Ce0.8Gd0.2O1.9 Powders Synthesized by Co-Precipitation and Amorphous Citrate Processes

2005 ◽  
Vol 498-499 ◽  
pp. 624-629 ◽  
Author(s):  
Márcia Caldeira Brant ◽  
Felipe da Silva Possa ◽  
Fernando Soares Lameiras
Keyword(s):  
Room Temperature ◽  
Simple Technique ◽  
Fluorite Structure ◽  
Theoretical Density ◽  
Precipitation Process ◽  
Doped Ceria ◽  
X Ray Diffraction ◽  
X Ray ◽  
Synthesis Techniques ◽  
Co Precipitation

Powders of Ce0.8Gd0.2O1.9 were synthesized by co-precipitation and amorphous citrate routes and their compositions and structures were compared. Co-precipitation process was carried out at room temperature, while amorphous citrate synthesis was performed at 60-70 °C. The powders obtained were calcined at 700 °C for 1 h. X-ray diffraction analyses showed that a single fluorite structure was formed by both synthesis techniques. Pellets from these powders were prepared by compaction at 30 kN/cm2 and sintered at 1593 °C in air. WDS analysis confirmed the homogeneity of the pellets. The sintered pellets obtained by amorphous citrate and by coprecipitation routes showed relative densities over 97 % of the theoretical density. These results indicated that the citrate amorphous route is an interesting and simple technique to prepare gadolinium-doped ceria powders with high sinterability.

Preparation and Electrochemical Performance of Mn3O4/GR Composites Electrode Material in Supercapacitors

2019 ◽  
Vol 807 ◽  
pp. 50-56
Author(s):  
Yun Long Zhou ◽  
Zhi Biao Hu ◽  
Li Mei Wu ◽  
Jiao Hao Wu
Keyword(s):  
Room Temperature ◽  
Raw Materials ◽  
Precipitation Method ◽  
Electrochemical Performances ◽  
Manganese Sulfate ◽  
X Ray Diffraction ◽  
X Ray ◽  
Co Precipitation ◽  
A Current ◽  
Discharge Test

Using hydrated manganese sulfate and general type graphene (GR) as raw materials, Mn3O4/GR composite has been successfully prepared by the liquid phase chemical co-precipitation method at room temperature. X-ray diffraction (XRD) was used to investigate the phase structure of Mn3O4powder and Mn3O4/GR composite; The electrochemical performances of the samples were elucidated by cyclic voltammetry and galvanostatic charge-discharge test in 0.5 mol/L Na2SO4electrolyte. The results show that the Mn3O4/GR composite possesses graphene phase and good reversibility; the composite also displays a specific capacitance of 318.8 F/g at a current density of 1 A/g.

scholarly journals Synthesis of Nanocrystalline Mg-Al Hydrotalcites in the Presence of Starch—the Effect on Structure and Composition

Materials ◽  
2020 ◽  
Vol 13 (3) ◽  
pp. 602
Author(s):  
Alicja Michalik ◽  
Bogna D. Napruszewska ◽  
Anna Walczyk ◽  
Joanna Kryściak-Czerwenka ◽  
Dorota Duraczyńska ◽  
...  
Keyword(s):  
Freeze Drying ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Synthesis Parameters ◽  
All Solutions ◽  
Co Precipitation ◽  
Starch Potato ◽  
Degree Of Order ◽  
Scanning Electron

The study describes the synthesis of Mg-Al hydrotalcite (Ht) with the use of starch as a structure controlling biotemplate. Syntheses were carried out at room temperature, by co-precipitation at pH = 10. The investigated synthesis parameters included the nature of the precipitating agent (NaOH/Na2CO3 or NH3aq/(NH4)2CO3), the nature of starch (potato, corn and cassava), the method of starch addition to reagents, the method of drying and the effect of washing. The materials were examined with X-ray diffraction, scanning electron microscopy/energy dispersive X-ray spectroscopy and infrared spectroscopy. The data show that synthesis of Ht materials in the presence of starch, with use of the ammonia-based precipitant, enabled preparation of nanocrystalline Ht with very fine (<50 nm) particle size. All investigated starches had a similar effect on the crystallinity and the grain size of Ht precipitates. Ht with the smallest nanocrystals was obtained when starch was present in all solutions used for synthesis, and the final product subjected to freeze drying. Washing with water was found to enhance recrystallization and exchange of nitrates for carbonates. Infrared spectra showed that an interaction exists between the biopolymer template and the Ht particles, resulting in a higher degree of order within the Ht-adhering starch component.

