Phase Transitions in the Co–Al–Nb–Mo System

Phase transitions in the Co-rich part of the Co–Al–Nb–Mo phase diagram are studied by energy dispersive spectroscopy (EDS), X-ray analysis, transmission electron microscopy (TEM), and differential scanning calorimetry (DSC) measurements. The obtained results were compared with the results for alloys of the binary Co–Al and ternary Co–Al–Nb, and Co–Al–Mo systems. Formation of the intermetallic phase with the L12 structure was found in a range of alloys with 10 at.% Al, 2–9 at.% Nb, and 3–7 at.% Mo. Intermetallic compound Co2Nb, Laves phase with the different chemical composition and crystal structure (C14 and C36) was detected in the Co–Al–Nb and Co–Al–Nb–Mo samples after vacuum solution treating at 1250 °C for 30 h.

Download Full-text

Crystal structure, microstructure, and magnetic properties of the Fe2CrSi nanostructured Heusler alloy elaborated by the mechanical alloying method

International Journal of Materials Research (formerly Zeitschrift fuer Metallkunde) ◽

10.1515/ijmr-2020-1110810 ◽

2020 ◽

Vol 111 (8) ◽

pp. 681-687

Author(s):

Fatiha Djaidi ◽

Hanane Mechri ◽

Mohammed Azzaz

Keyword(s):

Crystal Structure ◽

Electron Microscopy ◽

Magnetic Properties ◽

Mechanical Alloying ◽

Heusler Alloy ◽

Scanning Calorimetry ◽

X Ray ◽

Transmission Electron ◽

Disordered Crystal ◽

Microstructure And Magnetic Properties

Abstract The Fe2CrSi nanostructured Heusler alloy was prepared by mechanical alloying followed by heat treatment. The structure, microstructure, and magnetic properties of the samples were studied by the following analysis methods: X-ray diffraction, scanning electron microscopy with energy dispersive X-ray spectrometry, transmission electron microscopy, and a vibrating sample magnetometer. The a-Fe (Si, Cr) solid solution with a disordered body centered cubic (bcc) crystal structure was obtained after 24 h of milling. An example of the sample milled for 32 h with a disordered crystal structure a-Fe(Si, Cr) was chosen to investigate the transformation with temperature using differential scanning calorimetry. The effect of annealing temperatures on the structural, microstructural, and magnetic properties of the ordered Fe2CrSi Heusler phase for the sample milled for 32 h was investigated.

Download Full-text

Eco-Friendly Preparation of Nanofibrillated Cellulose from Water Hyacinth Using NaOH/Urea Pretreatment

Materials Science Forum ◽

10.4028/www.scientific.net/msf.990.225 ◽

2020 ◽

Vol 990 ◽

pp. 225-230

Author(s):

Kraiwit Pakutsah ◽

Duangdao Aht-Ong

Keyword(s):

Crystal Structure ◽

Electron Microscopy ◽

Water Hyacinth ◽

Aqueous Suspension ◽

Nanofibrillated Cellulose ◽

Cellulose Ii ◽

Cellulose I ◽

X Ray ◽

Transmission Electron ◽

Water Hyacinth Fiber

In this work, we described an effective approach to prepare nanofibrillated cellulose (NFC) with cellulose II structure under mild condition. Firstly, the water hyacinth (WH) was subjected to a series of a two-step chemical treatment, NaOH/urea pretreatment, and mechanical defibrillation at different defibrillation times. After that, raw water hyacinth fiber (RWF), bleached water hyacinth fiber (BWF), NaOH/urea pretreated water hyacinth fiber (PWF), and the resulting NFC were characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), Fourier transform infrared spectroscopy (FTIR), X-ray diffractometry (XRD) as well as rheological measurements. It was found that RWF and BWF exhibited cellulose I crystal structure, whereas PWF and the obtained NFC possessed cellulose II crystal structure. FTIR analysis confirmed the evidence that no other chemical reactions preferentially occurred during both NaOH/urea pretreatment and mechanical defibrillation. As evidenced by rheological properties analysis, the NFC aqueous suspension with a gel-like structure demonstrated a shear-thinning behavior. The obtained NFC could potentially be utilized as a reinforcement for polymeric composites.

Download Full-text

Preparation and Property of Al87Ce3Ni8.5Mn1.5 Nanophase Amorphous Composites

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.412.263 ◽

2011 ◽

Vol 412 ◽

pp. 263-266

Author(s):

Hong Wei Zhang ◽

Li Li Zhang ◽

Feng Rui Zhai ◽

Jia Jin Tian ◽

Can Bang Zhang

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Single Phase ◽

Volume Fraction ◽

Material Structure ◽

X Ray Diffraction ◽

Scanning Calorimetry ◽

X Ray ◽

Transmission Electron ◽

Different Temperatures

The higher mechanical strength of Al87Ce3Ni8.5Mn1.5 nanophase amorphous composites has been obtained with two methods. The first nanophase amorphous composites are directly produced by the single roller spin quenching technology. The method taken for the second nanophase amorphous composites is at first to obtain amorphous single-phase alloy, followed by annealed at different temperatures .The formative condition, the microstructure, the particle size, the volume fraction of α-Al phase and microhardness of nanophase amorphous composites etc have been investigated and compared by X-ray diffraction (XRD) and transmission electron microscopy (TEM) and differential scanning calorimetry (DSC). The microstructure of composites produced by the second method is higher than the former, the fabricated material structure of the system is more uniform and the process is easier to control.

