Elastic properties of double layered manganite La1.2Sr1.8-xCaxMn2O7 (x = 0.0-0.4)

Polycrystalline bulk samples of double layered manganite system La1.2Sr1.8-xCaxMn2O7 (x = 0.0-0.4) have been synthesized by the sol-gel method. Based on powder X-ray diffraction, it has been found that their lattice parameters decrease with increasing Ca content. The elastic behaviour of the system has been investigated at ~300 K employing ultrasonic pulse transmission technique at 1 MHz. The values of elastic moduli and acoustic Debye temperatures have been computed from the longitudinal and shear wave velocities. The measured values of elastic moduli have been corrected to zero porosity using various correction methods. The variation of elastic moduli with Ca content is interpreted in terms of the strength of interatomic bonding.