Mineralogy and formation of evaporite deposits from the Lewis Cliff ice tongue, Antarctica

2014 ◽  
Vol 27 (1) ◽  
pp. 73-84 ◽  
Author(s):  
Tingting Liu ◽  
David L. Bish ◽  
Richard A. Socki ◽  
Ralph P. Harvey ◽  
Eric Tonui
Keyword(s):  
Room Temperature ◽  
Precipitation Process ◽  
Secondary Mineral ◽  
X Ray Diffraction ◽  
Sulfate Ions ◽  
X Ray ◽  
Bodies Of Water ◽  
Evaporite Minerals ◽  
Glacial Tills ◽  
First Time

AbstractThe mineralogy of evaporites from the Lewis Cliff ice tongue (LCIT), Antarctica, and their mineral stabilities and transformation behaviours under different temperature and relative humidity (RH) conditions have been evaluated to elucidate formation mechanism(s). A variety of sodium (Na)-rich evaporite minerals were documented using RH-controlled powder X-ray diffraction (XRD) methods including Na-sulfates (mirabilite and thenardite), Na-carbonate/bicarbonates (nahcolite, occasional trona and natron) and Na-borates (qilianshanite and borax). Mirabilite begins to dehydrate to thenardite, and natron to trona and natrite when exposed to room temperature, even when maintained at RH values similar to those measured at the LCIT (50–70%). The boron-mineral qilianshanite was discovered for the first time in Antarctica within the evaporite mounds. The mirabilite-rich mounds are deduced to have formed via a freezing/sublimation process that occurred in glacial or subglacial bodies of water supplied by glacial tills containing microbially oxidized sulfate ions. The needle-like nahcolite crystals growing on the exteriors of the mounds suggest a dissolution/precipitation process involving atmospheric CO2 and water. The co-existence of nahcolite and boron-bearing minerals indicates the presence of a Na+-, HCO3-- and boron-bearing alkaline brine, which produces qilianshanite as a secondary mineral by reaction of nahcolite and borax in atmospheric CO2 and H2O.

Preparation and Characterization of Graphene Nanoplatelet/Magnetite Compound Powders

2011 ◽  
Vol 284-286 ◽  
pp. 464-469
Author(s):  
Guo Hua Chen ◽  
Hai Tao Tang
Keyword(s):  
Room Temperature ◽  
Nano Particles ◽  
X Ray Diffraction ◽  
Graphene Nanoplatelet ◽  
X Ray ◽  
Wet Chemical ◽  
Composition Structure ◽  
Co Precipitation ◽  
Graphite Sheets

Graphene nanoplatelet（GN）/ Magnetite compound powders with magnetite nano-particles coated on the surface of graphite sheets has been successfully prepared by the wet-chemical co-precipitation. The effects of reaction temperature and mole ratio of Fe2+/Fe3+ on ultimate products were investigated. It has been found that excellent magnetite/GN compound powders were obtained at 30 °C with the Fe2+/Fe3+ mole ratio of 5:1. The composition, structure and the electric and magnetic properties of products were characterized by X-ray diffraction, scanning electron microscopy, Fourier transform infrared spectroscopy, vibrating-sample magnetometer and four-point probe resistivity measurement.The compound powders have also exhibited the ferromagnetic properties at room temperature.

