Manganese Doped Zinc Silicate Research Articles

A novel approach to the preparation of manganese - doped zinc silicate luminescent material according to the precipitation method

The purpose of this work is to study the effect of some precipitation conditions on the luminescent properties of manganese-doped zinc silicate when synthesized in a new approach - impregnated precipitation method. The samples are characterized by thermal analysis, infrared IR, luminescent spectrum (PL), X-ray diffraction spectrum and scanning electron microscope (SEM). The results showed that manganese - doped zinc silicate luminescent material prepared by the impregnated precipitation method has higher luminescence than the traditional co-precipitation method. Samples with the highest luminescent properties were synthesized under the following conditions: concentration of Zn (CH3COO)2 is 1M, the precipitate aging time of 20 minutes, the washed filtered precipitate, impregnated with Mn2+ with a content of 1.5 % mol compared to the total metal, dried at 80 °C and then heat at 900 0C for 45 minutes. The obtained product is single-phase zinc silicate with composition of Zn1,97Mn0,03SiO4, rhombic structure with most particles varying in size of 0.3 - 0.5 µm, emitting green light with λmax = 525 nm when excited by UV rays with wavelength of 254 nm. Forming a single-phase Zn2SiO4 crystal at 900 0C for 45 minutes allowed to reduce the energy required for the sintering process compared with the solid - phase reaction method.

Elaboration and characterization of glass–ceramic enriched by heavily manganese doped zinc silicate nanoparticles for optoelectronic applications

Nanocrystallines Mn2+-doped zinc silicate (β-Zn2SiO4:Mn) embedded in SiO2 host matrix were synthesized in two steps. In the first one a sol–gel process was used for the elaboration of silica aerogel monolith enriched by ZnO:Mn nanoparticles using supercritical conditions of ethanol. In the second step a simple solid-phase reaction under natural atmosphere at 1500 °C was investigated. The structure and texture of the obtained nanocomposites were studied by X-ray diffraction and transmission electron microscopy respectively. The optical results indicate that the obtained nanocomposites have excellent luminescence properties in the visible range. In addition, the PL spectrum for the β-Zn2SiO4:Mn/SiO2 nanocomposite reveals a band centered at about 584 nm attributed to the 4T1–6A1 transitions of Mn2+ ions. The intensive yellow luminescence presents a red shift and the lifetime is relatively weak compared to the known luminescence properties of this material. The obtained results are attributed to the protocol used and the excess of Mn2+ ions. The linear diminishing behaviours of the PL integrate intensity with the operating temperature, and the variation of the time decay with the Mn2+ contents; make it possible to anticipate the utilization of this material in luminescence thermometry.

Precursors effect: Photo conversion from UV to green/yellow in willemite nano phosphors

Manganese doped zinc silicate (Zn1.89SiO4:Mn0.11) green and yellow nanophosphors were prepared by solution combustion method using fumed silica and tetraethyl ortho silicate (TEOS) as sources of silica. The phosphors are calcined at 950 °C for 3 h. The formation of α and β- Zn2SiO4:Mn2+phases of the samples were confirmed by powder XRD measurements. The morphology and composition of the samples are investigated by SEM, TEM, FTIR and EDAX. FTIR shows that the main absorption bands located in the frequency region between 400 and 1200 cm−1. The effects of different sources of silica on the photoluminescence (PL) properties of Zn2SiO4:Mn2+ were studied. Among the silica sources, TEOS gave green and yellow emission at 527 and 581 nm, on excitation at 262 and 292 nm respectively. Fumed silica source gave only green emission at 527 nm on excitation at 262 nm. The emissions are originated from the 4T1 to 6A1 transitions of Mn2+ ions. Luminescence decay curve measurement show double exponential decay behavior and fast decay time has been observed.

Barium and manganese-doped zinc silicate rods prepared by mesoporous template route and their luminescence property

Barium and manganese-doped zinc silicates was prepared under hydrothermal treatment by mesoporous template route employing mesoporous silica as an active template. The sample displays a rod-like morphology with a mean diameter of ∼40 nm and a mean length of ∼450 nm, which inherits the characteristics of mesoporous silica. The individual rods show single crystalline and assemble into bundle-like hierarchical structure along the channels of the mesoporous silica. When barium ions together with manganese ions are co-doped in zinc silicate, the green emission corresponding to manganese ions display a significant enhancement, especially for the sample with the barium doping concentration of 0.08, which indicates that an energy transfer from barium to manganese ions takes place. With further increasing barium concentration from 0.08 to 0.10, the recombination between the defects related to barium and the excitation states of the manganese dominates accompanying non-radiative transitions which can reduce the emission efficiency.

