scholarly journals Dielectric properties of bismuth titanate ceramics containing SiO2 and Nd2O3 as additives

2012 ◽  
Vol 6 (3) ◽  
pp. 117-122 ◽  
Author(s):  
Stanislav Slavov ◽  
Milena Krapchanska ◽  
Elena Kashchieva ◽  
Svetlin Parvanov ◽  
Yanko Dimitriev
Keyword(s):  
Room Temperature ◽  
Bismuth Titanate ◽  
Dielectric Materials ◽  
Dielectric Losses ◽  
X Ray Diffraction ◽  
Melt Quenching ◽  
X Ray ◽  
Quenching Method ◽  
Titanate Ceramics ◽  
Scanning Electron

Bismuth-titanate ceramics containing SiO2 and Nd2O3 as additives are synthesized by melt quenching method in the system Bi2O3-TiO2-Nd2O3-SiO2 in the temperature range of 1250-1500 ?C. The phase composition of the obtained materials is determined by X-ray diffraction analysis and energy dispersive spectroscopy. Using scanning electron microscopy different microstructures are observed in the samples depending on the composition. Different values of conductivity, dielectric losses and relative permittivity are obtained depending on the composition. It is established that all investigated samples are dielectric materials with conductivity between 10-9 and 10-13 (??cm)-1 at room temperature, dielectric permittivity from 1000 to 3000 and dielectric losses tg? between 0.0002 and 0.1.

Electrical Characteristics of Bismuth Titanate Ceramics and Glass-Ceramics, Containing SiO2 and Nd2O3 as Additives

2013 ◽  
Vol 538 ◽  
pp. 233-237 ◽  
Author(s):  
Stanislav S. Slavov ◽  
Milena Z. Krapchanska ◽  
Elena P. Kashchieva ◽  
Svetlin B. Parvanov ◽  
Yanko B. Dimitriev
Keyword(s):  
Bismuth Titanate ◽  
Glass Ceramics ◽  
Dielectric Losses ◽  
Electrical Characteristics ◽  
X Ray Diffraction ◽  
Graphite Electrodes ◽  
X Ray ◽  
Quenching Method ◽  
Titanate Ceramics ◽  
Thermal Stability Of

Bismuth-titanate ceramics containing SiO2and Nd2O3as additives are synthesized by melt quenching method in the system Bi2O3-TiO2-Nd2O3-SiO2at temperature 1450 oC. By X-ray diffraction analysis are determined the crystal phases participating in the materials: Bi4Ti3O12, Bi12TiO20and δ-Bi2O3. The addition of SiO2allows to control the glass formation ability of the supercooled melts. The addition of Nd2O3stimulates the thermal stability of the materials due to formation of solid solutions Bi4-xNdxTi3O12. Measurements of the electrical conductivity, capacitance and dielectric losses of selected samples are performed by DC resistible bridge and digital capacity meter (with frequency of 1 kHz) using two-terminal method and a suitable sample holder with graphite electrodes. It is established that for the investigated samples the activation energy of conductivity is in the range 1 – 1,3 eV, dielectric permittivity from 1000 to 3000 at (at 400 oC) and dielectric losses tgδ are between 0,0002 and 0,1.

Influence of NiO Nanoparticles on Magnetic Properties of Neodymium Doped Tellurite Glasses

2017 ◽  
Vol 268 ◽  
pp. 102-105 ◽  
Author(s):  
Md Rahim Sahar ◽  
Nur Amanina Mat Jan
Keyword(s):  
Room Temperature ◽  
X Ray Diffraction ◽  
Initial Curve ◽  
Melt Quenching ◽  
X Ray ◽  
Transmission Electron ◽  
Amorphous Nature ◽  
Quenching Method ◽  
Nio Nps ◽  
The Magnetic Field

Series of glass samples with composition (72.5-x)TeO2-15MgO-10Na2O-2.5Nd2O3-xNiO where 1.0 ≤ x ≤ 2.5 mol% are prepared using melt quenching method. The glasses are characterized via X-ray diffraction (XRD), transmission electron microscopy (TEM) and vibrating sample magnetometer (VSM). The XRD spectra confirmed the amorphous nature of prepared glasses. TEM images manifest the existence of NiO NPs which are homogeneously distributed in the glass matrix. The magnetization M(H) curve reveals that the glass displays an anomalous hysteresis behavior at room temperature. It is observed that M(H) is dependent on the NiO content. The initial curve of magnetization lies positively as a function of the magnetic field under 1000 H (O.e).