Effect of h-BN on Sintering Behavior, Microstructures and Mechanical Properties of YAG Bulk Composites

2016 ◽  
Vol 697 ◽  
pp. 395-398 ◽  
Author(s):  
Shi Bin Li ◽  
Jie Guang Song ◽  
Hong Ying Ru ◽  
Xiao Bo Bai
Keyword(s):  
Mechanical Properties ◽  
Volume Fraction ◽  
Precipitation Process ◽  
Sintering Behavior ◽  
Second Phase ◽  
X Ray Diffraction ◽  
Composite Powders ◽  
X Ray ◽  
Co Precipitation ◽  
Scanning Electron

The shell structure YAG composite powders with different volume fraction (15, 20 and 25vol%) micro h-BN have been prepared by co-precipitation process. The bulk composites were performed by pressure sintering at 1600°C under a pressure of 30MPa in vacuum. The mechanical properties (elastic modulus, hardness, and fracture toughness) and relative density of the composites were investigated detailedly. Furthermore, phase composition and microstructure of the composites were analyzed thoroughly by X-ray diffraction, scanning electron microscopy. Meanwhile, good machinability is maintained due to the low hardness of the second phase.

Y-Type Hexaferrites: Structural, Dielectric and Magnetic Properties

2012 ◽  
Vol 189 ◽  
pp. 209-232 ◽  
Author(s):  
Rajshree B. Jotania ◽  
Hardev Singh Virk
Keyword(s):  
Magnetic Properties ◽  
Quantum Interference ◽  
Room Temperature ◽  
Structural Changes ◽  
Ferromagnetic State ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Lcr Meter ◽  
Co Precipitation

This paper attempts to provide a historical survey of structure of various types of hexaferrites. It provides information about synthesis, characterization, structural, magnetic and dielectric properties of Y-type hexagonal ferrites using various chemical routes. We have prepared a series of cobalt doped Sr2Cu2-xCoxFe12O22(x = 0.0 to 1.0) hexaferrites using a wet chemical co-precipitation technique. The prepared hexaferrite precursors were calcined at 950 °C for 4 hours in a furnace and slowly cooled to room temperature. The crystal structure of Y-type hexaferrites is rather complicated. The chemical and structural changes were examined in detail by X-ray diffraction (XRD), Differential scanning calorimetry (DSC), Scanning electron microscopy (SEM), and Fourier transform infra-red (FTIR) spectroscopy. X-ray diffraction studies showed that sintering temperature as low as 950°C was sufficient to produce a single-phase Y-type hexaferrite material. The dielectric measurements were carried out over the frequency range of 100 Hz to 2 MHz at room temperature using an LCR meter to study the variation of dielectric constant and loss tangent with frequency. The magnetic properties of hexaferrite samples were investigated using a vibration sample magnetometer (VSM), and a superconducting quantum interference device (SQUID) magnetometer in the temperature range 30K to 200K. A change from ferromagnetic state to super paramagnetic state has been observed in Co doped Sr2Cu2-xCoxFe12O22(x= 0.6 to 1.0) hexaferrite. The novel applications of all types of hexaferrite materials have been described.

Synthesis and Gas Sensing Properties of SnO2-CuO Nanocomposites

2013 ◽  
Vol 645 ◽  
pp. 129-132 ◽  
Author(s):  
Jantasom Khanidtha ◽  
Suttinart Noothongkaew ◽  
Supakorn Pukird
Keyword(s):  
Room Temperature ◽  
Gas Sensing ◽  
Precipitation Method ◽  
Monoclinic Structure ◽  
X Ray Diffraction ◽  
Sem Images ◽  
X Ray ◽  
Sensing Properties ◽  
Gas Sensing Properties ◽  
Co Precipitation

SnO2-CuO nanocomposites have been synthesized with the simple co-precipitation method for gas sensing properties. Sn and CuO powder were the starting materials. The synthesized products were investigated by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results show that SnO2-CuO nanocomposites have a tetragonal and monoclinic structure, respectively. SEM images verify that the some microballs are up to 10 µm and nanorods have a diameter range from 10-100 nm, while length ranges a few micrometers. The nanocomposite products were highly sensitivity to CO2gas at room temperature.

