Nanocrystalline high melting point compound-based materials

Andrievski, R.A.

doi:10.1007/bf00445970

Cited by 90 publications

(22 citation statements)

References 81 publications

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“…Obviously, the granular nature of the original particle network is preserved as small contact areas or necks to adjacent particles are formed. Therefore, the fabrication process seems to be comparable with macroscopic sintering at elevated temperatures to produce nanophase materials [24][25][26]. In the following, the particle sintering process is termed type-A manipulation.…”

Section: Resultsmentioning

confidence: 99%

STM-assisted manipulation of Ag nanoparticles

Radojkovic

Schwartzkopff

Gabriel

et al. 1998

Applied Physics A: Materials Science & Processing

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We report scanning tunneling microscope (STM) investigations of inert-gas-evaporated Ag nanoparticles deposited on atomically flat, H-terminated Si(111) surfaces, to which they weakly stick. For the present purpose, nanoparticles having an average size of 3 nm are fabricated and the particle coverage on the substrate fluctuates between one and three monolayers. The weakly coupling particle network can repeatedly be imaged with the STM without inadvertently manipulating the fundamental building blocks. When the STM is operated in the field-emission regime and the tunnel current is kept between 50 pA and 39 µA, the temperature of the nanoparticles rises, thus stimulating local manipulation processes. Depending on the power density dissipated in the particles, we distinguish between a local sintering process leading to the formation of narrow necks to the nearest neighbors, while the original granular nature of the particle layer is maintained, and a complete fusion. In the latter case, stable nanometer-scale structures are fabricated which strongly interconnect with the underlying substrate. In combining nanoparticle-inherent properties with existing theory, we roughly estimate the temperature rise of the nanoparticles and confirm the possibility of particle liquefaction for the highest power densities generated.There is substantial interest in research and application of minute metal particles (nanocrystals or nanoparticles) as they present some peculiar features caused by their unusual optical, electronic, and thermodynamic properties relative to bulk metal [1]. For instance, if the energy needed to add one electron to an individual particle exceeds the mean thermal energy, single-electron charging processes, such as Coulomb blockade and Coulomb staircase, will develop. An approach has been to keep the tip of the scanning tunneling microscope (STM) stationary over an isolated Au island deposited onto * On leave to

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Section: Resultsmentioning

confidence: 99%

STM-assisted manipulation of Ag nanoparticles

Radojkovic

Schwartzkopff

Gabriel

et al. 1998

Applied Physics A: Materials Science & Processing

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“…The effect of temperature and high pressure on the density of Si 3 N 4 and TiN powders is shown in Fig. 5 [25,27,28].…”

Section: Deformation Processes and Consolidationmentioning

confidence: 99%

Research into sintering and related phenomena: personal experience

Андриевский

2011

Powder Metall Met Ceram

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The studies on deformation and diffusion processes during sintering are analyzed. Attention is paid to the effect of compressive and tensile stresses on shrinkage of silver, copper, and nickel powders. Superplastic deformation and displacement of particles as a whole are observed during shrinkage. Self-diffusion in transition metal carbides as well as their creep and neck growth during sintering are widely studied. The theory of effective diffusion coefficient is developed to be applied to diffusion-controlled processes in interstitial phases. The proposed relationships are shown to be applicable to creep and neck growth during sintering. Areas of further nanoscale studies are discussed.

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“…High purity S i c was produced The reaction mechanisms as explained by Kameyama are: Si + Sic2 -->2SiC in the periphery and SiK-->Sic in the central high temperature zones. [2] with the argon carrier gas, as shown in Fig. 4.…”

Section: Induction Dlasma Technology Evolutionmentioning

confidence: 99%

“…The different routes to produce UFP were reviewed by Andrievski (2). He distinguishes physical methods that include gas-condensation in inert or reactive gas and high energy destruction by milling, from chemical UFP preparation by synthesis and thermal decomposition.…”

Section: Introductionmentioning

confidence: 99%