Growth of crack free Nd2Ti2O7 thin films using La0.7Sr0.3MnO3±δ as a template layer for high temperature pyroelectric applications

Neodymium titanate (Nd2Ti2O7) is a ferroelectric as well as a pyroelectric material with a transition temperature of 1480 °C. Hence, Nd2Ti2O7 offers potential to be utilized as high temperature pyroelectric sensor in both bulk and thin film form. In this work, bulk Nd2Ti2O7 powders were synthesized using solid state reaction method, which were later pressed into the pellets. Later, thin films of Nd2Ti2O7 were deposited on commercially available platinized(111) silicon and Si(100) substrates via pulsed laser deposition technique. The huge c/a ratio (∼1.695) and the thermal expansion mismatch with most of the commonly used substrates like silicon and platinized silicon, results into crack formation in Nd2Ti2O7 thin films. Crack formation on Nd2Ti2O7 thin film, which deteriorates pyroelectric property of Nd2Ti2O7 film, was suppressed by the introduction of La0.7Sr0.3MnO3±δ buffer layer between the film and substrate. The calculated value of thermal expansion coefficient of Nd2Ti2O7 is 2.86 × 10−5 °C−1. Moreover, thermally generated strain between Nd2Ti2O7 film and platinum substrate was found to be around 2%. The piezoresponse force microscopy experiment confirms the existence of ferroelectric domains in the film. Pyroelectric coefficient (p) calculated from the pyrocurrent studies was estimated around 3.52 and 13.6 μC/m2K in the bulk and thin film, respectively.