Effect of Zn2+ Doping on Luminescence Properties of Red-Emitting Phosphors CaMoO4:Eu3+

2011 ◽  
Vol 189-193 ◽  
pp. 4308-4312
Author(s):  
Xian Zhang ◽  
Yue Cao
Keyword(s):  
Raw Materials ◽  
Xrd Analysis ◽  
Solid State Reaction Method ◽  
Peak Position ◽  
Sem Analysis ◽  
X Ray Diffraction ◽  
Near Ultraviolet ◽  
Maximum Value ◽  
Degree Of Crystallization ◽  
Peak Value

Red-emitting phosphors Ca0.7-xEu0.3Z<nx MoO4（X=0, 0.02, 0.04, 0.06, 0.08, 0.1）were fabricated by a solid state reaction method using (NH4)6Mo7O24•4H2O, CaCO3, Eu2O3and ZnO as raw materials at the temperature of 600°C, 700°C, 750°C, 800°C, 850°C and 900°C, respectively. Phase components, grain morphologies and luminescence spectrum properties of the samples were analyzed and studied by the X-ray diffraction (XRD), scanning electron microscope (SEM) and F-4500 spectrophotometer. XRD analysis showed, with the temperature increasing, the width of the diffraction peak became narrow, but the peak value increased indicating the degree of crystallization became better and pure Ca0.7Eu0.3MoO4phase can be obtained at 850°C. SEM analysis showed that below 800°C, the grain was small but contains lots defects, while above 850°C round-shaped regular grain of about 1µm can be obtained. Photoluminescence spectrum analysis showed the phosphors could be efficiently excited by a near- ultraviolet light with wavelength of 395nm or the blue-purple light with wavelength of 465nm, the emission peaks located at 592nm and 614nm respectively. The emitting intensity improved with the sintering temperature increased, and got the maximum value at 850°C, but a little decreased at 900°C. Zn2+doping has no effect on emission peak position but can efficiently improve the emitting intensity of Ca0.7Eu0.3MoO4and the best doping concentration is about X=0.08.

Properties of Recycled-Cement Produced from Waste Concrete

2011 ◽  
Vol 194-196 ◽  
pp. 1170-1175 ◽  
Author(s):  
Hong Mei Ai ◽  
Jing Wei ◽  
Jun ying Bai ◽  
Pu Guang Lu
Keyword(s):  
Compressive Strength ◽  
Raw Materials ◽  
Setting Time ◽  
Xrd Analysis ◽  
Sem Analysis ◽  
Cement Clinker ◽  
X Ray Diffraction ◽  
Waste Concrete ◽  
High Temperature Furnace ◽  
Mineral Components

This research aims to find a new way of “turning trash into treasure” for the waste concrete. In the research, waste concrete was first ground, then, after analyzing its mineral composition, combined with some other ingredients according to the modulus of the cement clinker to become raw materials of cement. Mixed raw materials were made to be a thin cake, and then sent into high temperature furnace (HTF) to sinter for a certain period of time. Properties of cement, such as the compressive strength, required water of standard consistence and setting time were tested. The composition and microstructure of clinker were analyzed with X-ray diffraction (XRD) analysis and scanning electron microscope (SEM) analysis. The experimental results showed that the main mineral components of clinker are C3S, β-C2S, CA2, CA, C3A, C4AF, the compressive strength of the recycled-cement is approximately equal to P.O32.5, there exists an optimum sintering temperature for the recycled-cement clinker with a given mix ratio of raw materials and content of seed crystal added,, and this temperature is usually much lower than the temperature adopted wildly in the cement plants.

scholarly journals Mining Wastes of an Albite Deposit as Raw Materials for Vitrified Mullite Ceramics

Minerals ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 232
Author(s):  
Pedro J. Sánchez-Soto ◽  
Eduardo Garzón ◽  
Luis Pérez-Villarejo ◽  
George N. Angelopoulos ◽  
Dolores Eliche-Quesada
Keyword(s):  
Particle Size ◽  
Raw Materials ◽  
Phase Evolution ◽  
Particle Size Analysis ◽  
Size Analysis ◽  
Mining Wastes ◽  
X Ray Diffraction ◽  
X Ray ◽  
Maximum Value

