Search results for "doping"

Europium doped zirconia luminescence

2010

Abstract The luminescence properties and crystalline structure of ZrO2:Eu nanocrystals doped with different concentrations of Eu were studied. Luminescence from the Eu2+ state was not observed even if the electrons and holes were created up to ∼1019 cm−3; thus it was suggested the Eu3+ was not an efficient trap for electrons possibly due to Eu3+ negative charge relative to the crystalline lattice. The mutual interaction between Eu3+ ions was not strong up to 5 at.% concentration. The stabilization of ZrO2 tetragonal as well as cubic structure by Eu3+ is possible.

Short-range order around Er3+ in silica waveguides containing aluminium, titanium and hafnium

2006

Er3+-doped silica waveguides, co-doped with aluminium, titanium, and hafnium oxides, were prepared using the sol-gel method and dip-coating processing. Here, we present a characterisation of the local environment around Er3+ ions, as determined from the Er L3-edge extended X-ray absorption fine structure (EXAFS) measurements performed at ESRF (France). The first coordination shell is composed of 5-6 oxygen atoms at distances ~2.32-2.35 A , slightly varying as a function of the modifier oxide. Er3+ nearest neighbors distance does not show a significant compositional dependence. On the contrary, outer shells analysis shows significant differences: Al2O3 doping (less than 2% mol) induces an or…

Effects of electrolyte doping on electrodeposited nanostructured manganese oxide and chromium oxide

2020

Abstract Electrolyte additions are used to control the functionality of a nanostructured oxide. Dopant ions affect the size and shape of deposit crystallites and modify the host structure. Such ions can be incorporated into the deposit or form a separate oxide phase. The manganese dioxide family of polymorphs with ion-molecular sieve properties represents the additional possibilities of “template” effects of dopant ions on the phase composition, heterovalent substitution in the cationic sublattice, changes in morphology and alteration of nanocrystallite size during electrocrystallisation. The effects of electrolyte doping in electrodeposited, non-stoichiometric manganese dioxide (NH4+, Li+ …

Electrochemical Synthesis of Hybrid Layered Thermoelectric Materials Based on PEDOT/SnS Doped with Ag

2021

Mesoporous SiC with Potential Catalytic Application by Electrochemical Dissolution of Polycrystalline 3C-SiC

2018

Electrochemical dissolution of highly doped (ρ ∼ 1 mΩ·cm, n-type) polycrystalline 3C-SiC in HF/H2O and HF/H2O/ethanol solutions allowed production of porous silicon carbide (por-SiC) and soluble carbon fluorooxide nanoparticles as a byproduct. The por-SiC is a crystalline material with large pore volume, surface area close to 100 m2 g–1, and open mesoporous structure. The surface of por-SiC is covered with a thin carbon-enriched layer, bearing carboxylic acid groups. Depending on the SiC resistivity, etchant composition, and current density, three different types of por-SiC morphology, namely, a macroporous tubular, mesoporous hierarchical, and mesoporous filamentary were revealed. A qualit…

Temperature Sensitivity of Multicrystalline Silicon Solar Cells

2019

This paper presents an experimental investigation of the temperature coefficients of multicrystalline silicon solar cells. The aim was to determine if some cell parameters can affect positively the temperature sensitivity without detrimental impact on the efficiency. Commercial solar cells with different bulk resistivities, compensation levels, and cell architectures have been studied. We report that the base net doping, the location of the solar cell along the brick and the cell architecture have significant impacts on the temperature coefficients. Moreover, we show how the change in recombination mechanisms along the ingot height affects the temperature coefficients. The compensation leve…

The search for defects in undoped SrAl2O4 material

2019

This research project was supported financially by ERDF Project No: Nr.1.1.1.1/16/A/182 .

Photoconductivity and photovoltaic effect in indium selenide

1983

Transport and phototransport properties of crystalline indium monoselenide (InSe) doped with a variety of elements are reported. Measured mobilities, lifetimes, and effective diffusion lengths of photoexcited carriers are used to interpret electrical and photovoltaic properties of several different structures. These include p‐n junctions, bismuth/p‐type InSe, platinum/n‐type InSe, and indium tin oxyde (ITO)/p‐type InSe. External solar efficiencies of the best devices are between 5% and 6%. The influence on the efficiency of the various parameters is evaluated, and ways of improvement are discussed.

Quenching and blue shift of UV emission intensity of hydrothermally grown ZnO:Mn nanorods

2015

Abstract ZnO:Mn alloyed nanorods (Mn nominal concentration – 3–5 wt%) were synthesized by using hydrothermal process at an optimized growth temperature of 200 °C and a growth time of 3 h. The XRD, SEM and Raman, FTIR investigations reveal that ZnO:Mn (Mn – 3–5 wt%) retained hexagonal wurtzite crystal structure with nanorod morphology. The HRTEM and SAED analysis confirm the single crystalline nature of hydrothermally grown ZnO and ZnO:Mn (5 wt%) nanorods. The ZnO:Mn nanorods (Mn – 0–5 wt%) displayed optical band gap in the range 3.23–3.28 eV. The blue shift of UV emission peak (PL) from 393 (ZnO) to 386 nm and quenching of photoluminescence emission in ZnO:Mn is due to the Mn incorporation …

Luminescence of Ce‐doped borate‐oxyfluoride glass ceramics

2007

In the present work we studied the possibility to obtain oxyfluoride glass ceramics based on a lithium and potassium borate glasses with addition of fluorides. Lithium-borate glasses without lanthanum fluoride are transparent up to 275 nm. In samples with LaF3 doped with Ce-activator, an additional absorption at about 300 nm and intense photoluminescence could be observed. Ce-doped potassium-borate glass with addition of fluorides LaF3, LiF and GdF3 was milky and not transparent, an intense photoluminescence has been observed, X-ray diffraction measurements showed a presence of well-pronounced crystalline phases of LiF as well as of GdBO3. (© 2007 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim)