Experimental determination of the eutectic temperature in air of the CuO–TiO2 pseudobinary system

Rubia, M.A. de la; Reinosa, J.J.; Leret, Pilar; Romero, J. J.; Frutos, J. de; Fernández, J. F.

doi:10.1016/j.jeurceramsoc.2011.07.026

Cited by 36 publications

(23 citation statements)

References 20 publications

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“…The current study measured the eutectic temperature of the TiO 2 -CuO system to be 1010 ± 10 C in air, which was higher than that reported in 2001 [14], but similar to that suggested by a DSC and TG study in 2012 [15]. This warrantees our re-assessment and a correction of the TiO 2 -CuO phase diagram reported in Ref.…”

Section: Further Discussion Of Activated Sintering Mechanisms and Beyondsupporting

confidence: 89%

“…That diagram reported in 2001 [14] represents the only TiO 2 -CuO phase diagram available in literature and has been widely cited. The more accurate measurements of the eutectic temperature and composition obtained in this study, which were consistent with the independent DSC/TG study in 2012 [15], demand a further assessment (and correction) of that TiO 2 -CuO phase diagram, which will also provide the thermodynamic function of the liquid phase that will be useful for the interfacial thermodynamic model presented and discussed in the following section.…”

Section: The Tio 2 -Cuo Binary Phase Diagram and Bulk Thermodynamic Fsupporting

confidence: 84%

“…In 2001, a binary TiO 2 -CuO phase diagram had been calculated via assuming that the liquid phase is an ideal solution, which produced an eutectic temperature of 919 C [14], being substantially lower than the~1000 C eutectic temperature that was later suggested via DSC and TG analysis in 2012 [15], which is confirmed more directly and accurately by the current study. That diagram reported in 2001 [14] represents the only TiO 2 -CuO phase diagram available in literature and has been widely cited.…”

Section: The Tio 2 -Cuo Binary Phase Diagram and Bulk Thermodynamic Fsupporting

confidence: 73%

“…However, Lu et al reported a computed eutectic temperature of 919 C for the TiO 2 -CuO system [14]. Recently, de la Rubia et al suggested that the eutectic temperature is~1000 C via differential scanning calorimetry (DSC) and thermogravimetric (TG) analysis, in conjunction with hot-stage microscopy [15]. These results casted doubt on the previously-hypothesized liquid-phase sintering mechanism for CuO-doped TiO 2 , since the significant densification appeared to occur well below the eutectic temperature, though what is the exact/real eutectic temperature was still controversial prior to this study.…”

Section: Introductionmentioning

confidence: 99%

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Probing the densification mechanisms during flash sintering of ZnO

et al. 2017

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a b s t r a c tThe eutectic temperature and composition of the TiO 2 -CuO system were carefully measured to be 1010 ± 10 C and 83CuO:17TiO 2 , respectively. Subsequently, a TiO 2 -CuO phase diagram was computed, representing a correction and major improvement from the phase diagram available in literature. Dilatometry measurements and isothermal sintering experiments unequivocally demonstrated the activated (enhanced) sintering of TiO 2 with the addition of CuO, occurring at as low as >300 C below the eutectic temperature. High resolution transmission electron microscopy (HRTEM) characterization of waterquenched specimens revealed the formation of nanometer-thick, liquid-like, intergranular films (IGFs), a type of grain boundary (GB) complexion (a.k.a. 2-D interfacial phase), concurrently with accelerated densification and well below the bulk eutectic temperature. Consequently, activated sintering is explained from the enhanced mass transport in this premelting-like complexion. An interfacial thermodynamic model was used to quantitatively explain and justify the stabilization of liquid-like IGFs below the eutectic temperature and the temperature-dependent IGF thicknesses measured by HRTEM. A GB l diagram was computed, for the first time for a ceramic system, to represent the thermodynamic tendency for general GBs in CuO-doped TiO 2 to disorder.

