scholarly journals Preparation, Characterization, and Evaluation of Humidity-Dependent Electrical Properties of Undoped and Niobium Oxide-Doped TiO2 : WO3 Mixed Powders

2017 ◽  
Vol 2017 ◽  
pp. 1-9 ◽  
Author(s):  
Pedro M. Faia ◽  
Juliano Libardi ◽  
Itamar Barbosa ◽  
Evando S. Araújo ◽  
Helinando P. de Oliveira
Keyword(s):  
Electrical Properties ◽  
Electrical Characterization ◽  
Ternary Systems ◽  
Ceramic Materials ◽  
Bet Surface Area ◽  
X Ray Diffraction ◽  
Order Of Magnitude ◽  
Diffraction Patterns ◽  
Pellet Form

The study of selective metal oxide-based binary/ternary systems has received increasing interest in recent years due to the possibility of producing efficient new ceramic materials for relative humidity (RH) detection, given the superior properties of the mixed compounds in comparison with pristine ones. The aim of this work was focused on preparation and characterization of non-doped and Nb2O5-doped TiO2 : WO3 pair (in the pellet form) and evaluation of corresponding humidity-dependent electrical properties. The microstructure of the samples was analyzed from scanning electron microscopy, X-ray diffraction patterns, Raman spectra, BET surface area analysis, and porosimetry. The electrical characterization was obtained from impedance spectroscopy (100 Hz to 40 MHz) in the 10–100% RH range. The results showed that adequate doping levels of Nb2O5 introduce important advantages due to the atomic substitution of Ti by Nb atoms in highly doped structures with different levels of porosity and grain sizes. These aspects introduced a key role in the excursion (one order of magnitude) in the bulk resistance and grain boundary resistance, which characterizes these composite ceramics as a promising platform for RH identification.

Deposition and Electrical Characterization of Epitaxial Pb(Mg1/3Nb2/3)O3-PbTiO3 (70/30) Thin Films

1997 ◽  
Vol 493 ◽  
Author(s):  
J-P. Maria ◽  
Wes Hackenberger ◽  
S. Trolier-McKinstry
Keyword(s):  
Dielectric Constant ◽  
Electrical Properties ◽  
Pulsed Laser ◽  
Electrical Characterization ◽  
Piezoelectric Actuators ◽  
Laser Deposition ◽  
Processing Conditions ◽  
X Ray Diffraction ◽  
X Ray

ABSTRACT(001)-oriented heterostructures consisting of LaAlCO3 substrates, SrRuO3 bottom electrodes, and Pb(Mg1/3Nb2/3) O3-PbTiO3 (PMN-PT) piezoelectric actuators were deposited by pulsed laser deposition (PLD). 4-circle x-ray diffraction analysis confirmed the epitaxial growth of each layer. In general, the electrical properties were found to be very sensitive to the processing conditions, in particular, the growth temperature. At growth temperatures below ∼620°C, the temperature dependence of the dielectric constant and the onset of a hysteritic polarization were found to be depressed by as much as 80 °C. When growth temperatures were increased above 660°C, electrical properties with temperature dependencies more consistent with those of single crystals were observed.

Synthesis and Characterization of Cubic Zirconia, (Zr,Gd,Pu)O2, Doped with 238Pu

2002 ◽  
Vol 713 ◽  
Author(s):  
Boris E. Burakov ◽  
Evgeniy B. anderson ◽  
Maria V. Zamoryanskaya ◽  
Maria A. Yagovkina ◽  
Elena V. Nikolaeva
Keyword(s):  
Extended Period ◽  
Ceramic Materials ◽  
Deionized Water ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cubic Zirconia ◽  
Ceramic Synthesis ◽  
Crystalline Ceramic ◽  
Diffraction Patterns

ABSTRACTCrystalline ceramic materials based on the cubic zirconia structure have been proposed as candidate waste forms for the immobilization of weapons grade Pu and other actinides. To evaluate a resistance of these materials to self-irradiation for extended period of time, polycrystalline samples of gadolinia-stabilized cubic zirconia, (Zr,Gd,Pu)O2, doped with approximately 10 wt.% 238Pu were synthesized and characterized. Ceramic synthesis was done by sintering in air at 1500°C for 4 hours using starting precursor materials based on coprecipitated and then calcined oxalates of Zr, Gd, Pu. No differences were observed among the zirconia X-ray diffraction patterns that were obtained immediately after ceramic synthesis, or at 88 and 201 days later. MCC-1 leach tests were performed on ceramic specimens in deionized water at 90°C for 28 days. It was found that without correction for ceramic porosity the initial Pu mass loss (NL) was 0.04 g/m2. This increased to 0.35 and 0.37 g/m2, respectively, 180 and 260 days later. Results obtained allow us to confirm that actinide-doped cubic zirconia is highly resistant to accelerated self-irradiation and therefore, is an efficient material for actinide immobilization in deep geological repositories.

