Thermodynamics versus kinetics of grain growth control in nanocrystalline zirconia

Nafsin, Nazia; Aguiar, J. Albino; Aoki, Toshihiro; Thron, Andrew M.; Benthem, Klaus van; Castro, Ricardo H. R.

doi:10.1016/j.actamat.2017.07.005

Cited by 43 publications

(39 citation statements)

References 58 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…However, until recently, the grain boundary energy has not been considered a variable to design (meta)stable nanocrystalline ceramics. Following theoretical framework developed for the control of nanocrystalline metal alloys [25][26][27][28][29][30], a few papers have reported virtual stopping of grain growth of ceramics by introducing dopants targeting a reduction of the grain boundary energy [7,[31][32][33]. The grain boundary energy was lowered to essentially zero [7], signifying a negligible driving force for coarsening.…”

Section: Thermodynamics Of Grain Growthmentioning

confidence: 99%

“…The control of grain growth by targeting grain boundary energy reduction can be well understood in the gadoliniumdoped yttria-stabilized zirconia (YSZ) system [7,31]. Although this may sound like a complicated system, it works well as a model since YSZ itself behaves like a host, and Gd as a dopant with expected segregation.…”

Section: Thermodynamics Of Grain Growthmentioning

confidence: 99%

See 1 more Smart Citation

Controlling sintering and grain growth of nanoceramics

Castro¹

2019

Cerâmica

View full text Add to dashboard Cite

Sintering and grain growth are fundamental processes affecting microstructural evolution of ceramics. The phenomenological models describing these processes as found in textbooks are simplifications of the very dynamic set of system’s parameters, which lead to limited predictability and the need for extensive empirical analyses for process optimization. One such simplification is the underestimation of interfacial energies and their relationships with diffusion paths and growth control. The goal of this paper is to clarify how thermodynamics of interfaces can provide opportunities for a more refined control of ceramic processing. On the first part of this paper we discuss the relevance of grain boundary energies in grain growth, showing that although grain boundary mobility is the preferred parameter choice for designing of grain growth inhibition, recent studies demonstrate dopants can be selected to annihilate the process driving force and enable thermally (meta)stable nanoceramics. In the second part of the paper, we point out shortcomings from the current sintering theory and discuss that both surface and grain boundary energies with their associated rates of interfacial area evolution represent a more comprehensive sintering description. This perspective offers tunable parameters that may set a new foundation for the design of sintering aids for optimal densification.

show abstract

Section: Thermodynamics Of Grain Growthmentioning

confidence: 99%

Section: Thermodynamics Of Grain Growthmentioning

confidence: 99%

Controlling sintering and grain growth of nanoceramics

Castro¹

2019

Cerâmica

View full text Add to dashboard Cite

show abstract

“…However, the separation of the kinetic and thermodynamic contributions is difficult with the addition of additives to the material, which are usually seen as physical barriers reducing the GB mobility and are mostly studied as kinetic phenomena. With the advancements of calorimetric techniques for the measurement of the interface energy of nanoparticles, it is possible to show that the surface energy does not remain constant with an increase in the doping content; thus, the nanostability is partially attributed to thermodynamic effects …”

