Titania as a Sintering Additive in Indium Oxide Ceramics

Abstract

The influence of TiO 2 additives on the sintering behavior therefore, the purpose of the present study is to investigate the role of TiO 2 as sintering additive in In 2 O 3 ceramics. of In 2 O 3 ceramics has been investigated. TiO 2 increases the densification rate, decreases the grain growth during the intermediate stage of sintering, and hinders the pore/ II. Experimental Procedure boundary breakaway that can affect the final stage of Starting powders were fine-grained (0.2 m mean particle sintering. For a given grain size, TiO 2 shifts the grain size and 1-3 m mean agglomerate size), high-purity (99.99 size/density trajectory toward higher densities. TiO 2 mainly wt%) In 2 O 3 (Metaleurop Recherche, Trappes, France). The acts by a second-phase mechanism, but it also may decrease powders were ultrasonically dispersed in ethanol mixed with the decomposition rate of In 2 O 3 . 0.8 wt% of a deflocculating agent. TiO 2 was added as a solution of titanium butoxide (Ti(O(CH 2 ) 3 CH 3 ) 4 , 99 wt% pure) pre- I. Introductionviously dissolved in absolute ethanol. Hydrolytic polycondensation of the titanium butoxide was obtained by adding T RANSPARENT and conductive thin films made of indium tin deionized water. In the remainder of the text, the materials oxide (ITO) are used in electronic and optoelectronic applidoped with titanium are named TiO 2 -In 2 O 3 and the titanium cations. 1 Direct-current magnetron sputtering of sintered ITO content is expressed as equivalent TiO 2 . After they were stirred targets is a common route for making ITO films. The quality of ultrasonically, the TiO 2 -In 2 O 3 powders were mixed with a the film is better when the target is dense, 2 and, moreover, dense binder (3 wt% of poly(vinyl butyral) dissolved in hot ethanol) targets better resist sputtering erosion. In particular, the surand a plasticizer (0.5 wt% of dibutyl phtalate), vacuum dried, faces of ion-eroded targets are degraded by conical protrusions and pressed to pellets (8 mm in diameter and 3-8 mm in height) ("black spots" or "nodules"), 3 whose number decreases when under a pressure of 150 MPa. The green density of the pellets the target porosity decreases. Unfortunately, ITO ceramics do not was ϳ56% of TD. densify easily. 4 We have previously 5 established the following.Sintering was conducted at temperatures ranging from 1300Њ (i) The typical density of ITO ceramics sintered at 1400ЊC to 1550ЊC, in air, using an electric oven with MoSi 2 heating for 3 h is only 90%. The microstructure is affected by small elements. Isothermal experiments were conducted by rapidly pores and large voids.introducing a preheated (600ЊC for 10 min) specimen into the (ii) ITO vaporizes during heat treatments when non-oxidizhot zone of the oven and heating it for various soaking times. ing atmospheres are used.Heating rates were very fast in comparison to those used for (iii) TiO 2 is an efficient sintering additive. For instance, constant-heating-rate experiments. Dilatometry experiments 0.5 wt% TiO 2 -ITO ceramics densify to nearly theoretical...

Sintering, microstructural development, and electrical properties of gadolinia-doped ceria electrolyte with bismuth oxide as a sintering aid

“…To support such a suggestion, it can also be assumed that at or below 1200 • C, the viscosity and surface tension of the formed liquid are too high impeding, thus, the diffusion of some material. Being this so, then our suggestions would be in close agreement with the suggestions of Cameron et al 18 and Nadaud et al 19 who reported that the grain size remained unchanged for relative density values lower than about 90%, i.e., when the porosity changed from being open and interconnected to closed. It must also be noted that all the above suggestions for this first region are based on the assumption that the Bi 2 O 3 amount present in the doped-GDC samples is close or near to the nominal composition, i.e., the weight loss due to a partial evaporation of Bi 2 O 3 , as shown in Fig.…”

Sintering Analysis of Undoped and Cobalt Oxide Doped Ceria Solid Solutions

“…The result that CoO 1− x ‐doped CGO possesses a higher activation energy than pure CGO, although the addition of cobalt oxide leads to a lower sintering temperature and higher shrinkage rate, is interesting. Increased activation energies for densification because of doping has been observed in several sintered materials, notably in TiO 2 ‐ and ZrO 2 ‐doped Al 2 O 3 , 30–32 in MnO‐doped ZnO, 33 in TiO 2 ‐doped In 2 O 3 , 34 in CeO 2 ‐ and HfO 2 ‐doped W, 35 and in Fe‐doped CeO 2 22 . The finding of an increased activation energy is coupled with a higher shrinkage rate and a lower temperature in several cases 22,30 .…”

Densification of Al-doped ZnO via preliminary heat treatment under external pressure

“…Evaporation and condensation at a high vapor pressure coarsen instead of density the particles. Indeed, the density of In 2 O 3 decreased with the increase in the sintering temperature from 1400 to 1500 • C [32]. A thermogravimetric analysis [32] also proved the decomposition of In 2 O 3 at above 1300 • C. In this respect, volatile materials such as In 2 O 3 or ZnO must be sintered at the lowest temperature possible to minimize the densification through volatilization.…”