scholarly journals Tuning Anatase-Rutile Phase Transition Temperature: TiO2/SiO2 Nanoparticles Applied in Dye-Sensitized Solar Cells

2019 ◽  
Vol 2019 ◽  
pp. 1-9 ◽  
Author(s):  
Billy N. Cardoso ◽  
Emerson C. Kohlrausch ◽  
Marina T. Laranjo ◽  
Edilson V. Benvenutti ◽  
Naira M. Balzaretti ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Surface Area ◽  
Phase Transition Temperature ◽  
Dye Sensitized Solar Cells ◽  
Rutile Phase ◽  
X Ray Diffraction ◽  
X Ray ◽  
Vis Spectroscopy ◽  
Molar Percent

TiO2/SiO2 nanoparticles with 3, 5, and 10 molar percent of silica, were synthesized by hydrothermal method and characterized by SEM, TEM, N2 adsorption-desorption isotherms, X-ray diffraction, and Raman and UV-Vis spectroscopy. While pristine TiO2 thermally treated at 500°C presents a surface area of 36 m2 g-1 (±10 m2 g-1), TiO2/SiO2 containing 3, 5, and 10 molar percent of silica present surface areas of 93, 124, and 150 m2 g-1 (±10 m2 g-1), respectively. SiO2 is found to form very small amorphous domains well dispersed in the TiO2 matrix. X-ray diffraction and Raman spectroscopy data show that anatase-to-rutile phase transition temperature is delayed by the presence of SiO2, enabling single-anatase phase photoanodes for DSSCs. According to the I×V measurements, photoanodes with 3% of SiO2 result in improved efficiency, which is mainly related to increased surface area and dye loading. In addition, the results suggest a gain in photocurrent related to the passivation of defects by SiO2.

X-ray Diffraction Topography of BaTiO3at Phase Transition Temperature

2009 ◽  
Vol 48 (9) ◽  
pp. 09KF01 ◽  
Author(s):  
Yasuhiro Yoneda ◽  
Yoshiki Kohmura ◽  
Yoshio Suzuki
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
X Ray Diffraction ◽  
X Ray

W-Doped VO2 (M) with Tunable Phase Transition Temperature

2013 ◽  
Vol 320 ◽  
pp. 483-487 ◽  
Author(s):  
Ming Li ◽  
Deng Bing Li ◽  
Jing Pan ◽  
Guang Hai Li
Keyword(s):  
Electron Microscopy ◽  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Variable Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Infrared Transmittance ◽  
Transmission Electron ◽  
Potential Applications

W-doped VO2 (B) nanoneedles were successfully synthesized by solgel combing with hydrothermal treatment, in which the polyethylene glycol (PEG) was used as both surfactant and reducing. The metastable VO2 (B) was completely transformed to thermochromic VO2 (M) after annealing at high purity N2 atmosphere. The DSC results exhibit a strong crystallographic transition, and the phase transition temperature of VO2 (M) can be reduced to about 38 °C by W-doping. Field emission scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and high-resolution transmission electron microscopy (HR-TEM) were used to characterize the morphology and crystalline structure of the samples. The variable-temperature infrared transmittance spectra of VO2 (M) demonstrate their potential applications in energy saving field.

scholarly journals The Effect of Cobalt Doping in Structural Phase Transition of SmFe1-xCoxAsO Measured by Low-temperature X-ray Diffraction

2012 ◽  
Vol 4 (3) ◽  
pp. 541-550 ◽  
Author(s):  
A. Khan ◽  
A. Rahman ◽  
S. Naher ◽  
H. Kaneko ◽  
Y. Yun ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Structural Phase Transition ◽  
Structural Transition ◽  
Critical Concentration ◽  
Structural Phase ◽  
Parent Compound ◽  
X Ray Diffraction ◽  
X Ray

The parent compound SmFeAsO shows structural phase transition from tetragonal to orthorhombic at the temperature TD = 144 K. In the compound SmFe1-xCoxAsO,  with increasing x the structural transition temperature TD and  SDW TN decreases and reaches 0 K at the critical concentration xc. The X-ray diffraction technique has been used here to study the structural phase transition temperature. It is observed that the (400) peak of the parent compound SmFeAsO splits into two peaks (400) and (040), when the temperature is lower than the structural transition temperature TD. The structural phase transition of Co doped compounds SmFe1-xCoxAsO has also been studied for x = 0, 0.01, 0.025 and 0.075. The phase transition temperature TD for SmFe0.99Co0.01AsO, SmFe0.975Co0.025AsO and SmFe0.925Co0.075AsO are 134 K, 118 K and 4 K, respectively. The phase diagram of TD versus lattice spacing reveals that the structural transition temperature decreases with shrinking lattice constant along c-axis similar to the decrease of the structural phase transition temperature with increasing Co concentration. The phase diagrams of   SmFe1-xCoxAsO and Sm(O1-xFx)FeAs show a similar nature.© 2012 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved.doi: http://dx.doi.org/10.3329/jsr.v4i3.10248 J. Sci. Res. 4 (3), 541-550 (2012)

scholarly journals Green synthesis of Ag/TiO2 Nanocomposite Assisted by Gambier Leaf (Uncaria gambir Roxb) Extract

