Structural Evolution and Physical Properties of Nano-Crystalline BiFeO3

2016 ◽  
Vol 852 ◽  
pp. 199-204
Author(s):  
Qing Rong Yao ◽  
Yi Hao Shen ◽  
Peng Cheng Yang ◽  
Huai Ying Zhou ◽  
Guang Hui Rao ◽  
...  
Keyword(s):  
Physical Properties ◽  
Crystallite Size ◽  
Structural Characterization ◽  
Structural Evolution ◽  
Average Crystallite Size ◽  
Decomposition Temperature ◽  
Type Structure ◽  
Effect Of Temperature ◽  
Structure Space ◽  
Nano Crystalline

The effect of temperature on the structural evolution and physical properties of nanocrystalline BiFeO3 compound has been studied systematically. The results show that the compound crystallizes in the hexagonal LiNbO3 type-structure (space group R3c) and the structural characterization was a=b=5.5979 Å, c=13.9163 Å and V=387.43 Å3. The average crystallite size was about 32.5 nm. The Neel temperature was the same in the vacuum and air conditions, but the decomposition temperature in the air condition was higher 190°C than that of the vacuum condition.

Structural evolution of a Ge-substituted SnSe thermoelectric material with low thermal conductivity

2018 ◽  
Vol 51 (2) ◽  
pp. 337-343 ◽  
Author(s):  
Federico Serrano-Sánchez ◽  
Norbert M. Nemes ◽  
José Luis Martínez ◽  
Oscar Juan-Dura ◽  
Marco Antonio de la Torre ◽  
...  
Keyword(s):  
Phase Transition ◽  
Thermal Conductivity ◽  
Structural Phase Transition ◽  
Structural Phase ◽  
Structural Evolution ◽  
Type Structure ◽  
Scanning Calorimetry ◽  
Space Group ◽  
Low Thermal Conductivity ◽  
Structure Space

Thermoelectric materials are expected to become new alternative sources of sustainable energy. Among them, the SnSe intermetallic alloy has been described as an excellent thermoelectric compound, characterized by an extremely low thermal conductivity with maximum performance at the onset of a structural phase transition at 800 K. Recently, novel SnSe derivatives with Ge substitution have been synthesized by a direct arc-melting technique. This produces nanostructured polycrystalline samples that exhibit a record high Seebeck coefficient, anticipating an excellent performance above room temperature. Here, the structural phase transition from a GeS-type structure (space groupPnma) to a TlI-type structure (space groupCmcm) is investigatedin situ vianeutron powder diffraction (NPD) in the temperature range 298–853 K for the selected composition Sn0.8Ge0.2Se. This transition takes place at 803 K, as shown by differential scanning calorimetry. The analysis from the NPD data shows a non-monotonic behaviour of the anisotropic displacement parameters upon entering the domain of theCmcmstructure. The energies of the atomic vibrations have been quantitatively analysed by fitting the temperature-dependent mean-square displacements to Einstein oscillators. The thermal conductivity of Sn0.8Ge0.2Se is as low as 0.35 W m−1 K−1at 773 K, which mostly represents the lattice thermal contribution.

scholarly journals Variation in the Adsorption of Lead(II) by a Range of Electrolytic Manganese Dioxides: Chemometric Examination of Correlation with Physical Properties

1997 ◽  
Vol 15 (8) ◽  
pp. 583-592
Author(s):  
Madhav P. Dahal ◽  
Geoffrey A. Lawrance ◽  
Marcel Maeder
Keyword(s):  
Physical Properties ◽  
Crystallite Size ◽  
Water Content ◽  
Adsorption Isotherms ◽  
Average Crystallite Size ◽  
Lead Ion ◽  
Electrolytic Manganese Dioxide ◽  
Degree Of Reduction ◽  
Electrolytic Manganese ◽  
Wide Range