Photo conversion from UV to green in Mn doped zinc silicate nanophosphors

Green light emitting Manganese doped Zinc Silicate phosphor particles Zn2-xMnxSiO4(0.05≤x≤0.11) were synthesized by solution combustion method at 500°C followed by sintering at a moderate temperature of 950°C for 3 hours duration. The XRD confirm that Zn2-xMnxSiO4 has a rhombohedral space group R3H and the particles are having size 70 to 80 nm. The SEM morphology shows small and circular shaped grains which are agglomerated .Energy dispersive spectroscopy analysis confirms the XRD results by showing the formation of Zn2SiO4: Mn crystals. Green photoluminescence, whose peak is located at 528 nm, was observed from the solution combustion synthesized phosphor particles under UV excitation (255 nm). This is because of the electronic transition of Mn2+ from upper 4T1 to 6A1 ground state. The level of Manganese doping does not affect the crystallinity. But the luminescence of nanophosphors increases with the Mn2+doping concentration.

Structural and optical characterization of nanoparticulate manganese doped zinc silicate phosphors prepared by sol–gel and combustion methods

The present study reports the synthesis, crystallographic structure and optical properties of manganese (Mn2+) doped zinc silicate (Zn2SiO4) nanoparticle phosphors prepared by sol–gel and combustion methods. For samples prepared by sol–gel method, the X-ray diffraction results showed phase transformation from amorphous to α-phase Zn2SiO4 due to annealing temperatures at 600°C to 1100°C, whereas for combustion samples an admixture of highly crystalline β-phase and hexagonal wurtzite structure of ZnO was observed at annealing temperature of 600°C. Photoluminescence spectra with Mn2+ concentrations ranging from 0.015–0.09mol% were compared for two methods. Emission band assigned to the 4T1(4G)→6A1(6S) electronic transition of Mn2+ was observed with maximum intensity at ~573nm for combustion samples and ~532nm for sol–gel samples upon UV-excitation by a Xenon lamp. Furthermore, the photoluminescence decay curves of annealed Zn2SiO4:Mn2+ samples were observed to be bi-exponential. The fast and slow decay components are due to the pair or cluster formation and isolated ions at higher doping concentration, respectively.

Effect of crystallographic phase on green and yellow emissions in Mn-doped zinc silicate nanoparticles incorporated in silica host matrix

Silica host matrix reached by manganese-doped zinc silicate nanoparticles (SiO2/Zn2SiO4:Mn) were in-situ synthesized by a sol–gel process. In our approach, we synthesis ZnO:Mn nanoparticles in supercritical conditions of ethanol. After the incorporation of these nanoparticles in silica host matrix, a heat treatment at 1200°C and 1500°C for 2h was performed for the elaboration of SiO2/Zn2SiO4:Mn nanocomposites. Then, these samples were characterized by various techniques such as X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM) and photoluminescence (PL). These samples exhibit broad green and yellow PL bands depending on synthesis temperature. The SiO2/Zn2SiO4:Mn prepared at 1200°C exhibit a green emission centered at about 525nm while the yellow emission centered at 575nm resulted from SiO2/Zn2SiO4:Mn prepared at 1500°C. These two emissions are originated from internal transition in Mn2+ ion doped zinc silicate nanoparticles and the emission wavelength is correlated to the local crystalline field which is fixed by the crystallographic phase.

Synthesis and evaluation of a PVDF–PT3MA–Zn2SiO4:Mn hybrid polymeric composite for optical device applications