Download Full-text

Ideal and Real Structure of Ti5O4(PO4)4: X-ray and HRTEM Investigations

Acta Crystallographica Section B Structural Science ◽

10.1107/s0108768198003590 ◽

1998 ◽

Vol 54 (6) ◽

pp. 722-731 ◽

Cited By ~ 17

Author(s):

F. Reinauer ◽

R. Glaum

Keyword(s):

Crystal Structure ◽

Electron Microscopy ◽

Structure Refinement ◽

Ideal Structure ◽

Crystal Data ◽

Asymmetric Unit ◽

X Ray Diffraction ◽

X Ray ◽

Transmission Electron ◽

The Ideal

The crystal structure of pentatitanium tetraoxide tetrakis(phosphate), Ti5O4(PO4)4, has been determined and refined from X-ray diffraction single-crystal data [P212121 (No. 19), Z = 4, a = 12.8417 (12), b = 14.4195 (13), c = 7.4622 (9) Å (from Guinier photographs); conventional residual R 1 = 0.042 for 2556 Fo > 4σ(Fo ), R 1 = 0.057 for all 3276 independent reflections; 282 parameters; 29 atoms in the asymmetric unit of the ideal structure]. The structure is closely related to those of β-Fe2O(PO4)-type phosphates and synthetic lipscombite, Fe3(PO4)4(OH). While these consist of infinite chains of face-sharing MO6 octahedra, in pentatitanium tetraoxide tetrakis(phosphate) only five-eighths of the octahedral voids are occupied according to □3Ti5O4(PO4)4. Four of the five independent Ti4+O6 show high radial distortion [1.72 ≤ d(Ti−O) ≤ 2.39 Å] and a typical 1 + 4 + 1 distance distribution. The fifth Ti4+O6 is an almost regular octahedron [1.91 ≤ d(Ti−O) ≤ 1.98 Å]. Partial disorder of Ti4+ over the available octahedral voids is revealed by the X-ray structure refinement. High-resolution transmission electron microscopy (HRTEM) investigations confirm this result.

Download Full-text

Crystallization of Amorphous Si In Al/Si Multilayers

MRS Proceedings ◽

10.1557/proc-230-189 ◽

1991 ◽

Vol 230 ◽

Cited By ~ 5

Author(s):

Toyohiko J. Konno ◽

Robert Sinclair

Keyword(s):

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Differential Scanning Calorimetry ◽

Layered Structure ◽

Heat Of Reaction ◽

X Ray Diffraction ◽

Scanning Calorimetry ◽

X Ray ◽

Transmission Electron ◽

Amorphous Si

AbstractThe crystallization of amorphous Si in a Al/Si multilayer (with a modulation length of about 120Å) was investigated using transmission electron microscopy, differential scanning calorimetry and X-ray diffraction. Amorphous Si was found to crystallize at about 175 °C with the heat of reaction of 11±2(kJ/mol). Al grains grow prior to the nucleation of crystalline Si. The crystalline Si was found to nucleate within the grown Al layers. The incipient crystalline Si initially grows within the Al layer and then spreads through the amorphous Si and other Al layers. Because of extensive intermixing, the original layered structure is destroyed. The Al(111) texture is also enhanced.

Download Full-text

Characterization of Zn0.96Al0.02Ga0.02O Thermoelectric Material

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.802.227 ◽

2013 ◽

Vol 802 ◽

pp. 227-231

Author(s):

Panida Pilasuta ◽

Pennapa Muthitamongkol ◽

Chanchana Thanachayanont ◽

Tosawat Seetawan

Keyword(s):

Crystal Structure ◽

Electron Microscopy ◽

Single Phase ◽

Hexagonal Structure ◽

Hexagonal Crystal Structure ◽

X Ray Diffraction ◽

Hexagonal Crystal ◽

X Ray ◽

Transmission Electron

Crystal structure of Zn0.96Al0.02Ga0.02O was analyzed by X-Ray diffraction (XRD) technique and the microstructure was observed by scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The XRD results showed single phase and hexagonal structure a = b = 3.24982 Å, and c = 5.20661 Å. The SEM and TEM results showed the grain size of material arrangement changed after sintering and TEM diffraction pattern confirmed hexagonal crystal structure of Zn0.96Al0.02Ga0.02O after sintering.