Electrical Characterization of the Graphene-SiC Heterojunction

2012 ◽  
Vol 717-720 ◽  
pp. 641-644
Author(s):  
Travis J. Anderson ◽  
Karl D. Hobart ◽  
Luke O. Nyakiti ◽  
Virginia D. Wheeler ◽  
Rachael L. Myers-Ward ◽  
...  
Keyword(s):  
Electrical Properties ◽  
Charge Carrier ◽  
Graphene Sheet ◽  
Carrier Transport ◽  
Electrical Characterization ◽  
Epitaxial Graphene ◽  
Charge Carrier Transport ◽  
Semiconductor System ◽  
Significant Research

Graphene, a 2D material, has motivated significant research in the study of its in-plane charge carrier transport in order to understand and exploit its unique physical and electrical properties. The vertical graphene-semiconductor system, however, also presents opportunities for unique devices, yet there have been few attempts to understand the properties of carrier transport through the graphene sheet into an underlying substrate. In this work, we investigate the epitaxial graphene/4H-SiC system, studying both p and n-type SiC substrates with varying doping levels in order to better understand this vertical heterojunction.

scholarly journals Preparation and Characterization of Porous Ceramic Membranes for Micro-Filtration from Clay/CuZn Using Extrusion Methods

2018 ◽  
Vol 156 ◽  
pp. 08015 ◽  
Author(s):  
Muh Amin ◽  
Muhammad Subri
Keyword(s):  
Porous Ceramic ◽  
Ceramic Materials ◽  
Ceramic Membranes ◽  
Extrusion Process ◽  
X Ray Diffraction ◽  
Percentage Composition ◽  
X Ray ◽  
Ceramic Support ◽  
Fabrication And Characterization

In this study, fabrication and characterization of ceramic membranes preparation was carried out. Porous ceramic membranes were fabricated by extrusion process from different percentage composition of CuZn on (80 wt% Clay, 10 wt% TiO2, 5 wt% Carbon and 5 wt% PVA). The fabricated membranes were sintered at 900°C for 1 hour in an electrical box furnace with heating rate 1oC/min and holding time for 1 hour. Apparent density and porosity were determined by standar methods for ceramic materials. Phase composition of the ceramic support was established by X-Ray Diffraction analysis. SEM studies of the membranes added at different CuZn were carried out.

scholarly journals Perbaikan Kelarutan Albendazol Melalui Pembentukan Kristal Multikomponen dengan Asam Malat

2020 ◽  
Vol 6 (1) ◽  
pp. 114-123
Author(s):  
Fikri Alatas ◽  
Fahmi Abdul Azizsidiq ◽  
Titta Hartyana Sutarna ◽  
Hestyari Ratih ◽  
Sundani Nurono Soewandhi
Keyword(s):  
Phase Solubility ◽  
Crystal Formation ◽  
Solubility Curve ◽  
X Ray Diffraction ◽  
Ethanol Mixture ◽  
X Ray ◽  
Grinding Method ◽  
Diffraction Patterns ◽  
Phase Solubility Curve

An effort to improve the solubility of albendazole (ABZ), an anthelmintic drug has been successfully carried out through the formation of multicomponent crystal with dl-malic acid (MAL). Construction of phase solubility curve of ABZ in MAL solution and crystal morphological observations after recrystallization in the acetone-ethanol (9:1) mixture were performed for initial prediction of multicomponent crystal formation. ABZ-MAL multicomponent crystal was prepared by wet grinding or also known as solvent-drop grinding (SDG) with acetone-ethanol (9:1) mixture as a solvent followed by characterization of the multicomponent crystal formation by powder X-ray diffraction and Fourier transform infrared (FTIR) methods. The solubility of ABZ-MAL multicomponent crystal was tested in water at ambient temperature and in pH 1.2, 4.5 and 6.8 of buffered solutions at 37°C. The phase solubility curve of the ABZ in the MAL solution showed type Bs. The ABZ-MAL mixture has a different crystalline morphology than pure ABZ and MAL after recrystallization in the acetone-ethanol mixture (9:1). The powder X-ray diffraction pattern and the FTIR spectrum of ABZ-MAL from SDG different from intact ABZ and MAL powder X-ray diffraction patterns and these results can indicate the ABZ-MAL multicomponent crystal formation. The ABZ-MAL multicomponent crystal has better solubility than pure ABZ in all media used. These results can be concluded that ABZ-MAL multicomponent crystal can be prepared by solvent-drop grinding method with acetone-ethanol (9:1) mixture as a solvent and can increase the solubility of albendazole.

