Search results for "Tantalate"

Non-Linearity Extremum in Niobium Doped Potassium Tantalate

1997

We report non-linear dielectric measurements in the KTaO 3 :Nb system (x Nb ≤ 0.05). The non-linear susceptibility diverges at low temperatures and reaches maximum values in the intermediate range (0.0075 ≤ x Nb ≤ 0.02). To account for this extremum non linearity, we propose a model of temperature dependent clusters which fits with a number of experimental reports. We also suggest that this model may be applied to the related compounds SrTiO 3 :Ca and KTaO 3 :Na.

All-Optical frequency Shifter in a Periodically Poled Lithium Tantalate Waveguide

2011

A frequency shifting device is fabricated and tested in a congruent Lithium Tantalate waveguide. Periodic poling for quasi-phase-matching and channels for operation in the near-infrared C-band were obtained, demonstrating a two-stage parametric conversion.

Frequency and temperature dependence of the electrical conductivity of KTaO3; Li and PbTiO3; La, Cu: Indication of a low temperature polaron mechanism

2008

Abstract Recently, the concept of polarons has again been at the focus of solid-state research, as it can constitute the basis for understanding the high-temperature superconductivity or the colossal magnetoresistance of materials. More than a decade ago there were some indications that polarons play an important role in explaining low temperature maxima in imaginary part of the dielectric constant e ″ ( T ) in ABO3 perovskites. In the present work we report the ac electrical conductivities of KTaO3; Li and PbTiO3; La, Cu and their frequency and temperature dependence. The real part of the complex ac conductivity was found to follow the universal dielectric response σ ′ ∝ ν s . A detailed t…

High resolution x-ray investigation of periodically poled lithium tantalate crystals with short periodicity

2009

Domain engineering technology in lithium tantalate is a well studied approach for nonlinear optical applications. However, for several cases of interest, the realization of short period structures (< 2 ��m) is required, which make their characterization difficult with standard techniques. In this work, we show that high resolution x-ray diffraction is a convenient approach for the characterization of such structures, allowing us to obtain in a nondestructive fashion information such as the average domain period, the domain wall inclination, and the overall structure quality.

Characterization of PP-cLT Waveguides for phase conjugation in the C + L band of Optical Communications

2010

Study of the defects in La3Ta0.5Ga5.5O14 single crystals

2016

Abstract Defects that are formed during crystal growth pose a serious obstacle for potential application of La 3 Ga 5.5 Ta 0.5 O 14 (LGT) as a laser or piezoelectric crystal. We have performed the study of the defects origin in LGT crystals grown in different atmospheres using optical, EPR and time-resolved luminescence characterization methods. The absorption bands detected in the transparency region at 290, 360 and 490 nm ( T =300 K) demonstrate different dependence on crystal annealing in vacuum and air. EPR analysis demonstrated that the defects responsible for these bands are non-paramagnetic. X-ray irradiation results in hole trapping by oxygen ions thus forming O − centers perturbed …

Nonlinear Disorder Mapping via Wave Mixing in poled Lithium Tantalate

2010

We introduce and test a simple approach for the characterization of domain distribution in bulk quadratic ferroelectric crystals, specifically periodically poled Lithium Tantalate with random mark-to space ratio.

Nonlinear Disorder Mapping via Three Wave Mixing in Poled Lithium Tantalate

2010

We introduce and test a simple approach for the characterization of domain distribution in bulk quadratic ferroelectric crystals, such as periodically poled Lithium Tantalate with random mark-to space ratio.

Facile hydrothermal synthesis of crystalline Ta2O5 nanorods, MTaO3 (M = H, Na, K, Rb) nanoparticles, and their photocatalytic behaviour

2014

Alkali metal tantalates are of interest for applications in photocatalysis as well as in high temperature resistance or capacitor dielectric materials. We have synthesized nanosized Ta2O5 rods and MTaO3 cubes (M = Na, K, Rb) hydrothermally and demonstrate the pH dependence of the synthesis of tantalum oxide and tantalate nanoparticles. The morphologies of the nanoparticles range from particle agglomerates in acidic reaction media over rods at neutral pH to tantalate cubes in basic reaction media. Whereas there is no apparent influence of the base cation on the particle morphology, there is a pronounced effect on the particle composition. At high base concentrations cubic tantalate particles…

Volume integrated phase modulator based on funnel waveguides for reconfigurable miniaturized optical circuits.

2015

We demonstrate the integration of a miniaturized 30(x) μm × 30(y) μm × 2.7(z) mm electro-optic phase modulator operating in the near-IR (λ = 980 nm) based on the electro-activation of a funnel waveguide inside a paraelectric sample of photorefractive potassium lithium tantalate niobate. The modulator forms a basic tassel in the realization of miniaturized reconfigurable optical circuits embedded in a single solid-state three-dimensional chip.