scholarly journals SINTESIS DAN KARAKTERISASI NANOFIBER KOMPOSIT Zn-PVDF KOPOLIMER

2014 ◽  
Vol 16 (1) ◽  
pp. 49-52
Author(s):  
Yelfira Sari ◽  
Muhamad Nasir ◽  
Chandra Risdian ◽  
Syukri Syukri
Keyword(s):  
Crystal Structure ◽  
Phase Structure ◽  
Research Study ◽  
Fiber Diameter ◽  
Average Diameter ◽  
Nanofiber Composite ◽  
Β Phase ◽  
Α Phase ◽  
Structure Morphology ◽  
Electrospinning Method

Sintesis nanofiber komposit Zn-PVDF kopolimer dengan metoda elektrospinning telah berhasil dilakukan. Proses pembuatan nanofiber komposit serta  morfologi yang terbentuk dipengaruhi oleh penambahan Zn-asetat dengan perubahan diameter rata-rata serat dari 357,13 nm menjadi 777,24 nm. Analisis FTIR menunjukkan bahwa struktur kristal nanofiber komposit Zn-PVDF kopolimer didominasi oleh strukturβ-phase, dengan bilangan gelombang 1190,08 cm-1 dan 487,99 cm-1 untuk struktur α-phase dan 1404,18 cm-1; 1280,73 cm-1; 1074,35 cm-1; 881,47 cm-1; dan 840,96 cm-1 untuk struktur β-phase.Kata kunci :nanofiber komposit, Zn-PVDF kopolimer komposit, elektrospinning,kristal struktur, morfologi, diameter fiber The fabrication of Zn-PVDF copolymer nanofiber composite has been investigated in this research study by using electrospinning method. Fabrication and morphology of nanofiber composite is influenced by the addition of Zn-acetate. The average diameter of nanofiber composites increase with an addition of Zn-acetate, from 357,13 to 777,24nm. FTIRanalysisshowedthat thecrystalstructure ofPVDFnanofiberis dominatedby β-phase , thewave number 1190,08 cm-1 and 487,99 cm-1 for α-phase structure and 1404,18cm-1; 1280,73cm-1; 1074,35cm-1; 881,47cm-1and840,96cm-1 for β-phase structure respectively.Key words : nanofiber composite, Zn-PVDF copolymer composite, electrospinning, crystal structure,  morphology, fiber diameter

Preparation of Ternary Rare Earth Sulfide LnxGd2-xS3 (Ln: La, Tb)

2010 ◽  
Vol 105-106 ◽  
pp. 812-814
Author(s):  
Hai Bin Yuan ◽  
Wei Xin Yi
Keyword(s):  
Crystal Structure ◽  
Rare Earth ◽  
Tetragonal Phase ◽  
Orthorhombic Phase ◽  
Oxide Powders ◽  
Β Phase ◽  
Α Phase ◽  
Formation Behavior ◽  
Sulfurization Time

We investigated the formation behavior of ternary rare earth sulfide LnxGd2-xS3 (Ln: La, Tb). Ternary rare earth sulfide LnxGd2-xS3 (Ln: La, Tb) was synthesized via the sulfurization of their commercial oxide powders using CS2 gas for short sulfurization time. It was found that ternary rare earth sulfide LnxGd2-xS3 (Ln: La, Tb) could be synthesized for a short sulfurization time of 3 h at 1100°C. For LaxGd2-xS3, it crystallizes in α phase (Orthorhombic phase), the crystal structure is different from rare earth sulfide La10S14-xOx which crystallizes in β phase (Tetragonal phase) but is same with rare earth sulfide α-Gd2S3. TbxGd2-xS3 also crystallizes in α phase, the crystal structure is same with rare earth sulfide α-Tb2S3.

