scholarly journals Effect of Preparation Method and Ni2+ Substitution on the Structural, Thermal, and Optical Properties of Nanocrystalline Lanthanum Zirconate Pyrochlore

Crystals ◽  
2021 ◽  
Vol 11 (12) ◽  
pp. 1463
Author(s):  
Fahad Alharthi ◽  
Rizwan Wahab ◽  
Salim Manoharadas ◽  
Basel F. Alrayes ◽  
Naushad Ahmad
Keyword(s):  
Optical Properties ◽  
Solid State ◽  
Sol Gel ◽  
Chemical Properties ◽  
Bet Surface Area ◽  
Solid State Method ◽  
Lanthanum Zirconate ◽  
Ft Ir ◽  
Xrd Patterns ◽  
Physical And Chemical

In order to establish the effective application of materials in a particular area, it is important to first investigate the physical and chemical properties, such as the crystallinity, structure, and the optical and surface properties. The objective of the present study is to fabricate thermally stable pyrochlore oxides, namely, lanthanum zirconate (La2Zr2O7, LZ) and Ni-doped lanthanum zirconate (La2Zr1.5Ni0.5O7, LZN) by the solid-state and sol-gel methods. The effects of the preparation and substitution of Zr4+ by Ni2+ for the resulting nanocrystalline samples were characterized in terms of structure, purity, porosity, the thermal and optical properties, and photoluminescence by different techniques: XRD, FT-IR, BET, EDS, TG-DTG, UV-Vis-DRS, and PL. The XRD results confirm that the pyrochlores prepared via the sol-gel method (LZ-sg and LZN-sg) had a cubic unit-cell lattice, whereas the solid-state method (LZ-s and LZN-s) had impurities of the oxides. The XRD patterns, LZ-sg and LZN-sg, were further treated with the Rietveld technique. The textural measurements reveal that LZ-sg had a higher BET surface area compared to LZN-sg. In addition, the substitution of Zr4+ by the Ni2+ ion provides rational evidence for the improvement in the oxygen mobility, as well as the optical and photoluminescence properties through the lowering of the optical band energy and the electron–hole pairs.

Preparation of Y2Ti2O7 Nanocrystal by Sol-Gel Method and its Characterization

2010 ◽  
Vol 97-101 ◽  
pp. 2175-2179 ◽  
Author(s):  
Zhong Sheng Chen ◽  
Wei Ping Gong ◽  
Teng Fei Chen ◽  
Guo Xuan Xiong ◽  
Guo Lin Huang
Keyword(s):  
Citric Acid ◽  
Solid State ◽  
Sol Gel ◽  
Bet Surface Area ◽  
Tetrabutyl Titanate ◽  
Preparation Process ◽  
Excellent Activity ◽  
Dta Analysis ◽  
Ft Ir ◽  
Average Size

Y2Ti2O7 nanocrystals have been prepared at the calcining temperature of 700-900°C by using tetrabutyl titanate as starting materials and citric acid as chelator. The preparation process was monitored by XRD, FT-IR and TG-DTA analysis. Compared with traditional solid state reaction (SSR), the present used methods can prepare can Y2Ti2O7 nanocrystals at a relatively low temperature (750°C) and with shortened reaction time (dwelling time of 1 h). The morphology and averge size of as-prepared products were analysized by FESEM. Results showed that the as-prepared Y2Ti2O7 with good dispersibility and narrow size-distritution were all sphere-like; the average size was about 40-50 nm, Also, the obtained products had higher BET surface area (32 m2/g). These properties are very helpful for a photocatalytic catalyst to achieve excellent activity.

scholarly journals The Influence Of NO/O2 On The NOx Storage Properties Over A Pt-Ba-Ce/γ-Al2O3 Catalyst