In this work, an examination of mining wastes of an albite deposit in south Spain was carried out using X-ray Fluorescence (XRF), X-ray diffraction (XRD), particle size analysis, thermo-dilatometry and Differential Thermal Analysis (DTA) and Thermogravimetric (TG) analysis, followed by the determination of the main ceramic properties. The albite content in two selected samples was high (65–40 wt. %), accompanied by quartz (25–40 wt. %) and other minor minerals identified by XRD, mainly kaolinite, in agreement with the high content of silica and alumina determined by XRF. The content of Na2O was in the range 5.44–3.09 wt. %, being associated with albite. The iron content was very low (<0.75 wt. %). The kaolinite content in the waste was estimated from ~8 to 32 wt. %. The particle size analysis indicated values of 11–31 wt. % of particles <63 µm. The ceramic properties of fired samples (1000–1350 °C) showed progressive shrinkage by the thermal effect, with water absorption and open porosity almost at zero at 1200–1250 °C. At 1200 °C, the bulk density reached a maximum value of 2.38 g/cm3. An abrupt change in the phase evolution by XRD was found from 1150 to 1200 °C, with the disappearance of albite by melting in accordance with the predictions of the phase diagram SiO2-Al2O3-Na2O and the system albite-quartz. These fired materials contained as main crystalline phases quartz and mullite. Quartz was present in the raw samples and mullite was formed by decomposition of kaolinite. The observation of mullite forming needle-shape crystals was revealed by Scanning Electron Microscopy (SEM). The formation of fully densified and vitrified mullite materials by firing treatments was demonstrated.

Structural, Dielectric and Electrical Studies of Ba4CaRTi3Nb7O30 (R = Eu, Dy) Ferroelectric System

2013 ◽  
Vol 547 ◽  
pp. 41-48 ◽  
Author(s):  
Prasun Ganguly ◽  
A.M. Biradar ◽  
A.K. Jha
Keyword(s):  
Single Phase ◽  
Microstructural Analysis ◽  
Tungsten Bronze ◽  
Negative Temperature ◽  
Xrd Analysis ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Orthorhombic Crystal ◽  
Paraelectric Phase Transition ◽  
Orthorhombic Crystal Structure

The polycrystalline samples of Ba4CaRTi3Nb7O30 (R = Eu, Dy), members of tungsten-bronze family, were prepared by high-temperature solid state reaction method and studied for their dielectric and electrical properties. X-ray diffraction (XRD) analysis reveals the formation of single-phase compounds having orthorhombic crystal structure at room temperature. Microstructural analysis by scanning electron microscope (SEM) shows that the compounds have well defined grains, which are distributed uniformly throughout the sample. Detailed dielectric properties of the compounds as a function of frequency and temperature show that the compounds undergo non-relaxor kind of ferroelectric-paraelectric phase transition of diffuse nature. Ferroelectric, piezoelectric and pyroelectric studies of the compounds have been discussed in this paper. The temperature dependence of dc conductivity of the compounds have been investigated. The conductivity study over a wide temperature range suggests that the compounds have negative temperature coefficient of resistance (NTCR) behaviour.

Development of Ternary Concrete Utilizing Agricultural Waste Material

2022 ◽  
Author(s):  
Sunita Kumari ◽  
Dhirendra Singhal ◽  
Rinku Walia ◽  
Ajay Rathee
Keyword(s):  
Rice Husk ◽  
Rice Husk Ash ◽  
Agricultural Waste ◽  
Xrd Analysis ◽  
Sem Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Concrete Mix ◽  
Maize Cob

Abstract The present project proposes to utilize rice husk and maize cob husk ash in the cement to mitigate the adverse impact of cement on environment and to enhance the disposal of waste in a sustainable manner. Ternary concrete / MR concrete was prepared by using rise husk and maize cob ash with cement. For the present project, five concrete mixes MR-0 (Control mix), MR-1 (Rice husk ash 10% and MR-2.5%), MR-2 (Rice husk ash 10% and MR-5%), MR-3 (Rice husk ash 10% and MR-2.5%), MR-4 (Rice husk ash 10% and MR-2.5%) were prepared. M35 concrete mix was designed as per IS 10262:2009 for low slump values 0-25mm. The purpose is to find the optimum replacement level of cement in M35 grade ternary concrete for I – Shaped paver blocks.In order to study the effects of these additions, micro-structural and structural properties test of concretes have been conducted. The crystalline properties of control mix and modified concrete are analyzed by Fourier Transform Infrared Spectroscope (FTIR), Scanning Electron Microscopy (SEM), and X-Ray Diffraction (XRD). The results indicated that 10% Rice husk ash and 5% maize cob ash replaced with cement produce a desirable quality of ternary concrete mix having good compressive strength. The results of SEM analysis indicated that the morphology of both concrete were different, showing porous structure at 7 days age and become unsymmetrical with the addition of ashes. After 28 day age, the control mix contained more quantity of ettringite and became denser than ternary concrete. XRD analysis revealed the presence of portlandite in large quantity in controlled mix concrete while MR concrete had the partially hydrated particle of alite.

scholarly journals Effect of Re and Tm-site on morphology structure and optical band gap of ReTmO3 (Re: La, Ce, Nd, Gd, Dy, Y and Tm: Fe, Cr) prepared by sol-gel method

