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Recently, several reports with a strong focus on compact, nonstationary optical atomic clocks have been published, including accounts of in-field deployment of these devices for demonstrations of chronometric levelling in different types of environments. We review recent progress in this research area, comprising compact and transportable neutral atom and single-ion optical atomic clocks. The identified transportable optical clocks strive for low volume, weight and power consumption while exceeding standard microwave atomic clocks in fractional frequency instability and systematic uncertainty. Some transportable clock projects additionally address requirements for metrology or serve the joint technology development between industrial and academic stakeholders. Based on the reviewed reports on nonstationary optical atomic clocks, we suggest definitions for transportable, portable and mobile optical atomic clocks. We conclude our article with an overview of possible future directions for developments of optical clock technology. [ABSTRACT FROM AUTHOR]

A new type of Heusler nanoparticles of the formula Fe3Ga has been prepared by facile synthesis approaches using pre-fabricated multi-walled carbon nanotubes. The tubes act as a template and a coating to protect the magnetic material from oxidation and agglomeration. For the purpose of comparison, the Fe3Ga bulk material was also prepared by a novel method from the metal precursors. The morphology, structural determinations and the magnetic properties of both types of materials are presented. Compared to the bulk material, an enhancement in coercivity was observed for the nanoparticles which make them excellent candidates for magnetic storage devices. Since bulk Galfenol is a known magnetostrictive material, it is worth studying the effect of downsizing this material to the nanoscale dimension on such properties. [ABSTRACT FROM AUTHOR]

A facilesynthesis approach for the synthesis of ternary intermetallicnanocrystals was demonstrated exemplarily with the Heusler compoundCo2FeGa. The method, involving prefabricated multiwalledcarbon nanotubes which act as a template and protective shell, resultsin the formation of mainly spherical, chemically stable, and crystallinenanoparticles with a well-defined diameter distribution. As an example,for novel functionalities arising from downscaling a bulk material,we observe an enhancement of the coercive field of the Co2FeGa nanocrystals by a factor of ≈30. Our work can facilitatethe exploration and eventually the tuning of physical properties ofternary and other intermetallic compounds at the nanoscale. [ABSTRACT FROM AUTHOR]

Downsizing well-established materials to the nanoscale is a key route to novel functionalities, in particular if different functionalities are merged in hybrid nanomaterials. Hybrid carbon-based hierarchical nanostructures are particularly promising for electrochemical energy storage since they combine benefits of nanosize effects, enhanced electrical conductivity and integrity of bulk materials. We show that endohedral multiwalled carbon nanotubes (CNT) encapsulating high-capacity (here: conversion and alloying) electrode materials have a high potential for use in anode materials for lithium-ion batteries (LIB). There are two essential characteristics of filled CNT relevant for application in electrochemical energy storage: (1) rigid hollow cavities of the CNT provide upper limits for nanoparticles in their inner cavities which are both separated from the fillings of other CNT and protected against degradation. In particular, the CNT shells resist strong volume changes of encapsulates in response to electrochemical cycling, which in conventional conversion and alloying materials hinders application in energy storage devices. (2) Carbon mantles ensure electrical contact to the active material as they are unaffected by potential cracks of the encapsulate and form a stable conductive network in the electrode compound. Our studies confirm that encapsulates are electrochemically active and can achieve full theoretical reversible capacity. The results imply that encapsulating nanostructures inside CNT can provide a route to new high-performance nanocomposite anode materials for LIB. [ABSTRACT FROM AUTHOR]