2019 ◽  
Vol 17 (1) ◽  
pp. 1459-1465
Author(s):  
Xuedong Feng ◽  
Jing Yi ◽  
Peng Luo
Keyword(s):  
Sol Gel ◽  
Chemical Properties ◽  
No Oxidation ◽  
Test Results ◽  
X Ray Diffraction ◽  
Storage Performance ◽  
Transmission Electron ◽  
Temperature Programmed ◽  
Physical And Chemical ◽  
Al2o3 Catalyst

AbstractWith the purpose of studying the influence of NO/O2 on the NOx storage activity, a Pt-Ba-Ce/γ-Al2O3 catalyst was synthesized by an acid-aided sol-gel method. The physical and chemical properties of the catalyst were characterized by X-ray diffraction (XRD) and Transmission Electron Microscope (TEM) methods. The results showed that the composition of the catalyst was well-crystallized and the crystalline size of CeO2 (111) was about 5.7 nm. The mechanism of NO and NO2 storage and NOx temperature programmed desorption (NO-TPD) experiments were investigated to evaluate the NOx storage capacity of the catalyst. Pt-Ba-Ce/γ-Al2O3 catalyst presented the supreme NOx storage performance at 350℃, and the maximum value reached to 668.8 μmol / gcat. Compared with O2-free condition, NO oxidation to NO2 by O2 had a beneficial effect on the storage performance of NOx. NO-TPD test results showed that the NOx species stored on the catalyst surface still kept relatively stable even below 350℃.

Photoluminescence Properties of Ca3Si2O7: Pr3+ Orange-Red Phosphors Prepared by High-Temperature Solid-State Method

2018 ◽  
Vol 73 (6) ◽  
pp. 555-558 ◽  
Author(s):  
Zhi-Qing Peng ◽  
Rong Chen ◽  
Wen-Lin Feng
Keyword(s):  
Crystal Structure ◽  
High Temperature ◽  
Solid State ◽  
Solid State Method ◽  
Light Emitting ◽  
Light Emitting Devices ◽  
Red Phosphors ◽  
Typical Sample ◽  
State Method ◽  
Xrd Patterns

AbstractNovel luminescent materials Ca3-xSi2O7: xPr3+ were successfully prepared by the high-temperature solid-state method. The crystal structure, morphology, and optical spectrum were characterised by X-ray diffraction (XRD), scanning electron microscopy (SEM), and spectroscopy, respectively. The XRD patterns of the samples indicate that the crystal structure is monoclinic symmetry. The SEM shows that the selected sample has good crystallinity although its appearance is irregular and scalelike. The peak of the excitation spectrum of the sample is located at around 449 nm, corresponding to 3H4→3P2 transition of Pr3+. The peak of the emission spectrum of the sample is situated at around 612 nm which is attributed to 3P0→3H6 transition of Pr3+, and the colour is orange-red. The optimum concentration for Pr3+ replaced Ca2+ sites in Ca3Si2O7: Pr3+ is 0.75 mol%. The lifetime (8.48 μs) of a typical sample (Ca2.9925Pr0.0075)Si2O7 is obtained. It reveals that orange-red phosphors Ca3-xSi2O7: xPr3+ possess remarkable optical properties and can be used in white light emitting devices.

Structuring-agent role in physical and chemical properties of Mo/SiO2 catalysts by sol-gel method

2018 ◽  
Vol 89 (2) ◽  
pp. 416-425
Author(s):  
William Giovanni Cortés-Ortiz ◽  
Alexander Baena-Novoa ◽  
Carlos Alberto Guerrero-Fajardo
Keyword(s):  
Sol Gel ◽  
Chemical Properties ◽  
Physical And Chemical Properties ◽  
Gel Method ◽  
Sol Gel Method ◽  
Physical And Chemical ◽  
And Chemical Properties

scholarly journals Effect of Saturated Steam Heat Treatment on Physical and Chemical Properties of Bamboo