A new hybrid organic/inorganic composite consisting of poly(3-thiophene methyl acetate) (PT3MA), poly(vinylidene fluoride) (PVDF) and manganese-doped zinc silicate (Zn2SiO4:Mn) has been synthesized and applied for the fabrication of an optical device. Recrystallized PVDF was used as a host matrix for the PT3MA polymer and Zn2SiO4:Mn inorganic compound. The active layer was deposited on an indium-tin-oxide (ITO)-coated glass substrate by the drop casting technique. A spin-coating method was also used for morphological comparison purposes. The synthesized material as well as the device (aluminium electrodes/PVDF–PT3MA–Zn2SiO4:Mn/ITO/glass) was characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), energy dispersive X-ray spectroscopy (EDX), dark current–voltage (I–V) characteristic curves, absorbance and photoluminescence (PL) spectroscopy. The results show spherical- and irregular-shaped microparticles both dispersed on and within the PVDF matrix, which correspond to PT3MA and Zn2SiO4:Mn, respectively. The hybrid composite shows strong luminescence at ≈525 nm superimposed by a broadband between 600 and 800 nm, originating from the Zn2SiO4:Mn radiative transitions and from the recombination of photogenerated carriers at PT3MA. At room temperature, the device presented semiconductor behaviour typically observed for photodetectors and a DC electrical conductivity of ≈0.37 μS cm−1.

Characterization of Manganese-doped Willemite Green Phosphor Gel Powders

Nanocrystalline manganese-doped zinc silicate (Zn2−xMnxSiO4; x = 0-12.0 mol%) powder phosphors were prepared by the sol-gel process. Zinc chloride, tetraethylorthosilicate, and manganese chloride were employed as precursors. The influences of water concentration on the crystallization and photoluminescence of the phosphors were investigated. Single-phase wiemite (α-Zn2SiO4) started to crystallize after calcining at 600°C for powders derived from low-water-conen so, whie β-Zn2SiO4 became the dominated phase with residual ZnO trace for high-water-content sol derived powders as calcining at below 900 °C. On firing at 800°–1200°C, the resulting phosphors had the average crystallite sizes of 15∼38 nm. With various content of water and heating the powders at 800°C, the prepared phosphors exhibited yellow and green emission peaking at 556 and 524 nm, respectively. Upon heating at 1200 °C, powder phosphors exhibited prominent photoluminescence emission bands peaked at 522∼526 nm, depending on the doping content. The luminous efficiency has been investigated as a function of dopant content and heating temperature.

Optical Properties and Photoluminescent Characteristics of Manganese-doped Zinc Silicate Thin Films

Optical Properties and Photoluminescent Characteristics of Manganese-doped Zinc Silicate Thin Films

Synthesis and characterization of Mn-doped Zn 2SiO 4/SiO 2 phosphor particles in core–shell structure

Manganese-doped zinc silicate (Zn 2SiO 4:Mn) is a kind of phosphor material that has a photo-luminescent (PL) and cathode-luminescent (CL) properties with intensive green light emission at 520 nm. The particles consisting of SiO 2@Zn 2SiO 4:Mn (SiO 2 core–Zn 2SiO 4:Mn shell) were synthesized via colloidal process and forced precipitation. After drying, the Zn/Mn precipitates were coated on the surface of SiO 2 particles. The Zn/Mn precipitates reacted with SiO 2 and transformed to Zn 2SiO 4:Mn by suitable calcination. The microstructure, crystalline phase, and luminescent characteristics of the products were studied. Besides, a CL device consisting of the core–shell powder was characterized.

Fabrication and characterization of photoluminescent Mn-doped-Zn2SiO4 films deposited on silicon by pulsed laser deposition

Manganese-doped zinc silicate photoluminescent films were prepared on silicon wafer using pulsed laser deposition technique. The effects of heat treatment on the optical and structural properties were investigated by means of X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), and photoluminescence (PL) spectra. It was found in XRD patterns and FTIR that crystalline zinc silicate was formed on the silicon wafer when the annealing temperature was above 700 °C. The PL spectra showed that the peak wavelength of the green emission was at 525 nm with a decay time of 12.5 ms.

Zn 2SiO 4:Mn phosphor particles prepared by spray pyrolysis using a filter expansion aerosol generator

Manganese-doped zinc silicate phosphor particles were prepared by spray pyrolysis using FEAG (Filter Expansion Aerosol Generator) process. The characteristics of cathodoluminescence, crystallinity, and morphology of Zn 2SiO 4:Mn particles were investigated. The as-prepared and calcined particles were spherical shape and 1 micrometer in diameter, and aggregation between particles was not observed even after calcination at high temperature. The particles prepared at 600°C had amorphous phase, and zinc oxide peaks appeared at 700°C. The peaks of the β-Zn 2SiO 4 with orthorhombic structure was obtained at 1000°C. Pure phase willemite structure was obtained after calcination at 1200°C for 5 h when adding the 80–90% of stoichiometric amount of zinc nitrate. The maximum cathodoluminescence (CL) intensity of particles was obtained at 1.3 mol% doping concentration of Mn. The particles calcined at 1200°C for 5 h has the maximum CL intensity of 198 cd/m 2.

