Our research

We are a materials chemistry group studying novel synthesis routes under extreme compression. We use cutting-edge techniques to subject samples to pressures on the order of millions of atmospheres, allowing us to access exotic states of matter and synthesize previously undiscovered solid-state compounds. We also use first-principles calculations to explore high-pressure phase space in silico, and to study the bulk properties of newly discovered phases.

X-ray Diffraction | Solid-State Synthesis

High-Pressure Synthesis

High pressure represents a vastly unexplored phase space where novel compounds can be synthesized and recovered back to ambient conditions. We use experimental high-pressure synthesis techniques to discover completely new solid-state compounds that could underpin future advances in technology.

Dynamic Compression | X-ray Diffraction | Modelling

Shockwave Chemistry

Shockwaves subject materials to very high pressures over extremely short timescales, potentially offering a route toward the kinetic control of solid-state transformations. We use cutting-edge ultrafast in situ X-ray diffraction methods to examine phase transformations under dynamic compression.

Magnetism | Spectroscopy | X-ray Diffraction

Novel Quantum Materials

Systems that exhibit magnetic frustration are a direct route to exotic new states of matter dominated by quantum fluctuations. Control over these delicate quantum states is an outstanding challenge in chemistry and physics. We are using high pressures to target novel quantum phases in geometrically frustrated systems.

Density Functional Theory | High-Throughput Computation

Structure Prediction

Modern first-principles methods can be used to accurately calculate the formation enthalpy of any given structure. We use random structure searching tools to perform high-throughput DFT calculations in search of undiscovered high-pressure phases. We also use machine learning methods to investigate how pressure can influence chemical disorder in the solid state.

Meet the Group

James Walsh

Assistant Professor
jpswalsh@umass.edu

 Curriculum Vitae
 (413) 545-1557 •  PSB 173

Scott Ambos

Graduate Student
sambos@umass.edu

Kim Bolduc

Graduate Student
kbolduc@umass.edu

Nick Manganaro

Graduate Student
nmanganaro@umass.edu

Paul Marshall

Graduate Student
pmarshall@umass.edu

Scott Thiel

Graduate Student
sthiel@umass.edu

Zeynep Alptekin

Undergraduate Student
zalptekin@umass.edu

Laura Casey

Undergraduate Student
lgcasey@umass.edu

Adam Hoolahan

Undergraduate Student
ahoolahan@umass.edu

Eli Jun

Undergraduate Student
sjun@umass.edu

Wyatt Mitchell

Undergraduate Student
wmitchell@umass.edu

Publications

Laboratory Tour

The Walsh Lab and associated office spaces are located on the first floor of the Physical Sciences Building at the University of Massachusetts Amherst. We also have space in the X-ray Laboratory in the basement of the Lederle Graduate Research Tower where our single crystal X-ray diffractometer is housed. Please reach out to Dr. Walsh if you would like to use any of our instruments for your research.

High-Pressure Tools

Our sample preparation room is equipped with all the tools necessary for setting up high-pressure experiments, including large working distance microscopes, an EDM drill for gasket preparation, a microfocused spectrometer for measuring ruby fluorescence, anvil mounting jigs, a sample polishing wheel, and various other support tools. We have a range of diamond anvil cells and assorted anvils and seats, allowing us to routinely access pressures up to 50 GPa.

X-ray Diffractometer

We have a dual-source Rigaku Synergy-S equipped with a HyPix-6000HE detector. Experiments can be run using either a Cu source (λ = 1.5406 Å) or a Ag source (λ = 0.5594 Å). The Oxford Cryostream 800 allows for single crystal measurements between 80–400 K. Powder samples can be measured in transmission mode at ambient temperatures. Samples can be studied under high pressures (up to 50 GPa) using diamond anvil cells.

Glovebox Microscope

Air-free preparation of micrometer-scale samples can be carried in our glovebox, which is equipped with a binocular microscope with a large working objective. This allows us to prepare air-sensitive single crystal samples for X-ray diffraction. The large working distance is also ideal for the preparation of diamond anvil cell experiments under inert atmospheres.