Photonic Applications of Rare-Earth-Doped Materials

MRS Bulletin ◽  
1999 ◽  
Vol 24 (9) ◽  
pp. 16-20 ◽  
Author(s):  
Andrew J. Steckl ◽  
John M. Zavada
Keyword(s):  
World War Ii ◽  
Rare Earth ◽  
Atomic Number ◽  
Permanent Magnets ◽  
Magnetic Moments ◽  
Energy Levels ◽  
Electronic Energy ◽  
Characteristic Energy ◽  
History Of ◽  
Re Elements

The elements of the lanthanide series, from Ce (atomic number 58) to Yb (atomic number 70), form a group of chemically similar elements that have in common a partially filled 4f shell. These so-called “rare earth” (RE) elements usually take on a 3+ ionic state (RE3+). Because the 4f electronic-energy levels of each lanthanide ion are shielded from external fields by 5s2 and 5p6 outer-shell electrons, RE3+ energy levels are predominantly independent of their surroundings.The characteristic energy levels of 4f electrons of the trivalent RE elements have been investigated in detail by Gerhard Heinrich Dieke and co-workers and were reported approximately 30 years ago. The Dieke diagram showing RE3+ energy levels is a familiar tool of scientists and engineers working with RE elements. However, the history of RE elements goes back to the year 1787 in the small Swedish town of Ytterby near Stockholm and to the gifted amateur mineralogist and military man Lt. Carl Axel Arrhenius. Arrhenius discovered an unusual black mineral in Ytterby (perceived initially as much rarer in occurrence and in concentration than the common ores or earths of aluminum, calcium, etc.). Many new elements were discovered by various chemists upon analysis of this black stone and others like it. The names given to these elements are variations of the location where the first discovery was made: yttrium, ytterbium, terbium, and erbium. The history of RE elements is fascinating and involves many other famous names in science: Berzelius, Gadolin, Bunsen.The properties of these elements and their multifaceted applications to science and industry are equally fascinating and have remained important to this day. Commercial applications of RE elements began after World War II, when their available quantity and purity were greatly enhanced by improved separation techniques developed as a part of the Manhattan Project. Until fairly recently, the main industrial application of RE elements has been in permanent magnets. The unpaired 4f electrons result in some RE elements having the highest magnetic moments of any element. The development and applications of RE magnets are reviewed in a very interesting article by Livingston3 in a previous MRS Bulletin issue. In this issue of MRS Bulletin, we have taken as our aim to review some of the properties and applications of RE elements relevant to photonics.

Parameter free calculation of the subgap density of states in poly(3-hexylthiophene)

2014 ◽  
Vol 174 ◽  
pp. 255-266 ◽  
Author(s):  
Jarvist M. Frost ◽  
James Kirkpatrick ◽  
Thomas Kirchartz ◽  
Jenny Nelson
Keyword(s):  
Density Of States ◽  
Energy Levels ◽  
Tight Binding ◽  
Electronic Energy ◽  
Film Structure ◽  
Dynamics Simulation ◽  
Characteristic Energy ◽  
Torsional Potential ◽  
Experimental Values ◽  
Electronic Energy Levels

We investigate the influence of intra-chain and inter-chain interactions on the sub-gap density of states in a conjugated polymer using a combination of atomistic molecular dynamics simulation of polymer film structure and tight-binding calculation of electronic energy levels. For disordered assemblies of poly-3-hexylthiophene we find that the tail of the density of hole states is approximately exponential with a characteristic energy of 37 meV, which is similar to experimental values. This tail of states arises mainly from variations in the electronic coupling between neighbouring monomers, and is only slightly influenced by interchain coupling. Thus, knowledge of the disorder in torsion between neighbouring monomers is sufficient to estimate the density of states for the polymer. However, the intrachain torsional disorder is determined largely by the packing of the chains rather than the torsional potential alone. We propose the combination of methods as a tool to design higher mobility conjugated polymers.

scholarly journals Magnetic structure analysis of rare earth permanent magnet Sm2Fe17N3

