Effects of Calcination Temperature on Crystal Structure of Pr-Nd Oxides

2011 ◽  
Vol 233-235 ◽  
pp. 2918-2921 ◽  
Author(s):  
Hui Qing Li ◽  
Rui Xiang Zhang ◽  
Hai Wang Liu ◽  
Shi Zhi Wang ◽  
Xian Ku Hao
Keyword(s):  
Crystal Structure ◽  
Calcination Temperature ◽  
Chloride Solution ◽  
Neodymium Oxide ◽  
Raw Material ◽  
Praseodymium Oxide ◽  
Hexagonal System ◽  
Binary Oxides ◽  
Hydrogen Carbonate ◽  
Ammonium Hydrogen

Ammonium hydrogen carbonate is taken as the precipitating agent to prepare Pr-Nd carbonates from the raw material of Pr-Nd chloride solution. Pr-Nd oxides have been prepared at different calcination temperature in the range of 800°C-1500°C. The oxides were characterized by XRD and XPS.Calcination temperature effects on the structure of Pr-Nd oxides and the valence state of Pr in Pr-Nd oxides have been studied; Results showed that praseodymium oxide full entered into the lattices of neodymium oxide. The crystal structure changed from cubic into hexagonal system with increasing calcination temperature.The valence of Pr in Pr-Nd binary oxides are Pr3+ and Pr4+.

Crystal Structure Stabilization of Gadolinium Aluminum Garnet (Gd3Al5O12) and Photoluminescence Properties

2013 ◽  
Vol 544 ◽  
pp. 245-251 ◽  
Author(s):  
Jin Kai Li ◽  
Ji Guang Li ◽  
Xiao Li Wu ◽  
Shao Hong Liu ◽  
Xiao Dong Li ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Thermal Decomposition ◽  
Solid Solutions ◽  
Elevated Temperatures ◽  
Particle Morphology ◽  
Mixed Solution ◽  
Photoluminescence Properties ◽  
Hydrogen Carbonate ◽  
Ammonium Hydrogen ◽  
Structure Stabilization

To suppress the thermal decomposition and to stabilize the crystal structure of Gd3Al5O12 (GdAG) garnet, doping GdAG with smaller Ln3+ (Ln=Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y, respectively) to form (Gd,Ln)AG solid solutions was proposed in work. Carbonate precursors of (Gd,Ln)AG with an approximate composition of (NH4)x(Gd,Ln)3Al5(OH)y(CO3)z•nH2O were synthesized via coprecipitation from a mixed solution of ammonium aluminum sulfate and rare earth nitrate, using ammonium hydrogen carbonate as the precipitant. The precursors and the calcination derived oxides were characterized using FT-IR spectroscopy, DTA/TG, XRD, BET and FE-SEM. The results showed that smaller Ln3+ doping can indeed stabilize GdAG against its thermal decomposition to a mixture of GdAlO3 (GdAP) and Al2O3 phases at elevated temperatures and at the same time effectively lowers the temperature for garnet crystallization. The carbonate precursors are loosely agglomerated and the resultant (Gd,Ln)AG powders show good dispersion and a fairly uniform particle morphology. The (Gd,Ln)AG solid solutions exhibit decreasing lattice parameters along with decreasing radius of the dopant ions at the same dopant content of 50 at%. Photoluminescence properties of some of the garnet solid solutions are also studied. The materials developed herein may potentially be used for photoluminescent and scintillation applications.

Study on the Prepartion of Slag Haycite for Phosphorus Removal Using Ammonium Hydrogen Carbonate as Pore Former

2014 ◽  
Vol 887-888 ◽  
pp. 723-726
Author(s):  
Xue Lian Li ◽  
Xiao Liu ◽  
Guo Ping Cao
Keyword(s):  
Phosphorus Removal ◽  
Microbial Growth ◽  
Steel Slag ◽  
Raw Material ◽  
Pore Former ◽  
Ammonium Hydrogen Carbonate ◽  
Sintering Time ◽  
Hydrogen Carbonate ◽  
Ammonium Hydrogen ◽  
Sintering Condition