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Section: Further Discussion Of Activated Sintering Mechanisms and Beyondsupporting

confidence: 89%

Section: The Tio 2 -Cuo Binary Phase Diagram and Bulk Thermodynamic Fsupporting

confidence: 84%

Section: The Tio 2 -Cuo Binary Phase Diagram and Bulk Thermodynamic Fsupporting

confidence: 73%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Probing the densification mechanisms during flash sintering of ZnO

et al. 2017

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“…4). Rubia et al [20] reported a eutectic melting point for this composition at about 1000 °C and it seems likely that the formation of the large coarse grains may be the result of a liquid-phase sintering mechanism. The Cu-rich small grains and intergranular phase observed in the FE-SEM images (Fig.…”

Section: Compositionmentioning

confidence: 81%

Effect of sintering conditions on microstructure and dielectric properties of CaCu3Ti4O12 (CCTO) ceramics

2015

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The influence of sintering temperature and dwell time on the microstructure formation and dielectric properties of CaCu3Ti4O12 ceramics was investigated. For sintering temperatures of 1050 and 1100 °C significant differences in the CaCu3Ti4O12 ceramic microstructure and the segregation of a CuOx-rich phase towards the grain boundary (GB) areas were observed with increasing dwell time. In addition to the formation of a semiconducting bulk and insulating grain boundary phase the segregated CuOx forms an intergranular phase, and the effects of this phase on the dielectric properties are rather intriguing. At sintering temperature below 1050 °C only small amounts of CuOx segregate, whereas sintering above 1050 °C (e.g., 1100 °C) leads to increased evaporation of the CuOx. Therefore, the effects of the CuOx-rich intergranular phase upon the dielectric properties are felt strongest in samples sintered at 1050 °C. Such effects are discussed in terms of microstructural variations due to liquid phase sintering behavior facilitated by the TiO2-CuOx-eutectic, which appears to be melted at high sintering temperature prior to evaporation of CuOx at prolonged dwell times at the highest sintering temperatures (1100 °C).

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Subnanometer‐sized CuO_x Clusters on TiO₂ as Active Photocatalysts for Ammonia Production from Photocatalytic Nitration Reduction Reaction

Chang,

Chen,

et al. 2024

ChemCatChem

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The Haber‐Bosch process is commonly used to produce ammonia while consuming energy and yielding huge emissions of carbon dioxide. Finding an alternative way to produce ammonia sustainably is a promising research direction with less CO2 emission. Photochemical nitrate reduction reaction (NtRR) to ammonia (NH3) could solve the nitrate pollutant problem in water and approach to produce ammonia with a more environmentally friendly process and lower energy consumption. In this work, the subnanometer‐sized copper oxide clusters decorated on titanium oxide nanoparticles (CuOx‐TiO2) were synthesized through the hydrothermal method and calcination treatment. CuOx‐TiO2 demonstrated impressively conversion rate of NO3‐ to NH3 with a yield of 153.09 μg‐gcat‐1‐h‐1 in KNO3 solution. The characteristic structure analysis revealed CuOx clusters with ~less than 1 nm decorated on TiO2 nanoparticles. From in‐situ X‐ray absorption fine structure (XAFS) spectroscopic technique, the transformation of the oxidation state of Cu clusters and the changes of local structure in the CuOx‐TiO2 were observed. The photocatalytic reaction mechanism of nitrate reduction on the CuOx‐TiO2 was successfully revealed. These discoveries have broad implications for the functional advancement of catalysts based on subnanometer‐sized clusters. Our findings may pave the way for exploring advanced ammonia synthesis routes with reduced energy consumption and carbon emissions.

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Experimental determination of the eutectic temperature in air of the CuO–TiO2 pseudobinary system

Cited by 36 publications

References 20 publications

Probing the densification mechanisms during flash sintering of ZnO

Probing the densification mechanisms during flash sintering of ZnO

Effect of sintering conditions on microstructure and dielectric properties of CaCu3Ti4O12 (CCTO) ceramics

Subnanometer‐sized CuO_x Clusters on TiO₂ as Active Photocatalysts for Ammonia Production from Photocatalytic Nitration Reduction Reaction

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Experimental determination of the eutectic temperature in air of the CuO–TiO2 pseudobinary system

Cited by 36 publications

References 20 publications

Probing the densification mechanisms during flash sintering of ZnO

Probing the densification mechanisms during flash sintering of ZnO

Effect of sintering conditions on microstructure and dielectric properties of CaCu3Ti4O12 (CCTO) ceramics

Subnanometer‐sized CuOx Clusters on TiO2 as Active Photocatalysts for Ammonia Production from Photocatalytic Nitration Reduction Reaction

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Subnanometer‐sized CuO_x Clusters on TiO₂ as Active Photocatalysts for Ammonia Production from Photocatalytic Nitration Reduction Reaction