Influence of pH Values on the Morphology and Down-Conversion Luminescence Properties of Zinc Tungstate Micro Nano Crystal Synthesized by a Hydrothermal Method

2014 ◽  
Vol 599-601 ◽  
pp. 58-62 ◽  
Author(s):  
Hui Wang ◽  
Lian Li Liu ◽  
Bing Hou ◽  
Jun Jiao Kou ◽  
Li Li Wang
Keyword(s):  
Hydrothermal Method ◽  
Ph Value ◽  
Raw Materials ◽  
Luminescent Properties ◽  
Complexing Agent ◽  
Excitation Wavelength ◽  
Ph Values ◽  
Nano Crystal ◽  
Conversion Spectrum ◽  
Down Conversion

As the raw materials of Na2WO4•2H2O and ZnSO4•7H2O, ZnWO4 micron spheres and nanorods were synthesized with CH3COOH as the complexing agent by a hydrothermal method at 180 °C for 24h. We analyzed the effect of different pH values in reaction solutions on phase compositions, morphologies and luminescent properties of the ZnWO4 powders. The as-synthesized products were characterized by XRD and SEM. The down-conversion spectrum was measured with spectrophotometer under the excitation wavelength of 291nm. The results indicated that there was a wide emission peaks at 400~550nm. The luminescent intensities of ZnWO4 nanorods synthesized at pH value of 9, 10 and 11 were much stronger than that of ZnWO4 micron spheres synthesized between the pH values of 4 to 8.

Preparation of Xonotlite Whiskers from Carbide Slag

2010 ◽  
Vol 434-435 ◽  
pp. 787-789
Author(s):  
Fei Liu ◽  
Ling Ke Zeng ◽  
Jian Xin Cao ◽  
Qian Lin ◽  
Jing Li
Keyword(s):  
Ph Value ◽  
Raw Materials ◽  
Removal Rate ◽  
Hydrothermal Conditions ◽  
Hydrothermal Route ◽  
Synthesis Conditions ◽  
Ph Values ◽  
Carbide Slag ◽  
Xrd Techniques ◽  
First Time

Carbide slag was used as raw materials for the first time to prepare xonontlite whiskers via a hydrothermal route without special instruments and synthesis conditions. And the effect of pH value of emulsion of carbide slag and hydrothermal conditions on removal rate of impurities, morphology and crystallinity of synthesized xonotlite whiskers were explored using ICP, SEM and XRD techniques. The results indicated that the carbide slag after purification could be used to prepare xonotlite whiskers, and different pH values of emulsion of carbide slag had great impact on the removal rate of impurities and morphology of xonotlite whiskers. Xonotlite whiskers with 20-40 μm in length and 100-500 nm in diameter were hydrothermally synthesized at 230 °C for 15 h with using silicic acid as kiesel material.

Two three-dimensional cadmium(ii) coordination polymers based on 5-amino-tetrazolate and 1,2,4,5-benzenetetracarboxylate: the pH value controlled syntheses, crystal structures and luminescent properties

CrystEngComm ◽  
2014 ◽  
Vol 16 (21) ◽  
pp. 4633-4640 ◽  
Author(s):  
Di-Chang Zhong ◽  
Wen-Guan Lu ◽  
Ji-Hua Deng
Keyword(s):  
Crystal Structures ◽  
Coordination Polymers ◽  
Ph Value ◽  
Three Dimensional ◽  
Luminescent Properties ◽  
Ph Values

Two 3D cadmium(ii) coordination polymers have been prepared by controlling the pH values of the reaction mixture.

