Phase relations and linear thermal expansion of cubic solid solutions in the Th1−xMxO2−x/2 (M=Eu, Gd, Dy) systems

Mathews, M.D.; Ambekar, B.R.; Tyagi, A.K.

doi:10.1016/j.jnucmat.2004.12.007

Cited by 18 publications

(15 citation statements)

References 12 publications

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“…These calculated values agree with the experimental data of Kim et al 7) very well, while the agreement with the experimental data of Mathews et al 32) is somewhat worse. The reason for the difference in agreement is attributable to the difference in sample preparation conditions for the two experimental studies.…”

Section: Resultssupporting

confidence: 72%

“…The diffusion coefficients of O ions were calculated at 1273 K. Figure 2 shows lattice parameter changes of the Gd-doped thoria as a function of Gd fraction. The experimental lattice parameter values 7,32) decrease with Gd fraction, as shown in the figure. Details of these lattice parameter changes are discussed later.…”

Section: Simulation Proceduresmentioning

confidence: 79%

“…The reason for the difference in agreement is attributable to the difference in sample preparation conditions for the two experimental studies. 7,32) Since it cannot be decided at the present which experimental data is correct, it is difficult to quantitatively discuss the differences between calculated and experimental lattice parameters. Therefore, the monotonic decrease tendencies of the lattice parameters with an increase in Gd fraction are discussed here.…”

Section: Resultsmentioning

confidence: 99%

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Molecular Dynamics Study on Defect Structure of Gadolinia-Doped Thoria

Osaka

Adachi

Kurosaki

et al. 2007

Journal of Nuclear Science and Technology

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A molecular dynamics study on the defect structure of Gd-doped thoria was carried out. The partially ionic two-body potential was used with empirically obtained parameters for Th, Gd and O ions in the fluorite structure. Different defect structures were assumed and their effects on the lattice parameter were investigated. Molecular dynamics simulations were carried out with Gd fractions and temperatures ranging from 0 to 45% and from 298 to 1200 K, respectively. Diffusion coefficients of O ions in the Gd-doped thoria having various Gd fractions were also calculated at 1273 K. Comparison of the calculated results with the experimental ones lead to the conclusion that the Gd-oxygen vacancy-Gd type cluster is the most likely defect structure in the Gd-doped thoria.

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Section: Resultssupporting

confidence: 72%

Section: Simulation Proceduresmentioning

confidence: 79%

Section: Resultsmentioning

confidence: 99%

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Molecular Dynamics Study on Defect Structure of Gadolinia-Doped Thoria

Osaka

Adachi

Kurosaki

et al. 2007

Journal of Nuclear Science and Technology

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“…Based on the much higher melting point of ThO 2 (3390°C) compared to that of UO 2 (2827°C), and the fact that metal diffusion speeds are lower in ThO 2 [49], one can expect that higher sintering temperatures or different sintering techniques are necessary to obtain a comparable density and homogeneity in gadolinium concentration. Indeed, the powder metallurgical route applied by Mathews et al [42] uses several heating (at different temperatures and very prolonged sintering times of 36-48 h) and regrinding steps to obtain single-phased samples. Muta et al [15] also used multiple grinding and sintering steps and in addition, the final sintering was performed via spark plasma sintering under pressure.…”

Section: Discussionmentioning

confidence: 99%

“…In the specific case of Gd 2 O 3 -doped UO 2 production, powder metallurgical routes were described by Grossman et al [32], Yuda and Une [33], and Riella et al [34], coprecipitation processes by Manzel and Dörr [35], Fukushima et al [36], Miyake et al [37], Riella et al [34], Leyva et al [38], and Durazzo et al [39], and sol gel routes by Gündüz et al [40,41]. For the synthesis of Gd 2 O 3 -doped ThO 2 , powder metallurgical routes were described by Mathews et al [42] and Muta et al [15], and co-precipitation processes by Horlait et al [13].…”

Section: Introductionmentioning

confidence: 99%

Synthesis of UO2 and ThO2 doped with Gd2O3

Baena

Cardinaels

Vos

et al. 2015

Journal of Nuclear Materials

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Diffraction and Thermal Expansion of Solids

Tyagi

Achary

2010

Thermodynamic Properties of Solids

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Thermal expansion of materials is a topic of age-old interest to mankind in view of the chronological development of several devices and technologies [1,2]. The concept of thermal expansion and knowledge of thermal expansion coefficient of materials remain important for any structural materials experiencing a temperature gradient. The structural materials include any material used in technology to build a mechanically or electronically integrated physical entity. In particular, the thermal properties are of interest when any structural assembly faces a temperature variation. Thermal expansion effects have been well considered right from the metals and ceramic parts of cookwares to the highly sophisticated mechanical structures, such as buildings, bridges, air/spacecraft, vessels, kilns, furnaces, and so on. In particular, metals such as steel, copper, and so on that are important structural parts show a significant expansion with temperature. Thus, in all these materials, thermal expansion was exploited either to enhance or to nullify any temperature-induced dimensional instability, for example, the utilization of thermal expansion in automatic cut-off switch using bimetals is well known. The discovery of Invar (an alloy of 35% Ni and 65% Fe) and subsequent modified compositions as Elinvar, Kovar, Alnico, and so on have found immense applications in modern technologies, such as design of high-accuracy clocks, shadow mask in television screen, and so on [3]. In addition, low thermal expansion in fused silica and controllable thermal expansion in materials with glass and glass-ceramic compositions have been discovered and used in precise optical instruments, mirror substrates, glass-metal junctions [4,5]. A large number of crystalline materials with low thermal expansion are also discovered [6]. Thermal expansion data of ceramics have been a prime consideration in the designing of electrolyte and electrodes of solid oxide fuel cells [7]. Similarly, thermal expansion data of nuclear fuel materials are significant in preventing detrimental effects of fuel-clad interaction and unwanted swelling of fuel pins [8]. Nuclear reactor performance is mainly restricted by the thermal expansion and thermal conductivity of the fuel pellets under irradiation conditions. In these j197 applications, the material property is more significant than the structural assembly and hence the structural materials are tuned as per their thermal expansion behavior. However, the thermal expansion behavior of electronic materials causing temperature-induced dimensional instability leading to circuit failure also needs to be dealt with. Considering such aspects, several Invar-type alloys and metal matrix composites are developed in recent years [9]. Thus, the thermal expansion data of any material are the first requisite for the development of most of the technologies.In general, it is known that all materials expand or contract with the rise or fall of temperature. The thermal expansion of any material is explained as a relative change in dimens...

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Phase relations and linear thermal expansion of cubic solid solutions in the Th1−xMxO2−x/2 (M=Eu, Gd, Dy) systems

Cited by 18 publications

References 12 publications

Molecular Dynamics Study on Defect Structure of Gadolinia-Doped Thoria

Molecular Dynamics Study on Defect Structure of Gadolinia-Doped Thoria

Synthesis of UO2 and ThO2 doped with Gd2O3

Diffraction and Thermal Expansion of Solids

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