Pulsed laser deposition of silicate phosphor thin films

Three types of silicate phosphor thin films, emitting in the red-green-blue (RGB) primary colors, were fabricated by pulsed laser deposition, including manganese and lead doped calcium silicate (CaSiO3:MnPb) for red color, manganese doped zinc silicate (Zn2SiO4:Mn) for green color and cerium doped yttrium silicate (Y2SiO5:Ce) for blue color. A correlation was observed between photoluminescence intensity with film crystallinity and surface morphology. RGB phosphor thin films with excellent color saturation were obtained. Luminescence mechanisms for these phosphor thin films are discussed.

Deposition of (Zn, Mn)2SiO4 for plasma display panels using charged liquid cluster beam

Films of manganese doped zinc silicate have been deposited using the charged liquid cluster beam technique. The deposition conditions were found to have a large impact on the morphology and photoluminescence intensity of these films. The photoluminescence intensity was maximized at a manganese content near δ=0.04 in (Zn1−δMnδ)2SiO4. No phases other than zinc silicate were detectable with manganese contents up to δ=0.08.

P‐40: Red, Green, and Blue Silicate Phosphor Thin Films by Laser Deposition

AbstractThree kinds of silicate phosphor thin films, emitting in the red‐green‐blue (RGB) primary colors, were fabricated by pulsed laser deposition: manganese and lead doped calcium silicate (CaSiO3:MnPb) for red color, manganese doped zinc silicate (Zn2SiO4:Mn) for green color, and cerium doped yttrium silicate (Y2SiO5:Ce) for blue color. A good correlation was found between photoluminescence intensity and film crystallinity and surface morphology.

Charged Liquid Cluster Beam Technique and Deposition of Manganese Doped Zinc Silicate for Plasma Display Panels

AbstractThe charged liquid cluster beam technique is inherently suited to fabricating uniform, conformal coatings of controlled chemical compositions and stoichiometries. The technique has the ability to produce and use nanometer‐scale charged drops of liquid precursors for thin film deposition and to utilize atomic scale mixing present in liquid precursors to achieve a film of uniform stoichiometry. Films of manganese doped zinc silicate, (Zn1−δMnδ)2SiO4, have been deposited using the CLCB technique. The deposition conditions were found to have a large impact on the morphology and photoluminescence intensity of the films. No phases other than zinc silicate were detectable with manganese contents up to δ=0.08.

Trapping and luminescence mechanisms in manganese-doped zinc silicate phosphorsa tunneling model

We have investigated electron trapping and luminescence (phosphorescence, thermoluminescence and photostimulated luminescence) mechanisms in Mn and Mn+As doped Zn2SiO4 phosphors. The intensities of both the phosphorescence and photostimulated luminescence are found to decay with time approximately as (time)-1. The generally accepted model of such a decay of phosphorescence, based on thermal release of electrons from a broad distribution of trap energy levels, cannot explain the observed decay of the photostimulated luminescence. In order to explain both results we have developed a new model based on radiative recombination by tunneling between holes trapped on Mn ions and electrons in shallow traps or in excited states of the deeper traps. We derive a simple expression which describes for both experiments at all times the decay of the light intensity and its dependence on experimental conditions. The agreement between theory and experiment is found to be excellent.

Energy storage effect and retrieval in manganese doped zinc silicate

It is shown that a significant amount of energy can be stored at room temperature for long periods in the manganese activated zinc silicates upon excitation by short wavelength UV photons (>3.65eV), and X-ray radiation. The stored energy can be stimulated by long wavelength photons (infrared and red) resulting in visible green emission. This effect has potential application in high energy radiation detection and imaging.

Efficiency enhancement in manganese-doped zinc silicate phosphor with AlPO4 substitution

Large increases in the efficiency of the conventional P1 phosphor (Zn2SiO4 : Mn) have been achieved by substituting various combinations of III and V oxides for SiO2, e.g., Zn2−yMnySi1−2xAlxPxO4. The photoluminescence efficiency of these phosphors exhibit strong dependence on the AlPO4 substitution concentration x having highest efficiency for x=0.5–1.5%. Cathodoluminescence and decay measurements show that such materials can have CL efficiency greater than the commercial zinc silicates and still have comparable persistence characteristics.