Dr Dan Porter

Supervised by

  • Jon Goff First/primary/lead supervisor

    1/10/0813/12/13

Personal profile

My research is based around Sodium Cobaltate (NaxCoO2), a crystalline material with numerous interesting properties, including superconductivity, topological insulator states and excellent thermoelectric properties. Thermoelectric materials allow temperature gradients to be converted to useful energy, with applications converting waste heat into electricity or the potential for solid state refrigerator devices that can efficiently cool microprocessors.

By doping Sodium Cobaltate with Strontium or Calcium, the thermoelectric power of the material increases (dramatically in the case of Strontium) and we also observe a change in the diffraction pattern from single crystals of these doped systems indicating a change in the crystal structure. Using high quality single crystals grown in-house at Royal Holloway or from Oxford, I have performed diffraction experiments using a lab based x-ray diffractometer and also on SXD at ISIS. 

In collaboration with the theorist Michel Roger, I have developed software including reverse Monte Carlo (RMC) programs that can analyse the complex data sets taken from these experiments and solve the crystal structures. 

Aside from atomic structures, I have spent time measuring electronic and magnetic properties, performing resonant x-ray experiments on I16 (hard x-rays) and I10 (soft x-rays) at Diamond, and polarised neutron experiments on IN20 at the ILL. By comparing the resonant x-ray data with first-principles calculations from density functional theory, I have been able to study the ordering of charges within the Cobalt-Oxide layers of Sodium Cobaltate, where we found that the charges follow the previously predicted coulomb landscape generated by the Sodium ordering, thus firmly linking these properties.

Specialities: 
Single crystal neutron diffraction
Single crystal x-ray diffraction
Resonant x-ray scattering
Measurement of Seebeck coefficient and thermoelectic properties
MATLAB
JANA2006 Crystallographic Refinement Software

Personal profile

I completed my first degree at the University of Liverpool in 2008 with a 1st in Physics (MPhys). I then moved down to Royal Holloway to start my PhD.

Away from my research I enjoy playing badminton and squash and I am also a member of the university fencing team, where I compete regularly against other universities in foil, epee and sabre.

Research interests

My research is based around Sodium Cobaltate (NaxCoO2), which is a very interesting crystalline material. Amongst other properties, Sodium Cobaltate exhibits excellent thermo-electric properties, allowing temperature gradients to be converted to potential differences - recovering electrical energy from wasteful heat sources (the Seebeck effect) or on the flip-side the material can be used as a solid state refrigerator to cool microscopic components in processors (the Peltier effect).

By doping Sodium Cobaltate with Strontium or Calcium, the thermo-electric power of the material increases (dramatically in the case of Strontium) and we also observe different diffraction images from single crystals of these doped systems indicating a change in the crystal structure. Using high quality single crystals grown in house at RHUL and from Oxford, I perform diffraction experiments using a lab based x-ray diffractometer and also on instruments at the large ISIS (neutrons) and Diamond (synchrotron x-rays) facilities.

I have developed software including Reverse-Monte-Carlo programs that can analyse the complex data sets taken from these experiments and solve the crystal structures. We hope that understanding the intricacies of the crystal structures will give us a unique insight into the reasons why doping Sodium Cobaltate changes the thermoelectric properties.

Teaching

I am a demonstrator for 1st year undergraduates in labs and maths demonstration classes.

Teaching

I have experience in the following techniques and programs:
Single crystal neutron diffraction
Single crystal x-ray diffraction
Resonant x-ray scattering
Reverse Monte-Carlo
Measurement of Seebeck coefficient and thermoelectic properties
MATLAB
JANA2006 Crystallographic Refinement Software

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