Fast, microwave-assisted synthesis of monodisperse HfO2 nanoparticles

Roo, Jonathan De; Keukeleere, Katrien De; Feys, Jonas; Lommens, Petra; Hens, Zeger; Driessche, Isabel Van

doi:10.1007/s11051-013-1778-z

Cited by 54 publications

(69 citation statements)

References 42 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…27 The reaction mixtures of the prop+EtOH, prop+H2O, ethoxide and acetate precursor are similar to the propoxide precursor, suggesting that only the ligand exchange and ether elimination takes place according to the first reaction scheme. The reaction mixture of the prop+TFA precursor on the other hand is similar to the chloride precursor, suggesting that also here the additional acid catalyzed condensation takes place (scheme 2).…”

Section: Resultsmentioning

confidence: 90%

“…We explored if a microwaveassisted solvothermal treatment for ZrO2 NCs results in NCs with identical properties in terms of diameter and crystallinity, yet at much shorter reaction times, since microwaves directly heat the precursor solution, resulting in faster and more homogenous heating. [26][27][28] In the original benzyl alcohol synthesis, zirconium propoxide was used as a precursor to synthesize cubic ZrO2 NCs. However, it has been shown before that the use of different precursor types can lead to different formation reaction mechanisms.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Fast and Tunable Synthesis of ZrO₂ Nanocrystals: Mechanistic Insights into Precursor Dependence

Keukeleere¹,

Roo

Lommens³

et al. 2015

Inorg. Chem.

Self Cite

View full text Add to dashboard Cite

ABSTRACT:In this work, ZrO2 nanocrystals (NCs) are synthesized via a solvothermal treatment in benzyl alcohol, which is an established method for the synthesis of many metal oxide nanocrystals. We found that the use of microwave heating allows for a reduction in reaction time from 2 days in the autoclave to merely 4 hours in the microwave. Furthermore, we were able to tune the crystallographic phase from pure cubic to pure monoclinic zirconia by changing the reaction mechanism through the use of a different zirconium precursor. Via GC-MS measurements we found that the release of a strong acid during synthesis controls the key mechanism behind the control over crystal phase formation. The as-synthesized ZrO2 NCs (cubic or monoclinic) are small in size (3 -10 nm), yet aggregated. However, aggregrate-free NCs are generated through a surface-functionalization with carboxylic acid ligands, providing stabilization in apolar solvents via steric hindrance. Solution 1 H NMR was used to study the details of this post-modification step and the surface chemistry of the resulting aggregate-free NCs. This led to the conclusion that not only a different crystal structure but also a different surface chemistry is obtained depending on the precursor composition.

show abstract

Section: Resultsmentioning

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Fast and Tunable Synthesis of ZrO₂ Nanocrystals: Mechanistic Insights into Precursor Dependence

Keukeleere¹,

Roo

Lommens³

et al. 2015

Inorg. Chem.

Self Cite

View full text Add to dashboard Cite

show abstract

“…10,49 Dodecanoic acid is dissociatively adsorbed on the HfO 2 NC surface ( Figure 1A), a binding motif classified as NC(X) 2 . 39 Since it was already shown that ligand exchange processes with carboxylic acids are governed by acidity 4,10,54,55 and that it proved possible to transfer NaYF 4…”

Section: Resultsmentioning

confidence: 99%

Amino Acid-Based Stabilization of Oxide Nanocrystals in Polar Media: From Insight in Ligand Exchange to Solution ¹H NMR Probing of Short-Chained Adsorbates

et al. 2016

Self Cite

View full text Add to dashboard Cite

1 AbstractLigand exchange is a crucial step between nanocrystal synthesis and nanocrystal application. Although colloidal stability and ligand exchange in nonpolar media is readily established, the exchange of native, hydrophobic ligands with polar ligands is less systematic. In this paper, we present a versatile ligand exchange strategy for the phase transfer of carboxylic acid capped HfO 2 and ZrO 2 nanocrystals to various polar solvents, based on small amino acids as the incoming ligand. To gain insight in the fundamental mechanism of the exchange, we study this system with a combination of FTIR, zeta potential measurements and solution 1 H NMR techniques. The detection of surface-associated, small ligands with solution NMR proves challenging in this respect. Tightly bound amino acids are undetectable but their existence can be proven through displacement with other ligands in titration experiments. Alternatively, we find that methyl moieties belonging to bound species can circumvent these limitations because of their more favorable relaxation properties as a result of internal mobility.

show abstract

“…35 Our synthesis is facilitated by the presence of starting materials, such as the LiOH precursor, 36 that strongly couple with microwaves and with materials with high dielectric constants such as the HfO 2 that can effectively couple with microwave radiations at high temperatures, in a similar way to the ZrO 2 precursor. [37][38][39] Undoped Li 6 Hf 2 O 7 and doped compounds up to x = 0.05 were obtained as single phase samples at a temperature of 850…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Ionic Conductivity Studies of In- and Y-Doped Li₆Hf₂O₇as Solid-State Electrolyte for All-Solid State Li-Ion Batteries

