First study on lattice potential energy determination from ultrasonic mean sound velocity for polycrystalline Ca1+xCu3-xTi4O12 perovskites and mono-crystalline counterparts

For the first time the lattice energies (ULP) for multi-crystalline specimens of perovskite system, Ca1+xCu3−xTi4O12 with x = 0.0−1.0, have been calculated using mean sound velocity data by employing Kudriavtsav’s approach. The observed decrease in ULP as a function of Ca2+− substitution has been described considering the structural and microstructural parameters. Using four different estimation models lattice energy (ULS) values for mono–crystalline counterparts have been calculated. The difference between ULP and ULS (ULS >ULP) has been discussed based on grain boundary and grain contribution and the existence of voids and micro-cracks in multi-crystalline ceramics. A straightforward method proposed to determine ULS for multi-cationic oxide systems founded on the oxide additivity rule was adequate.