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Institution

National Physical Laboratory

FacilityLondon, United Kingdom
About: National Physical Laboratory is a facility organization based out in London, United Kingdom. It is known for research contribution in the topics: Dielectric & Thin film. The organization has 7615 authors who have published 13327 publications receiving 319381 citations.


Papers
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Journal ArticleDOI
TL;DR: In this article, the authors describe the theory underlying the Kibble balance and practical techniques required to construct such an instrument to relate a macroscopic physical mass to the Planck constant with an uncertainty, which is achievable at present, in the region of 2 parts in 10^8.
Abstract: The redefinition of the SI unit of mass in terms of a fixed value of the Planck constant has been made possible by the Kibble balance, previously known as the watt balance. Once the new definition has been adopted, the Kibble balance technique will permit the realisation of the mass unit over a range from milligrams to kilograms. We describe the theory underlying the Kibble balance and practical techniques required to construct such an instrument to relate a macroscopic physical mass to the Planck constant with an uncertainty, which is achievable at present, in the region of 2 parts in 10^8. A number of Kibble balances have either been built or are under construction and we compare the principal features of these balances.

165 citations

Journal ArticleDOI
TL;DR: In this article, a calorimeter has been constructed for the determination of exothermic heats of alloying, and the results of this measurement agree with those obtained by Oelsen and Middel using quite a different method.

165 citations

Journal ArticleDOI
TL;DR: In this article, a technique was developed for the determination of the absolute surface energies of iron and iron alloys at temperatures of up to the melting point, based upon the measurement of the contractile forces in thin foils.
Abstract: A technique has been developed for the determination of the absolute surface energies of iron and iron alloys at temperatures of up to the melting point. The technique is based upon the measurement of the contractile forces in thin foils. All measurements are made in situ and chemical equilibrium is maintained throughout the experiment. The results show that phosphorus in dilute solid solution decreases progressively the surface energy of iron at 1450 °C from 2100 ergs cm -2 to 1200 ergs cm -2 , for increasing phosphorus contents of up to 0.36%. Results were also obtained for the γ phase in which the effect is less pronounced. Absolute grain boundary energies were also determined as a function of phosphorus content. From the strain rate of the foils which move by a diffusion creep mechanism, it was deduced that the self diffusion coefficient increases linearly with phosphorus content. Application of the Gibbs adsorption theorem has permitted the evaluation of the extents of equilibrium segregation of the solute to interfaces. The maximum levels are 2.3 x 10 -9 g-atom cm -2 at surfaces and 1.1 x 10 -9 g-atom cm -2 at grain boundaries. The relevance of these measurements to the problem of the intergranular brittle fracture of iron/phosphorus alloys is discussed.

164 citations

Journal ArticleDOI
TL;DR: A review of different synthesis techniques employed all over the world for the development of industrially important nanophosphors and extent of particle size reduction achieved is discussed in this article, where the particle size has to be restricted to 3-5 nm to get the real advantage of quantum confinement.
Abstract: Nanophosphors have been extensively investigated during the last decade due to their application potential for various high-performance displays and devices. These act as a strategic component in almost all displays. Synthesis of nanophosphors can be accomplished in two ways namely, chemical and physical methods. Under chemical methods, different routes such as colloidal, capping, cluster formation, sol–gel, electrochemical, etc., are being followed. Physical methods widely used are molecular beam epitaxy, ionised cluster beam, liquid metal ion source, consolidation, sputtering and gas aggregation of monomers. Chemical precipitation in presence of capping agents, reaction in microemulsions, sol–gel reaction and autocombustion are commonly used techniques for synthesis of nanophosphors. However, the particle size has to be restricted to 3–5 nm to get the real advantage of quantum confinement. In other words, the particle size must be less than twice of Bohr radii of exciton as quantum confinement regime is limited to that size. A brief review of different synthesis techniques employed all over the world for the development of industrially important nanophosphors and extent of particle size reduction achieved is discussed.

164 citations

Journal ArticleDOI
TL;DR: In this paper, a transfer standard for the fluence and mean energy of neutrons produced in the 3H(d, n)4He reaction is described which is suitable for postal exchange between the National Physical Laboratory and other centres.

164 citations


Authors

Showing all 7655 results

NameH-indexPapersCitations
Rajesh Kumar1494439140830
Akhilesh Pandey10052953741
A. S. Bell9030561177
David R. Clarke9055336039
Praveen Kumar88133935718
Richard C. Thompson8738045702
Xin-She Yang8544461136
Andrew J. Pollard7967326295
Krishnendu Chakrabarty7999627583
Vinod Kumar7781526882
Bansi D. Malhotra7537519419
Matthew Hall7582724352
Sanjay K. Srivastava7336615587
Michael Jones7233118889
Sanjay Singh71113322099
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
202315
202242
2021356
2020438
2019434
2018406