Amores

Corr

Cussen

2017

J. Electrochem. Soc.

View full text Add to dashboard Cite

The development of all solid-state lithium batteries is reliant on suitable high performance solid state electrolytes. Here, we present the synthesis and ionic conductivity of the In-and Y-doped Li 6 Hf 2 O 7 materials; Li 6+x Hf 2-x M x O 7 (M = In 3+ , Y 3+ ). Microwaveassisted synthesis was used to give phase pure material after heating for 4 hours at 850 • C. The ionic conductivity of the materials is increased with the insertion of interstitial lithium ion within the structure from 0.02 to 0.25 mS cm −1 at 174 • C and the activation energy for ionic conduction is lowered from 0.97 (4) Conventional lithium-ion batteries provide exceptionally high energy densities, making them the most popular option for mobile/portable applications.1 Nevertheless, safety issues and limitations on the operating voltages associated with the use of liquid electrolytes as ionic media for Li-ion diffusion between the electrodes, have led to the proposed introduction of all-solid state batteries, where this liquid electrolyte is replaced by a Li-ion solid-state conductor.2-4 The use of solid-state electrolytes would allow access to higher operating voltages and could address many safety concerns. 2,3 There are several candidate systems as solid-state electrolytes, 5 with four families being the most widely studied: the air stable NASICON-like LiMM (PO 4 ) 3 structures, 6 lithium containing garnet materials with ionic conductivity up to 1.3 mS cm −1 , 7-10 La 2/3 Li 1/3 TiO 3 perovskites in the same range of conductivities, 11,12 and the most recent thio-LISICON Li 10 GeP 2 S 12 materials with conductivities topping the 10 mS cm −1 , 13-15 matching those of liquid electrolytes. However, despite achieving ionic conductivities comparable with those of liquid electrolytes, different drawbacks -such as instability at low voltages or large grain-boundary resistances, [16][17][18][19] have hampered their full implementation. Thus, the search for new candidate materials remains a challenge for the realization of next generation of Li-ion batteries.The structure of the Li 6 Hf 2 O 7 shown in Figure 1 contains Li + ions in 5-fold oxygen coordination in a square pyramid geometry and Hf 4+ ions octahedrally coordinated by oxide. The lithium ions form pair of chains through the structure. This monoclinic phase can be considered as an anion-deficient NaCl rock salt structure with Li + and Hf 4+ ions on the Na + positions and the oxide occupying 7 / 8 of the anion positions. 20,21 The presence of these vacant positions and the availability of interstitial positions in the structure suggests it should be possible to tailor the lithium stoichiometry in order to modify the ionic conductivity of the material to generate a solid lithium electrolyte.Non stoichiometry is a well-studied pathway for increasing lithium conductivity in battery materials. This has been studied in cathode materials such as Li x CoO 2 , 22 the solid-state electrolyte 23 LiMgPO 4 and the low voltage electrode material LiVO 2 .24 Specifically, the role of interstitial lithium ...

show abstract

Fast, microwave-assisted synthesis of monodisperse HfO2 nanoparticles

Cited by 54 publications

References 42 publications

Fast and Tunable Synthesis of ZrO₂ Nanocrystals: Mechanistic Insights into Precursor Dependence

Fast and Tunable Synthesis of ZrO₂ Nanocrystals: Mechanistic Insights into Precursor Dependence

Amino Acid-Based Stabilization of Oxide Nanocrystals in Polar Media: From Insight in Ligand Exchange to Solution ¹H NMR Probing of Short-Chained Adsorbates

Synthesis and Ionic Conductivity Studies of In- and Y-Doped Li₆Hf₂O₇as Solid-State Electrolyte for All-Solid State Li-Ion Batteries

Contact Info

Product

Resources

About

Fast, microwave-assisted synthesis of monodisperse HfO2 nanoparticles

Cited by 54 publications

References 42 publications

Fast and Tunable Synthesis of ZrO2 Nanocrystals: Mechanistic Insights into Precursor Dependence

Fast and Tunable Synthesis of ZrO2 Nanocrystals: Mechanistic Insights into Precursor Dependence

Amino Acid-Based Stabilization of Oxide Nanocrystals in Polar Media: From Insight in Ligand Exchange to Solution 1H NMR Probing of Short-Chained Adsorbates

Synthesis and Ionic Conductivity Studies of In- and Y-Doped Li6Hf2O7as Solid-State Electrolyte for All-Solid State Li-Ion Batteries

Contact Info

Product

Resources

About

Fast and Tunable Synthesis of ZrO₂ Nanocrystals: Mechanistic Insights into Precursor Dependence

Fast and Tunable Synthesis of ZrO₂ Nanocrystals: Mechanistic Insights into Precursor Dependence

Amino Acid-Based Stabilization of Oxide Nanocrystals in Polar Media: From Insight in Ligand Exchange to Solution ¹H NMR Probing of Short-Chained Adsorbates

Synthesis and Ionic Conductivity Studies of In- and Y-Doped Li₆Hf₂O₇as Solid-State Electrolyte for All-Solid State Li-Ion Batteries