Phase transitions in Na[sub 2][ital A]C[sub 60] ([ital A]=Cs, Rb, and K) fullerides

Journal Article · Sun May 01 00:00:00 EDT 1994 · Physical Review, B: Condensed Matter; (United States)

DOI:https://doi.org/10.1103/PhysRevB.49.12307· OSTI ID:6658239

Tanigaki, K; Hirosawa, I; Manako, T; Tsai, J S; Mizuki, J; Ebbesen, T W ^[1]

---

1. Fundamental Research Laboratories, NEC Corporation, 34-Miyukigaoka, Tsukuba 305 (Japan)

The ternary system fullerides Na[sub 2][ital A]C[sub 60] ([ital A]=Cs, Rb, and K) are studied by differential scanning calorimetry in the temperature range of 100 to 450 K. All show reproducible phase transitions at the transition temperatures of 299 K ([Delta][ital H]=2.5[plus minus]0.5 J/g) for Na[sub 2]CsC[sub 60], 313 K ([Delta][ital H]=2.7[plus minus]0.5 J/g) for Na[sub 2]RbC[sub 60], and 305 K ([Delta][ital H]=3.1[plus minus]0.5 J/g) for Na[sub 2]KC[sub 60]. Orientational ordering of the fullerene unit is responsible for the observed phase transitions ([ital T][sub sc-fcc]) from a high-temperature face-centered-cubic (fcc) to a low-temperature simple-cubic (sc) phase. The observed [ital T][sub sc-fcc] and enthalpy can be compared to those for pristine C[sub 60] which has [ital T][sub sc-fcc]=256.5 K ([Delta][ital H]=8[plus minus]0.5 J/g). The observed behavior is discussed in terms of the balance between the C[sub 60][sup 3[minus]]-C[sub 60][sup 3[minus]] intermolecular interaction and the C[sub 60][sup 3[minus]]-[ital A][sup +] Coulombic interaction as a function of lattice parameter.

• OSTI ID: 6658239
• Journal Information: Physical Review, B: Condensed Matter; (United States), Vol. 49:17; ISSN 0163-1829
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
CESIUM COMPOUNDS
CRYSTAL-PHASE TRANSFORMATIONS
SUPERCONDUCTIVITY
FULLERENES
POTASSIUM COMPOUNDS
RUBIDIUM COMPOUNDS
SODIUM COMPOUNDS
CALORIMETRY
CUBIC LATTICES
ENTHALPY
FCC LATTICES
INTERMOLECULAR FORCES
LATTICE PARAMETERS
TEMPERATURE DEPENDENCE
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 0273-0400 K
TEMPERATURE RANGE 0400-1000 K
ALKALI METAL COMPOUNDS
CARBON
CRYSTAL LATTICES
CRYSTAL STRUCTURE
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
ELEMENTS
NONMETALS
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
TEMPERATURE RANGE
THERMODYNAMIC PROPERTIES
360202* - Ceramics
Cermets
& Refractories- Structure & Phase Studies
360207 - Ceramics
Cermets
& Refractories- Superconducting Properties- (1992-)