Maclean, Ian Daniel.2014-10-2119921992AAINN80101http://hdl.handle.net/10222/55315A new instrument for the measurement of the expansion properties of mechanically weak materials is developed. This device uses a three-terminal capacitance technique in tandem with a negative feedback scheme to monitor length changes in compounds of low quasi-dimensionality with a resolution of 0.1 ppm. A novel technique of "self-heated" expansion allows the calculation of the absolute thermal expansion coefficient without the complication of cell-correction effects. High-resolution thermal expansion results are shown for the quasi-two-dimensional charge-density-wave (CDW) compound 2H-TaSe$\sb2$. The previously unknown thermal expansion properties of the quasi-one-dimensional CDW compounds o-TaS$\sb3$ and NbSe$\sb3$ are presented as well. Measurements of the length changes of the latter two materials as a function of applied electric field allow the estimation of the zero-frequency Young's modulus changes in the non-linear regime. These results are interpreted within a phase-relaxation model of CDW elasticity incorporating a continuous distribution of relaxation times. Refinements of both the instrument and the technique are discussed.Thesis (Ph.D.)--Dalhousie University (Canada), 1992.Engineering, Mechanical.Engineering, Materials Science.text