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H.-P. Klein

Bio: H.-P. Klein is an academic researcher from Saarland University. The author has contributed to research in topics: Nanocrystalline material & Nanocrystal. The author has an hindex of 1, co-authored 1 publications receiving 571 citations.

Papers
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Journal ArticleDOI
TL;DR: In this paper, randomly oriented "nanocrystal" with sizes d below 10 nm, were compacted into a nanocrystalline solid, which consists of crystalline domains and a connective matrix without any short or long range order.

590 citations

Proceedings ArticleDOI
01 Jan 2023
TL;DR: In this article , various combinations of topping/bottoming cycles and machine schemes are compared, and some materials have the potential to be used in a topping cycle for providing simultaneously cold and high temperature waste heat to a bottoming cycle.
Abstract: Sorption Heat Pumps are promising devices for the rational and environmentally friendly use of energy. The commonly used working pairs have no Ozone layer Depletion Potential (ODP) and a negligible Global Warming Potential (GWP). In the field of liquid sorption, lithium bromide-water (LiBr-H20) and water-ammonia (H2O-NH3) machines are commercialized, while among the solid sorption machines only silicagel-water devices are produced in small series. To cover a larger fraction of the potential market, sorption devices need to have a performance close to the overall performance of compression devices, taking into account the efficiency of electricity generation. This is possible by coupling systems operating with different working pairs. A topping cycle allowing its waste heat to drive a bottoming device increases the efficiency significantly, and thus contributes to a higher competitiveness of the sorption technology. Some materials have the potential to be used in a topping cycle for providing simultaneously cold and high temperature waste heat to a bottoming cycle. Suitable materials are ammonia salts and metal hydrides, which cover a large temperature range from very low to very high temperatures. Favourable materials for bottoming cycles are silicagel-water and lithium bromide-water. In this paper various combinations of topping/bottoming cycles and machine schemes are compared.

Cited by
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Journal ArticleDOI
TL;DR: In this paper, it has been shown that submicrometer-grained structures may be produced in a wide range of materials (e.g. pure metals, metallic alloys including superalloys, intermetallics, semiconductors) by subjecting these materials to a very high plastic strain using either equal-channel angular (ECA) pressing or torsion straining under high pressure.

1,655 citations

Journal ArticleDOI
TL;DR: In this paper, a classification of nanostructure morphology according to the mechanism responsible for the magnetic properties is presented, followed by a brief discussion of some promising experimental techniques in synthesis and measurements.
Abstract: Understanding the correlation between magnetic properties and nanostructure involves collaborative efforts between chemists, physicists, and materials scientists to study both fundamental properties and potential applications. This article introduces a classification of nanostructure morphology according to the mechanism responsible for the magnetic properties. The fundamental magnetic properties of interest and the theoretical frameworks developed to model these properties are summarized. Common chemical and physical techniques for the fabrication of magnetic nanostructures are surveyed, followed by some examples of recent investigations of magnetic systems with structure on the nanometer scale. The article concludes with a brief discussion of some promising experimental techniques in synthesis and measurements.

1,522 citations

Journal ArticleDOI
TL;DR: A grain refinement mechanism induced by plastic deformation during the SMA treatment in Fe was proposed in this article, which involves formation of dense dislocation walls (DDWs) and dislocation tangles (DTs) in original grains and in the refined cells under further straining.

889 citations

Journal ArticleDOI
TL;DR: In this article, the main applications of current interest including some discussions of the underlying phenomena are dealt with, including some experiments for synthesizing nanoparticles in the gas phase aiming at any of the above mentioned functional applications.

713 citations