2014 ◽  
Vol 70 (a1) ◽  
pp. C1460-C1460 ◽  
Author(s):  
Kotaro Saito ◽  
Nobuhito Inami ◽  
Yasuo Takeichi ◽  
Tetsuro Ueno ◽  
Ryoko Sagayama ◽  
...  
Keyword(s):  
Rare Earth ◽  
Neutron Diffraction ◽  
Magnetic Structure ◽  
Structure Analysis ◽  
Permanent Magnets ◽  
Nearest Neighbor ◽  
Magnetic Moments ◽  
High Coercivity ◽  
Diffraction Measurement ◽  
Fe Sites

Rare earth intermetallic compound Sm2Fe17N3 exhibits notalble magnetic properties such as high Curie temperature and high coercivity which are very suitable for permanent magnets [1,2]. Although microscopic magnetic structure is one of the basic information for magnetic materials, there is no report about the magnetic structure of Sm2Fe17N3 for our knowledge. This is because samarium's neutron absorption cross section is huge enough to make researchers hesitate to have neutron diffraction experiments of Sm compounds. We have carried out powder neutron diffraction measurement of Sm2Fe17N3 with a straightforward solution to the problem by taking long measurement time. Synchrotron x-ray diffraction measurements with single crystal has also been done to obtain initial crystal structure parameters for magnetic structure analysis and we have succeeded to analyze the magnetic structure of Sm2Fe17N3 at room temperature. Among four Fe sites in the unit cell, while one Fe site which is the nearest neighbor of nitrogen shows smaller magnetic moment than normal iron, two Fe sites show enhancement in their magnetic moments. This phenomenon can be understood as 'cobaltization' of Fe by the adjacent nitrogen through hybridization.

For the Love of a Mother—Henry Moseley’s Rare Earth Research

2017 ◽  
Vol 47 (4) ◽  
pp. 529-567
Author(s):  
K. M. Frederick-Frost
Keyword(s):  
Rare Earth ◽  
Atomic Number ◽  
Physical Property ◽  
Published Data ◽  
World War ◽  
Rare Earth Research ◽  
The First World War ◽  
History Of ◽  
Corrected Data ◽  
First World

In December 1913 and April 1914, Henry Moseley, a British physicist, published data that is now famed for being the first experimental evidence for the atomic number as a physical property of the nucleus. Shortly after, in June 1914, Moseley used x-ray spectroscopy to analyze several rare earth elements provided by Georges Urbain. Moseley failed to publish his conclusions before his death in the First World War. Despite the efforts of his mother and colleagues, a posthumous publication never materialized. This essay explores the question of why. An in-depth evaluation of extant artifacts and archival materials at the Museum of the History of Science in Oxford related to Moseley’s rare earth research reveals nuances in the process by which he collected and corrected data to form his conclusions. Whereas Moseley was confident his data did not support the claim that Urbain isolated the element with atomic number 72, it failed to inspire Ernest Rutherford to see the work through publication after Moseley’s death. Archival materials reveal some of the pressures that could have prevented publication, including Rutherford’s unfamiliarity with Moseley’s process—but more importantly, the fact that this data would influence the debate over the discovery of element 72. Interestingly, it is likely this controversy led to the retention of relevant archival material. By tracing the actors that created and curated a particular collection of documents and spectra, one can explore how rare earth knowledge was produced and verified in the first few decades of the twentieth century.

Basicity or Ionicity – A New Approach for Understanding Glass Properties

2008 ◽  
Vol 39-40 ◽  
pp. 129-134
Author(s):  
Adrian Volceanov
Keyword(s):  
Energy Levels ◽  
Electronic Energy ◽  
New Approach ◽  
Novel Approach ◽  
History Of ◽  
Chemical Character ◽  
Electronic Energy Levels ◽  
Major Adjustment ◽  
Global Mean ◽  
Glass Properties

Basicity of glass is still a challenge in spite of various attempts to measure or calculate it. The values assigned for basicity of glasses, either calculated or experimentally determined, are not always in full agreement with actual facts, and discrepancies among the theoretical ones are not unusual. For instance, SiO2 is described by a single basicity value even if the polymorphs of SiO2 are quite different. Only few attempts were made to face this challenge. Present paper deals with a novel approach on theoretical ionicity / basicity based on electronic energy levels or band structure of solids. Another major adjustment takes into account the possibility of decomposing ionicity of complex chemical bondings into a sum of binary bondings. Considering the distribution of the interbonding angles specific for vitreous systems, it is possible to estimate both a local ionicity (basicity) of bondings and a global (mean) basicity of glass. The variation of basicity (ionicity) with temperature is also presented, this finding being able to open a new view on thermal history of glass considered through chemical character of bondings.

