the materials synthesized by sol-gel method and lyophilization and sintered by microwaves.


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