Engineering of LiTaO 3 Nanoparticles by Flame Spray Pyrolysis: Understanding In Situ Li-Incorporation into the Ta 2 O 5 Lattice.

Lithium tantalate (LiTaO 3 ) 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 3 nanoparticles using a scalable Flame Spray Pyrolysis (FSP) technology, that allows the formation of LiTaO 3 nanomaterials in a single step. Raman, XRD and TEM studies allow for comprehension of the formation mechanism of the LiTaO 3 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 Ta 2 O 5 nanophase. In this way, via control of the HTPRT in the FSP process, we synthesized a series of nanostructured LiTaO 3 particles of varying phase composition from {amorphous Li/Ta 2 O 5 /LiTaO 3 } to {pure LiTaO 3 , 15-25 nm}. Finally, the photophysical activity of the FSP-made LiTaO 3 was validated for photocatalytic H 2 production from H 2 O. These data are discussed in conjunction with the role of the phase composition of the LiTaO 3 nanoparticles. More generally, the present work allows a better understanding of the mechanism of ABO 3 perovskite formation that requires the incorporation of two cations, A and B, into the nanolattice.