Crystal structure of monoclinic hafnia (HfO<sub>2</sub>) revisited with synchrotron X-ray, neutron diffraction and first-principles calculations

Pathak, S.; Das, P.; Das, Tilak; Mandal, Guruprasad; Joseph, Boby; Sahu, Manjulata; Kaushik, S. D.; Siruguri, V.

doi:10.1107/s2053229620013960

Cited by 9 publications

(5 citation statements)

References 55 publications

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“…The PDF can indeed be refined using the monoclinic HfO 2 crystal structure with space group P2 1 /c. 61 All refined parameters are presented in Table S3. The refined crystal size appeared to be 10 Å.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…The local correlations related to the final monoclinic structure are already present (Hf–O = 2.1 Å, Hf–Hf (edge-sharing) = 3.5 Å, and Hf–Hf (corner-sharing) = 4.0 Å). The PDF can indeed be refined using the monoclinic HfO 2 crystal structure with space group P 2 1 / c . All refined parameters are presented in Table S3.…”

Section: Resultsmentioning

confidence: 99%

“…The PDFs were analysized with real-space Rietveld refinements using PDFgui . Monoclinic HfO 2 crystal structure with space group P 2 1 / c was used in the refinements . To follow the formation pathway, sequential refinement was performed.…”

Section: Methodsmentioning

confidence: 99%

“…89 Monoclinic HfO 2 crystal structure with space group P2 1 /c was used in the refinements. 61 To follow the formation pathway, sequential refinement was performed. Nyquist data sampling was applied, and the refinements were initiated from the final crystalline product in the backward direction.…”

Section: ■ Conclusionmentioning

confidence: 99%

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From Gel to Crystal: Mechanism of HfO₂ and ZrO₂ Nanocrystal Synthesis in Benzyl Alcohol

Goossens,

Aalling-Frederiksen,

Tack

et al. 2024

J. Am. Chem. Soc.

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Nonaqueous sol−gel syntheses have been used to make many types of metal oxide nanocrystals. According to the current paradigm, nonaqueous syntheses have slow kinetics, thus favoring the thermodynamic (crystalline) product. Here we investigate the synthesis of hafnium (and zirconium) oxide nanocrystals from the metal chloride in benzyl alcohol. We follow the transition from precursor to nanocrystal through a combination of rheology, EXAFS, NMR, TEM, and X-ray total scattering (PDF analysis). Upon dissolving the metal chloride precursor, the exchange of chloride ligands for benzylalkoxide liberates HCl. The latter catalyzes the etherification of benzyl alcohol, eliminating water. During the temperature ramp to the reaction temperature (220 °C), sufficient water is produced to turn the reaction mixture into a macroscopic gel. Rheological analysis shows a network consisting of strong interactions with temperature-dependent restructuring. After a few minutes at the reaction temperature, crystalline particles emerge from the gel, and nucleation and growth are complete after 30 min. In contrast, 4 h are required to obtain the highest isolated yield, which we attribute to the slow in situ formation of water (the extraction solvent). We used our mechanistic insights to optimize the synthesis, achieving high isolated yields with a reduced reaction time. Our results oppose the idea that nonaqueous sol−gel syntheses necessarily form crystalline products in one step, without a transient, amorphous gel state.

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Section: ■ Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: ■ Conclusionmentioning

confidence: 99%

See 2 more Smart Citations

From Gel to Crystal: Mechanism of HfO₂ and ZrO₂ Nanocrystal Synthesis in Benzyl Alcohol

Goossens,

Aalling-Frederiksen,

Tack

et al. 2024

J. Am. Chem. Soc.

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“…23 Hafnium oxide, one of the most commonly studied chemical compositions for hafnium-based nanomaterials, may exhibit an amorphous nature or exist in four different crystal systems. Monoclinic hafnia (P2 1 /c) 128 is the most stable phase under standard conditions 122 but transitions to a tetragonal (P4 2 / nmc) or cubic (Fm3̅ m) phase at higher temperatures. 129 Likewise, two distinct orthorhombic phases have been observed at high pressures (Pbca and Pnma), and both exhibit ferroelectric properties.…”

