Engineering of LiTaO Nanoparticles by Flame Spray Pyrolysis: Understanding Li-Incorporation into the TaO Lattice.

Lithium tantalate (LiTaO) perovskite finds wide use in pyroelectric detectors, optical waveguides and piezoelectric transducers, stemming from its good mechanical and chemical stability and optical transparency. Herein, we present a method for synthesis of LiTaO nanoparticles using a scalable Flame Spray Pyrolysis (FSP) technology, that allows the formation of LiTaO nanomaterials in a single step. Raman, XRD and TEM studies allow for comprehension of the formation mechanism of the LiTaO nanophases, with particular emphasis on the penetration of Li atoms into the Ta-oxide lattice. We show that, control of the High-Temperature Particle Residence Time (HTPRT) in the FSP flame, is the key-parameter that allows successful penetration of the -otherwise amorphous- Li phase into the TaO nanophase. In this way, via control of the HTPRT in the FSP process, we synthesized a series of nanostructured LiTaO particles of varying phase composition from {amorphous Li/TaO/LiTaO} to {pure LiTaO, 15-25 nm}. Finally, the photophysical activity of the FSP-made LiTaO was validated for photocatalytic H production from HO. These data are discussed in conjunction with the role of the phase composition of the LiTaO nanoparticles. More generally, the present work allows a better understanding of the mechanism of ABO perovskite formation that requires the incorporation of two cations, A and B, into the nanolattice.