A neutron diffraction study of the thermal stability of the α-quartz-type structure in germanium dioxide

The structure of the alpha-quartz-type form of germanium dioxide was refined at room temperature and up to 1344 K by the Rietveld method using time-of-flight neutron powder diffraction data. The intertetrahedral bridging angle theta and the tilt angle delta exhibit thermal stabilities that are among the highest observed in alpha-quartz homeotypes. The temperature dependence of these angles is found to be a function of the structural distortion in these materials. Structure-property relationships predict that due to its highly distorted structure, germanium dioxide is potentially a high-performance piezoelectric material. The high stability of the above structural parameters as a function of temperature infers that the corresponding piezoelectric properties should also be retained under these conditions. At the present time, problems related to phase stability and crystal growth need to be resolved before the alpha-quartz-type form of germanium dioxide can be used as a piezoelectric material. (C) 2002 Elsevier Science (USA).