Phase equilibria in the Cd{sub 3}As{sub 2}-CdGeAs{sub 2}-CdAs{sub 2} system

Journal Article · Mon Aug 01 04:00:00 EDT 1994 · Inorganic Materials

OSTI ID:98708

Nipan, G D; Nikolaeva, L N ^[1]

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1. Kurnakov Institute of General and Inorganic Chemistry, Moscow (Russian Federation)

Earlier studies of the vapor pressures for the Ge-Cd{sub 3}As{sub 2}-CdGeAs{sub 2} system allowed us (1) to determine the temperature dependence of the vapor pressure for the S{sub I}S{sub II}S{sub III}V monovariant equilibrium (where S{sub I}, S{sub II}, and S{sub III} designate solid solutions based on crystalline Ge, Cd{sub 3}As{sub 2}, and CdGeAs{sub 2}, respectively, and V designates vapor); (2) to find the p-T coordinates and the compositions of the melt L and vapor involved in the S{sub I}S{sub II}S{sub III}LV invariant five-phase eutectic equilibrium; and (3) to calculate the thermodynamic functions for CdGeAs{sub 2}. The present work also deals with the Cd-Ge-As system and focuses on compositions that fall in the Cd{sub 3}As{sub 2}-CdGeAs{sub 2}-CdAs{sub 2} (IV) triangle. In analysis of the phase equilibria, we employed primarily static vapor-pressure measurements with a quartz Bourdon pressure gage. For the invariant eutectic equilibrium Cd{sub 3}As{sub 2}-CdGe{sub 1-x}As{sub 2}-CdAs{sub 2}-melt-vapor (x greater than or equal to 0.1), the pressure (8600 Pa), temperature (867 K), melt composition (35 at.% Cd + 7 at.% Ge + 58 at.% As), and vapor composition (3.5 at.% Cd + 96.5 at.% As) were determined. For CdGe{sub 1-x}As{sub 2}, there was determined a reversible polymorphic transformation at 820-830 K, supposedly chalchopyrite-sphalerite.

• OSTI ID: 98708
• Journal Information: Inorganic Materials, Journal Name: Inorganic Materials Journal Issue: 8 Vol. 30; ISSN INOMAF; ISSN 0020-1685
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CADMIUM ARSENIDES
GERMANIUM ARSENIDES
PHASE DIAGRAMS
PHASE TRANSFORMATIONS
SOLID SOLUTIONS
SPHALERITE
TEMPERATURE DEPENDENCE
VAPORS