Image analysis as an improved melting criterion in laser-heated diamond anvil cell

TL;DR

This paper introduces a novel image analysis method for accurately determining melting points in laser-heated diamond anvil cells, enabling precise measurements of low-melting-temperature materials like tellurium at high pressures.

Contribution

The study presents an innovative speckle interference pattern analysis technique combined with a customized IR pyrometer for objective melting detection in LHDAC experiments.

Findings

Successful measurement of tellurium melting curve up to 35 GPa

Good agreement with previous data up to 10 GPa

Enhanced precision in low-temperature melting measurements

Abstract

The precision of melting curve measurements using laser-heated diamond anvil cell (LHDAC) is largely limited by the correct and reliable determination of the onset of melting. We present a novel image analysis of speckle interference patterns in the LHDAC as a way to define quantitative measures which enable an objective determination of the melting transition. Combined with our low-temperature customized IR pyrometer, designed for measurements down to 500K, our setup allows studying the melting curve of materials with low melting temperatures, with relatively high precision. As an application, the melting curve of Te was measured up to~$\rm35\,GPa$. The results are found to be in good agreement with previous data obtained at pressures up to~$\rm10\,GPa$.