Section: Introductionmentioning

confidence: 99%

Li₂O‐doped MgAl₂O₄ nanopowders: Energetics of interface segregation

et al. 2019

View full text Add to dashboard Cite

Manufacturing nanoceramics is challenging owing to the instability of the grain size resulting from the high driving force toward growth associated with the interfaces. Nanometric ceramics of some oxides have exceptional mechanical and optical properties, eg, magnesium aluminate spinel (MgAl 2 O 4 ). The production of these fully conformed ceramics requires a precursor powder, which generally contains sintering-promoting additives. Li salts are typically used as sintering promoters for MgAl 2 O 4 , but the interface stability associated with the segregation of the additive is poorly understood. In this study, MgAl 2 O 4 samples containing 0-2.86 mol% Li ions were synthesized via a simultaneous-precipitation method in an ethylic medium and subsequently calcined at 800°C in air. The nanopowders exhibited only the MgAl 2 O 4 phase, and the crystallite size was determined by the Li 2 O concentration. The crystallite size was changed via the chemical modification of the interfaces by the segregation of Li ions. The solubility in the bulk material was very low at the fabrication temperature, and small amounts of Li ions saturated the bulk material and segregated to the grain boundaries (GBs), significantly stabilizing the grain-grain interface compared with the surface. The resulting powder was then aggregated further owing to the initial stage of sintering. The surface excess obtained via the selective lixiviation method confirmed that the segregation to the GBs was greater than that to the surface. Energetics calculations confirmed these results, indicating a high enthalpy of segregation at the GBs (ΔH segr GB = −52.0 kJ∕mol) compared with that at the surfaces (ΔH segr s = −31.5 kJ/mol). The enthalpy of segregation together with theinterface excess allowed us to estimate the reduction in the interface energy with Li + segregation of 0.8% to the surface and 11.2% to the GBs. The Li + segregation to the surfaces started by Al 3+ substitution, and for powders with ≥1.8 mol% Li ions, Mg +2 was preferentially substituted at the surfaces.

show abstract

“…They form an isolating thin layer that covers the grains and acts as a kinetic barrier for further grain growth and grain joining inhabitation. This behavior was noted in several other ceramic systems …”

Section: Resultsmentioning

confidence: 89%

Dielectric and piezoelectric performance of gadolinium‐doped lead lanthanum zirconate titanate

Mansour

Eid

El-Latif

et al. 2017

Int J Applied Ceramic Tech

View full text Add to dashboard Cite

In this article, polycrystalline samples of Gd3+ ion‐modified lead lanthanum zirconate titanate PLGZT: (Pb0.94‐xGdxLa0.06)(Zr0.52Ti0.48)O3; x = 0, 2, 4, 6, and 8% have been prepared by the sol‐gel autocombustion strategy. The structural properties of the prepared samples were analyzed by X‐ray diffraction profile (XRD), Fourier transform infrared spectra (FT‐IR), transmission electron microscopy (TEM), and scanning electron microscopy (SEM). The samples were assigned to pure PZT perovskite tetragonal structure. Ag electrodes were made on both sides of the disks for measurements of electrical and dielectric properties at different temperatures ranging from 30 to 500°C at various frequencies. The maximum dielectric constant, Curie temperature (TC), dielectric loss at TC, and the piezoelectric charge coefficient d33 ranges of the investigated samples were found to be 1850 to 2420, 350 to 399°C, 0.023 to 0.026, and 299 to 532 pC/N, respectively. Higher coefficients were reached for the 4 % Gd substitution. Finally, the obtained results indicate that these materials can be good candidates for ultrasonic transducers.

show abstract

Thermodynamics versus kinetics of grain growth control in nanocrystalline zirconia

Cited by 43 publications

References 58 publications

Controlling sintering and grain growth of nanoceramics

Controlling sintering and grain growth of nanoceramics

Li₂O‐doped MgAl₂O₄ nanopowders: Energetics of interface segregation

Dielectric and piezoelectric performance of gadolinium‐doped lead lanthanum zirconate titanate

Contact Info

Product

Resources

About

Thermodynamics versus kinetics of grain growth control in nanocrystalline zirconia

Cited by 43 publications

References 58 publications

Controlling sintering and grain growth of nanoceramics

Controlling sintering and grain growth of nanoceramics

Li2O‐doped MgAl2O4 nanopowders: Energetics of interface segregation

Dielectric and piezoelectric performance of gadolinium‐doped lead lanthanum zirconate titanate

Contact Info

Product

Resources

About

Li₂O‐doped MgAl₂O₄ nanopowders: Energetics of interface segregation