Electrospun Tin Oxide Nanofibers with Different Precursor Solution

2011 ◽  
Vol 675-677 ◽  
pp. 275-278
Author(s):  
Xue Bai ◽  
Di Jia ◽  
Bo Wen Cheng ◽  
Wei Min Kang ◽  
Quan Xiang Li
Keyword(s):  
Crystal Structure ◽  
Tin Oxide ◽  
Precursor Solution ◽  
Average Diameter ◽  
Surface Element ◽  
Rutile Structure ◽  
Inorganic Hybrid ◽  
Hybrid Nanofibers ◽  
Electrospinning Method ◽  
Crystalline Forms

In this paper, electrospinning method was adopted to prepare tin oxide nanofibers membrane with three kinds of novel precursor solution PVP/C12H24O4Sn, PVP/ C4H10OSn and PVP/SnCl4. The morphology, surface element, thermal analysis and crystal structure of the fibers membrane were investigated by SEM, EDS, TG-DTA and XRD. The results showed that the organic/inorganic hybrid nanofibers with an average diameter of 300～700 nm can be obtained by electrospinning. But after calcined at 600°C, the loose and porous tin oxide nanofibers membrane with an average diameter of 100～250 nm can be obtained only by using PVP/SnCl4 as preceusor solution, moreover, it showed good fiber forming property. From XRD spectra, it was found that the rutile structure tin oxide finally obtained without other crystalline forms.

Influence of Molecular Weight on the Morphology and Structure of Electrospun Polyvinylidene Fluoride (PVDF)

2021 ◽  
Vol 1025 ◽  
pp. 293-298
Author(s):  
Aminatul Sobirah Zahari ◽  
Muhammad Hafiz Mazwir ◽  
Izan Izwan Misnon
Keyword(s):  
Molecular Weight ◽  
Polyvinylidene Fluoride ◽  
Analytical Techniques ◽  
Average Diameter ◽  
Pvdf Membrane ◽  
Β Phase ◽  
Membrane Morphology ◽  
Electrospinning Method ◽  
High Flexibility ◽  
Morphology Characterization

Polyvinylidene fluoride (PVDF) reveals outstanding properties such as lightweight, high flexibility and temperature independence material compared to other polymers. In this study, PVDF as a function of molecular weight was prepared by using an electrospinning method in order to study the influences of the molecular weight of the PVDF membrane on the morphology. Analytical techniques such as field emission scanning electron microscope (FESEM), Fourier transform infrared (FTIR) and X-ray diffraction (XRD) were used to characterize the electrospun PVDF membranes. FESEM was used for morphology characterization and also to measure the diameter of fibers while XRD and FTIR were employed to examine crystalline phase membranes. The lowest molecular weight has the smallest average diameter of fibers. Besides, a combination of both α-phase and β-phase crystalline was showed by XRD and FTIR results. This is because the crystalline phases and membrane morphology depend on the polymer molecular weight. In this research, it was found that the largest β-phase fraction for the electrospun PVDF membrane is 80.25 % with a molecular weight at 180,000 g/mol.

scholarly journals Electron diffraction, X-ray powder diffraction and pair-distribution-function analyses to determine the crystal structures of Pigment Yellow 213, C23H21N5O9

2009 ◽  
Vol 65 (2) ◽  
pp. 189-199 ◽  
Author(s):  
Martin U. Schmidt ◽  
Stefan Brühne ◽  
Alexandra K. Wolf ◽  
Anette Rech ◽  
Jürgen Brüning ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Distribution Function ◽  
Electron Diffraction ◽  
Powder Diffraction ◽  
Pair Distribution Function ◽  
Structural Information ◽  
Domain Size ◽  
X Ray ◽  
Β Phase ◽  
Α Phase

The crystal structure of the nanocrystalline α phase of Pigment Yellow 213 (P.Y. 213) was solved by a combination of single-crystal electron diffraction and X-ray powder diffraction, despite the poor crystallinity of the material. The molecules form an efficient dense packing, which explains the observed insolubility and weather fastness of the pigment. The pair-distribution function (PDF) of the α phase is consistent with the determined crystal structure. The β phase of P.Y. 213 shows even lower crystal quality, so extracting any structural information directly from the diffraction data is not possible. PDF analysis indicates the β phase to have a columnar structure with a similar local structure as the α phase and a domain size in column direction of approximately 4 nm.