scholarly journals PECHINI SYNTHESIS AND CHARACTERIZATION OF Eu3+ DOPED ZnCo2O4 SPINELS

2005 ◽  
Vol 03 (2) ◽  
pp. 24-29
Author(s):  
P.M. PIMENTEL ◽  
A.M.G. PEDROSA ◽  
H.K.S. SOUZA ◽  
C.N.S. JÚNIOR ◽  
R.C.A. PINTO ◽  
...  
Keyword(s):  
Spinel Structure ◽  
Pechini Method ◽  
Synthesis Temperature ◽  
X Ray Diffraction ◽  
X Ray ◽  
Spinel Oxides ◽  
Diffraction Patterns ◽  
Pechini Synthesis ◽  
Spinel Structures

Spinel oxides with the composition ZnCo2O4 and ZnCo2O4:Eu3+ have been synthesized by the Pechini method and characterized by X-ray diffraction, infrared spectroscopy, thermal analysis and scanning electron microscopy. IR spectroscopy revealed the presence of n1 and n2 bands, typical of spinel structures. The formation of monophase cubic spinel structure was confirmed by X-ray diffraction patterns. Extra lines corresponding to other phase has been observed in the powders calcined at 900 ºC. The results showed the extremely lower synthesis temperature than those presents in conventional methods.

scholarly journals Synthesis and Characterization of Co-Mo/γ-Alumina Catalyst from local Kaolin clay for Hydrodesulfurization of Iraqi Naphtha

2021 ◽  
Vol 11 (1) ◽  
pp. 84-106
Author(s):  
Nada Sadoon Ahmed zeki ◽  
Sattar Jalil Hussein ◽  
Khalifa K. Aoyed ◽  
Saad Kareem Ibrahim ◽  
Ibtissam K. Mehawee
Keyword(s):  
Surface Area ◽  
Sulfur Removal ◽  
Sulfuric Acid Concentration ◽  
Bet Surface Area ◽  
X Ray Diffraction ◽  
X Ray ◽  
Mo Catalyst ◽  
Pressure Time ◽  
Al2o3 Catalyst

This work deals with the hydrodesulfurization of three types of naphtha feedstocks; mixednaphtha (WN), heavy naphtha (HN) & light naphtha (LN) with a sulfur content of 1642.1,1334.9 & 709 ppm respectively, obtained from Missan refinery using prepared Co-Mo/γ-Al2O3catalyst. The Iraqi white kaolin was used as a starting material for the preparation of γ-Al2O3support, transferring kaolin to meta-kaolin was studied through calcination at differenttemperatures and durations, kaolin structure was investigated using X-Ray diffractiontechniques.High purity 94.83%. Crystalline γ-Al2O3 with a surface area of 129.91 m2/gm, pore volume0.9002 cm3/g was synthesized by extraction of Iraqi kaolin with H2SO4 at different acid to clayweight ratios, acid concentrations & leaching time. Ethanol was used as precipitating agent; theresultant gel was dried and calcined at 70OC, 10 hrs & 900 OC, 2 hrs respectively.The effects of different parameters on the average crystallinity and extraction % ofsynthesized γ-Al2O3 were studied like; acid: clay ratio, sulfuric acid concentration, leachingtime, leaching temperature & kaolin conversion to metakaolin. Characterization of prepared γ-Al2O3 & Co-Mo catalyst were achieved by X-ray diffraction, FTIR-spectra, texture properties& BET surface area, BJH N2 adsorption porosity, AFM, SEM, crush strength & XRF tests. Co-Mo/ γ-Al2O3 catalyst with final loading 5.702 wt% and 21.45 wt% of Co and Mo oxidesrespectively was prepared by impregnation methods.The activity of prepared Co-Mo/γ-Al2O3 catalyst after moulding to be tested forhydrodesulfurization (HDS) of naphtha feedstock W.N, H.N & L.N was performed using apilot hydrotreating unit at petroleum research & development centre, at different operatingconditions. Effects of temperature, LHSV, pressure, time & pore size distribution were studied,the best percentage of sulfur removal is increased with decreasing LHSV to 2 hr-1 as a generaltrend to be 89.71, 99.72, 99.20 % at 310oC for the whole naphtha, heavy naphtha and lightnaphtha feedstocks respectively, at 34 bar pressure and 200/200 cm3/cm3 H2/HC ratio.

scholarly journals Preparation and characterization of oleogels with tallow and partially hydrolyzed tallow as organogelators