ROOM TEMPERATURE PHOTOLUMINESCENCE OF POLYCRYSTALLINE SIC PREPARED FROM CARBON-SATURATED SI MELT

2002 ◽  
Vol 16 (06n07) ◽  
pp. 1047-1051
Author(s):  
JIANPING MA ◽  
ZHIMING CHEN ◽  
GANG LU ◽  
MINGBIN YU ◽  
LIANMAO HANG ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Photoelectron Spectroscopy ◽  
Room Temperature ◽  
Uv Light ◽  
X Ray Diffraction ◽  
X Ray ◽  
Room Temperature Photoluminescence ◽  
Composition And Structure ◽  
Light Excitation ◽  
Scanning Electron

Intense photoluminescence (PL) has been observed at room temperature from the polycrystalline SiC samples prepared from carbon-saturated Si melt at a temperature ranging from 1500 to 1650°C. Composition and structure of the samples have been confirmed by means of X-ray photoelectron spectroscopy, X-ray diffraction and scanning electron microscopy. PL measurements with 325 nm UV light excitation revealed that the room temperature PL spectrum of the samples consists of 3 luminescent bands, the peak energies of which are 2.38 eV, 2.77 eV and 3.06 eV, respectively. The 2.38 eV band is much stronger than the others. It is suggested that some extrinsic PL mechanisms associated with defect or interface states would be responsible to the intensive PL observed at room temperature.

Influence of Silicon Nitride on Properties of Corundum Based Castable

2013 ◽  
Vol 634-638 ◽  
pp. 2358-2361
Author(s):  
Jun Cong Wei ◽  
Li Rong Yang
Keyword(s):  
Electron Microscopy ◽  
Thermal Shock ◽  
Thermal Shock Resistance ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
Cold Strength ◽  
X Ray ◽  
Refractory Castables ◽  
Shock Resistance ◽  
Scanning Electron

The effects of Si3N4 addition on the room temperature physical properties and thermal shock resistance properties of corundum based refractory castables were investigated using brown corundum, white corundum and alumina micropowder as the starting materials and pure calcium aluminate as a binder. The phase composition, microstructure, mechanical properties of corundum based castables were investigated by means of X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that as the increase in Si3N4 addition, the bulk density decreased and apparent porosity increased, the cold strength deduced. However, the residual strength rate increased. That is, the thermal shock resistance was improved. This is because even though the introduction of Si3N4 inhibited the sintering of material and deduced the compactness, microcracks were produced in the materials due to a difference in thermal expansion coefficient. So the thermal shock resistance of corundum based castable was improved.

N-type Ba0.2Co4Sb11.5Te0.5: Optimization of thermoelectric properties by different pressures

2019 ◽  
Vol 33 (03) ◽  
pp. 1950027 ◽  
Author(s):  
Jiaxiang Chen ◽  
Xiaopeng Jia ◽  
Yuewen Zhang ◽  
Haiqiang Liu ◽  
Baomin Liu ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Scanning Electron Microscopy ◽  
Seebeck Coefficient ◽  
Room Temperature ◽  
X Ray Diffraction ◽  
Absolute Value ◽  
X Ray ◽  
Coefficient Increase ◽  
Maximum Power Factor ◽  
Scanning Electron

The polycrystalline skutterudite [Formula: see text] were successfully synthesized from 1.5 GPa to 3.5 GPa by the high pressure and high temperature (HPHT) method. Negative Seebeck coefficient confirmed the n-type conductivity of all samples. The phase compositions of samples were investigated by X-ray diffraction (XRD) and the microstructures were observed by scanning electron microscopy (SEM). It was found that the grains appeared smaller and the grain boundaries became more abundant when pressures were higher. We measured the electrical properties from room temperature to 723 K. Both the electrical resistivity and absolute value of Seebeck coefficient increase with the increasing synthetic pressure. At 723 K, the maximum power factor of [Formula: see text] was obtained for the sample synthesized under 3 GPa. The maximum ZT value of 0.61 was reached by [Formula: see text] synthesized under 3 GPa and measured at 723 K.

