Crystallographic Features of the A-Type and CE-Type Antiferromagnetic States in the Simple-Perovskite Manganite System Sr1-xNdxMnO3

2011 ◽  
Vol 409 ◽  
pp. 532-537
Author(s):  
Yusuke Onezawa ◽  
Yasuhide Inoue ◽  
Masazumi Arao ◽  
Yasumasa Koyama
Keyword(s):  
Room Temperature ◽  
Three Dimensional ◽  
Electronic System ◽  
Paramagnetic State ◽  
Heating Process ◽  
In Situ Observation ◽  
Perovskite Manganite ◽  
Transmission Electron ◽  
Highly Correlated

The electronic states of Sr1-xNdxMnO3 with the simple perovskite structure are characterized by a three-dimensional highly-correlated electronic system. To understand the detailed features of the A-and CE-type antiferromagnetic states in this system, their crystallographic features for x = 0.47, 0.48, and 0.50 have been investigated mainly by both x-ray powder diffraction and transmission electron microscopy. It was found at room temperature that the crystal structure for x = 0.47 was determined to have the monoclinic C2/m symmetry, while the orthorhombic Imma structure was confirmed for x = 0.48 and 0.50. The in-situ observation for x = 0.47 indicated that, in the heating process from room temperature, the C2/m-to-Imma transition occurred in the paramagnetic state, and that the A-type antiferromagnetic state appeared below about 200 K on cooling. In addition, the cooling from room temperature for x = 0.48 and 0.50 resulted in the direct transitions from the orthorhombic Imma state to the A-and CE-type antiferromagnetic states, respectively. Based on these features, we simply discussed the physical origin of the appearance of the paramagnetic state with the monoclinic symmetry for x = 0.47.

Possible Orbital-Ordered State in the Highly-Correlated Electronic Material Sr1-xCexMnO3

2014 ◽  
Vol 922 ◽  
pp. 230-236
Author(s):  
Takehiro Hanaoka ◽  
Yasuhide Inoue ◽  
Yasumasa Koyama
Keyword(s):  
Room Temperature ◽  
Three Dimensional ◽  
Electronic System ◽  
Careful Analysis ◽  
Perovskite Manganite ◽  
Orbital Ordering ◽  
Teller Distortion ◽  
Jahn Teller ◽  
Diffraction Patterns ◽  
Highly Correlated

The simple perovskite manganite Sr1-xCexMnO3 (SCMO) has a highly-correlated electronic system with a three-dimensional character. Because the presence of orbital-ordered states of eg electrons can be expected in SCMO, the crystallographic features of SCMO samples with 0.09 ≤ x ≤ 0.20 have been investigated mainly by transmission electron microscopy. In addition to fundamental reflections due to the simple perovskite structure, their electron diffraction patterns at room temperature exhibited both the presence of superlattice reflections at k = ()c in the cubic notation and the splitting of fundamental and superlattice reflections. The careful analysis of these reflections indicated that the superlattice reflections originated from the R25-type rotational displacement of oxygen octahedra about one of the <100>c directions. On the other hand, the splitting of the reflections was found to be due to a {110}c banded structure consisting of two tetragonal bands with different c/a values.　Because one of two tetragonal bands had the c/a value of about 1.028, the splitting reflects the introduction of the Jahn-Teller distortion as a response of a lattice system to orbital ordering. It is thus understood that the C-type orbital ordering of eg electrons should be involved in the state at room temperature for 0.09 ≤ x ≤ 0.20 in SCMO.

Crystallographic Features of the C-Type Orbital-Ordered, and Charge- and Orbital-Ordered States in the Simple Perovskite Manganite Ca1-xLaxMnO3

2012 ◽  
Vol 706-709 ◽  
pp. 1612-1617
Author(s):  
Yasuhide Inoue ◽  
Masazumi Arao ◽  
Daisuke Shiga ◽  
Yasumasa Koyama
Keyword(s):  
Three Dimensional ◽  
Electronic System ◽  
Lattice System ◽  
Perovskite Manganite ◽  
Orbital Ordering ◽  
Transverse Lattice ◽  
Type Orbital ◽  
Antiferromagnetic Ordering ◽  
Monoclinic Distortion ◽  
Highly Correlated

The C-type orbital-ordered (CTOO), and charge-and orbital-ordered (COO) states are present in the simple perovskite manganite Ca1-xLaxMnO3, which has a three-dimensional highly-correlated electronic system. In this study, the crystallographic features of the CTOO and COO states have been investigated mainly by transmission electron microscopy to understand responses of a lattice system to these orderings. Of these two states, the cooling from the disordered orthorhombic Pnma (DO) state around x = 0.20 resulted in the CTOO state with the monoclinic P21/m symmetry. As a result of the monoclinic distortion as a response of the lattice system, the CTOO state consisted of a banded structure that was characterized by an alternating array of two monoclinic domains with different β values. In 0.30 < x < 0.50, on the other hand, the appearance of the COO state from the DO state on cooling accompanied a transverse lattice modulation with q = []DO as a response to orbital ordering in the COO state. The subsequent cooling in the COO state led to the antiferromagnetic ordering with a large lattice dilatation. In other words, no change in the crystal symmetry occurs in the appearance of the antiferromagnetic ordering.