Crystal structure of the high-pressure monoclinic phase-II of cristobalite, SiO2

2000 ◽  
Vol 64 (3) ◽  
pp. 569-576 ◽  
Author(s):  
M. T. Dove ◽  
M. S. Craig ◽  
D. A. Keen ◽  
W. G. Marshall ◽  
S. A. T. Redfern ◽  
...  
Keyword(s):  
Crystal Structure ◽  
High Pressure ◽  
High Temperature ◽  
Neutron Diffraction ◽  
Phase Ii ◽  
Monoclinic Phase ◽  
Β Phase ◽  
Α Phase ◽  
Temperature And Pressure ◽  
Pressure Phase

AbstractThe crystal structure of the high-pressure phase-II of cristobalite has been solved by neutron diffraction (space group P21/c, a = 8.3780(11) Å, b = 4.6018(6) Å, c = 9.0568(13) Å, β = 124.949(7)°, at P = 3.5 GPa). This phase corresponds to a distortion of the high-temperature cubic β-phase, rather than of the ambient temperature and pressure tetragonal α-phase.

Polymorphism of Ti3SiC2

2002 ◽  
Vol 17 (5) ◽  
pp. 948-950 ◽  
Author(s):  
R. Yu ◽  
Q. Zhan ◽  
L. L. He ◽  
Y. C. Zhou ◽  
H. Q. Ye
Keyword(s):  
Crystal Structure ◽  
Electron Microscopy ◽  
High Resolution ◽  
Lower Energy ◽  
High Resolution Electron Microscopy ◽  
Β Phase ◽  
Α Phase ◽  
Bright Spots ◽  
Resolution Electron ◽  
Intuitive Interpretation

We investigated the crystal structure of Ti3SiC2 by means of high-resolution electron microscopy (HREM). Two polymorphs, α– and β–Ti3SiC2, were identified. The amount of the α phase was larger than the β phase, indicating that the former has lower energy than the latter. We also found that the bright spots in HREM images of Ti3SiC2 do not necessarily correspond to the atomic columns; thus an intuitive interpretation of the image contrast in terms of the stacking sequences of the close-packed layers should be made cautiously

Phasengleichgewichte und intermediäre Phasen im System Al–Te / Phase Relations and Intermediate Phases in the Al–Te System

1988 ◽  
Vol 43 (2) ◽  
pp. 182-188 ◽  
Author(s):  
Rüdiger Kniep ◽  
Peter Blees
Keyword(s):  
Crystal Structure ◽  
Thermal Decomposition ◽  
Random Distribution ◽  
Direct Methods ◽  
Cubic Phase ◽  
Ternary Compounds ◽  
Β Phase ◽  
Zinc Blende ◽  
Α Phase ◽  
Intermediate Phases

The binary system Al-Te contains the intermediate phases AlTe (m.p. 857 °C, syntectic). Al2Te3 (α-phase stable up to 720 °C; β-phase: m.p. 903 °C, congruent) and Al2Te5 (stable between 415 °C and 465 °C, incongruent). The crystal structure of α-Al2Te3 is monoclinic (super-structure; a = 41.565(8) Å, b = 7.189(1) Å, c = 25.477(7) Å, β = 90.21(2)°. Z = 48. Dx = 4.57g/cm3). Te positions of the sub-cell (monoclinic P21; a/3, b, c/6, β) were determined by direct methods; Te atoms are arranged in close-packed layers which are stacked along [100] with the sequence ABCBA. A metastable cubic phase of composition Al2Te3 (Zinc blende-type-structure; a = 5.949(1) Å; Al with random distribution) is obtained by thermal decomposition of ternary compounds AlTeX (X = Cl, Br, I)

Crystallographic and molecular mechanics investigation of an order–disorder transition and dimorphism in 5H,10H-dithiolo[2,3-b]-2,5-benzodithiocine-2-thione

2000 ◽  
Vol 56 (6) ◽  
pp. 1011-1017 ◽  
Author(s):  
Zahid H. Chohan ◽  
William T. A. Harrison ◽  
R. Alan Howie ◽  
Bruce F. Milne ◽  
James L. Wardell
Keyword(s):  
Crystal Structure ◽  
Saddle Point ◽  
Molecular Mechanics ◽  
Title Compound ◽  
The Other ◽  
Molecular Mechanics Calculations ◽  
Disorder Transition ◽  
X Ray ◽  
Β Phase ◽  
Α Phase

