High-pressure cell for simultaneous dielectric and neutron spectroscopy

TL;DR

This paper introduces a novel high-pressure cell enabling simultaneous dielectric and neutron spectroscopy, allowing comprehensive analysis of molecular dynamics across a wide timescale range under various temperature and pressure conditions.

Contribution

The work presents a unique high-pressure cell design that integrates dielectric and neutron measurements, facilitating simultaneous data collection on molecular dynamics in supercooled liquids and glasses.

Findings

Successful verification with dipropylene glycol data

Operates up to 500 MPa and 320 K

Captures dynamics from kilo- to picoseconds

Abstract

In this article we report on the design, manufacture and testing of a high-pressure cell for doing simultaneous dielectric and neutron spectroscopy. This cell is a unique tool for studying dynamics on different timescales, from kilo- to picoseconds, covering universal features such as the alpha relaxation and fast vibrations at the same time. The cell, constructed in cylindrical geometry, is made in high-strength aluminum alloy and operates up to 500 MPa in a temperature range between roughly 2 and 320 K. In order to measure the scattered neutron intensity and the sample capacitance simultaneously, a cylindrical capacitor is positioned within the bore of the high-pressure container. The capacitor consists of two concentric electrodes separated by insulating spacers. The performance of this setup has been successfully verified by collecting simultaneous dielectric and neutron spectroscopy data on dipropylene glycol, using both backscattering and time-of-flight instruments. We have carried out the experiments at different combinations of temperature and pressure in both supercooled liquid and glassy state.