Lithium Niobate Single Crystals and Powders Reviewed—Part I

Abstract

A review of lithium niobate single crystals and polycrystals in the form of powders has been prepared. Both the classical and recent literature on this topic are revisited. It is composed of two parts with sections. The current part discusses the earliest developments in this field. It treats in detail the basic concepts, the crystal structure, some of the established indirect methods to determine the chemical composition, and the main mechanisms that lead to the manifestation of ferroelectricity. Emphasis has been put on the powdered version of this material: methods of synthesis, the accurate determination of its chemical composition, and its role in new and potential applications are discussed. Historical remarks can be found scattered throughout this contribution. Particularly, an old conception of the crystal structure thought as a derivative structure from one of higher symmetry by generalized distortion is here revived.

State of the Art in Crystallization of LiNbO3 and Their Applications

“…In stoichiometric LiNbO 3 , along c row direction, the O octahedral interstitials are filled by Li ions (one-third), Nb ions (one-third), and empty (one-third), forming -Li-Nb--Li-Nb-sequence [18][19][20]. Much experimental and simulation effort have been made in the past in order to understand the defect structure in LN crystal [8]. Several defect models have been constructed-i. )…”

“…The Li vacancy model is mostly accepted nowadays thanks to a great number of investigations, some of them very important and performed in the 1990s. This is given in detail in [8]. Since these defects are charged, further defects with counter charges are required in order to guarantee overall charge neutrality [23].…”

“…When use above reported characterizations, the applicability and calibration method need to be concerned. Some indirect optical and nonoptical methods for the determination of the chemical composition of LN single crystals can be referred to [8].…”

“…LiNbO 3 crystallized as R3c space group below Curie temperature shows spontaneous polarization that leads to its ferroelectric and piezoelectric properties [4,5]. Physical and chemical characteristics of LiNbO 3 are mainly determined by Li/Nb ratio, impurity cations, vacancies in a cation sublattice [6][7][8]. Different sizes of LiNbO 3 ranging from nanoscale and microscale to bulk size have been synthesized by solid state method, hydrothermal/solvothermal method, Czochralski (Cz) growth method, etc.…”

New Trends in Lithium Niobate: From Bulk to Nanocrystals

“…A general review on lithium niobate (LiNbO 3 , LN) single crystals, as well as powders, which have been given a new emphasis, is presented in two parts by Sánchez-Dena et al [1,2]. They discuss the crystal structure, the methods for the determination of chemical composition, the defect structures induced by the incorporation of hydroxyl ions, and the so-called optical damage resistant ions (e.g., Mg 2+ ), also discussing the origins of ferroelectricity, together with its possible association with ferromagnetism in LiNbO 3 doped with paramagnetic 3d cations.…”