Ultrasonic studies of structural phase transitions and superconductivity in La2−xBaxCuO4−δ and La2−xSrxCuO4−δ

Tetsuo Fukase, Tetsuo Nomoto, Tetsuo Hanaguri, Takayuki Goto, Yoji Koike

Research output: Contribution to journalArticlepeer-review

40 Citations (Scopus)


Attenuation and velocity of 7 MHz longitudinal ultrasound in polycrystalline ceramic La2−xBaxCuO4−δ and La2−xBaxCuO4−δ have been measured in the temperature range from 300 K to 1.5 K. On cooling a pronounced softening of the lattice is observed for 0.09 ≤ × ≤ 0.20 just above the transition temperature Tdl from the tetragonal phase to the orthorhombic phase. A large attenuation peak is observed at Tdl . The further low-temperature transformation from the orthorhombic phase to the tetragonal low-temperature phase is observed, with partial lattice stiffening and a small attenuation peak at Td2, not only in La2−xBaxCuO4−δ but also in La2−xSrxCuO4−δ The mechanism of the unusual TC reduction around x = 0.12 is proposed on the basis of the distortion of CuO2 basal planes from a square to a rhombus below Td2.

Original languageEnglish
Pages (from-to)1289-1290
Number of pages2
JournalPhysica B: Condensed Matter
Publication statusPublished - 1990

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Electrical and Electronic Engineering


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