Vaaisible upconversion emission of Er3+-doped and Er3+/Yb3+-codoped LiInO2

Lithium-indium oxide is a high-density (5.9 g center dot cm(-3)), wide band-gap semiconductor with promising applications for scintillating detection of solar neutrinos as well as for efficient phosphorescence when doped with Er3+ or Sm3+ ions. In this report, we demonstrate visible upconversion emission of Er3+-doped LiInO2 synthesized by a simple solid-state chemistry procedure and discuss mechanisms responsible for pumping the Er3+ ions to upper levels. Intense upconversion emission is observed in the green and red spectral regions under near-infrared excitation, and it is greatly enhanced by co-doping with Yb3+ ions. We also examined the upconversion intensity change as a function of temperature, and, consequently, possible applications of this material as a low-temperature sensor

Photoluminescence of Eu- and Sm-doped LiInO2 phosphor powders

Lithium-indium oxide doped with Eu3+ or Sm3+ is prepared by a solid-state chemistry method and its properties are analyzed with respect to its possible application as a phosphor material. X-ray diffraction confirmed that the present synthesis yields a product in tetragonal structural form (space group I4(1)/amd) with no impurity phases. The optical band gaps of 3.4 eV for the Eu3+ sample and 3.5 eV for Sm3+ are found. Photoluminescence emission measurements showed that rare-earth ions substitute In in sites of D-2d symmetry with single-exponential emission decays of 1.5 ms for the Eu3+-doped sample and 2.3 ms for the Sm3+ case

Low temperature photoluminescence emission of Zn2SiO4:Eu3+ phosphor powder

Phosphor materials are of special interest due to their important applications ranging from solid state lightning and displays to biomedicine. Understanding the spectroscopic properties of these materials is important for optimizing their emission for technological applications. Zinc silicate (Zn2SiO4) has been identified as a very suitable host matrix for many rare-earth and transition metal dopant ions with excellent luminescent properties in the blue, green and red spectral zones. Here, we present high resolution measurements of low-temperature photoluminescence of trivalent europium doped zinc silicate particles prepared by combination of so-gel and combustion synthesis route. We observed and analyzed 5D(0) - GT F-7(J) spin forbidden f-f electronic transitions at low temperatures, as well as emission kinetics from D-5(0) level and lifetime-temperature dependence

Low temperature photoluminescence emission of Zn2SiO4:Eu3+ phosphor powder

Phosphor materials are of special interest due to their important applications ranging from solid state lightning and displays to biomedicine. Understanding the spectroscopic properties of these materials is important for optimizing their emission for technological applications. Zinc silicate (Zn2SiO4) has been identified as a very suitable host matrix for many rare-earth and transition metal dopant ions with excellent luminescent properties in the blue, green and red spectral zones. Here, we present high resolution measurements of low-temperature photoluminescence of trivalent europium doped zinc silicate particles prepared by combination of so-gel and combustion synthesis route. We observed and analyzed 5D(0) - GT F-7(J) spin forbidden f-f electronic transitions at low temperatures, as well as emission kinetics from D-5(0) level and lifetime-temperature dependence

Experimental evidence of second harmonic photoacoustic signal generation in metals

The capability of photoacoustic (PA) spectroscopy for the detection of the second harmonic thermal waves on metal surfaces is investigated. Expressions for the first and second harmonic amplitude and phase PA spectra are derived from the one-dimensional nonlinear heat conduction equation using stepwise successive approximation method. First and second harmonic amplitude and phase PA spectra of nickel sample are measured in a heat reflection PA configuration. PA amplitude intensity dependence on excitation intensity exhibit characteristic behavior, it has linear dependence in the case of first harmonic and square dependence in the case of second. Experimental data were in excellent agreement with theoretical calculations. Modulation frequency dependence of amplitude and phase provided sufficient data for the thermal properties evaluation from PA measurements