In-Situ Observation of Deformation Associated with R-Phase in NiTi Shape Memory Alloy

1995 ◽  
Vol 404 ◽  
Author(s):  
Y. Gao ◽  
Y. Q. Liu ◽  
K. H. Wu
Keyword(s):  
Martensite Transformation ◽  
Room Temperature ◽  
Strain Curve ◽  
Deformation Mode ◽  
Niti Shape Memory Alloy ◽  
In Situ Observation ◽  
Stress Strain Curve ◽  
Second Stage ◽  
Transmission Electron

AbstractAn in-situ straining experiment was performed in a transmission electron microscope (TEM) on the polycrystalline Ti49Ni51 alloy with full R-phase at room temperature. The reorientation of Rphase variants to a single, favorable one was observed under small stress at the beginning of straining, corresponding to the deformation mode of the first yielding stage. During further straining, the observation showed that the reoriented R-phase undergoes a stress-induced martensite transformation, and this dynamic process was considered to contribute to the second stage deformation in the R-phase stress-strain curve. The orientation relationship between the R-phase and stress-induced martensite has been determined and the internal (001)M twins were found in the stressinduced martensite plates.

In situ observation of the martensitic transformation in (Mg,Y)-PSZ

1986 ◽  
Vol 44 ◽  
pp. 500-501
Author(s):  
R-R. Lee
Keyword(s):  
Martensitic Transformation ◽  
High Strength ◽  
Nucleation And Growth ◽  
In Situ Observation ◽  
Considerable Potential ◽  
Transmission Electron ◽  
Structural Applications ◽  
Applied Stresses ◽  
Kinetics Of

Partially-stabilized ZrO2 (PSZ) ceramics have considerable potential for advanced structural applications because of their high strength and toughness. These properties derive from small tetragonal ZrO2 (t-ZrO2) precipitates in a cubic (c) ZrO2 matrix, which transform martensitically to monoclinic (m) symmetry under applied stresses. The kinetics of the martensitic transformation is believed to be nucleation controlled and the nucleation is always stress induced. In situ observation of the martensitic transformation using transmission electron microscopy provides considerable information about the nucleation and growth aspects of the transformation.

In situ TEM observations of melting in nanosized eutectic Pb-Cd inclusions embedded in Al

1996 ◽  
Vol 54 ◽  
pp. 986-987
Author(s):  
S. Hagège ◽  
U. Dahmen ◽  
E. Johnson ◽  
A. Johansen ◽  
V.S. Tuboltsev
Keyword(s):  
Electron Microscope ◽  
Melt Spinning ◽  
Ternary Alloys ◽  
Solid Matrix ◽  
Eutectic System ◽  
In Situ Tem ◽  
In Situ Observation ◽  
Orientation Relationships ◽  
Transmission Electron

Small particles of a low-melting phase embedded in a solid matrix with a higher melting point offer the possibility of studying the mechanisms of melting and solidification directly by in-situ observation in a transmission electron microscope. Previous studies of Pb, Cd and other low-melting inclusions embedded in an Al matrix have shown well-defined orientation relationships, strongly faceted shapes, and an unusual size-dependent superheating before melting.[e.g. 1,2].In the present study we have examined the shapes and thermal behavior of eutectic Pb-Cd inclusions in Al. Pb and Cd form a simple eutectic system with each other, but both elements are insoluble in solid Al. Ternary alloys of Al (Pb,Cd) were prepared from high purity elements by melt spinning or by sequential ion implantation of the two alloying additions to achieve a total alloying addition of up to lat%. TEM observations were made using a heating stage in a 200kV electron microscope equipped with a video system for recording dynamic behavior.

scholarly journals In Situ Observation of Electron-Beam-Induced Formation of Nano-Structures in PbTe

Nanomaterials ◽  
2021 ◽  
Vol 11 (1) ◽  
pp. 163
Author(s):  
Iryna Zelenina ◽  
Igor Veremchuk ◽  
Yuri Grin ◽  
Paul Simon
Keyword(s):  
Electron Beam ◽  
Gas Phase ◽  
Threshold Current ◽  
Threshold Current Density ◽  
Atomic Scale ◽  
In Situ Observation ◽  
Nano Structures ◽  
Transmission Electron ◽  
Initial Crystal

Nano-scaled thermoelectric materials attract significant interest due to their improved physical properties as compared to bulk materials. Well-shaped nanoparticles such as nano-bars and nano-cubes were observed in the known thermoelectric material PbTe. Their extended two-dimensional nano-layer arrangements form directly in situ through electron-beam treatment in the transmission electron microscope. The experiments show the atomistic depletion mechanism of the initial crystal and the recrystallization of PbTe nanoparticles out of the microparticles due to the local atomic-scale transport via the gas phase beyond a threshold current density of the beam.