Single-crystal X-ray structures are presented for three forms of 5H,10H-dithiolo[2,3-b]-2,5-benzodithiocine-2-thione. The α (at 150 K) and α′ (at ambient) forms are very similar and differ only in the presence of crystallographic m symmetry in the molecules of α′, which is absent in the case of α. This pair is related by an order–disorder transition. The β phase (also determined at 150 K) has a different structure in terms of the molecular packing from either of the other two and therefore constitutes a true polymorph. Molecular mechanics calculations indicated that the most stable CHCl3-solvated conformations for the title compound were a pair of twisted U-shaped enantiomers, UR and UL , i.e. similar to the arrangements found in the α and β phases, with the low-lying saddle point between them corresponding to the situation in the α′ phase. These calculations also indicated that the most stable CHCl3-solvated conformation for the related dibromo-5H,10H-dithiolo[2,3-b]-2,5-benzodithiocine-2-thione was Z-shaped, in agreement with the crystal structure determined earlier for its DMSO solvate [Wang et al. (1998). Synthesis, pp. 1615–1618].

scholarly journals Crystal structure across the β to α phase transition in thermoelectric Cu2−xSe

IUCrJ ◽  
2017 ◽  
Vol 4 (4) ◽  
pp. 476-485 ◽  
Author(s):  
Espen Eikeland ◽  
Anders B. Blichfeld ◽  
Kasper A. Borup ◽  
Kunpeng Zhao ◽  
Jacob Overgaard ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Phase Transition ◽  
Structural Changes ◽  
Negative Thermal Expansion ◽  
Structural Rearrangement ◽  
High Performing ◽  
Β Phase ◽  
Α Phase ◽  
Starting Point ◽  
Cu Migration

The crystal structure uniquely imparts the specific properties of a material, and thus provides the starting point for any quantitative understanding of thermoelectric properties. Cu2−xSe is an intensely studied high performing, non-toxic and cheap thermoelectric material, and here for the first time, the average structure of β-Cu2−xSe is reported based on analysis of multi-temperature single-crystal X-ray diffraction data. It consists of Se–Cu layers with additional copper between every alternate layer. The structural changes during the peculiarzTenhancing phase transition mainly consist of changes in the inter-layer distance coupled with subtle Cu migration. Just prior to the transition the structure exhibits strong negative thermal expansion due to the reordering of Cu atoms, when approached from low temperatures. The phase transition is fully reversible and group–subgroup symmetry relations are derived that relate the low-temperature β-phase to the high-temperature α-phase. Weak superstructure reflections are observed and a possible Cu ordering is proposed. The structural rearrangement may have a significant impact on the band structure and the Cu rearrangement may also be linked to an entropy increase. Both factors potentially contribute to the extraordinaryzTenhancement across the phase transition.

The Effect of Reaction Parameters on the Structural NaYF4 Microcrystals

2014 ◽  
Vol 1044-1045 ◽  
pp. 141-144
Author(s):  
Xin Li Li ◽  
Zhan Hong Ma ◽  
Yun Fei Wang ◽  
Feng Zhang Ren ◽  
Rong Hui Xu
Keyword(s):  
Crystal Structure ◽  
Hydrothermal Method ◽  
Phase Formation ◽  
Hexagonal Phase ◽  
Reaction Parameters ◽  
Β Phase ◽  
Structure Morphology ◽  
Addition Amount

NaYF4 microcrystals were synthesized using a hydrothermal method, and the effects of the EDTA and NaF addition amount on the crystal structure, morphology and size were systematically studied. When the NaF addition amount increase, the size of the NaYF4 microcrystal increase, the excess F- ions promote the formation of β-phase of NaYF4. EDTA significantly modifies the morphology of the crystals. When addition the EDTA the crystals transition from irregular silkworm-like microcrystal to hexagonal microprisms. And the EDTA also promote the hexagonal phase formation.

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