Casting single crystal shaped

However, due to the cheap computer power available, evaluation of single-crystal neutron diffraction data (at the level of atomic coordinates in the unit cell and the Debye-Waller factors associated with them) is a routine task nowadays. The trick is to apply direct methods of phase determination - methods that depend on the many mutual relationships (inequalities and probabilities) between structure factors and their phases. The simplest such constraint is that scattering power in solids is concentrated on atoms, which are well-defined regions by their size and shape. (For pioneering applications, see the works published by Karle and Karle (1966), Bernal and Watkins (1972) and Jonsson and Hamilton (1972).) Similar conditions cannot be cast into exact mathematical equations, but computer algorithms can easily cope with them. 

The major alloy of tin recovered from archaeological sites is pewter. This can be divided into those containing lead and lead-free alloys. The former could have a lead content ranging from 67 % (equivalent to plumbers solder) down to 15%. The French in Elizabethan times kept the lead of their wine goblets to below 18% as above this, the wine would become tainted As the lead and tin are insoluble in one another, they are classed as a two-phase alloy and articles could only be manufactured by casting. The lead-tree pewter was invariably an alloy of tin with a small amount of copper (0.5-7% for pewter recovered from the Maty Rose). The copper dissolved in the tin crystal structure resulted in a single-phase structure, which was considerably harder than pure tin. Hence this class of pewter could be subjected to a limited amount of mechanical working to achieve the final shape. 

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