<p> A high temperature polymorph of α-Cu2P2O7 was found above 70°C. The lattice parameters and space groups of both phases were determined from X-ray photographs. The crystal structures of α and β-Cu2P2O7 were refined by crystallographic least squares analysis and the molecular geometry obtained was compared with that of other closely related compounds of the transition metal ion pyrophosphate series. The central oxygen atom was found to have enhanced thermal motion or disorder in agreement with I.R. spectroscopic studies of Lazarev. The bond lengths obtained for the P2O7^4- ion were discussed in reference to values predicted by Cruickshank. Evidence of a Jahn-Teller effect was found in the case of the Cu++ ion. A description is given of a relatively efficient method of measuring intensities of Bragg reflections, using a single crystal diffractometer.</p> / Thesis / Master of Science (MSc)