Sökning: "high-pressure physics"

Visar resultat 6 - 10 av 67 avhandlingar innehållade orden high-pressure physics.

1. 6. Computational Material Design : Diluted Magnetic Semiconductors for Spintronics

   Författare :Lunmei Huang; Rajeev Ahuja; Walter Temmerman; Uppsala universitet; []
   Nyckelord :Physics; Density functional theory; Diluted magnetic semiconductor; Ferromagnetism; Defect; Phase transition; High pressure; Thermal elastic constant; Fysik;

   Sammanfattning : The present thesis deals with the application of ab-initio electronic structure calculations based on density functional theory for material design.The correlation between magnetic properties and electronic structures has been investigated in detail for diluted magnetic semiconductors (DMS), which have promising application for spintronics devices. LÄS MER

3. 7. Ab initio Lattice Dynamics : Hydrogen-dense and Other Materials

   Författare :Duck Young Kim; Rajeev Ahuja; Richard Needs; Uppsala universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; Density functional theory; Density functional perturbation theory; Hydrogen-dense materials; Phase transition; High pressure; Ab initio lattice dynamics; Superconductivity; Quasi-particle approximation; Physics; Fysik;

   Sammanfattning : This thesis presents a theoretical study of materials under high pressure using ab initio lattice dynamics based on density functional theory and density functional perturbation theory using both super-cell and linear response approach. Ab initio lattice dynamics using super-cell approach is applied to compare our theoretical predictions with experimental findings. LÄS MER

4. 8. Designing and Tuning the Properties of Materials by Quantum Mechanical Calculations

   Författare :Jailton Souza de Almeida; Rajeev Ahuja; Patrizia Monachesi; Uppsala universitet; []
   Nyckelord :Physics; Density Functional Theory; Electronic Structure; Phase Transitions; High Pressure; Optical Properties; Dielectric Functions; Semiconductors; Metals; Fysik;

   Sammanfattning : In many materials, changes in chemical composition, pressure or temperature can induce metal to insulator transitions. It is recently observed in yttrium hydride, for example, changes from a shiny mirror (YH2) to a transparent window (YH3), which has important technological application in optical devices. LÄS MER

5. 9. Microactuators for Powerful Pumps

   Författare :Roger Bodén; Klas Hjort; Jan-Åke Schweitz; Johan Nilsson; Uppsala universitet; []
   Nyckelord :TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; µTAS; chromatography; high pressure; lab-on-a-chip; microactuator; microdispenser; micropump; on-chip; paraffin; PCM; point-of-care; Engineering physics; Teknisk fysik;

   Sammanfattning : When paraffin wax melts it exhibits a large, relatively incompressible volume expansion. This can be used in microactuators for strong and large displacements, a rare combination among actuators. Furthermore, paraffin is inexpensive, inert and environmentally friendly, as well as easily processed and actuated. LÄS MER

7. 10. Development and applications of theoretical algorithms for simulations of materials at extreme conditions

   Författare :Igor Mosyagin; Igor Abrikosov; Sergey Simak; Andrei Postnikov; Linköpings universitet; []
   Nyckelord :NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; NATURVETENSKAP; NATURAL SCIENCES; TEKNIK OCH TEKNOLOGIER; ENGINEERING AND TECHNOLOGY; NATURVETENSKAP; NATURAL SCIENCES;

   Sammanfattning : Materials at extreme conditions exhibit properties that differ substantially from ambient conditions. High pressure and high temperature expose anharmonic, non-linear behavior, and can provoke phase transitions among other effects. Experimental setups to study that sort of effects are typically costly and experiments themselves are laborious. LÄS MER