Determination of the Chemical Composition of Lithium Niobate Powders

Abstract

Existent methods for determining the composition of lithium niobate single crystals are mainly based on their variations due to changes in their electronic structure, which accounts for the fact that most of these methods rely on experimental techniques using light as the probe. Nevertheless, these methods used for single crystals fail in accurately predicting the chemical composition of lithium niobate powders due to strong scattering effects and randomness. In this work, an innovative method for determining the chemical composition of lithium niobate powders, based mainly on the probing of secondary thermodynamic phases by X-ray diffraction analysis and structure refinement, is employed. Its validation is supported by the characterization of several samples synthesized by the standard and inexpensive method of mechanosynthesis. Furthermore, new linear equations are proposed to accurately describe and determine the chemical composition of this type of powdered material. The composition can now be determined by using any of four standard characterization techniques: X-Ray Diffraction (XRD), Raman Spectroscopy (RS), UV-vis Diffuse Reflectance (DR), and Differential Thermal Analysis (DTA). In the case of the existence of a previous equivalent description for single crystals, a brief analysis of the literature is made.

Omni‐functional crystal: Advanced methods to characterize the composition and homogeneity of lithium niobate melts and crystals

“…Oswaldo et al. [ 42 ] have reported the following formulas for determining niobium content in LN powder at ∼876 cm −1 : $$\begin{equation}{\left( {{{\rm{C}}_{{\rm{Nb}}}}} \right)_{\rm{L}}}\left[ {{\rm{mol}}\% } \right] = [256.4103 \times \left( {{\Gamma _{\rm{L}}}/2{{\rm{x}}_{\rm{c}}}} \right) + 43.5385] \pm 0.4,\end{equation}$$ $$\begin{equation}{\left( {{{\rm{C}}_{{\rm{Nb}}}}} \right)_{\rm{G}}}\left[ {{\rm{mol}}\% } \right] = [588.2353 \times \left( {{\Gamma _{\rm{G}}}/2{{\rm{x}}_{\rm{c}}}} \right) + 42.7059] \pm 0.5.\end{equation}$$…”

“…Schlarb et al suggested using only the 876 cm −1 mode. [4,5] Oswaldo et al [42] have reported the following formulas for determining niobium content in LN powder at ∼876 cm −1 :…”

State of the Art in Crystallization of LiNbO3 and Their Applications

“…Therefore, the development of the precise analysis method to detect the chemical composition (Li content) of LiNbO 3 is very important. Table 2 shows available testing methods for determine Li content of LiNbO 3 , for example, X-ray diffraction (XRD), Raman spectroscopy (RS), UV-vis diffuse reflectance (DR), and differential thermal analysis (DTA) [31][32][33][34][35][36]. In Raman spectroscopy, the Li content can be calculated according to the linewidth (Γ) at 876 cm −1 [37][38][39].…”

Recent Progress in Lithium Niobate

“…In paper [4], determination of chemical composition between congruent and stoichiometric LiNbO 3 powders was worked out by four analytical techniques. Sample preparations were done by mechanosynthesis.…”