Section: Characterization and Morphologymentioning

confidence: 99%

Synthesis and Bioapplication of Emerging Nanomaterials of Hafnium

Skrodzki,

Molinaro,

Brown

et al. 2024

ACS Nano

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A significant amount of progress in nanotechnology has been made due to the development of engineered nanoparticles. The use of metallic nanoparticles for various biomedical applications has been extensively investigated. Biomedical research is highly focused on them because of their inert nature, nanoscale structure, and similar size to many biological molecules. The intrinsic characteristics of these particles, including electronic, optical, physicochemical, and surface plasmon resonance, that can be altered by altering their size, shape, environment, aspect ratio, ease of synthesis, and functionalization properties, have led to numerous biomedical applications. Targeted drug delivery, sensing, photothermal and photodynamic therapy, and imaging are some of these. The promising clinical results of NBTXR3, a high-Z radiosensitizing nanomaterial derived from hafnium, have demonstrated translational potential of this metal. This radiosensitization approach leverages the dependence of energy attenuation on atomic number to enhance energy−matter interactions conducive to radiation therapy. High-Z nanoparticle localization in tumor issue differentially increases the effect of ionizing radiation on cancer cells versus nearby healthy ones and mitigates adverse effects by reducing the overall radiation burden. This principle enables material multifunctionality as contrast agents in X-ray-based imaging. The physiochemical properties of hafnium (Z = 72) are particularly advantageous for these applications. A well-placed K-edge absorption energy and high mass attenuation coefficient compared to elements in human tissue across clinical energy ranges leads to significant attenuation. Chemical reactivity allows for variety in nanoparticle synthesis, composition, and functionalization. Nanoparticles such as hafnium oxide exhibit excellent biocompatibility due to physiochemical inertness prior to incidence with ionizing radiation. Additionally, the optical and electronic properties are applicable in biosensing, optical component coatings, and semiconductors. The wide interest has prompted extensive research in design and synthesis to facilitate property fine-tuning. This review summarizes synthetic methods for hafnium-based nanomaterials and applications in therapy, imaging, and biosensing with a mechanistic focus. A discussion and future perspective section highlights clinical progress and elaborates on current challenges. By focusing on factors impacting applicational effectiveness and examining limitations this review aims to support researchers and expedite clinical translation of future hafnium-based nanomedicine.

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Nuclear techniques for studying thin films

Das

2024

Comprehensive Materials Processing

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Crystal structure of monoclinic hafnia (HfO₂) revisited with synchrotron X-ray, neutron diffraction and first-principles calculations

Cited by 9 publications

References 55 publications

From Gel to Crystal: Mechanism of HfO₂ and ZrO₂ Nanocrystal Synthesis in Benzyl Alcohol

From Gel to Crystal: Mechanism of HfO₂ and ZrO₂ Nanocrystal Synthesis in Benzyl Alcohol

Synthesis and Bioapplication of Emerging Nanomaterials of Hafnium

Nuclear techniques for studying thin films

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Crystal structure of monoclinic hafnia (HfO2) revisited with synchrotron X-ray, neutron diffraction and first-principles calculations

Cited by 9 publications

References 55 publications

From Gel to Crystal: Mechanism of HfO2 and ZrO2 Nanocrystal Synthesis in Benzyl Alcohol

From Gel to Crystal: Mechanism of HfO2 and ZrO2 Nanocrystal Synthesis in Benzyl Alcohol

Synthesis and Bioapplication of Emerging Nanomaterials of Hafnium

Nuclear techniques for studying thin films

Contact Info

Product

Resources

About

Crystal structure of monoclinic hafnia (HfO₂) revisited with synchrotron X-ray, neutron diffraction and first-principles calculations

From Gel to Crystal: Mechanism of HfO₂ and ZrO₂ Nanocrystal Synthesis in Benzyl Alcohol

From Gel to Crystal: Mechanism of HfO₂ and ZrO₂ Nanocrystal Synthesis in Benzyl Alcohol