scholarly journals EFFECT OF OPERATIONAL PARAMETER ON PHOTOCATALYTIC DEGRADATION OF OXAMYL PESTICIDE

2020 ◽  
Vol 4 (12) ◽  
pp. 74-84
Author(s):  
Brijesh Pare ◽  
Satish Piplode ◽  
Vaishali Joshi
Keyword(s):  
Photocatalytic Activity ◽  
Photocatalytic Degradation ◽  
Room Temperature ◽  
Light Irradiation ◽  
Solar Light ◽  
X Ray Diffraction ◽  
Operational Parameter ◽  
X Ray ◽  
Solar Light Irradiation ◽  
Scanning Electron

Flower like bismuth oxy chloride (BiOCl) was successfully synthesized by a simple hydrolytic method at room temperature. The precursor and as-prepared samples were characterized by X-ray diffraction (XRD), High Resolution Field Emission Scanning Electron Microscope (HR FESEM). The results indicated that the as-prepared BiOCl sample is self-assembled hierarchically with nano sheets. The photocatalytic activity of BiOCl was tested on the degradation of the Oxamyl (OM) under solar light irradiation. The results showed that pesticide molecules could be efficiently degraded over BiOCl under solar light irradiation. All the experiment were carried out in the following reaction condition, [OM] = 10-4 mol dm-3, BiOCl NPs= 40mg/50ml, pH= 6.3. Effect of operational parameter such as concentration of H2O2, K2S2O8, FeCl3, Fenton’s reagent (Fe3+/H2O2) and N2, O2 purging on the photocatalytic degradation was observed.

Surface analytical study of uranium exposed to low pressures of hydrogen at ∼ 80°C

2012 ◽  
Vol 1444 ◽  
Author(s):  
Robert M. Harker ◽  
Afiya H. Chohollo
Keyword(s):  
Room Temperature ◽  
Analytical Study ◽  
Treatment Cycle ◽  
X Ray Diffraction ◽  
Standard Samples ◽  
X Ray ◽  
Surface Precipitation ◽  
Pre Treatment ◽  
Low Pressures ◽  
Scanning Electron

ABSTRACTIdentical samples of uranium coupons were prepared and each exposed to hydrogen for different times (where this time is significantly less than a classically understood ‘induction time’). Samples were prepared from rolled depleted uranium stock: as-received oxide was removed on all surfaces and two faces (~12x12 mm) were polished to a sub-micron standard. Samples were individually taken through a Vacuum Thermal Pre-Treatment cycle from room temperature to 200°C to the reaction temperature (80°C) over 40 hours and subsequently exposed to 10 mbar O2 for 24 hours. After O2 was removed, the samples were exposed to hydrogen for pre-determined times of up to 48 minutes. Examination of the samples by Scanning Electron Microscopy (SEM) has, as expected, identified small features protruding from the surface believed to have been caused by sub-surface precipitation of UH3. In general these features are circular and isolated from each other, have a diameter of less than 3μm and appear as either ‘flat-topped’ or ‘domed’ morphology. In addition, longer time exposure samples show a predominance of ‘area attack’ where coalesced sub-surface precipitation appears to be confined to particular metal grains. X-Ray Diffraction (XRD) data show an increase in the quantity of UH3 with time.

