Top-Seeded Solution Crystal Growth and Functional Properties of Polar LiFeP₂O₇

Abstract

Large single crystals of LiFeP₂O₇, a multifunctional polar material, were successfully grown by using a top-seeded solution growth (tssg) technique. The morphologies of the single crystals with different rotation speeds are described. Functional properties such as second-harmonic generation (SHG), piezoelectricity, pyroelectricity, and ferroelectricity were measured. LiFeP₂O₇ is SHG active, with an SHG efficiency of approximately 200 × α-SiO₂ using 1064 nm radiation. The material is piezoelectric, with a <i>d</i>₂₂ value of 1.2 pC/N, and pyroelectric, with pyroelectric coefficients of 9.25 μC/m²K (1 kHz) and 10.6 μC/m²K (50 Hz) at 60 °C. Although polar, LiFeP₂O₇ is not ferroelectric; that is, the polarization is not “switchable”. Optical spectra indicate that the absorption edge is approximately 480 nm, with transmission up to 4.3 μm