The Film World’s Cooperative Store: Institutions and Films of the 1930s and 1940s

2018 ◽  
Author(s):  
C. Claire Thomson
Keyword(s):  
World War Ii ◽  
Meat Products ◽  
Public Information ◽  
Early History ◽  
World War ◽  
International Context ◽  
German Occupation ◽  
History Of ◽  
The Uk ◽  
The Impact

This chapter traces the early history of state-sponsored informational filmmaking in Denmark, emphasising its organisation as a ‘cooperative’ of organisations and government agencies. After an account of the establishment and early development of the agency Dansk Kulturfilm in the 1930s, the chapter considers two of its earliest productions, both process films documenting the manufacture of bricks and meat products. The broader context of documentary in Denmark is fleshed out with an account of the production and reception of Poul Henningsen’s seminal film Danmark (1935), and the international context is accounted for with an overview of the development of state-supported filmmaking in the UK, Italy and Germany. Developments in the funding and output of Dansk Kulturfilm up to World War II are outlined, followed by an account of the impact of the German Occupation of Denmark on domestic informational film. The establishment of the Danish Government Film Committee or Ministeriernes Filmudvalg kick-started aprofessionalisation of state-sponsored filmmaking, and two wartime public information films are briefly analysed as examples of its early output. The chapter concludes with an account of the relations between the Danish Resistance and an emerging generation of documentarists.

Recasting Bourgeois Europe

2015 ◽  
Author(s):  
Charles S. Maier ◽  
Charles S. Maier
Keyword(s):  
World War Ii ◽  
Social Vulnerability ◽  
Group Representation ◽  
Political Stability ◽  
Status Quo ◽  
European History ◽  
World War ◽  
History Of ◽  
Country Analysis ◽  
Economic Stabilization

The author, one of the most prominent contemporary scholars of European history, published this, his first book, in 1975. Based on extensive archival research, the book examines how European societies progressed from a moment of social vulnerability to one of political and economic stabilization. Arguing that a common trajectory calls for a multi country analysis, the book provides a comparative history of three European nations—France, Germany, and Italy—and argues that they did not simply return to a prewar status quo, but achieved a new balance of state authority and interest group representation. While most previous accounts presented the decade as a prelude to the Depression and dictatorships, the author suggests that the stabilization of the 1920s, vulnerable as it was, foreshadowed the more enduring political stability achieved after World War II. The immense and ambitious scope of this book, its ability to follow diverse histories in detail, and its effort to explain stabilization—and not just revolution or breakdown—have made it a classic of European history.

Creatures of Cain

2018 ◽  
Author(s):  
Erika Lorraine Milam
Keyword(s):  
World War Ii ◽  
Human Nature ◽  
Race And Gender ◽  
Late Night ◽  
Hollywood Films ◽  
Political Debates ◽  
American Science ◽  
Human Exceptionalism ◽  
History Of ◽  
And Gender

After World War II, the question of how to define a universal human nature took on new urgency. This book charts the rise and precipitous fall in Cold War America of a theory that attributed man's evolutionary success to his unique capacity for murder. The book reveals how the scientists who advanced this “killer ape” theory capitalized on an expanding postwar market in intellectual paperbacks and widespread faith in the power of science to solve humanity's problems, even to answer the most fundamental questions of human identity. The killer ape theory spread quickly from colloquial science publications to late-night television, classrooms, political debates, and Hollywood films. Behind the scenes, however, scientists were sharply divided, their disagreements centering squarely on questions of race and gender. Then, in the 1970s, the theory unraveled altogether when primatologists discovered that chimpanzees also kill members of their own species. While the discovery brought an end to definitions of human exceptionalism delineated by violence, the book shows how some evolutionists began to argue for a shared chimpanzee–human history of aggression even as other scientists discredited such theories as sloppy popularizations. A wide-ranging account of a compelling episode in American science, the book argues that the legacy of the killer ape persists today in the conviction that science can resolve the essential dilemmas of human nature.

Sign in / Sign up

Export Citation Format

Share Document