2018 ◽  
Vol 64 (4) ◽  
pp. 381
Author(s):  
Muhammad Tufiq Jamil ◽  
Javed Ahmad ◽  
Syed Hamad Bukhari ◽  
Murtaza Saleem
Keyword(s):  
Band Gap ◽  
Sol Gel ◽  
Xrd Analysis ◽  
Sem Analysis ◽  
X Ray Diffraction ◽  
Orthorhombic Crystal ◽  
X Ray ◽  
Average Grain Size ◽  
Auto Combustion ◽  
Uv Visible

Rare earth nano sized pollycrystalline orthoferrites and orthocromites ReT mO3 (Re = La, Nd, Gd, Dy, Y and T m = Fe, Cr) have been synthesized by sol-gel auto combustion citrate method. The samples have been characterized by means of X-ray diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray spectroscopy (EDX), and UV-visible spectroscopy. The samples are single phase as confirmed by XRD analysis and correspond to the orthorhombic crystal symmetry with space group pbnm. Debye Scherer formula and Williamson Hall analysis have been used to calculate the average grain size which is consistent with that of determined from SEM analysis and varied between 25-75 nm. The elemental compositions of all samples have been checked by EDX analysis. Different crystallographic parameters are calculated with strong structural correlation among Re and Tm sites. The optical energy band gap has been calculated by using Tauc relation estimated to be in the range of 1.77 - 1.87 eV and 2.77 - 3.14 eV, for ReFeO3 and ReCrO3, respectively.

Hierarchical Nanostructured ZnO-CuO Nanocomposite and its Photocatalytic Activity

2015 ◽  
Vol 35 ◽  
pp. 21-26 ◽  
Author(s):  
Susmita Das ◽  
Vimal Chandra Srivastava
Keyword(s):  
Photocatalytic Activity ◽  
Pure Copper ◽  
Ultra Violet ◽  
Xrd Analysis ◽  
Sem Analysis ◽  
X Ray Diffraction ◽  
X Ray ◽  
Ultra Violet Radiation ◽  
One Step ◽  
Uv Visible

Metal oxide nanocomposite (ZnO-CuO) was successfully synthesized by one step homogeneous coprecipitation method and further characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron micrograph (SEM), X-ray diffraction analysis (XRD) and UV-visible diffuse reflectance spectra. XRD analysis exhibited presence of pure copper oxide and zinc oxide within the nanocomposite. SEM analysis indicated that the ZnO-CuO nanocomposite was consisted of flower shaped ZnO along with leaf shaped CuO. Photocatalytic activity of nanocomposite was evaluated in terms of degradation of methylene blue (MB) dye solution under ultra-violet radiation. Results showed that the photocatalytic efficiency of ZnO-CuO nanocomposite was higher than its individual pure oxides (ZnO or CuO).

Structure and Electrical Characteristics of BaTiO3 and Ba0.99Er0.01TiO3 Ceramics

2018 ◽  
Vol 280 ◽  
pp. 127-133 ◽  
Author(s):  
F. A. Ismail ◽  
Rozana Aina Maulat Osman ◽  
Mohd Sobri Idris ◽  
N.A.M. Ahmad Hambali
Keyword(s):  
Perovskite Phase ◽  
Microstructural Analysis ◽  
Xrd Analysis ◽  
Solid State Reaction Method ◽  
X Ray Diffraction ◽  
Conventional Solid State Reaction ◽  
Grain Sizes ◽  
Capacitance Voltage ◽  
Ion Incorporation ◽  
Voltage Breakdown

Conventional solid state reaction method was used to prepare BaTiO3 and Ba0.99Er0.01TiO3 ceramics. Influence of Er3+ ion incorporation on their structural, microstructural and electrical properties was studied. The phase pure samples were obtained when heated at 1400 °C for overnight. The tetragonal perovskite phase of BaTiO3 and Ba0.99Er0.01TiO3 was confirmed by using X-ray Diffraction (XRD) analysis which is in agreement with results obtained from Rietveld refinement analysis. The lattice parameters and unit cell volume of BaTiO3 increased when doped with Erbium. Microstructural analysis of BaTiO3 and Ba0.99Er0.01TiO3 ceramics showed that the grain sizes of BaTiO3 and Ba0.99Er0.01TiO3 significantly decreased. The dielectric properties of BaTiO3 and Ba0.99Er0.01TiO3 were investigated as a function of temperature and frequency. It revealed that the Curie temperature (TC) increased by doping Er content from 110 °C to 120 °C. Ba0.99Er0.01TiO3 exhibited the high value of dielectric constant (ε=5929) at TC of 120 °C. The capacitance-voltage characteristic revealed that the voltage breakdown for both BaTiO3 and Ba0.99Er0.01TiO3 exceeded 30 V.

