Thermal Properties of Nanoscale Materials

Group Leader: Javier Rodríguez-Viejo

Main Research Lines

  • Heat capacity of low-dimensional materials

  • Phase transitions in ultrathin films with emphasis on size effects. Influence of external fields on heat capacity and phase transitions

  • Cross-plane and in-plane thermal transport in thin films and low-dimensional materials, including membranes and single nanowires, characterized by electrical measurements

  • Design, development and characterization of thermoelectric devices for energy harvesting and sensing applications

  • Growth and characterization of ultrastable organic thin film glasses with applications in OLEDs and solar cells

The Thermal Properties of Nanoscale Materials group (GTNaM), active at the UAB since 2000, has become affiliated to the ICN2 in January 2021. Its activities mainly revolve around the study of thermal properties of disordered and nanoscale materials, with special focus on the ultrathin film limit and low-dimensional solids.

Most of GTNaM senior members are university professors or lecturers with a 50% affiliation to ICN2 in research. Aitor Lopeandia, PhD 2007 at UAB and Marie Curie fellow at Neel Institute, is an expert in the development of thermal tools and thermal measurements of thin films and low-dimensional solids. Marta González, PhD 2006 and Marie Curie fellow at Vrije University, works on phase transitions of inorganic thin films and organic glasses. Cristian Rodríguez-Tinoco, PhD at UAB 2016 and postdocs in Poland and Belgium, has very recently joined the group as a tenure-track UAB lecturer with expertise in nanocalorimetry and dielectric spectroscopy that he has successfully used to investigate the relaxation dynamics of organic materials. Jordi Fraxedas, PhD 1990, CSIC Scientific Researcher, has very recently joined the group to bring his expertise in organic thin films and surface science using conventional and synchrotron radiation-based characterization techniques.

The GTNaM has been working on nanocalorimetry for many years, with the commitment to investigate phase transitions in ultrathin films. This technique can be used to explore phase transitions in layered 2D materials or in very thin oxide membranes. We are starting collaborations with other ICN2 groups to measure the influence of size on the phase transitions of ferroelectric oxides and to directly measure the heat capacity of layered transition metal dichalcogenides.

In the area of thermal transport, the group is looking for a deeper understanding of nanoscale heat transport with the aim of manipulating heat and controlling thermal transport, in order to develop new thermally-driven devices and technologies. To this purpose, we investigate phonon transport and thermoelectric-related phenomena in low-dimensional or disordered materials, with special interest in understanding mixed effects between electrons, phonons and/or photons. This know-how is further used to design and develop thermoelectric devices that can operate as energy harvesters or thermal sensors in a variety of environments. Currently, the group is working in a European Project, developing new structures and methodologies to measure the thermal conductance of individual semiconductor nanowires by means of electrical techniques, without the pervasive influence of the thermal contact resistance that often represents a major source of error in the evaluation of the thermal conductivity.

Since we established our partial affiliation with the ICN2, we have started to set up a new laboratory having an UHV evaporation chamber for organic thin films, which will be equipped with in-situ nanocalorimetry characterization, and another independent high vacuum chamber for nanocalorimetric measurements of low-dimensional materials.

Group Leader

Javier Rodríguez-Viejo

UAB Professor and Senior Group Leader
javier.rodriguez@icn2.cat

Javier Rodríguez-Viejo is Full Professor of Applied Physics at the Autonomous University of Barcelona (Universitat Autònoma de Barcelona, UAB) and leads the Group of Thermal Properties of Nanoscale Materials at the UAB and the ICN2. He performed the experimental part of his doctoral thesis at the Institut des Materiaux et Procedés CNRS, France and received his PhD in Physics from UAB in 1992. He continued his studies as a postdoctoral researcher at the Massachusetts Institute of Technology, working with Prof. Klavs F. Jensen (Chemical Eng. and Material Science Dep.) and Prof. M.G. Bawendi (Chemistry Dep.) on the synthesis of highly-luminescent CdSe(ZnS) quantum dots and the deposition of thin film quantum dot composites by electrospray organometallic chemical vapor deposition. His research in this field resulted in several patents and papers, one of which is among the most highly cited papers in semiconductor nanoparticles. In May 1997 he was appointed Associate Professor of Applied Physics at the Physics Department of UAB and in 2011 became Full Professor at the same university. He has been visiting scientist at Air Products in Allentown, US (July-August 2008) and Harvard University (May-September 2016).

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