Sökning: "Incommensurate structure"

Visar resultat 1 - 5 av 16 avhandlingar innehållade orden Incommensurate structure.

1. 1. Structure-Magnetic Relationships in the Fe-Mn-P-Si System for Energy Applications

   Författare :Viktor Höglin; Yvonne Andersson; Per Nordblad; Martin Sahlberg; Mogens Christensen; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Magnetocaloric; X-ray powder diffraction; Neutron powder diffraction; Magnetization measurements; Phase diagram; Crystal structure; Magnetic structure; Incommensurate structure; Ferromagnetic; Antiferromagnetic; Fe2P; Fe-Mn-P-Si.; Kemi med inriktning mot oorganisk kemi; Chemistry with specialization in Inorganic Chemistry;

   Sammanfattning : Demands for new, energy-efficient appliances have greatly increased in response to our growing need for a more environmentally friendly society. Magnetic refrigeration is a technique that utilizes the magnetocaloric effect, with possible energy savings of up to 30% compared to commercial gas compression refrigerators. LÄS MER

3. 2. Chemical Tuning of the Magnetic Interactions in Layer Structures

   Författare :Sabina Ronneteg; Rolf Berger; J. Paul Attfield; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Inorganic chemistry; neutron powder diffraction; magnetometry; layered magnetic structure; incommensurate helical structure; ThCr2Si2 type structure; antiferromagnetism; ferromagnetism; electronic structure calculations; Oorganisk kemi; Inorganic chemistry; Oorganisk kemi;

   Sammanfattning : Thin metal films have found their use in many magnetic devices. They form pseudo two-dimensional systems, where the mechanisms for the magnetic interactions between the layers are not completely understood. LÄS MER

4. 3. Modulations in Intermetallic Families of Compounds

   Författare :Hanna Lind; Sven Lidin; Gervais Chapuis; Stockholms universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; intermetallic; incommensurate structure; single crystal X-ray diffraction; Inorganic chemistry; Oorganisk kemi;

   Sammanfattning : This thesis is based on a study of five distinct intermetallic systems with the aim of expanding the general knowledge of aperiodically modulated crystal structures. Families of compounds that contain a variety of superstructures together with incommensurately modulated structures have been investigated mainly by means of single crystal X-ray diffraction and higher dimensional structure models. LÄS MER

5. 4. The Structural Basis for Magnetic Order in New Manganese Compounds

   Författare :Therese Eriksson; Yvonne Andersson; Helmer Fjellvåg; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Inorganic chemistry; Crystal structure; Magnetic structure; Manganese compounds; Transition metal silicides; Transition metal germanides; Magnetic frustration; Neutron powder diffraction; X-ray diffraction; Magnetisation measurements; DFT; Oorganisk kemi; Inorganic chemistry; Oorganisk kemi;

   Sammanfattning : Materials with new or improved properties are crucial for technological development. To provide the foundation for future successful products, it is important to prepare and characterise new chemical compounds that could show unusual properties. LÄS MER

7. 5. Magnetic ordering and crystal structure in selected transition- metal compounds

   Författare :Hui-Ping Liu; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Chemistry; transition-metal compounds; magnetic ordering; crystal structure; magneticstructure; neutron diffraction; Kemi; Chemistry; Kemi; Inorganic Chemistry; oorganisk kemi;

   Sammanfattning : Applications of magnetic materials are inherently related to their crystal, magnetic and electronic structures. In this thesis, experimental and theoretical methods have been focused on magnetic bulk materials from novel chemical synthesis, to X-ray diffraction for initial phase characterisation, and crystal and magnetic structure studies to explain their complex magnetic properties. LÄS MER