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.

https://www.mdpi.com/2073-4352/10/11/990/pdf

Lithium Niobate Single Crystals and Powders Reviewed—Part I

Growth and properties of Ru-doped lithium niobate crystal

Lithium niobate (LiNbO3 or LN) and lithium tantalate (LiTaO3 or LT) crystals, which have been widely applied in many fields such as electro-optics, birefringence, nonlinear optics, photorefraction, piezoelectricity and other areas, are reviewed. The studies of the properties and growth techniques are reviewed to give a brief idea of the growth of LN and LT crystals with high quality. The anti-site defects of these crystal materials have been accepted as one of the key factors constraining the improvement of their properties. This review shows the simulated calculation and structure of anti-site defects in LN/LT crystals and their effect on the physical properties and summarizes the recent progress in theoretical and technical processes, including the improved applications. We reviewed two main methods for the elimination of anti-site defects: doping of metal ions and growth of stoichiometric crystals. Finally, the prospects for future studies are outlined.

Formation mechanism and elimination methods for anti-site defects in LiNbO3/LiTaO3 crystals

Site symmetries of Cu2+ ions in LiNbO3 crystals

http://www.skaczmarek.zut.edu.pl/150-Growth-BW-2000.pdf

Growth and characterization of lithium tantalate single crystals doped with Ho, Tm, Nd, Yb, Pr and doped by diffusion with Cr and Cu

Single crystals of lithium niobate doped with 0.03 and 0.1 at.% of Cu or Fe ions were grown by the Czochralski technique. Optical absorption spectra in visible and infrared regions before and after • irradiation with doses up to 10 5 Gy were measured and positions of both dopants in LiNbO 3 lattice were analyzed according to changes in optical absorption in the range of OH group absorption. Some properties of crystals doped with Cu during the growth processes were compared to those for specimens doped by thermodiffusion. It was observed that doping with Cu results in an increase of crystal resistance to radiation.

http://www.skaczmarek.ps.pl/130-Growth-CRT-99.pdf

Growth and Characterization of LiNbO3 Single Crystals Doped with Cu and Fe Ions

Absorption and additional absorption of LiNbO 3 crystals doped with Cr 3+ during growth or by diffusion process were investigated before and after γ-irradiation with a dose of 10 5 Gy and also before and after proton irradiation with a fluency of 10 14 cm -2 . It was found that chromium ions may be mtroduced into LiNbO 3 crystals also as Cr 2+ . ESR measurements of Cr:LiNbO 3 crystals irradiated by γ-rays and electrons were performed. Paramagnetic peak after γ and electron irradiation was observed, which vanishes after annealing at 400°C for 3h both in optical and ESR spectra. Mn 2+ lines were also observed, which diminish after electron irradiation only.

M. Swirkowicz

Papers

Growth and Characterization of LiNbO3 Single Crystals Doped with Cu and Fe Ions

Radiation defects in LiNbO3 single crystals doped with Cr3+ ions