Molecules ◽  
2020 ◽  
Vol 25 (8) ◽  
pp. 1999 ◽  
Author(s):  
Qiuyi Wang ◽  
Xinwu Wu ◽  
Chenglong Yuan ◽  
Zhichao Lou ◽  
Yanjun Li
Keyword(s):  
Heat Treatment ◽  
Moisture Content ◽  
Treatment Time ◽  
Flexural Modulus ◽  
Initial Moisture Content ◽  
Chemical Properties ◽  
Saturated Steam ◽  
Xrd Patterns ◽  
Physical And Chemical ◽  
Steam Heat

The aim of this study was to investigate the effects of the heat treatment time and initial moisture content of bamboo on the corresponding chemical composition, crystallinity, and mechanical properties after saturated steam heat treatment at 180 °C. The mechanism of saturated steam heat treatment of bamboo was revealed on the micro-level, providing a theoretical basis for the regulation of bamboo properties and the optimization of heat treatment process parameters. XRD patterns of the treated bamboo slices were basically the same. With the increase in the initial moisture content of bamboo, the crystallinity of bamboo increased first and then decreased after treatment. Due to the saturated steam heat treatment, the content of cellulose and lignin in bamboo slices increased while the content of hemicellulose decreased, but the content of cellulose in bamboo with a 40% initial moisture content increased first and then decreased. The shear strength of treated bamboo changed little within 10 min after saturated steam heat treatment, and then decreased rapidly. During the first 20 min with saturated steam heat treatment, the compressive strength, flexural strength, and flexural modulus of elasticity of the treated bamboo increased, and then decreased.

scholarly journals A rapid microwave synthesis of green-emissive carbon dots with solid-state fluorescence and pH-sensitive properties

2018 ◽  
Vol 5 (7) ◽  
pp. 180245 ◽  
Author(s):  
Tingting Yu ◽  
Haijiao Wang ◽  
Chongzheng Guo ◽  
Yanli Zhai ◽  
Jianzhou Yang ◽  
...  
Keyword(s):  
Solid State ◽  
Photoelectron Spectroscopy ◽  
Phthalic Acid ◽  
Chemical Properties ◽  
Carbon Quantum Dots ◽  
Feed Ratio ◽  
Quantum Yields ◽  
Ph Sensing ◽  
Wavelength Emission ◽  
Physical And Chemical

The emerging carbon quantum dots (CQDs) have been attracting significant attention for their prominent fluorescence, excellent stability and outstanding biocompatibility. Here, we report a facile one-step synthesis of highly fluorescent CQDs by using phthalic acid and triethylenediamine hexahydrate as precursors through a simple microwave-assisted method. The reaction time needed is only 60 s, which is less time-consuming than most previous reports. The phthalic acid with a benzene ring can improve the photoluminescence properties of CQDs as it can provide foreign sp 2 conjugating units, and then finally result in long-wavelength emission. The synthesized CQDs were fully characterized by transmission electron microscopy, X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. Besides, the impacts of different freed ratio on physical and chemical properties of CQDs were investigated in detail. The prepared CQDs exhibited strong green fluorescence with a broad maximum emission wavelength. The quantum yields of the CQDs can reach 16.1% in aqueous solution and they were successfully used in cell imaging with good biocompatibility. Moreover, in solid state, the CQDs with the feed ratio of 1 : 0.5 showed a strong green–yellow fluorescence which may have great potential to fabricate optoelectronic devices. Furthermore, the prepared CQDs also showed high pH sensitivity and can act as a fluorescence nanosensor for pH sensing.

Properties of Nano-Hybrid Sol-Gel Materials Synthesized from Colloidal Silica-Silane Containing Epoxy Silane

2007 ◽  
Vol 336-338 ◽  
pp. 2278-2281 ◽  
Author(s):  
Moon Kyong Na ◽  
Dong Pil Kang ◽  
Hoy Yul Park ◽  
Myeong Sang Ahn ◽  
In Hye Myung
Keyword(s):  
Contact Angle ◽  
Colloidal Silica ◽  
Flat Surface ◽  
Coating Layer ◽  
Sol Gel ◽  
Chemical Properties ◽  
Coating Films ◽  
Initial Stage ◽  
Physical And Chemical ◽  
And Chemical Properties