Download Full-text

Lack of a threefold rotation axis in α-Fe2O3and α-Cr2O3crystals

Acta Crystallographica Section B Structural Science Crystal Engineering and Materials ◽

10.1107/s205252061500342x ◽

2015 ◽

Vol 71 (2) ◽

pp. 203-208 ◽

Cited By ~ 8

Author(s):

Michał Stękiel ◽

Radosław Przeniosło ◽

Izabela Sosnowska ◽

Andrew Fitch ◽

Jacek B. Jasiński ◽

...

Keyword(s):

Crystal Structure ◽

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Rotation Axis ◽

Magnetic Ordering ◽

Evidence Based ◽

Space Group ◽

X Ray ◽

Space Groups ◽

Transmission Electron

The crystal structure of α-Fe2O3and α-Cr2O3is usually described with the corundum-type trigonal crystal structure based on the space group R\bar 3c. There are, however, some observations of the magnetic ordering of both α-Fe2O3and α-Cr2O3that are incompatible with the trigonal symmetry. We show experimental evidence based on X-ray powder diffraction and supported by transmission electron microscopy that the symmetry of the crystal structure of both α-Fe2O3and α-Cr2O3is monoclinic and it is described with the space groupC2/c(derived from R\bar 3c by removing the threefold rotation axis). The magnetic orderings of α-Fe2O3and α-Cr2O3are compatible with the magnetic space groupsC2/candC2/c′, respectively. These findings are in agreement with the idea from Curie [(1894),J. Phys.3, 393–415] that the dissymmetry of the magnetic ordering should be associated with a dissymmetry of the crystal structure.

Download Full-text

Preparation and Luminescence Properties of ZnS: Cu/Fe Nanocrystalline

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.1033-1034.1054 ◽

2014 ◽

Vol 1033-1034 ◽

pp. 1054-1057

Author(s):

Xiang Zhang ◽

Jin Liang Huang ◽

Li Hua Li

Keyword(s):

Crystal Structure ◽

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Thioglycolic Acid ◽

Luminescent Properties ◽

X Ray Diffraction ◽

X Ray ◽

Zinc Blende ◽

Transmission Electron ◽

Fe Nanoparticles

ZnS: Cu/Fe nanocrystals were synthesized by hydrothermal method with thioglycolic acid as a stabilizer. The phases, grain size and luminescent properties of the nanocrystals were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and fluorescence photometer respectively. The results showed that ZnS: Cu/Fe nanoparticles have a particle size about 7nm and possess a cubic zinc blende crystal structure. The luminous intensity of ZnS: Cu/Fe nanocrystals was strongly when they were reacted at 140°C for 12 hours.

Download Full-text

Characterization of β′ Precipitate Phase in Aged Mg-12Gd-2Y-0.5Sm-0.5Sb-0.5Zr Alloy

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.194-196.1357 ◽

2011 ◽

Vol 194-196 ◽

pp. 1357-1360

Author(s):

Ke Jie Li ◽

Quan an Li ◽

Xiao Hui Zhang

Keyword(s):

Crystal Structure ◽

Electron Microscopy ◽

Aged Alloy ◽

Ordered Structure ◽

Precipitate Phase ◽

X Ray Diffraction ◽

X Ray ◽

Long Period ◽

Transmission Electron

The Mg-12Gd-2Y-0.5Sm-0.5Sb-0.5Zr alloy was prepared under flux protection. The morphology and crystal structure of β′ precipitate phases in aged alloy has been studied using transmission electron microscopy and X-ray diffraction. The orientation relationship between β′ precipitate and matrix could existed as [ 010]BαB// [ 00]Bβ′B, (01 0) BαB// (020)Bβ′B and (0001)BαB was coherent with (001)Bβ′B; [0001]BαB// [001]Bβ′B, (1 00)BαB// (240)Bβ′B and ( 010)BαB was coherent with (0A_,8EEA0)Bβ′B. The HREM images indicated that the β' precipitates have a long-period ordered structure at the same time.

Download Full-text

FABRICATION AND CHARACTERISTICS OF ALN NANOWIRES

Modern Physics Letters B ◽

10.1142/s0217984901003068 ◽

2001 ◽

Vol 15 (30) ◽

pp. 1455-1458 ◽

Cited By ~ 8

Author(s):

H. CHEN ◽

X. K. LU ◽

S. Q. ZHOU ◽

X. H. HAO ◽

Z. X. WANG

Keyword(s):

Crystal Structure ◽

Electron Microscopy ◽

Transmission Electron Microscopy ◽

Single Phase ◽

X Ray Diffraction ◽

X Ray ◽

Selected Area Electron Diffraction ◽

Transmission Electron ◽

Sublimation Method ◽

Scanning Electron

Single phase AlN nanowires are fabricated by a sublimation method. They were characterized by means of X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), typical selected area electron diffraction (SAED) and high-resolution transmission electron microscopy (HRTEM). The SEM and TEM images show that most of the nanowires have diameters of about 10–60 nm. The crystal structure of AlN nanowires revealed by XRD, SAED and HRTEM shows the AlN nanowires have a wurtzite structure.

Download Full-text