Date of Award

1986

Document Type

Thesis

Department

Physics

First Advisor

Dr. Glenn Good

Second Advisor

Dr. Wayne Everett

Third Advisor

Dr. Tom Auffenberg

Abstract

The beauty of many of the crystalline solids has attracted man's attention from the earliest times. Eventually the science of crystallography developed from studies of their shapes. The word crystal sterns from the Greek word "krystallos" meaning "clear ice." The word was first applied to describe the clear quartz crystals found in the Swiss Alps. The crystals were thought to be formed from water under conditions of extreme cold.

The earliest recorded crystallographic observation was in 1597 by Andreas Libarius. He noticed that crystals of different substances often have characteristic shapes. He suggested that the salts in mineral water could be identified by examining the shapes of the crystals deposited after the water had evaporated. Almost a century later the work of two Danish men, Niclaus Steno and Erasmus Bartholinus, led to the realization that while the faces of different crystals may vary in size and shape, the angle between corresponding pairs of faces is the same. Steno postulated that a crystal must grow from a nucleus by deposition of material in layers, so that a flat face remains parallel to itself as it grows outward.

Toward the end of the Eighteenth century the French crystallographer J.B.L. de Rome de I'isle discovered that all crystals of any one substance exhibit the same interfacial angle regardless of the facial sizes. the was somewhat successful in attempting to derive these angles from a few geometrical "primitive forms." Abbe Rene Just Hauy, a colleague of I'isle, emphasized the elementary shapes into which some crystals, such as calcite, could be cleaved. He showed that the many different shapes exhibited by crystals of the same substance could all be constructed by regular repetition of a small fundamental unit of characteristic size and shape.

The Nineteenth century saw a steady development of crystallography in the light of Hauy's observations. The study of the external shapes of crystals continued to advance with the development of detailed relationships between the observable geometry of faces and the sizes and shapes of the internal units. Speculations about the constitution of units continued during this period until they were rationalized by the foundations of modern atomic theory at the beginning of this century. Crystalline solids were then recognized as regular, repeating arrangements of the constituent atoms to fill the whole volume of a crystal. Subsequent developments in the present century ave made it possible to determine the size and shape of these units and the relative dispositions of the various atoms within them.

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