Porous slag haycite for phosphorus removal was made from slag, as the main raw material, clay, as binder, and ammonium hydrogen carbonate, as a pore forming agent. And the influence of material ratio and sintering condition were investigated. The best ratio of steel slag: Clay: ammonium hydrogen carbonate was 53.5%:42.5%:4% as ascertained, and the best sintering temperature 800°C, sintering time 60min. The porosity of slag haycite was 2 times more than original slag, and the specific surface area was increased evidently, thus very conducive to microbial growth.

scholarly journals Fabrication of Dy2O3 Transparent Ceramics by Vacuum Sintering Using Precipitated Powders

2020 ◽  
Vol 7 (1) ◽  
pp. 6
Author(s):  
Dianjun Hu ◽  
Xin Liu ◽  
Ziyu Liu ◽  
Xiaoying Li ◽  
Feng Tian ◽  
...  
Keyword(s):  
Near Infrared ◽  
Optical Quality ◽  
Precipitation Method ◽  
Infrared Range ◽  
Transparent Ceramics ◽  
Vacuum Sintering ◽  
Hydrogen Carbonate ◽  
Ammonium Hydrogen ◽  
Liquid Precipitation ◽  
Near Infrared Range

As a kind of promising material for a Faraday isolator used in the visible and near infrared range, Dy2O3 transparent ceramics were prepared by vacuum sintering from the nano-powders synthesized by the liquid precipitation method using ammonium hydrogen carbonate as precipitant with no sintering aids. The synthesized precursor was calcinated at 950 °C–1150 °C for 4 h in air. The influences of the calcination temperature on the morphologies and phase composition of Dy2O3 powders were characterized. It is found that the Dy2O3 powder calcinated at 1000 °C for 4 h is superior for the fabrication of Dy2O3 ceramics. The Dy2O3 transparent ceramic sample prepared by vacuum sintering at 1850 °C for 10 h, and subsequently with air annealing at 1400 °C for 10 h, from the 1000 °C-calcined Dy2O3 powders, presents the best optical quality. The values of in-line transmittance of the optimal ceramic specimen with the thickness of 1.0 mm are 75.3% at 2000 nm and 67.9% at 633 nm. The Verdet constant of Dy2O3 ceramics was measured to be −325.3 ± 1.9 rad/(T·m) at 633 nm, about 2.4 times larger than that of TGG (Tb3Ga5O12) single crystals.

Structure of ammonium hydrogen succinate above and below the phase transition around 170K

1996 ◽  
Vol 52 (2) ◽  
pp. 323-327 ◽  
Author(s):  
A. Hirano ◽  
Y. Kubozono ◽  
H. Maeda ◽  
H. Ishida ◽  
S. Kashino
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Hydrogen Bonds ◽  
Order Phase Transition ◽  
Space Group ◽  
X Ray ◽  
Ammonium Hydrogen ◽  
Significant Change ◽  
Short Hydrogen Bonds ◽  
Second Order Phase Transition

For crystals of ammonium hydrogen succinate it is known that the space group is P{\bar 1} with Z = 2 at 293 K and the second-order phase transition occurs around 170 K. X-ray crystal structure analyses above and below 170 K have been carried out in order to study the change in mode of short hydrogen bonds between the hydrogen succinate ions. The space group was determined to be P{\bar 1} at 150 and 190 K by structure analysis. No ordering of the H-atom positions in the short hydrogen bonds occurs by the phase transition. The hydrogen bonds show a decrease in the O...O distances with a decrease in temperature from 290 to 190 K, but no significant change in the geometries between 190 and 150 K. Disorder of the NH4 + ion is not observed at 297, 190 and 150 K. Significant change through the phase transition is found only in the geometry of one of the N—H...O hydrogen bonds between ammonium and hydrogen succinate ions.

scholarly journals Crystal structure of poly[[di-μ3-acetato-tetraaquabis(μ2-cyclohexane-1,4-dicarboxylato)dilanthanum(III)] dihydrate]

2017 ◽  
Vol 73 (12) ◽  
pp. 1926-1930
Author(s):  
R. Drisya ◽  
U. S. Soumya Mol ◽  
P. R. Satheesh Chandran ◽  
M. Sithambaresan ◽  
M. R. Sudarsankumar
Keyword(s):  
Crystal Structure ◽  
Coordination Mode ◽  
Three Dimensional ◽  
Raw Material ◽  
Water Molecules ◽  
Supramolecular Network ◽  
Formula Unit ◽  
Remarkable Feature ◽  
Two Component ◽  
Coordinated Water

