To the Unified Model of Condensed State

Abstract

To the Unified Model of Condensed StateThe problem of unified model of condensed state can be solved by using solid-like model of liquids. A liquid arises when in a heated crystal a universal process of microcrack formation takes place that leads to originating a great number of very small crystals: microcrystallites. In the paper the two basic notions: the effective temperature of crystal surfaces and the internal thermal stresses in crystals are discussed. These notions make possible the microcrystallite model of liquids and the unified model of condensed state. Thus, the microcracks, resulted from thermal stresses, below the melting point lead only to decreased strength of crystals but above melting point the microcracks are spread all over the crystal bulk and cause splitting of the crystal into microcrystallites that are moving freely, in short, making up a liquid. The simple relations for these processes are given. In the end of the paper the identical features of the condensed states, solid and liquid, has been considered. IntroductionCondensed state includes solids (crystals) and liquids. But their properties are different and, therefore, a unified model is not an easy problem to formulate. If we know very well what a solid is, we can say far less about a liquid, that is, the problem is far from being settled. The difficulties begin with explanation of crystal-liquid transition which takes place, as a rule, at very distinct temperature. This is hard to understand, if the only involved process is order-disorder transition. Further, the one set of properties of liquids make them to be similar to solids and the other set-similar to gases. So we have two groups of models of the liquid state: solid-like and gas-like. But the solid-like models cannot usually explain the gas-like properties of liquids and vice versa. Thus, we may say that the problem of unified model of condensed state is the problem of true nature of liquid state. There are two methods of dealing with the liquid state. The first method makes no suppositions about the nature of liquids, except one -liquid is characterized by a relatively disordered structure. The second method makes use of eyesight presentations and, therefore, proposes at once to accept very definite assumptions about the liquid state. Respectively, there are two sets of models of liquids: statistical and eyesight models. But the first method is not free of assumptions also. These appear in process of mathematical treatments in form of "a first or rough approximation" and so on. On the other hand, the eyesight presentations, as a rule, have made at once all of needed assumptions and there is no necessity for them in the subsequent treatment.Recently the unified model of condensed state for metals and alloys had been discussed (BAuM). The author (BAUM) arrived at this conclusion taking into consideration a great deal of measurement of physical properties of liquid and solid metals near melting points and observations of structural transitions in liquid metals and alloys. Natural...

The Microcrystallite Model of Liquids for Noble Gases and Other Non‐Metals

“…So it seems the ratio Aala,, is more adequate for this representation. This ratio Aa/aa, is from 0.14 to 0.44 (see the Table) and the mean value is equal to 0.3 whereas the mean value estimated earlier for 15 metals, was 0.33 (VLASOV 1987). Thus, the supposed MML seems to be of an universal nature.…”

“…Recently the microcrystallite model of liquids (MML) had been introduced ( VLASOV 1987VLASOV , 1989VLASOV , 1990/1,2; VLASOV, REZ; VLASOV 1992). According to the MML, liquids consist of the microcrystallites (MC) having nearly spherical forms and identical sizes.…”

To the new theory of crystal strength

“…There is another way to determine y. Below it will be substantiated that y may be taken from the experiments on the melting curves (pressure relations of melting points) if the microcrystallite model of liquids (VLASOV 1987(VLASOV /2, 1989(VLASOV , 1990(VLASOV , 1991(VLASOV , 1992 is holding. That is, y = dP/dT where d T is the change in the melting point when the pressure increased by dP.…”