The adsorption of lead(II) by a range of ‘boutique’ electrolytic manganese dioxide (EMD) samples which differ in a range of physical properties has been followed at pH 5, 20°C and an ionic strength of 0.5, employing a wide range of initial lead ion concentrations from 5 × 10−5 mol/dm3 to 5 × 10−2 mol/dm3. Adsorption isotherms all fitted quite well to a simple Langmuir adsorption equation. The Langmuir parameters vary significantly for the different samples and good correlations between them and some physical properties (% water content, open circuit voltage and average crystallite size) are apparent. Further, Principal Component Regression (PCR) reveals excellent correlations between the lead(II) adsorption isotherms and some of the physical properties (water content, average crystallite size, density, total pore volume, electric conductivity, porosity, etc). A qualitative understanding of the relationship between the isotherms and the physical properties can be achieved. Adsorption of lead on partially chemically reduced EMD samples falls as the degree of reduction increases, associated with a drop in available hydrolysable surface groups with increasing degree of reduction.

Pulse Plasma Sintering of Nano-Crystalline Cu Powder

2006 ◽  
Vol 114 ◽  
pp. 239-244 ◽  
Author(s):  
Andrzej Michalski ◽  
Marcin Rosiński ◽  
D. Siemiaszko ◽  
Jakub Jaroszewicz ◽  
Krzysztof Jan Kurzydlowski
Keyword(s):  
Relative Density ◽  
Crystallite Size ◽  
Average Crystallite Size ◽  
Pulse Plasma ◽  
Sintering Process ◽  
Nanocrystalline Copper ◽  
Nano Crystalline ◽  
Plasma Sintering ◽  
Copper Powders ◽  
Pulse Plasma Sintering

Nanocrystalline copper powders, produced by the reduction of the CuO with hydrogen, were consolidated using the pulse plasma sintering (PPS) method. The sintering process was carried out at temperatures between 500 and 900 oC under a load of 60 MPa for 5 min. The average crystallite size of the sintered component obtained at 500 oC was about 80nm and at 900 oC 1880 nm. The components produced at 500 oC had a relative density of 90 %, and those sintered at 900 oC 92 %; their hardness was 215 and 140 HV0.1, respectively.

scholarly journals Analysis of Crystallinity and Physical Properties of the Bio-solar Gemstone

2020 ◽  
Vol 8 (3) ◽  
pp. 151-160
Author(s):  
Ismail Ismail ◽  
Akmal NIzar ◽  
Murzal . ◽  
Zulkarnain Jalil
Keyword(s):  
Specific Gravity ◽  
Physical Properties ◽  
Crystallite Size ◽  
Average Crystallite Size ◽  
Crystalline Material ◽  
X Ray Diffraction ◽  
X Ray

Abstract – Bio-solar is one of the natural gemstones found in the province of Aceh in Indonesia. A recent study suggested that this gemstone could be considered as a vesuvianite type of gemstone. Nevertheless, detail information of this bio-solar gemstone is still unknown. We do not know whether the bio-solar gemstone is crystalline or amorphous. The specific gravity and the hardness of this gemstone are also still unknown. This information is essential to determine the quality of a gem. To answer those questions, we have used x-ray diffraction to study the bio-solar gemstone from the province of Aceh in Indonesia. The physical properties (specific gravity and hardness) of this gemstone have also been measured. We found that the bio-solar gemstone is composed by CaO, SiO2, MgO, Al2O3, Fe2O3, and TiO2 phases. Our results revealed that the bio-solar gem is a crystalline material, not amorphous. The average crystallite size of this gemstone is found to be 353 Å (35 nm). Moreover, the specific gravity of bio-solar gemstone is found to be 3.09 – 3.34. Its hardness is 3 to 4 mohs. Thus, the bio-solar is a good quality gemstone. Our finding confirmed that the bio-solar could be classified as a vesuvianite gemstone.

