THE ROLE OF POLARIZATION IN DETERMINING SOME THERMAL AND MECHANNICAL PROPERTIES OF NON-METALLIC SOLIDS – EFFECT OF TEMPERATURE AND PRESSURE ON THE SCREENING DEMANDS OF CATIONS

摘要

An experimental program in the field of surface chemistry and structural chemistry of glass, sponsored by the Office of Naval Research, has led to a new approach to solid state chemistry. The formation of solids and the structural changes occurring in solids seem to be governed by two basic principles: the need for additional screening of the positive cores of the atoms beyond that of their own electrons and the establishment of electroneutrality in the smallest possible volume. The second principle is well established and is used as a guide in crystal chemistry. The discovery of the principle that most atoms at ordinary temperature require additional screening of their cores made it possible to explain some phenomena for which hitherto no adequate explanation has been offered(la,b). The widely different melting temperatures of compounds such as CO2, SiO2, ZrO2, and ZrO2 was one of the first basic problems for which an explanation could be offered(lc). The viscosity of glasses of simple but widely varied compositions could be interpreted on a basis similar to that proposed for the melting(ld). It is the object of this report to interpret the effects of temperature and pressure changes on the volume of some crystals and glasses. In spite of the paramount importance of thermal expansion, this property is not yet understood even for the simplest solids such as MgO and the alkali halides.n Recently the behavior of matter under pressure has become of technical importance. This paper offers an explanation for the effect of pressure on glass formation and the properties of glasses formed under pressure.