2019 ◽  
Vol 22 (6) ◽  
pp. 250-255 ◽  
Author(s):  
Sry Wahyuni ◽  
Syukri Syukri ◽  
Syukri Arief
Keyword(s):  
Silver Nanoparticles ◽  
Green Synthesis ◽  
Diffuse Reflectance Spectroscopy ◽  
Irradiation Time ◽  
Rutile Phase ◽  
X Ray Diffraction ◽  
Silver Surface ◽  
X Ray ◽  
Synthesis Of Nanoparticles ◽  
Vis Spectroscopy

Studies of green synthesis of nanoparticles mediated by plants extract is extensively explored and studied in recent time due to eco-friendliness, cost-effectiveness, and use a minimum amount of toxic chemicals in the process of inorganic material synthesis. In this study, the immobilization of silver nanoparticles on the surface of titanium dioxide (TiO2) was carried out using Uncaria gambier Roxb. leaf extract as a silver ion (Ag+) reducing agent. The synthesized Ag/TiO2 nanocomposite was characterized by UV-Vis spectroscopy, X-ray diffraction (XRD), and Diffuse Reflectance Spectroscopy (DRS). The formation of silver nanoparticles was confirmed through UV-Vis spectroscopic analysis, which showed a silver surface plasmon resonance (SPR) band at 426 nm. The X-ray diffraction pattern shows that Ag can inhibit the transition of the anatase into rutile phase. The presence of Ag particles in TiO2 can increase the absorption ability from an initial wavelength of 407 nm to 438 nm. Based on the results of Rhodamin B degradation, it can be seen that Ag/TiO2 has a higher photocatalytic activity than bare TiO2 with 99% percent degradation at 120 minutes of irradiation time.

scholarly journals Effect of Zr Doping on the Magnetic and Phase Transition Properties of VO2 Powder

Nanomaterials ◽  
2019 ◽  
Vol 9 (1) ◽  
pp. 113
Author(s):  
Jing Xu ◽  
Haiying Wang ◽  
Zhihong Lu ◽  
Zhenhua Zhang ◽  
Zhaorui Zou ◽  
...  
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Magnetic Measurements ◽  
Measurement Techniques ◽  
Rutile Phase ◽  
Saturation Magnetic Moment ◽  
Doping Effects ◽  
Powder Samples

In this work, V1−xZrxO2 powder (x = 0, 0.01, 0.02, 0.04) was synthesized by two step hydrothermal method. The micro-topography, magnetic and phase transition properties have been investigated using various measurement techniques. All prepared V1−xZrxO2 powder samples exhibit monoclinic structure at room temperature. With the Zr4+ ions doping concentration increased, the shapes of VO2 particles change from spherical to rectangular slice. Besides, the saturation magnetic moment of the samples decrease with the increase of doped Zr4+ ions concentration, while their phase transition temperature increase gradually with Zr ions doping at a rate of around 2 °C/at% on average. We investigated the Zr doping effects on V-V dimers and confirmed the role of V-V dimers in phase transition. We speculate that more V-V dimers form with Zr doping by magnetic measurements, which result in the monoclinic phase of Zr-doped VO2 sample is more stable than rutile phase. Therefore the phase transition temperature is elevated by Zr doping in our experiment. We further consider that the VO2 phase transition should be ascribed to Peierls transition caused by the changing of V-V dimers.