Dielectric Properties and Raman Spectroscopy in Ca-Substituted Na0.5Bi0.5TiO3 Ferroelectric Ceramics

2011 ◽  
Vol 324 ◽  
pp. 298-301 ◽  
Author(s):  
Roy Jean Roukos ◽  
Olivier Bidault ◽  
Julien Pansiot ◽  
Ludivine Minier ◽  
Lucien Saviot
Keyword(s):  
Raman Spectroscopy ◽  
Dielectric Properties ◽  
Room Temperature ◽  
Rhombohedral Phase ◽  
Xrd Analysis ◽  
Solid State Reaction Method ◽  
Ferroelectric Ceramics ◽  
Dielectric Measurements ◽  
X Ray Diffraction ◽  
X Ray

Lead free Na0.5Bi0.5TiO3 (NBT) and (Na0.5Bi0.5TiO3)1-x(CaTiO3)x (NBT-CT) piezoelectric ceramics with the perovskite structure were studied. The NBT and NBT-CT samples were synthesized using a solid-state reaction method and characterized with X-ray diffraction (XRD), Raman spectroscopy and dielectric measurements for several compositions (x = 0, 0.07, 0.15) at room temperature. The XRD analysis showed a stabilization of a rhombohedral phase at a low concentration of Ca (0 < x <0.15), whereas Raman spectra reveal a strong modification for the sample with x = 0.15. The dielectric properties of these ceramics were studied by measuring impedance in the 79-451K temperature range for unpoled and field cooling with an electric field (FC) conditions.

LiMn2O4 Powders Prepared by Solution Combustion Synthesis in Ethanol and Water Systems

2010 ◽  
Vol 160-162 ◽  
pp. 554-557
Author(s):  
Gui Yang Liu ◽  
Jun Ming Guo ◽  
Yan Nan Li ◽  
Bao Sen Wang
Keyword(s):  
Electrochemical Performance ◽  
Combustion Synthesis ◽  
Raw Materials ◽  
Solution Combustion Synthesis ◽  
Xrd Analysis ◽  
Manganese Acetate ◽  
X Ray Diffraction ◽  
Solution Combustion ◽  
Voltage Range ◽  
Ethanol System

Spinel LiMn2O4 powders have been prepared at 500 for 5h by solution combustion synthesis in water or ethanol system, using lithium and manganese acetate as raw materials and no fuels. The structure and morphology of the products have been analyzed by X-ray diffraction (XRD) and scanning electron microscopy (SEM), respectively. The electrochemical performance has been charged or discharged in coin-type battery. XRD analysis indicates that the purity and crystallinity of the product prepared in ethanol are much better than these of the product prepared in water. SEM investigation indicates that the particles of the product prepared in ethanol are smaller and more dispersed than these of the products prepared in water. The product prepared in ethanol also exhibits better electrochemical performance than that of the product prepared in water. The initial discharge capacity of the product prepared in ethanol is 120mAh/g, and remains 110mAh/g after 20 cycles, at a current density of 50mA/g and in the voltage range of 3.2-4.35V.

Synthesis and luminescence properties of the red phosphor CaZrO3:Eu3+ for white light-emitting diode application

Open Physics ◽  
2011 ◽  
Vol 9 (4) ◽  
Author(s):  
Junli Huang ◽  
Liya Zhou ◽  
Yuwei Lan ◽  
Fuzhong Gong ◽  
Qunliang Li ◽  
...  
Keyword(s):  
White Light ◽  
Light Emitting Diode ◽  
Red Light ◽  
Average Diameter ◽  
Xrd Analysis ◽  
X Ray Diffraction ◽  
Solid State Method ◽  
Light Emitting ◽  
Near Ultraviolet ◽  
Light Region

AbstractEu3+-doped CaZrO3 phosphor with perovskite-type structure was synthesized by the high temperature solid-state method. The samples were characterized by X-ray diffraction, scanning electron microscopy, fluorescence spectrophotometer and UV-vis spectrophotometer, respectively. XRD analysis showed that the formation of CaZrO3 was at the calcinations temperature of 1400°C. The average diameter of CaZrO3 with 4 mol% doped-Eu3+ was 2µm. The PL spectra demonstrated that CaZrO3:Eu3+ phosphor could be excited effectively in the near ultraviolet light region (397 nm) and emitted strong red-emission lines at 616 nm corresponding to the forced electric dipole 5 D 0 → 7 F 2 transitions of Eu3+. Meanwhile, the light-emitting diode was fabricated with the Ca0.96ZrO3:Eu0.043+ phosphor, which can efficiently absorb ∼ 400 nm irradiation and emit red light. Therefore Ca0.96ZrO3:Eu0.043+ may have applications for a near ultraviolet InGaN chip-based white light-emitting diode.

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