Electromagnetic radiation approximately equal to band-gap energy has been established as responsible for the dissociation of amorphous As2Se3 and As2S3. The dissociation is accompanied by an optical densification observable as a ``photographic'' effect in thin films of these materials. The dissociation can be expressed by the following equations: As2Se3→ lim hvxAs+As2−xSe3, 0<x<2 As2S3→ lim hv2As+3S.The densification is reversible by thermal cycling to higher temperatures. A detailed analysis of the experimental results is given and a mechanism is proposed which explains the photodecomposition reactions and the thermally induced reversibility in As2Se3. The photographic cycling characteristics of As2Se3 are discussed in the light of its potential device application.
Rutile crystals of controlled composition have been grown from Na2O·3B2O3 and K2O·3B2O3 fluxes. The compositions were controlled by the use of various atmospheres of known oxygen activity as the equilibrium vapor phase. The crystals are prisms 2 to 10 mm in length and 0.1 to 0.3 mm in thickness. The morphology of the crystals and their response to changes in temperature, oxygen activity, and flux composition are described. The average dislocation density is 4×104 cm−2, but dislocation-free areas can be found.
Phase equilibria were determined by standard quench methods in binary systems NIO-B208, the binary join Li,O.B,O,-NiO, and three other sections through the Liz0.Bz03-B20a-Ni0 system. The only new compound observed was 2Ni0.B,03, which is stable from 1303" to 1480°C.
The phase equilibria for the
normalAs‐Sb2Se3‐normalSe
ternary system were determined by sealed system DTA and quench methods. The
As2Se3‐Sb2Se3
and
normalAs‐Sb2Se3
ternary sections are true binary systems exhibiting simple eutectic behavior. The general phase relationships are discussed and the liquidus behavior and liquid structure of the selenium rich part of the ternary are treated in detail. A nonregular thermodynamic solution model is used to describe the solution behavior and calculate the size of structural units present in the ternary liquid. A physical interpretation, in terms of these structural units, is given for the observed incipient liquid immiscibility.
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