Varistor Ceramic: Residual Strain and Texture Analysis by Neutron Time-of-Flight Diffraction
Strain/stress experiments for characterization of micro- and macro-strain distribution and texture experiments were carried out on a varistor ceramic using neutron-TOF-diffraction. By a radial strain scan, residual strain has been determined on the (1010 ), (0002), (1012), and (1120 ) Bragg reflections of the hexagonal ZnO as well as on the (400) reflections of the cubic spinel Zn7Sb2O12. Residual strain values in the range of -1.5x10-4 (contraction) and 4x10-4 (dilatation) were observed for ZnO, with indications of macro-strains across the cylindrical sample and substantial micro-strains between the different phases. The texture on both phases (ZnO, Zn7Sb2O12) is characterized by a weak, non-ideal fibre texture around the cylinder axis. The results indicate that the texture pattern might coincide with the strain. To our knowledge, these are the first texture and residual strain investigations in metal oxide varistor elements and they will be discussed in detail.
W. Reimers and S. Quander
C. Scheffzük et al., "Varistor Ceramic: Residual Strain and Texture Analysis by Neutron Time-of-Flight Diffraction", Materials Science Forum, Vols. 524-525, pp. 781-786, 2006