This book introduces the ideas and concepts of nonlinear dielectric spectroscopy, outlines its history, and provides insight into the present state of the art of the experimental technology and understanding of nonlinear dielectric effects. Emphasis is on what can be learned from nonlinear experiments that could not be derived from the linear counterparts. The book explains that nonlinear dielectric spectroscopy can be used as a tool to measure structural recovery or physical aging, as well as connections between dynamics and thermodynamic variables such as enthalpy and entropy. Supercooled liquids in their viscous regime are ideal candidates for investigating nonlinear effects, because they are particularly sensitive to changes in temperature, and thus also to changes in the electric field. Other interesting materials covered are plastic crystals and complex liquids near criticality. The book also points out that, compared with other techniques such as mechanical shear experiments, the nonlinear regime of dielectric spectroscopy is special in the sense that the energies involved always remain small compared with thermal energies. To demonstrate this, nonlinear features of mechanical experiments are discussed. Theoretical approaches to nonlinear effects are particularly complicated because the tools available for the linear regime no longer apply. As a result, there is no single generally accepted theory to nonlinear dielectric responses of real liquids. Various approaches to nonlinear dielectric features have been reported, and the different aspects are communicated in several chapters. The book communicates recent progress most effectively through individual contributions from specialists in their respective fields.Chapter 'Third and Fifth Harmonic Responses in Viscous Liquids' is available open access under a Creative Commons Attribution 4.0 International License via link.springer.com.

The field of non-crystalline materials has seen the emergence of many challeng ing problems during its long history. In recent years, the interest in polymeric and biological disordered matter has stimulated new activities which in turn have enlarged the organic and inorganic glass community. The current research fields and recent progress have extended our knowledge of the rich phenomenol ogy of glassy systems, where the role of disorder is fundamental for the underlying microscopic dynamics. In addition, despite the lack of a unified theory, many interesting theoretical models have recently evolved. The present volume offers the reader a collection of topics representing the current state in the understanding of disorder effects as well as a survey of the basic problems and phenomena involved. The task of compiling a book devoted to disordered systems has benefited much from a seminar organized by the W.-E. Heraeus Foundation in Bad Honnef in April 1992, where we had the opportunity to discuss the project with most of the authors. Here we wish to thank the Heraeus Foundation for their support, and the authors and Springer-Verlag, especially Dr. Marion Hertel, for the pleasant cooperation."