Influence of Temperature on the Order-Disorder Transition in Gd2Zr2O7

2016 ◽  
Vol 697 ◽  
pp. 386-389 ◽  
Author(s):  
Jing Lin Shi ◽  
Zhi Xue Qu ◽  
Qun Wang
Keyword(s):  
Fluorite Structure ◽  
Precipitation Method ◽  
X Ray Diffraction ◽  
Inconsistent Result ◽  
Disorder Transition ◽  
X Ray ◽  
Influence Of Temperature On ◽  
Diffraction Patterns ◽  
Co Precipitation ◽  
Increasing Temperature

Chemical co-precipitation method was used to prepare Gd2Zr2O7 powders. The powders were then heated in air at 1500°C, 1510°C, 1525°C, 1530°C, 1550°C, 1575°C, 1600°C for 5 h, and 1575°C, 1600°C for 10 h, respectively. The samples after heat treatment were characterized by X-ray diffraction and Raman spectroscopy. X-ray diffraction patterns reveal that order-disorder transition of Gd2Zr2O7 occurs between 1550°C and 1575°C. Prior to the transition, the relative intensity of peaks corresponding to the super-lattice of pyrochlores increases with the increasing temperature. On the other hand, Raman spectra give an inconsistent result from the X-ray diffraction data. No appreciable difference can be observed for all the samples though with peaks broadening as temperature increases. The spectra of the samples indicated as fluorite structure in X-ray diffraction patterns appear with six resolvable peaks which is quite different from the spectrum of ideal fluorite structure.

scholarly journals A Study of Photocatalytic Degradation of Betalain Pigment from Kitchen Waste, Semiconductive Nanostructured TiO2 Used as a Photocatalyst

2018 ◽  
Vol 15 (3) ◽  
pp. 272-278
Author(s):  
G. Muthukumar ◽  
B Arjunkumar ◽  
R. Vignesh ◽  
G. Ramalingam
Keyword(s):  
Beta Vulgaris ◽  
Room Temperature ◽  
Precipitation Method ◽  
Polluted Water ◽  
Tio2 Powder ◽  
X Ray Diffraction ◽  
Kitchen Waste ◽  
X Ray ◽  
Co Precipitation ◽  
Betalain Pigment

Well crystallinenanostructured TiO2 powder was synthesised by Co-precipitation method using Titanium (IV) isopropoxide and CTAB are precursor materialsto maintain in 1:1 ratio concentration. The synthesised power was structurally, morphologically and optically analysed to using X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM) and UV-Vis absorption spectra. The betalain pigment of polluted water was prepared from Beta vulgaris extract at room temperature (RT). The 89% of betalain pigment was degraded at 40 min from Beta vulgaris extract polluted water using as-prepared TiO2 powder as a photocatalystmaterial under visible light.

scholarly journals Resistivity Enhancement of Sr-Hexaferrite Using Rare Earth Dopant to Minimize Energy Losses

2018 ◽  
Vol 778 ◽  
pp. 195-199 ◽  
Author(s):  
Nahall Niazi ◽  
Omer Farooq ◽  
Fatima Tuz Zahra ◽  
Muhammad Anis-ur-Rehman
Keyword(s):  
Room Temperature ◽  
Single Phase ◽  
Hexagonal Structure ◽  
Precipitation Method ◽  
Strontium Hexaferrite ◽  
Energy Losses ◽  
X Ray Diffraction ◽  
High Frequencies ◽  
X Ray ◽  
Co Precipitation

Strontium hexaferrite is a material of choice due its various magnetic applications. Energy losses are a prominent issue in these magnetic materials. To lower these energy losses, we need to improve the resistivity by reducing eddy current losses. In this work nanoparticles of Gadolinium (Gd) doped Sr-hexaferrite (SrFe12-xGdxO19 x =0 .0, 0.1) have been synthesized by co-precipitation method. Structural analysis was done by using X-ray diffraction technique (XRD). It was found that the formation of single phase i.e. hexagonal structure has been achieved when the samples were sintered at 920°C for 20 minutes. AC electrical properties such as conductivity (𝜎ac), dielectric constant (ε′), dielectric loss (tanδ) and impedance (Z); real (Z') and imaginary (Z") parts have been studied as a function of frequency at room temperature. Aim of the work was to enhance the resistivity and was successfully achieved. Gd doped sample is proposed as an energy efficient material to be used in devices working at high frequencies.

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