Effects of pH Values on the Structure, Composition and Luminescence of CaWO4:Tb3+ Thin Films

2012 ◽  
Vol 531-532 ◽  
pp. 204-207
Author(s):  
Lian Ping Chen ◽  
Yuan Hong Gao
Keyword(s):  
Thin Films ◽  
Ph Value ◽  
Electrochemical Techniques ◽  
Luminescent Properties ◽  
X Ray Diffraction ◽  
Step Method ◽  
X Ray ◽  
Ph Values ◽  
Effects Of Ph ◽  
Rare Earth Doped

It is hardly possible to obtain rare earth doped CaWO4thin films directly through electrochemical techniques. A two-step method has been proposed to synthesize Tb3+-doped CaWO4thin films. X-ray diffraction, energy dispersive X-ray analysis, spectrophotometer were used to characterize their phase, composition and luminescent properties. Results reveal that Tb3+-doped CaWO4films have a tetragonal phase. The ratio of n(Tb)/[n(Ca)+n(Tb)+n(Na)] decreases with the increase of pH value of TbCl3solutions. When the pH value (adjusted by NaOH) is higher than 5, Na element has been detected in CaWO4:Tb3+thin films. Based on the analysis on the composition and luminescence, it can be concluded that the pH value of TbCl3solutions must be no higher than 9.1, otherwise, no Tb3+-doped CaWO4thin films can be obtained. Under the excitation of 237 nm, sharp emission peaks at 543 and 489 nm have been observed for Tb3+-doped CaWO4:Tb3+thin films.

Effect of pH Value on Preparation of La2CuO4 Microcrystallites Synthesized by Sol-Gel Process

2012 ◽  
Vol 512-515 ◽  
pp. 231-234 ◽  
Author(s):  
Yi Feng Li ◽  
Jian Feng Huang ◽  
Li Yun Cao ◽  
Jian Peng Wu
Keyword(s):  
Optical Band Gap ◽  
Ph Value ◽  
Raw Materials ◽  
Sol Gel ◽  
Complexing Agent ◽  
Solution Ph ◽  
Crystallization Property ◽  
Water As Solvent ◽  
Sol Gel Process ◽  
Single Sphere

La2CuO4 crystallites were prepared via a sol-gel process using lanthanum nitrate and cupric nitrate as raw materials, distilled water as solvent, citric acid as complexing agent and ammonia to control the pH value. The as-prepared La2CuO4 crystallites were characterized by XRD, FESEM, TEM and UV-Vis spectra. Results show that the crystallization property of La2CuO4 crystallites increases firstly and then decreases with increasing of the solution pH value from 1.0 to 2.5, but all of the samples exhibit single sphere-like morphology. It is found that when the solution pH value is controlled at 2.0, the grains display uniform distribution and the size ranges from 100nm to120nm after sintering at 600°C for 2 hours. The optical band gap of the as-prepared La2CuO4 crystallites is calculated to be 1.38eV.

The pH Influence on the Preparation of Hollow Fe2O3 Spheres by Hydrothermal Method

2013 ◽  
Vol 669 ◽  
pp. 119-123
Author(s):  
Liang Qiao ◽  
Jie Chen ◽  
Li Qiang Jiang ◽  
Jing Wu Zheng
Keyword(s):  
Hydrothermal Method ◽  
Hollow Sphere ◽  
Ph Value ◽  
Block Structure ◽  
Raw Materials ◽  
Hollow Spheres ◽  
Structure Form ◽  
Ph Influence ◽  
Influence Of Ph

In this paper Fe2O3 precursor coating on the surface of carbon balls was prepared by hydrothermal method using Fe(NO3)3·9H20 and glucose as the raw materials. After calcination Fe2O3 hollow sphere could be achieved. The influence of pH value on the preparation of hollow Fe2O3 spheres was studied using XRD and SEM respectively. The results show that the pH value has no effect on the formation of Fe2O3 phase, but has a giant influence on the morphology of the hollow spheres. The Fe2O3 hollow spheres were achieved when the pH value was between 3 and 7. The particles with sheet and block structure form when pH7. The mechanism was studied, When 3

scholarly journals An application of classical and instrumental methods of analysis in quality control of beer

2015 ◽  
Vol 60 (4) ◽  
pp. 477-503
Author(s):  
Milos Rajkovic ◽  
Ivana Sredovic-Ignjatovic ◽  
Ljubisa Ignjatovic ◽  
Viktor Nedovic ◽  
Slobodan Prijic
Keyword(s):  
Ph Value ◽  
Raw Materials ◽  
Chloride Ions ◽  
Chromatography Method ◽  
Ph Values ◽  
Phosphate Ions ◽  
Hydrogen Carbonate ◽  
City Water ◽  
Safety Of Drinking Water ◽  
Instrumental Methods

