Photochromic Sodalites: From Natural Minerals to Advanced Applied Materials.

ConspectusWhile photochromic natural sodalites, an aluminosilicate mineral, were originally considered as curiosities, articles published in the past ten years have radically changed this perspective. It has been proven that their artificial synthesis was easy and allowed compositional tuning. Combined with simulations, it has been shown that a wide range of photochromic properties were achievable for synthetic sodalites (color, activation energy, reversibility, etc.

Reusable radiochromic hackmanite with gamma exposure memory.

Radiochromic films are used as position-sensitive dose meters in medical physics and radiation processing. The currently available films like those based on lithium-10,12-pentacosdiynoate or leucomalachite green are either toxic or non-reusable, or both. There is thus a great need for a sustainable solution for radiochromic detection.

The structural origin of the efficient photochromism in natural minerals.

SignificanceNatural photochromic minerals have been reported by geologists for decades. However, the understanding of the photochromism mechanism has a key question still unanswered: What in their structure gives rise to the photochromism's reversibility? By combining experimental and computational methods specifically developed to investigate this photochromism, this work provides the answer to this fundamental question. The specific crystal structure of these minerals allows an unusual motion of the sodium atoms stabilizing the electronic states associated to the colored forms.