Eu3+ doped YNbO4 phosphor properties for fluorescence thermometry

We prepared an efficient YNbO4:Eu3+ phosphor using a simple solid-state reaction method and examined its photoluminescent properties in order to investigate the possibility for its usage in phosphor thermometry. Photoluminescence measurements were performed in the temperature range 303-803 K, and the fluorescence intensity ratio (FIR) of the paired emissions lines of Eu3+ (D-5(1) - GT F-7(1) and D-5(0) - GT F-7(1) transitions) was studied as a function of temperature. The sample crystalline structure is confirmed by XRD measurements. The material is proved to have a good potential for the development of thermographic phosphors. It exhibits maximum temperature sensitivity of approximately 3.5 x 10(-3) K-1 in the temperature region around 700 K. (C) 2013 Elsevier Ltd. All rights reserved.8th International Conference on Luminescence Detectors and Transformers of Ionizing Radiation (LUMDETR), Sep 10-14, 2012, Martin Luther Univ Halle Wittenberg, Halle, German

Influence of copper on hardness of amorphous As-Se-I thin films

The paper reports on hardness of thin amorphous films of the Cux(As38.5Se54I7.5)(100-x) type for x=10, 15, 20 and 25 at-% evaluated by microindentation measurements and instrumented nanoindentation testing. Values of determined microhardness are in the interval of 748-1137 MPa, while nanohardness are in the interval of 930-1591 MPa and can be regarded as moderate in the category of chalcogenide glasses. Isotropic mechanical properties on thin films surface are determined. Influence of copper on mechanical properties of As-Se-I films is discussed in terms of possible structural units in glass matrix

Temperature quenching of luminescence emission in Eu3+- and Sm3+-doped YNbO4 powders

We prepared Eu3+- and Sm3+-doped YNbO4 phosphor powders using a simple solid-state reaction method and examined their photoluminescence properties in order to investigate the possibility for their usage in phosphor thermometry. Photoluminescence measurements were performed in the temperature range 303-773 K, and the fluorescence intensity ratio of the paired emissions lines was studied as a function of temperature. The results have shown that YNbO4:Eu3+ possesses the absolute sensitivity of approximately 3 Chi 10(-3) K-1 at about 700 K, while relative sensitivity changes within the range of 0.5-2.7% K-1. YNbO4:Sm3+ has the maximum sensitivity of around 7 Chi 10(-4) K-1 at about 700 K with the relative sensitivity of 0.43% K-1 around 500 K. Calculated temperature sensitivities of samples show that these materials have a good potential for the development of therrnographic phosphors. Experimental lifetime measurements recorded at 303-773 K were fitted using a temperature dependent charge transfer model, TDCT. This model yields good agreement between experimental and fitted lifetime data. The sample crystalline structure is confirmed by XRD measurements. (C) 2014 Elsevier B.V. All rights reserved

Niobium and zinc doped titanium-tin-oxide solid-solution ceramics: Synthesis, structure and electrical characterization

This paper describes the processing, microstructure, optical and electrical properties of the nanocrystalline (NC) niobium and zinc doped titanium-tin-oxide (TTO:NZ) based ceramics. Variety of techniques was employed (X-ray diffraction, scanning electron microscopy, energy dispersive, Raman and impedance spectroscopy) in the characterization of the obtained TTO:NZ, which confirmed the formation of NC solid-solution matrix with Ti0.8Sn0.2O2 composition. A specific highly dense (approximately 97% of the theoretical density was reached) varistor like microstructure (matrix metal-oxide grains surrounded by the grain-boundary regions) and accordingly resembling electrical properties (breakdown electric field of approximately 130 V/mm and nonlinearity coefficient of α ≈ 6.5) were achieved through double cation doping and elected condition of the mechanochemical solid-state synthesis. Impedance response analysis of TTO:NZ ceramics by means of an equivalent electrical circuit based on the brick-layer model for polycrystalline materials revealed the presence of two temperature dependent electrical relaxation phenomena of the non-Debye type as well as the negative temperature coefficient of resistance behavior