Investigations on Dielectric phase transition behavior of Pb(Fe0.5-xScx)Nb0.5O3 Multiferroic Ceramics

MRS Advances ◽  
2016 ◽  
Vol 1 (9) ◽  
pp. 585-590
Author(s):  
Bandi Mallesham ◽  
Ranjith Ramadurai
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Transition Temperature ◽  
Essential Feature ◽  
Low Frequency ◽  
Cation Ordering ◽  
X Ray Diffraction ◽  
Dielectric Phase ◽  
Diffraction Patterns ◽  
The Stability

ABSTRACTPhase pure Pb[(Fe0.5-xScx)Nb0.5]O3 [x = 0 to 0.5] multiferroic relaxors have been synthesized to study the effect of Sc on dielectric phase tansition. Rietveld refinement of x-ray diffraction patterns confirm that the structure transforms from monoclinic (Cm) to rhomobohedral (R3m) at x = 0.3. Absence of low frequency dielectric response in compositions with low Sc content attributed to interfacial polarizabilty arising due to differences in conductivities of grain and grain boundary. Moreover, value of diffusivity parameter (γ) of high of Sc content compositions is near to 2, confirms relaxor charactertistic of these compositions. However, an essential feature of relaxors i.e., frequency dependent dielectric permittivity as a function of temperature is observed only in x = 0.5 composition [Pb(Sc0.5Nb0.5)O3 (PSN)]. In addition, ferroelectric phase transition temperature (Tmax) increases initially at lower Sc content (upto x ≤ 0.25), and further drops beyond x ≥ 0.3. Such behavior of Tmax in these compositions is due to the onset of B'-B" local cation ordering at x = 0.3. High temperature Raman spectra of Pb(Sc0.5Nb0.5)O3 (x = 0.5) confirm the stability of cation ordering in compositions with high Sc content well above the phase transition temperature.

Study on the Microstructure and Storage Heat Performance of Mg-25Al-15Zn-xCu Alloys

2015 ◽  
Vol 1120-1121 ◽  
pp. 1104-1108
Author(s):  
Hong Yan Wen ◽  
Xiao Ming Fan ◽  
Xiao Min Cheng
Keyword(s):  
Phase Transition ◽  
Transition Temperature ◽  
Phase Change ◽  
Latent Heat ◽  
Phase Transition Temperature ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Optical Microstructure ◽  
Solid Solution Matrix ◽  
And Storage

With the help of optical microstructure(OM), X-ray diffraction(XRD) and differential scanning calorimetry(DSC), the microstructure and storage heat performance of Mg-based phase change thermal storage alloys were investigated.The results show that the microstructure of Mg-25Al-15Zn-xCu (x=0, 2%, 8% and 14%, respectivly) alloys are mainly composed of primary crystal α (Mg) solid solution matrix, β-Mg17Al12, CuZn, MgAl2Cu and Mg32(Al,Zn)49 phases. The phase transition temperature of Mg-25Al-15Zn and Mg-25Al-15Zn-8Cu alloys ​​are 412.1 °C and 405.9 °C respectively; and phase change latent heat values of that were 175.4 J/g and 209.3 J/g. The addition of Cu led to the formation of new phase, reducing the phase transition temperature and increasing the value of phase change latent heat.

scholarly journals Removal of Congo Red Dye using Synthesised Copper(II) Activated Carbon from Date Seeds

2021 ◽  
Vol 14 ◽  
pp. 1-9
Author(s):  
Nur rahimah Said ◽  
Hazirah Syahirah Zakria ◽  
Siti Nor Atika Baharin ◽  
Nurul' Ain Jamion
Keyword(s):  
Activated Carbon ◽  
Surface Area ◽  
Congo Red ◽  
Bet Surface Area ◽  
Activation Process ◽  
X Ray Diffraction ◽  
X Ray ◽  
Effective Removal ◽  
Vis Spectroscopy ◽  
Red Dye

Azo dyes are recognised as contaminants from the textile and printing industries that lead to human toxicity. Copper(II) activated carbon (CuAC) is an effective removal agent of dyes in these industries. The purpose of this study is to synthesise and characterise CuAC from date seeds. In addition, the efficiency of CuAC as a removal of Congo red (CR) in aqueous solution is also studied. Activated carbon (AC) was prepared from date seeds using phosphoric acid as activating agent, followed by activation process in a furnace at 500 ℃ for 2 hours. Copper(II) nitrate was used in the impregnation of AC to produce CuAC. The AC and CuAC were characterised using Attenuated Total Reflectance Fourier-Transform Infrared Spectroscopy (ATR-FTIR), BET surface area (SBET), Scanning Electron Microscope-Energy Dispersive X-Ray Spectroscopy (SEM-EDX), Atomic Absorption Spectroscopy (AAS) and X-Ray Diffraction (XRD). UV-VIS Spectroscopy was used to determine dye concentrations after treatment with removal agent of CuAC. The characterisation data proved that the CuAC has been successfully synthesised with 0.33% Cu(II) loaded onto AC and its surface area increased from 8.37 m2/g to 384.82 m2/g. The dye removal study was conducted at 10 ppm concentration of dye. Result revealed that 0.2 g of CuAC at pH 2 in 90 min removed 100% of CR dye.

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