Compositional, Structural and Morphological Analyses of Bulk GeS Alloy and its Thin Films

2021 ◽  
Vol 1039 ◽  
pp. 398-405
Author(s):  
Munira M.J. Al-Haji ◽  
Raad M.S. Al-Haddad
Keyword(s):  
Electron Microscopy ◽  
Thin Films ◽  
Thermal Evaporation ◽  
Source Material ◽  
Morphological Properties ◽  
X Ray Diffraction ◽  
Melt Quenching ◽  
X Ray ◽  
Vacuum Thermal Evaporation ◽  
Scanning Electron

Bulk Germanium monosulphide (GeS) alloy was synthesized using the usual melt-quenching technique. Its grains were used as the source material to deposit thin films by vacuum thermal evaporation. Thin-films samples were doped with 1, 2, and 3 at.% indium by thermal co-evaporation and annealed in a vacuum at temperatures 373, 473 and 550 K for an hour. Compositional, structural, and morphological properties of the bulk GeS alloy and its thin films were investigated by Energy Dispersive X-Ray Spectroscopy (EDS), X-Ray Diffraction (XRD), and Scanning Electron Microscopy (SEM) techniques. The analyses verified the stoichiometry (GeS) of the starting material in the prepared thin films. They also revealed that the thin films under study are amorphous, homogeneous, without any cracks deposited uniformly on the glass substrate with thickness 650 to 700 nm.

The Influence of Mn Doping on the Dielectric Properties of Ba0.5Sr0.5TiO3 Ceramics

2016 ◽  
Vol 859 ◽  
pp. 18-23 ◽  
Author(s):  
Li Ping Zhao ◽  
Wen Hong Tao ◽  
Xing Hua Fu ◽  
Wen Zhe Cao ◽  
Guo Yuan Cheng ◽  
...  
Keyword(s):  
Dielectric Properties ◽  
Material Properties ◽  
Room Temperature ◽  
Sol Gel ◽  
Barium Nitrate ◽  
Strontium Nitrate ◽  
X Ray Diffraction ◽  
Mn Doping ◽  
X Ray ◽  
Scanning Electron

(Ba0.5Sr0.5)1-xMnxTiO3(x=0,0.01,0.03,0.05)ceramics were prepared via a new sol-gel method with titannium oxide, strontium nitrate, barium nitrate and manganous nitrate as raw materials.The effect of Mn doping on the microstructure and dielectric properties of the BST were characterized by field scanning electron microscopy,x-ray diffraction and impedance analyser.It was found that the dopted ions could not alter the basic crystal strcuture and they only improved the material properties as modified ions when x≤0.3.The (Ba0.5Sr0.5)1-xMnxTiO3 ceramics sintered at 1250°C for 2h exhibited good dielectric properties(er=1330,tand=0.03)at room temperature and f=1KHz when x=0.03 and the grains were regular and uniform ,indicating a dense microstrcture.

Room temperature conversion of X0.3V2O5· nH2O phase into X2V6O16· nH2O phase Influence of the nature of the cation X+

2004 ◽  
Vol 848 ◽  
Author(s):  
Olivier Durupthy ◽  
Saïd Es-salhi ◽  
Nathalie Steunou ◽  
Thibaud Coradin ◽  
Jacques Livage
Keyword(s):  
Vanadium Oxide ◽  
Room Temperature ◽  
Interlayer Space ◽  
Water Molecules ◽  
X Ray Diffraction ◽  
X Ray ◽  
Oxide Phases ◽  
New Phase ◽  
Supernatant Solution ◽  
Scanning Electron

ABSTRACTVarious cations (Li+, Na+, K+, NH4+, Cs+, Mg2+, Ca2+, Ba2+) were introduced during the formation of a V2O5. nH2O gel. Cation intercalated Xy V2O5. nH2O (y = 0.3 for X = Li+, Na+, K+, NH4+ or y = 0.15 for Mg2+, Ca2+, Ba2+) were first obtained at room temperature but some of them evolve upon ageing into a new phase: XV3O8. nH2O for X = Na+, K+, NH4+ and Cs+ or XV6O16. nH2O for X = Mg2+, Ca2+, Ba2+. All the vanadium oxide phases were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM) and infrared spectroscopy (IR); the supernatant solutions were analysed by 51V NMR spectroscopy. These vanadium oxide phases exhibit a layered structure with cations and water molecules intercalated within the interlayer space. The formation of the different phases depends mainly on the pH of the supernatant solution and on the nature of the cation.

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