Microscopic view of disorder in the ordered phase of superionic RbAg/sub 4/I/sub 5/

Journal Article · Fri Jul 01 04:00:00 EDT 1983 · Phys. Rev. B: Condens. Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.28.82· OSTI ID:5696565

Pasternak, M

Moessbauer spectroscopy in /sup 129/I was employed to verify the existence and investigate the properties of local disorder in the ''ordered'' state of the superionic conductor RbAg/sub 4/I/sub 5/. Studies were conducted in the temperature range of 4--180 K covering the low-temperature ..gamma.. phase (T<122 K) and part of the high-conductivity, disordered ..beta.. phase. The absorption spectra at all temperatures were analyzed with two iodine sites, characterized by their quadrupole splitting and isomer-shift values and a third site with a nonsplit single line. It was found that the electric field gradient (efg) at the /sup 129/I nucleus, produced by the neighboring Ag ions, has a continuous linear temperature dependence down to 4.2 K. The hyperfine constants and the Debye-Waller factor showed no discontinuity at T/sub c/. The anomalous existence of the single line has been attributed to a fast fluctuating efg due to local hopping of the Ag ions. This dynamic disorder is present even at low temperatures where (8--10)% of Ag ions are locally hopping, and its occurrence increases drastically at T>T/sub c/. A nonharmonic Debye-Waller factor was observed from which a linear temperature-dependent Debye temperature could be derived.

• Research Organization: Department of Physics and Astronomy, Tel Aviv University, Ramat Aviv, 69978 Tel Aviv, Israel
• OSTI ID: 5696565
• Journal Information: Phys. Rev. B: Condens. Matter; (United States), Journal Name: Phys. Rev. B: Condens. Matter; (United States) Vol. 28:1; ISSN PRBMD
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360104* -- Metals &amp; Alloys-- Physical Properties
ALKALI METAL COMPOUNDS
BETA DECAY RADIOISOTOPES
BETA-MINUS DECAY RADIOISOTOPES
CRYSTALS
DEBYE TEMPERATURE
DEBYE-WALLER FACTOR
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
HALIDES
HALOGEN COMPOUNDS
INTERMEDIATE MASS NUCLEI
INTERNAL CONVERSION RADIOISOTOPES
IODIDES
IODINE 129
IODINE COMPOUNDS
IODINE ISOTOPES
IONIC CONDUCTIVITY
IONIC CRYSTALS
ISOTOPES
MOESSBAUER EFFECT
NUCLEI
ODD-EVEN NUCLEI
ORDER PARAMETERS
ORDER-DISORDER TRANSFORMATIONS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
RADIOISOTOPES
RUBIDIUM COMPOUNDS
RUBIDIUM IODIDES
SILVER COMPOUNDS
SILVER IODIDES
SPECTROSCOPY
TRANSITION ELEMENT COMPOUNDS
VERY LOW TEMPERATURE
YEARS LIVING RADIOISOTOPES