Potassium Lithium Niobate Single Crystals Research Articles

Ternary system Li 2O–K 2O–Nb 2O 5: Re-examination of the 30 mol% K 2O isopleth and growth of fully stoichiometric potassium lithium niobate single crystals by the micro-pulling down technique

Potassium lithium niobate (KLN) single crystals have attractive properties for non-linear optical applications based on frequency conversion of laser diodes in the blue range. Especially, fully stoichiometric K 3Li 2Nb 5O 15 crystals would be capable of doubling a laser light in the near UV range. Using powder X-ray diffraction and DSC experiments, we have re-investigated the 30 mol% K 2O isopleth of the ternary system Li 2O–K 2O–Nb 2O 5 in order to explore the possibility of a limited existence field for this phase. From our results, it was shown that the stoichiometric KLN phase exists between 970 and 1040 °C, temperature at which it undergoes a non-congruent melting. From this conclusion, compositionally homogeneous a-axis oriented single crystals fibers of stoichiometric K 3Li 2Nb 5O 15 were successfully grown by the micro-pulling down technique with pulling rates in the range 0.3–0.7 mm min −1. The crystal length was between 10 and 120 mm for an apparent diameter near 500 μm. The fibers, characterized by optical microscopy, X-ray diffraction and Raman spectroscopy, appeared free of macro-defects and of good quality and their stoichiometric composition was also confirmed.

Acoustic Anomalies of Potassium Lithium Niobate Single Crystals near the Ferroelectric Phase Transition Temperature

Acoustic Anomalies of Potassium Lithium Niobate Single Crystals near the Ferroelectric Phase Transition Temperature

The influence of composition on optical properties of ferroelectric potassium lithium niobate single crystals

Homogeneous crack-free Potassium Lithium Niobate (KLN) single crystals with different Li content were grown up by the TSSG technique. Lattice vibration spectra of these samples were investigated using Raman spectroscopy. The results showed that characteristic Raman spectra of the [NbO6]7− octahedral ions were strikingly influenced by the Li ions. Thus, the symmetric bend vibration mode ν5 of the KLN sample with higher Li content was split into three Raman peaks, while the sample with lower Li content displayed a single peak, supporting that the bend vibration modes of the [NbO6]7− octahedrons were obviously perturbed by Li ions occupying C-sites. Enhanced Raman peak intensities of the KLN sample post-annealed at 900°C for 24h evidenced that content of defects in KLN crystal might be reduced. The transmittance spectra showed that the crystal with higher Li content had better transmittance intensity.

Infrared OH? Absorption Bands in Potassium Lithium Niobate Single Crystals

The existence of protons (H + ) was characterized by infrared absorption spectroscopy in potassium lithium niobate single crystals with a lower than 1.5 Li content. The as-grown crystals showed a broad OH stretching vibration near 3500 cm -1 and contained about 5.5 × 10 18 cm -3 protons. Especially, the concentration of the protons increased about one order of the magnitude after heat treatment in a humid atmosphere. From the measurements of the polarization dependence of the OH - absorption bands in this crystal, we can expect that the OH - ions vibrate along the c-axis and O-O edges of an oxygen octahedron. It shows a different aspect in comparison with LiNbO 3 single crystals due to the different structure and the cation environment.

Preparation and characterization of pure and Ce4+-doped potassium lithium niobate single crystals

Preparation and characterization of pure and Ce4+-doped potassium lithium niobate single crystals

Growth and Properties of Tetragonal Tungsten Bronze Type Potassium Lithium Niobate Single Crystals

AbstractTetragonal tungsten bronze type potassium lithium niobate single crystals with the Nb/Li ratio larger than 3 are grown by the flux pulling method in our laboratory, and it dose not crack when cooling through the paraelectric/ferroelectric phase transition. Crystal growth is studied in two orientations with growth along [100] and [001], and the latter's quality is superior to that of the former. The lattice constants are a = 1.2575 nm and c = 0.3997 nm at 298 K. A Curie temperature is about 480 ± 3°C.