Three kinds of colloidal silica (CS)/silane sol solutions were synthesized in variation with parameters such as different acidity and reaction time. Sol solutions were prepared from HSA CS/ methyltrimethoxysilane (MTMS), LS CS/MTMS and LS CS/MTMS/γ -Glycidoxypropyltri methoxysilane (ES) solutions. In order to understand their physical and chemical properties, sol-gel coating films were fabricated on glass. Coating films on glass, obtained from LS/MTMS sol, had high contact angle, also, much enhanced flat surface in the case of LS/MTMS sol was observed in comparison with HSA/ MTMS sol. From all sol-gel solutions, seasoning effect of for enhancing properties of sol-gel coating layer on glass was observed while such sol-gel solutions were left for 7days. In initial stage of sol-gel reaction, all most of sol solutions used in this work seem to be unstable, formation of coating films was a little hazy and rough. However, improved coating films as observed in 4days later. LS/MTMS/ES sol solutions were synthesized with ES, adding to LS/MTMS sol. Contact angle of LS/MTMS/ES sol-gel coating films decreased, since ES played a role in forming hydrophilic hydroxyl sol. The elastic portion of coating films prepared from LS/MTMS/ES sol increased with addition of ES, but thermal stability decreased a little.

scholarly journals Thermal Expansion of MgTiO3 Made by Sol-Gel Technique at Temperature Range 25–890 °C

Crystals ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 887 ◽  
Author(s):  
Tamir Tuval ◽  
Brian A. Rosen ◽  
Jacob Zabicky ◽  
Giora Kimmel ◽  
Helena Dilman ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Solid State ◽  
Sol Gel ◽  
Lattice Parameters ◽  
Published Data ◽  
Temperature Structure ◽  
Solid State Method ◽  
Synthesis Technique ◽  
Thermal Expansion Coefficients ◽  
Reported Data

MgTiO3 is a material commonly used in the industry as capacitors and resistors. The high-temperature structure of MgTiO3 has been reported only for materials synthesized by the solid-state method. This study deals with MgTiO3 formed at low temperatures by the sol-gel synthesis technique. Co-precipitated xerogel precursors of nanocrystalline magnesium titanates, with Mg:Ti ratio near 1:1, were subjected to thermal treatment at 1200 °C for 5 h in air. A sample with fine powders of MgTiO3 (geikielite) as a major phase with Mg2TiO4 (qandilite) as a minor phase was obtained. The powder was scanned on a hot-stage X-ray powder diffractometer at temperatures between 25 and 890 °C. The lattice parameters and the atomic positions of the two phases were determined as a function of temperature. The thermal expansion coefficients of the geikielite were derived and compared with previously published data using the solid-state synthesis technique, providing insights on trends in materials properties at elevated temperature as a function of synthesis. It was found that the deviation of the present results in comparison to previously reported data do not originate from the method of synthesis but rather from the fact that there is an asymmetric solubility gap in geikielite. The lattice parameters of this study present the property of stoichiometric MgTiO3 and are compared to previously reported non-stoichiometric MgTiO3 with excess of Ti. The values of lattice parameters of the non-stoichiometric versus temperature of geikielite found the same for both solid-state reaction and sol-gel products.

Impact of solid-state photochemical [2+2] cycloaddition on coordination polymers for diverse applications

2020 ◽  
Vol 49 (28) ◽  
pp. 9556-9563 ◽  
Author(s):  
Samim Khan ◽  
Basudeb Dutta ◽  
Mohammad Hedayetullah Mir
Keyword(s):  
Solid State ◽  
Coordination Polymers ◽  
Chemical Properties ◽  
Physical And Chemical Properties ◽  
Physical And Chemical ◽  
Fine Tune ◽  
And Chemical Properties

This Frontier article highlights the advancement of [2+2] photocycloaddition reactions within coordination polymers to fine tune their diverse physical and chemical properties.

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