Mechanical amorphous-crystalline mixture

In order to anticipate problems and to interpret observations under the extreme conditions of shock compression, it is necessary to consider structural and electronic characteristics of PVDF. Although the phenomenological piezoelectric properties of PVDF are similar to those of the piezoelectric crystals, the structure of the materials is far more complex due to its ferroelectric nature and a heterogeneous mixture of crystalline and amorphous phases which are strongly dependent on mechanical and electrical history. 

Similarly, a number of amorphous alloys based on Fe-Zr, Ni-Zr, Co-Zr, Ni-Nb, have not shown any increase in activity over that expected for the mechanical mixture of the crystalline components [571]. For Ni-Nb the overpotential has even increased. Only Cu-Ti alloys have shown apparent synergetic effects, but the results of Machida et al. [89] (cf. Fig. 32) should also be taken into account. Jorge et al. [152] have observed higher activity for the amorphous form of Cu-Ti alloys, but they have attributed it to the preferential dissolution of Ti in the amorphous sample under cathodic load, with formation of a relatively porous Cu layer. The same effect was obtained more rapidly by means of HF etching [89,152]. 

Thus, the final result of mechanical activation of anhydrous oxides mixtures is determined by the correlation between the processes of formation of crystalline Ca2Fe20s and its amorphization. 

The reaction mechanism of this system involved the transfer of phases across the solid liquid interface. Hence, quantification using Equation (22) produced values that were overestimated. To determine the absolute phase abundances, powdered diamond was selected as an inert internal standard and was weighed into the starting solids. Acid was then added to this mixture and the standard concentration taken as its weight fraction of the sample in its entirety, i.e., solids and liquids in total. For each dataset the results of the quantitative phase analysis were adjusted according to the known amount of standard present in the system [Equation (16)]. This allowed the determination of variation in the amorphous content of the system to be assessed via Equation (17)] as well as the formation and consumption of crystalline phases. The amorphous content... 

The fact that zeolite seed crystals can improve the mechanical strength of the synthesized discs, was reported in synthesis of zeolite ZSM-5 with vapor phase method. Zeolite ZSM-5 disc was prepared with ethylenediamine (EDA) and ammonia solution (or distilled water) as liquid phase while the mixture of amorphous aluminosilicate gel, zeolite ZSM-5 seed crystals was the solid phase. The obtained ZSM-5 discs not only have high mechanical strength (up to 3.5 X lO Pa/m ) but also high relative crystallinity. It was also found that the mechanical strength would further increase by replacing the water with ammonia solution in liquid phase. The increase of mechanical strength of zeolite seed crystal may result from the fact that seeds serve as binders to cause close assembly of small zeolite ZSM-5 particles. 

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