Structural Characterization of Nano-Crystalline BaTiO3 Powder Prepared Using Hydrothermal Method

2011 ◽  
Vol 324 ◽  
pp. 205-208 ◽  
Author(s):  
Ziyad S. A. Al Sarraj ◽  
Mukhlis M. Ismail ◽  
Sabah M. Ali ◽  
Wan Q. Cao
Keyword(s):  
Ftir Spectroscopy ◽  
Crystallite Size ◽  
Structural Characterization ◽  
Tetragonal Phase ◽  
Room Temperature ◽  
Annealing Temperature ◽  
Nano Crystalline ◽  
Vibrational Bands ◽  
Ft Raman

BaTiO3powders were prepared hydrothermally using TiCl4, Ba(OH)2.8H2O and NH4OH as starting materials at 150°C for 2h. The structure of the prepared nanocystalline BT powders were a metastable cubic perovskite according to XRD and HRTEM analysis, while FT Raman spectra showed that BT powders have a tetragonal structure. Hydroxyl and carbonate groups were observed in all prepared powders that showed in FTIR spectroscopy as vibrational bands. The tetragonal phase of BT powder was identified clearly by slow scan XRD at 2θ between 44.6 to 46°. The crystallite size of BT powders have increased with the increase of annealing temperature from 19 nm at room temperature to 70 nm at 1000°C.

scholarly journals Effect of Calcination Temperature on Physical properties of Ni0.6Zn0.4Fe2O4  Ferrite nanoparticles

2021 ◽  
Author(s):  
sivakumar pendyala ◽  
G.k.Sivasankara Yadav
Keyword(s):  
Physical Properties ◽  
Crystallite Size ◽  
Calcination Temperature ◽  
Sol Gel ◽  
Average Crystallite Size ◽  
Combustion Method ◽  
Ferrite Nanoparticles ◽  
Calcination Temperatures ◽  
Auto Combustion ◽  
Lcr Meter

Abstract The influence of Calcination temperature on the physical properties of Ni0.6Zn0.4Fe2O4 ferrite nanoparticles were investigated. These ferrite nanoparticles have been synthesized by sol-gel auto combustion method using citric acid as fuel agent at different calcination temperatures (4000C, 5000C and 6000C). The Morphological investigation, average crystallite size and microstructure of the material were examined by using X-ray diffraction (XRD) and confirmed by field emission scanning electron microscope (FESEM) and FTIR spectra. The Effects of calcination temperature on the dielectric and magnetic properties were calculated by using LCR meter and vibrating sample magnetometer (VSM). The XRD result shows a single-phase cubic spinel structure with average crystallite size increases from 27 to 29.5 nm, with an increase of temperature. The highest saturation magnetization was found at a calcination temperature 6000C with value 80.39 emu/g, and the value coercive field (Hc) was inverse with the crystallite size.

Influence of Preparation Temperature on Performance of Ce1-xPrxO2 Ultrafine Powder Prepared by a Microemulsion Process

2008 ◽  
Vol 368-372 ◽  
pp. 784-786 ◽  
Author(s):  
Jun Yang ◽  
Zhen Feng Zhu ◽  
Jing Ping Li
Keyword(s):  
Crystallite Size ◽  
Calcination Temperature ◽  
Average Crystallite Size ◽  
Ultrafine Powder ◽  
Microemulsion System ◽  
Sem Images ◽  
Preparation Temperature ◽  
Annealing Conditions

A W/O microemulsion system composed of OP-emolsifier / water / cyclohexane / 1-Pentanol was adopted to prepare ultrafine Ce1-xPrxO2 powder via the reaction between the precipitants of cerium and praseodymium salt solved in the nano reactors. The influence of the annealing conditions on the preparation of Ce1-xPrxO2 powder was investigated. It was shown that, with the increase of calcination temperature from 400 °C to 800 °C, the average crystallite size of the particles increases from 9.5 nm to 25.8 nm. FE-SEM images showed that shape of the particles is layered and sheet-like.

Structural and physical properties of the nano-crystalline Al-substituted Cr–Cu ferrite

2013 ◽  
Vol 343 ◽  
pp. 286-292 ◽  
Author(s):  
M.A. Amer ◽  
T.M. Meaz ◽  
A.G. Mostafa ◽  
H.F. El-Ghazally
Keyword(s):  
Physical Properties ◽  
Nano Crystalline
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