The title compound, {[La2(CH3COO)2(C8H10O4)2(H2O)4]·2H2O}nor [La2(ac)2(e,a-cis-1,4-chdc)2(H2O)4]·2H2O, whereacis acetate and 1,4-chdc is cyclohexane-1,4-dicarboxylate anion, is a binuclear lanthanum(III) complex. Each metal atom is decacoordinated by four O atoms from two distinct 1,4-chdc2−ligands, four O atoms from three acetate groups and two O atoms from coordinated water molecules to form a distorted bicapped square-antiprismatic geometry. Two non-coordinated water molecules are also present in the formula unit. The most remarkable feature of this compound is that it possesses a onlycisconformation for cyclohexane-1,4-dicarboxylic acid, although the raw material consists of a mixture ofcisandtransisomers. The μ3-η2:η2coordination mode of the bridging acetate group and the flexible dicarboxylate fragments of 1,4-chdc2−results in the formation of infinite two-dimensional lanthanide–carboxylate layers within the crystal structure. The directionality of strong intermolecular O—H...O and weak C—H...O interactions provides robustness to the layers, which leads to the construction of a three-dimensional supramolecular network. The crystal studied was refined as a two-component twin.

DEVELOPMENT OF A METHOD FOR QUANTITATIVE DETERMINATION OF THE AMOUNT OF FLAVONOIDS IN TRIPLEUROSPERMUM INODORUM’S FLOWERS

2021 ◽  
pp. 157-166
Author(s):  
Blinova O.L. ◽  
Gileva A.A. ◽  
Hlebnikov A.V. ◽  
Belonogova V.D. ◽  
Turyshev A.Y.
Keyword(s):  
Quantitative Determination ◽  
Aluminum Chloride ◽  
Chloride Solution ◽  
Uv Spectra ◽  
Raw Material ◽  
Spectral Studies ◽  
Scientific Medicine ◽  
Differential Spectrophotometry ◽  
The Stability

Chamomilla recutita is used in scientific medicine. Tripleurospermum inodorum (L.) Sch. Bip. is widely spread among possible impurities of Chamomilla recutita (L.) Rauschert. This plant is perspective for establishment into scientific medicine but it can’t change Chamomilla recutita (L.) Rauschert. Purpose of research: development of a method for the quantitative determination of the amount of flavonoids in terms of rutin in Tripleurospermum inodorum’s flowers using differential spectrophotometry. Materials and methods. The samples prepared in different parts of Russia were used as objects of research. (2017 – 2020). Spectral studies were carried out in the wavelength range of 350-430 nm with a step of 1 nm using a spectrophotometer SF-2000. Results. To determine the analytical wavelength, the UV spectra of alcohol extraction of Tripleurospermum inodorum’s flowers were studied. Maximum of absorption was noticed at wavelength 370 nm. The differential spectrum of the same extraction with an aluminum chloride solution of 2% in 96% alcohol has a maximum at a length of 410±2 nm, which coincides with the maximum of the Standard Sample (SS) of rutin. The largest number of flavonoids is extracted by 70% alcohol. The maximum optical density and the highest output of the number of flavonoids from the raw material is observed at a degree of grinding of 2 mm with a single extraction for 60 minutes. In the conditions of complexation, the optimal ratio of the volume of the test solution and aluminum chloride with a solution of 2% in 96% alcohol is the ratio of 1:1. The stability of the complex with an aluminum chloride solution of 2% in 96% alcohol is observed in 40 minutes after the start of the reaction and retains it for 30 minutes. Findings. The method is developed and the parameters of the quantitative determination of the amount of flavonoids in Tripleurospermum inodorum flores are determined in terms of rutin using differential spectrophotometry.

Microhardness and Crystal Structure of Iron Films Electrodeposited from Iron (II) Chloride Solution

1995 ◽  
Vol 73 (1) ◽  
pp. 31-33 ◽  
Author(s):  
Shun-ichi Yoshimura ◽  
Sachio Yoshihara ◽  
Takashi Shirakashi ◽  
Ei-ichi Sato
Keyword(s):  
Crystal Structure ◽  
Chloride Solution ◽  
Iron Films
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