Voyage dans le Cristal - A Journey into Crystals

Voyage dans le cristal is a major exhibition, now on display in Grenoble before touring other French cities. The exhibition presents to the general public the science and the beauty of matter in the crystalline state. The exhibition was mounted with the contribution of numerous partner laboratories under the management of the Grenoble Museum of Natural History and the French Association of Crystallography.

Voyage dans le cristal recounts humanity’s interaction with crystals, through art and science, from prehistoric times to the present day. It invites the public on a voyage to discover crystals in their many aspects: their wonder and mystery; their place in the history of science; their use in multiple contemporary applications.

Crystals provoke wonder, become symbols, inspire study

Already in prehistoric times, in the search for wealth under the earth’s surface, Man had discovered multiply facetted stones. Such stones provoked wonder and admiration; from Antiquity onwards, they became subjects of philosophical and scientific enquiry.

[quartz] 
"Imagining crystals"
Carangeot's copper gauges and goniometer.
Coll. MNHN

Abbé Haüy's wooden models.
Coll. Jussieu, UPMC
 
[historical apparatus]
[synchrotron radiation diffraction pattern]
[protein crystals]
[vaporization of diamond]

Their colours and multiple geometries inspired mysticism and fascination: crystals became symbolic objects, often associated with virtues or supernatural powers. Their transparency, their rarity and their apparent inalterability led early to their use as ornaments. Man learnt to cut them skilfully, to enhance their sparkle and light.

Crystallography: the birth and triumph of a science

In the 16th and 17th centuries, natural philosophers held two opposing points of view about crystals: did they grow facetted from inert matter, or were they sculpted solids? In the 18th century, with no techniques yet available for probing deep into a crystal, scientists began to deduce their internal structure from observations of their external geometry.

Thus, the discovery of the invariance of the angles between the facets for a given type of crystal led scientists to define a crystal as a regular stacking of elementary building blocks. The work of Romé de l’Isle, of abbé Haüy and many others gave birth to a new science: 'crystallography'. Together with astronomy, mechanics and optics, crystallography is one of the oldest of the physical sciences.

In the mid 19th century, still without any proper tool for seeing a crystal’s structure, the concepts of periodicity and molecular order gave the explanation of their shape and symmetry. The 1895 discovery of the mysterious 'X-rays' inspired the work of Laue and the Braggs, father and son, who used crystals in order to understand these new rays. In return, their 'diffraction' experiments showed how crystals were indeed made of regular arrays of atoms, finally making it possible to 'journey' into the heart of a crystal.

Crystals for research and applications: scientists 'grow' crystals

From the beginning of the 20th century, the birth of crystal chemistry enabled chemists to 'grow' crystals, to 'visualize' their structure, and thus to invent new materials. The same methods have spread through the sciences of pharmacy and biology, where fundamental research leads to the synthesis of new pharmaceuticals.

[Exhibition poster]A Crystallography exhibition presented from April 25 to September 27, 2009 at the old Palace of the Dauphiné Parliament in Grenoble, France

Crystals are all around, they are in shells, pearls, corals and bones; sedimentary chalks once were life! Crystals are at the heart of metallurgy. Metals and alloys are made up of a multitude of crystals, and crystal defects determine the mechanical properties of metal objects and play a key role in forging, laminating and milling. Crystals for microelectronics need to be nearly perfect, and either very pure or with minute concentrations of impurities purposely added for tuning their properties. Crystals also become solid state lasers or light sources in displays, or 'LEDs' for traffic signals or Christmas decorations... By its composition, its structure, its density, a natural crystal is a messenger from the heart of the earth. This messenger role of crystals is useful also in archaeology and in studies of heritage objects. Many applications are based on the two classic crystals, quartz, which marks time in our watches, and diamond, symbol of wealth but just one member of the carbon family. That family gives us graphite, the fullerenes, carbon nano tubes and graphene.

Crystals are an everyday object, found everywhere

The discoveries of the 20th century have dispelled the mysteries concerning the atomic structure and the physical properties of crystals, giving them 'a new place at the heart of modern civilization'. Thanks to Crystallography, crystals are now research tools used in investigations that cover an immense range, from the composition of our planet Earth to the microscopic structures of materials and the molecules of Life.

From Jean-Louis Hodeau & Ronald Cox
(AFC : French Association of Crystallography & Institut Néel – CNRS – Grenoble)
Contact : hodeau@grenoble.cnrs.fr