MIT Unit Affiliation:
Lab Affiliation(s):
Schuh Group
Post Doc Sponsor / Advisor:
Prof. Christopher A Schuh
Areas of Expertise:
  • Nanocrystalline metals and alloys
  • Interfacial phenomena in solids
  • Dewetting of thin films
Date PhD Completed:
May, 2015
Expected End Date of Post Doctoral Position:
November 26, 2018

Dor Amram

  • Post Doctoral

MIT Unit Affiliation: 

  • Materials Science and Engineering

Lab Affiliation(s): 

Schuh Group

Post Doc Sponsor / Advisor: 

Prof. Christopher A Schuh

Date PhD Completed: 

May, 2015

Top 3 Areas of Expertise: 

Nanocrystalline metals and alloys
Interfacial phenomena in solids
Dewetting of thin films

Personal Statement: 

My research as a Fulbright and MIT-Technion Postdoctoral Fellow is now underway at the Department of Materials Science and Engineering, Massachusetts Institute of Technology, in the group of Prof. Christopher A Schuh. 

I am a scientist and an engineer, and the fields of Materials and Nanotechology are closest to my heart. Performing research in these fields is my broad objective, and teaching others what I've learned is another (and also a passion).

Currently I'm interested in "interface engineering" - structural and/or chemical modifications of interfaces (surface, grain boundaries, etc.) in materials, to better understand their complex nature and improve engineering properties. My preferred method to tackling this is harnessing thermodynamics as an ally - various interfacial phenomena may be employed to create stable, modified interfaces even in nanomaterials (where the surface/volume ratio is very large).

Expected End Date of Post Doctoral Position: 

November 26, 2018

Research Projects: 

Title: Stability of nanocrystalline metallic alloys: interface engineering with nature's blessing

Description: This research is focused on the design, fabrication and characterization of thermodynamically-stable nanocrystalline metallic alloys. Nanocrystalline metallic alloys are metallic materials which are made of up of many nano-scale crystallites (“grains”), typically ranging in size between 1-50 nanometers. These materials exhibit significantly improved properties over their conventional coarse-grained counterparts, yet their nanostructure is a double-edged sword as their thermal stability as inherently poor.

The main challenge of this project is to "tame the nanostructure" and my approach differs from the mainstream since it is based on thermodynamic, rather than kinetic principles. In other words, by careful interface engineering I attempt to alter the fundumental "desires" of the material to favor a nanostructure as its most-stable configuration. In that sense, it can be referred to as interface engineering with nature's blessing.

Thesis Title: 

Morphology and Microstructure Evolution in Au-Fe Bilayers on Sapphire

Thesis Abstract: 

This research thesis revolves around a chronological journey through the “life” of a thin bilayer on a substrate (gold/iron/sapphire). Three main “stops” in this journey, each relies on the conclusions of the previous, lead to an applicative research goal - obtaining core(iron)-shell(gold) nanoparticles by annealing the films at elevated temperatures (600-1100°C).

1.      As-deposited microstructure of thin films: we obtained single-crystalline gold thin films on sapphire, having exceptional crystal quality and thermal stability, by using the iron layer as a “seed”. The seed layer accommodates the large difference between the lattice parameters of gold and sapphire, which would otherwise result in a typical polycrystalline film containing many structural defects.

2.      Anisotropic dewetting: upon annealing, the films agglomerate into particles due to poor adhesion between metals (gold, iron) and the ceramic substrate (sapphire - aluminum oxide). At temperatures lower than the films’ melting temperature, this is termed ‘solid-state dewetting’. The unique microstructure of the films leads to a unique dewetting behavior, which had not been observed before. We developed a quantitative model which accounts for surface-energy and diffusion anisotropies (dependence of those properties on crystallographic direction), and described the dewetting kinetics in the films well.

3.      Phase transformations in micro- and nanoparticles: when dewetting of a single-crystalline film is complete, structurally-perfect particles are obtained. Phase transformations in alloy particles (gold/iron) are expected to proceed differently from bulk systems due to the “size effect”. We explored two transformations: (1) precipitation of iron from a gold solid-solution; (2) the a?g transformation of iron and iron-gold alloys. Our main conclusion was that, contrary to the current paradigm, phase transformation proceed differently even in sub-micrometer-sized particles, and not only in nanometer-sized particles, where capillary forces dominate. Particularly, segregation (migration of a solute atom to a surface/interface to reduce its energy) of gold to all surfaces and interfaces of iron nanoparticles greatly affected the kinetics and morphology of the phase transformations.

We capitalized on the latter main result to fulfil the applicative research goal by employing a segregated gold layer as the shell, demonstrated the ability to bind organic molecules to their surfaces, and explored their magnetic properties. Such nanoparticles could find promising uses in bio-medical, data storage and catalytic applications, due to the unique combination of a magnetic iron core and an inert gold shell. Compared to other fabrication methods, we suggested a simple process which leads to nanoparticles with a high degree of purity and structural perfection.

Top 5 Awards and honors (name of award, date received): 

J. William Fulbright Postdoctoral Fellowship, 2015
MIT-Technion Postdoctoral Fellowship, 2015
Acta Materialia Student Award, 2014
Minerva Short-Term Research Grant, 2014
Gutwirt, Jacobs, and Russell Berrie PhD Scholarships, 2010

5 Recent Papers: 

Contact Information:
77 Massachusetts Avenue
8-139
Cambridge
MA
02139
(617) 388-0920