Nonlocal protons and deuterons opposed to disorder: a single-crystal neutron diffraction study of KH0.76D0.24CO3 and a theoretical framewok

TL;DR

This study uses neutron diffraction to reveal that protons and deuterons in KH$_{0.76}$D$_{0.24}$CO$_3$ are not randomly disordered but occupy distinct sublattices, supported by a new theoretical framework for nonlocal observables.

Contribution

It introduces a novel theoretical framework for understanding nonlocal observables and macroscopic states in crystals with proton and deuteron sublattices.

Findings

Protons and deuterons form separate sublattices in KH$_{0.76}$D$_{0.24}$CO$_3$.

Neutron diffraction shows no disorder but distinct proton and deuteron positions.

Theoretical model supports nonlocal quantum states in the crystal.

Abstract

We show with neutron diffraction that a single-crystal of potassium hydrogen deuterium carbonate at room temperature, namely KH$_{0.76}$D$_{0.24}$CO$_3$, is isomorphous with the KHCO$_3$ and KDCO$_3$ derivatives. Protons and deuterons are not disordered particles located at definite sites and Bragg peaks are best fitted with separate H and D sublattices. We propose a theoretical framework for nonlocal observables and macroscopic states compatible with the crystal field.