In order to control the quality of beer and raw materials for production of beer in Belgrade Beer Industry (BIP), water is analyzed (city, technological and demineralized water). Measurements of pH values indicated the increased pH values in the sample of tehnological water, which had no impact on wort hopping, since the tested samples of wort, young beer and final product had a pH value within the expected range. After processing city water, a sample of tehnological water was found with increased carbonate hardness, which is caused by the increased content of sodium hydrogen carbonate. Analysing the titration alkalinity, titration acidity and buffering power, it was found that the alkalinity was decreasing which is in accordance with the determination of pH values of wort and beer samples (young beer and final product). Analyzing the content of anions and cations in the examined water samples, it has been shown that the concentration of these examinated anions (Cl-, NO3 -, SO4 2- and PO4 3-) and cations (NH4 +, Na+, K+, Ca2+, Mg2+) are within the limits prescribed by the Regulations on hygienic safety of drinking water, and thus by the Regulations of quality and other requirements for beer. The contents of anions in wort and beer samples (young beer and final product) were determined by ion chromatography method. The contents of sulphate and nitrate ions were within the recommended limits. The concentration of chloride ions was above 150 mg/dm3, which may have an impact on the sensory properties of beer, while changes in the content of phosphate ions were insignificant.

scholarly journals Change of acidity of the environment in the process of decomposition of apatitis sulfuric acid

2019 ◽  
Vol 81 (1) ◽  
pp. 325-328
Author(s):  
R. F. Sabirov ◽  
A. F. Makhotkin ◽  
Yu. N. Sakharov
Keyword(s):  
Sulfuric Acid ◽  
Phosphoric Acid ◽  
Ph Value ◽  
Raw Materials ◽  
Batch Reactor ◽  
Glass Electrode ◽  
Monocalcium Phosphate ◽  
Rapid Decomposition ◽  
Ph Values ◽  
Phosphoric Acids

An experimental study of the decomposition process of Kovdorsky apatite with certain particle sizes, in a 1 dm3 batch reactor with stirring of the reaction mixture, initial phosphoric acid concentration 17% by weight, in the system: Apatite-H3PO4 – H2SO4-H2O. Sulfuric acid was introduced in stoichiometric amount at the beginning of the process. The process was carried out at a ratio L:S 2.5:1, at a temperature of 78– 82 °C. The process was monitored by the method of joint determination of sulfuric and phosphoric acids by titrimetric analysis of the composition of the reaction mixture in the presence of methyl orange, and then phenolphthalein. Determined the concentration of phosphoric acid, the concentration of excess or deficiency of sulfuric acid and the concentration of monocalcium phosphate gel were determined. The acidity of the reaction mixture was recorded according to the indications of a Ph-meter (pH-105 MA with a combined glass electrode – ESK-10603). In the system: Apatite-H3PO4-H2SO4-H2O, when analyzing the obtained experimental values of these parameters, it was shown that during the process the pH of the reaction mixture rises to pH 6.3 for about 30 minutes, and then decreases to pH 4.5–5. Comparison of the dependence of pH values on the concentration of sulfuric acid in an aqueous solution of phosphoric acid and the pH values of the reaction mixture with the corresponding concentrations of sulfuric and phosphoric acids shows that the pH value of the reaction mixture is determined by the presence in the mixture between weft product - monocalcium phosphate gel. The process of decomposition of apatite in the system Apatite-H3PO4-H2SO4-H2O proceeds in several stages. At the beginning, a rapid decomposition of phosphate raw materials with phosphoric acid and a corresponding change in the pH of the reaction mixture, associated with the accumulation of monocalcium phosphate in solution, takes place. Then there is a slow decomposition of monocalcium phosphate with sulfuric acid and a corresponding decrease in pH to 4.5–5. The pH value at the end of the process is determined by the physicochemical properties of phosphoric acid present in the reaction mixture. At all stages of the process there is a constant increase in the concentration of phosphoric acid associated with the decomposition of monocalcium phosphate gel.

