High-temperature thermodynamics of dilute solutions of hydrogen and deuterium in tantalum and in dilute tantalum--oxygen solid solutions

Journal Article · Wed Feb 01 04:00:00 EST 1978 · J. Solid State Chem.; (United States)

DOI:https://doi.org/10.1016/S0022-4596(78)90178-0· OSTI ID:6704004

Dantzer, P G; Kleppa, O J

We report a comparison between the partial enthalpies of solution of hydrogen (..delta.. anti H/sub H/) and of deuterium (..delta.. anti H/sub D/) in tantalum at 715/sup 0/K and find ..delta.. anti H/sub D/ - ..delta.. anti H/sub H/ = -220 cal mole/sup -1/. This allows a calculation of the average vibrational frequency of hydrogen which is 1350 cm/sup -1/. On the basis of this result we have made a new estimate of the ''residual'' excess entropy (anti S/sub H//sup E/ - anti S/sub H/(vibr) - anti S/sub H/(el)) for hydrogen and deuterium and find a value of 4.6 cal /sup 0/K/sup -1/ mole/sup -1/. This is consistent with occupancy by hydrogen of the tetrahedral interstitial sites, and may possibly reflect occupancy of both tetrahedral and octahedral sites. The presence of oxygen in solid solution in tantalum in amounts of 1 to 3 at.% makes the partial enthalpy of solution more negative, and also reduces the partial entropy by about 1 cal /sup 0/K/sup -1/ mole/sup -1/. The net effect of these two terms is to increase the partial pressure of hydrogen compared to pure tantalum at low oxygen contents, but to reduce the partial pressure at higher oxygen contents (N/sub 0/ > or approximately 0.03/sub 5/).

• Research Organization: Univ. of Chicago
• OSTI ID: 6704004
• Journal Information: J. Solid State Chem.; (United States), Journal Name: J. Solid State Chem.; (United States) Vol. 24:1; ISSN JSSCB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102 -- Metals & Alloys-- Structure & Phase Studies
360104 -- Metals & Alloys-- Physical Properties
37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY
400202* -- Isotope Effects
Isotope Exchange
& Isotope Separation
CRYOGENIC FLUIDS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DEUTERIUM
DILUTION
DISPERSIONS
ELEMENTS
ENERGY LEVELS
ENTHALPY
ENTROPY
EXCITED STATES
FLUIDS
HIGH TEMPERATURE
HYDROGEN
HYDROGEN ISOTOPES
IMPURITIES
INTERSTITIALS
ISOTOPE EFFECTS
ISOTOPES
LIGHT NUCLEI
METALS
MIXTURES
NONMETALS
NUCLEI
ODD-ODD NUCLEI
OXYGEN
PHYSICAL PROPERTIES
POINT DEFECTS
PRESSURE DEPENDENCE
REFRACTORY METALS
SOLID SOLUTIONS
SOLUTIONS
STABLE ISOTOPES
TANTALUM
TEMPERATURE DEPENDENCE
THERMODYNAMIC PROPERTIES
TRANSITION ELEMENTS
VIBRATIONAL STATES