Mixing Effects in the Crystallization of Supercooled Quantum Binary Liquids

TL;DR

This study investigates how impurities like neon influence the crystallization process of supercooled quantum liquid mixtures of parahydrogen and orthodeuterium, revealing effects on growth rates and crystalline structure through spectroscopy and simulations.

Contribution

It demonstrates the impact of neon impurities on crystallization kinetics and structure in supercooled quantum liquids, combining experimental Raman spectroscopy with path-integral simulations.

Findings

Ne impurities reduce crystal growth rates

Impurities significantly alter crystalline structure

Growth rates correlate with quantum particle size ratios

Abstract

By means of Raman spectroscopy of liquid microjets we have investigated the crystallization process of supercooled quantum liquid mixtures composed of parahydrogen (pH$_2$) diluted with small amounts of up to 5\% of either neon or orthodeuterium (oD$_2$), and of oD$_2$ diluted with either Ne or pH$_2$. We show that the introduction of Ne impurities affects the crystallization kinetics in both the pH$_2$-Ne and oD$_2$-Ne mixtures in terms of a significant reduction of the crystal growth rate, similarly to what found in our previous work on supercooled pH$_2$-oD$_2$ liquid mixtures [M. K\"uhnel et {\it al.}, Phys. Rev. B \textbf{89}, 180506(R) (2014)]. Our experimental results, in combination with path-integral simulations of the supercooled liquid mixtures, suggest in particular a correlation between the measured growth rates and the ratio of the effective particle sizes originating from quantum delocalization effects. We further show that the crystalline structure of the mixture is also affected to a large extent by the presence of the Ne impurities, which likely initiate the freezing process through the formation of Ne crystallites.