Influence of pH on the Morphology of Yttrium Oxide Hydroxide Nitrate Nanocrystal

2007 ◽  
Vol 336-338 ◽  
pp. 2176-2178 ◽  
Author(s):  
Zhang Lian Hong ◽  
Huang Guo ◽  
Li Xia Peng ◽  
Min Quan Wang
Keyword(s):  
Hydrothermal Method ◽  
Yttrium Oxide ◽  
Ph Value ◽  
High Ph ◽  
Ph Values ◽  
Starting Solution ◽  
Primary Mechanism ◽  
Oxide Hydroxide ◽  
Influence Of Ph

Yttrium oxide hydroxide nitrate (Y4O(OH)9NO3), which was prepared by polyvinyl alcoholassisted hydrothermal method from the Y(NO3)3 and KOH starting solution, was characterized by XRD and FE-SEM. The results revealed that pH value of the starting solution is an important factor which determines the morphology and size of the products. The obtained products varied from lamina microprisms to circular nanorods when the pH value increased from 7.0 to 8.0. In the high pH value above 8.0, the size of nanorods decreased with increasing pH value. A primary mechanism was proposed to explain the evolution of morphology and size of Y4O(OH)9NO3 products prepared under various pH values.

scholarly journals The pH Effect on the Growth of Hexagonal and Monoclinic Hydroxyapatite Synthesized by the Hydrothermal Method

2020 ◽  
Vol 2020 ◽  
pp. 1-10
Author(s):  
S. López-Ortiz ◽  
D. Mendoza-Anaya ◽  
D. Sánchez-Campos ◽  
M. E. Fernandez-García ◽  
E. Salinas-Rodríguez ◽  
...  
Keyword(s):  
Hydrothermal Method ◽  
Growth Habit ◽  
Ph Value ◽  
Hexagonal Phase ◽  
Ph Effect ◽  
Rietveld Analysis ◽  
Crystalline Phases ◽  
Ph Values ◽  
Crystallographic Characteristics

Summary. In the present work, a study of H+ effects on the microstructure and morphology of hydroxyapatite synthesized by the hydrothermal method is reported. The synthesis was realized with pH values of 10, 9.6, 9, 8, and 7. To know the particle size distribution, growth habit, chemical composition, and crystalline phases present, SEM-EDS, XRD, AFM, and FTIR spectroscopy techniques were used and completed with Rietveld analysis. The obtained results showed an important effect of H+ on the morphological and crystallographic characteristics of the hydroxyapatite, demonstrating that the shape and nanoparticle size, as well as the number of crystalline phases, can change depending on the pH during the synthesis. It was observed that there is an increase in the formation of the monoclinic phase and a decrease of the hexagonal phase when the pH value diminishes from 9.6 to 7. The crystallite size also decreases from 46.69 to 19.56 nm. An explanation of the role of pH on the final characteristics of the hydroxyapatite was related to the amount of H+ and OH- ions, and it was included in this work.

Synthesis and Luminescent Properties of Europium Doped Zirconia Nanoparticles

2020 ◽  
Vol 985 ◽  
pp. 177-184
Author(s):  
Hoang Viet Nguyen ◽  
Van Huan Pham ◽  
Vuong Hung Pham
Keyword(s):  
High Temperature ◽  
Solid State ◽  
Hydrothermal Method ◽  
Ph Value ◽  
Luminescent Properties ◽  
Solid State Lighting ◽  
Hydrothermal Time ◽  
Hydrothermal Temperature ◽  
Potential Applications ◽  
Zirconia Nanoparticles

This paper reports a tunable luminescence of europium (Eu 3+) doped zirconia (ZrO2) nanoparticles as a function of hydrothermal temperature, europium concentrations, time and pH value. The nano-sized Eu doped ZrO2 (Eu:ZrO2) particle was synthesized by hydrothermal method at the temperature of 200 °C and time up to 48 h. The nano-sized Eu:ZrO2 particles have a diameter of about 10 nm. The luminescent properties of nano-sized Eu:ZrO2 particle was enhanced in the sample when high temperature, high Eu 3+ concentration and prolonging hydrothermal time were used at pH 7. These results suggest the use of Eu:ZrO2 nanoparticles followed by thermal annealing in tuning the luminescence of Eu:ZrO2 nanoparticles which have potential applications as phosphors in solid state lighting.

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