Photoluminescence Enhancement of CdS Nanocrystals Fabricated on Dithiocarbamate Functionalized PET Substrates

2012 ◽  
Vol 512-515 ◽  
pp. 1511-1515
Author(s):  
Chun Lin Zhao ◽  
Li Xing ◽  
Xiao Hong Liang ◽  
Jun Hui Xiang ◽  
Fu Shi Zhang ◽  
...  
Keyword(s):  
Room Temperature ◽  
Hexagonal Structure ◽  
Diffraction Measurement ◽  
X Ray Diffraction ◽  
Visible Absorption ◽  
X Ray ◽  
Cds Nanocrystals ◽  
Morphological Studies ◽  
Transmission Electron

Cadmium sulfide (CdS) nanocrystals (NCs) were self-assembled and in-situ immobilized on the dithiocarbamate (DTCs)-functionalized polyethylene glycol terephthalate (PET) substrates between the organic (carbon disulfide diffused in n-hexane) –aqueous (ethylenediamine and Cd2+ dissolved in water) interface at room temperature. Powder X-ray diffraction measurement revealed the hexagonal structure of CdS nanocrystals. Morphological studies performed by scanning electron microscopy (SEM) and high-resolution transmission electron microscope (HRTEM) showed the island-like structure of CdS nanocrystals on PET substrates, as well as energy-dispersive X-ray spectroscopy (EDS) confirmed the stoichiometries of CdS nanocrystals. The optical properties of DTCs modified CdS nanocrystals were thoroughly investigated by ultraviolet-visible absorption spectroscopy (UV-vis) and fluorescence spectroscopy. The as-prepared DTCs present intrinsic hydrophobicity and strong affinity for CdS nanocrystals.

scholarly journals Morphology and Mechanical Properties of Fossil Diatom Frustules from Genera of Ellerbeckia and Melosira

Nanomaterials ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 1615
Author(s):  
Qiong Li ◽  
Jürgen Gluch ◽  
Zhongquan Liao ◽  
Juliane Posseckardt ◽  
André Clausner ◽  
...  
Keyword(s):  
Fracture Behavior ◽  
Three Dimensional ◽  
Mechanical Tests ◽  
Fracture Force ◽  
Thickness Change ◽  
X Ray ◽  
Transmission Electron ◽  
Percentage Concentration ◽  
Morphology Characterization

Fossil frustules of Ellerbeckia and Melosira were studied using laboratory-based nano X-ray tomography (nano-XCT), transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS). Three-dimensional (3D) morphology characterization using nondestructive nano-XCT reveals the continuous connection of fultoportulae, tube processes and protrusions. The study confirms that Ellerbeckia is different from Melosira. Both genera reveal heavily silicified frustules with valve faces linking together and forming cylindrical chains. For this cylindrical architecture of both genera, valve face thickness, mantle wall thickness and copulae thickness change with the cylindrical diameter. Furthermore, EDS reveals that these fossil frustules contain Si and O only, with no other elements in the percentage concentration range. Nanopores with a diameter of approximately 15 nm were detected inside the biosilica of both genera using TEM. In situ micromechanical experiments with uniaxial loading were carried out within the nano-XCT on these fossil frustules to determine the maximal loading force under compression and to describe the fracture behavior. The fracture force of both genera is correlated to the dimension of the fossil frustules. The results from in situ mechanical tests show that the crack initiation starts either at very thin features or at linking structures of the frustules.

In situ observation of ordering process in FePt films during annealing in a transmission electron microscope

2006 ◽  
Vol 99 (12) ◽  
pp. 123905 ◽  
Author(s):  
K. Kawai ◽  
S. Honda ◽  
M. Nawate ◽  
M. Komatsu ◽  
K. Kawabata
Keyword(s):  
Electron Microscope ◽  
Transmission Electron Microscope ◽  
In Situ Observation ◽  
Transmission Electron

In Situ Synchrotron X-Ray Diffraction Study of a Deformed Cu-Fe-P Alloy during Heating

2016 ◽  
Vol 850 ◽  
pp. 191-196 ◽  
Author(s):  
Wei Wang ◽  
Cun Lei Zou ◽  
Ren Geng Li ◽  
Wen Wen ◽  
Hui Jun Kang ◽  
...  
Keyword(s):  
Room Temperature ◽  
Lattice Distortion ◽  
Copper Matrix ◽  
Heating Process ◽  
Recrystallization Process ◽  
Full Width ◽  
X Ray Diffraction ◽  
Dramatic Decrease ◽  
X Ray

In situ synchrotron X-ray diffraction was used to study a deformed Cu-0.88 Fe-0.24 P alloy during heating process. The measurements were performed at room temperature and also at high temperatures up to 893 K in order to determine the recovery, ageing and recrystallization process. With the increase of temperature, the angles of copper matrix peaks moved left and the FWHM (full width at half maximum) decreased slightly. Fe3P precipitates were first detected at 533 K, reached the maximum at 673 K, and re-dissolved into matrix at 853 K. A dramatic decrease in FWHM was observed accompanied by the precipitation of Fe3P phases, indicating the reduction of lattice distortion of copper matrix.

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