2021 ◽  
Vol 72 (1) ◽  
pp. e388
Author(s):  
E. Keskin Uslu ◽  
E. Yılmaz
Keyword(s):  
Loss Modulus ◽  
Solid Fat Content ◽  
X Ray Diffraction ◽  
Shear Rates ◽  
Peroxide Values ◽  
Time Sweep ◽  
Diffraction Patterns ◽  
Time Sweep Test ◽  
Addition Level

The aim of this study was to evaluate the organogelation potential of tallow fat (TF) and partially hydrolyzed tallow fat (HTF) against saturated monoglyceride (MG) and a saturated monoglyceride + diglyceride mixture (MDG) as the organogelators. TF itself created oleogel at a 30% addition level, while HTF, MG and MDG oleogels were prepared at 10% addition levels. Fatty acid composition data showed that the oleogel of HTF (HTFO) was quite similar to those of MG and MDG oleogels. Solid fat content, free fatty acidity and peroxide values were found to be in acceptable ranges for HTFO. Thermal properties, crystal morphology and X-ray diffraction patterns were also evaluated. Rheological analyses indicated that all oleogels had higher storage modulus (G´) than loss modulus (G´´). The time-sweep test showed that after applying higher shear rates, the gels re-formed at rest. Further, all oleogels maintained their gelled consistency until around 54 °C. The results suggest that HTF could be a cheap, efficient, fast melting, safe and readily available organogelator.

Growth and Characterization of bulk GaN by Ga Vapor Transport

2004 ◽  
Vol 831 ◽  
Author(s):  
Phanikumar Konkapaka ◽  
Huaqiang Wu ◽  
Yuri Makarov ◽  
Michael G. Spencer
Keyword(s):  
Growth Rates ◽  
Vapor Transport ◽  
Spiral Growth ◽  
X Ray Diffraction ◽  
X Ray ◽  
Force Microscopy ◽  
Atomic Force ◽  
Bulk Gan ◽  
Diffraction Patterns

ABSTRACTBulk GaN crystals of dimensions 8.5 mm × 8.5 mm were grown at growth rates greater than 200μm/hr using Gallium Vapor Transport technique. GaN powder and Ammonia were used as the precursors for growing bulk GaN. Nitrogen is used as the carrier gas to transport the Ga vapor that was obtained from the decomposition of GaN powder. During the process, the source GaN powder was kept at 1155°C and the seed at 1180°C. Using this process, it was possible to achieve growth rates of above 200 microns/hr. The GaN layers thus obtained were characterized using X-Ray diffraction [XRD], scanning electron microscopy [SEM], and atomic force microscopy [AFM]. X-ray diffraction patterns showed that the grown GaN layers are single crystals oriented along c direction. AFM studies indicated that the dominant growth mode was dislocation mediated spiral growth. Electrical and Optical characterization were also performed on these samples. Hall mobility measurements indicated a mobility of 550 cm2/V.s and a carrier concentration of 6.67 × 1018/cm3

Probing the Phase Transition in Nanocrystalline TiO2 Powders by Positron Lifetime (PAL) Technique

2011 ◽  
Vol 319-320 ◽  
pp. 151-159 ◽  
Author(s):  
E.M. Hassan ◽  
Basma A.A. Balboul ◽  
M.A. Abdel-Rahman
Keyword(s):  
Positron Annihilation ◽  
Anatase Phase ◽  
Rutile Phase ◽  
Bet Surface Area ◽  
X Ray Diffraction ◽  
Positron Annihilation Lifetime ◽  
Nanocrystallite Size ◽  
Heat Treated ◽  
Degussa P25

Positron annihilation techniques (PAT) have recently been successfully employed for the characterization of phase transitions in metals and compounds. In the present study, positron annihilation lifetime (PAL) measurements have been carried out on a nanocrystalline titania (TiO2) in the form of powders that had been heat-treated at temperatures ranging from 300 to 1273K. The PAL spectra were analyzed into two lifetime components. The shorter lifetime τ1 (185-300 ps) is attributed to positron annihilation in vacancies and the longer lifetime τ1 (400-580 ps) to positrons in microviods at interfaces. The rutile phase of TiO2 powders was utilized as a reference in order to compare their behavior with the commercially supplied and widely available anatase phase (Degussa P25). The influence of the heat-treatment upon the nanostructure during the transition of the anatase to rutile phase were also investigated by X-ray diffraction (XRD), TEM and BET surface area methods. Understanding of this effect is expected to enhance our knowledge of the morphology and nanocrystallite size of TiO2 powders and their T-dependence, and hence their physical properties.

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