MÖSSBAUER STUDY OF STRUCTURAL–CHEMICAL TRANSFORMATION IN TWO-DIMENSIONAL IRON–OXYGEN NANOSTRUCTURES IN THE COURSE OF TRANSPORT REDUCTION

2000 ◽  
Vol 07 (01n02) ◽  
pp. 1-6
Author(s):  
V. M. SMIRNOV ◽  
G. P. VORONKOV ◽  
V. G. SEMENOV ◽  
V. G. POVAROV ◽  
I. V. MURIN
Keyword(s):  
Silica Surface ◽  
Covalent Bonding ◽  
Iron Silicate ◽  
Chemical Transformations ◽  
Two Dimensional ◽  
Mössbauer Study ◽  
Nanoscale Structures ◽  
Reduction Of Iron ◽  
Oxygen Groups ◽  
Surface Monolayers

Structural–chemical transformations of quasi-two-dimensional iron–oxygen nanostructures occurring at transport reduction were studied using NGR spectroscopy. It has been found that isolated iron–oxygen groups [i.e. groups containing iron and oxygen atoms: ≡Si–O–Fe(OH)2 and (≡Si–O–)2–FeOH] forming surface monolayers were not reduced at T = 400–600° C because of their covalent bonding with the silica surface. Reduction of iron oxide microparticles (microstructures) at T ≥ 600°C C resulted in the formation of metal iron in the form of α-Fe. It has been revealed that in the course of transport reduction (TR) of the samples with deposited monolayers (one or four monolayers) at T ≥ 600° C bulk phases of iron silicate and metal iron were formed. It has also been shown that the features of structural–chemical transformations of supported iron–oxygen nanolayers were in relation with the specific character of phase formation within nanoscale structures.

SURFACE MAGNETIC ORDERING OF Fe-O and Ti-O GROUPS DISPOSED ON DIAMAGNETIC SUPPORT

2001 ◽  
Vol 08 (03n04) ◽  
pp. 295-302 ◽  
Author(s):  
V. M. SMIRNOV ◽  
N. P. BOBRYSHEVA ◽  
M. G. OSMOLOWSKY ◽  
V. G. SEMENOV ◽  
I. V. MURIN
Keyword(s):  
Magnetic Susceptibility ◽  
Surface Layer ◽  
Silica Surface ◽  
Magnetic Ordering ◽  
Magnetic Effect ◽  
Two Dimensional ◽  
Silica Support ◽  
Oxygen Groups

Multiplex dependence of the magnetic susceptibility of iron and titanium-oxygen two-dimensional nanostructures on the amount of metal–oxygen groups deposited on a silica surface was found. The effect of two-dimensional ferrimagnetism was observed. Its appearance is explained by the existence of magnetization areas arising only for certain amounts of Fe–O groups in the surface layer of silica. In the case of samples containing surface Ti–O groups, the structure-induced magnetic effect was observed. Such an effect is caused by an increase of the diamagnetism polarizing component and by the ordering action of silica support on Ti–O bonds.

Nanolevel Structuring – Design of Novel Functional Highly-Organized Solids and Materials

2004 ◽  
Vol 99-100 ◽  
pp. 227-230
Author(s):  
O. Osmolowskaia ◽  
V. Smirnov ◽  
V. Semenov
Keyword(s):  
Magnetic Properties ◽  
Silica Surface ◽  
Magnetic Ordering ◽  
Two Dimensional ◽  
Spin Arrangement ◽  
Oxygen Groups ◽  
Layer Composition

The perspectives of synthesis of highly-organized nanostructured solids and materials with various levels of microscopic organization are discussed. The synthesis and the magnetic properties of mixed Fe-Eu-oxygen groups on silica surface are given as an example. It is shown that spin arrangement ions and the appearance of two-dimensional magnetic ordering are defined to the structural induced effects of sublayer as well as the first layer composition.

A Mössbauer study of the quasi two-dimensional antiferromagnet TlFe2−x Se2

1990 ◽  
Vol 54 (1-4) ◽  
pp. 563-566 ◽  
Author(s):  
L. Häggström ◽  
A. Seidel ◽  
R. Berger
Keyword(s):  
Two Dimensional ◽  
Mössbauer Study

Two-Dimensional Hierarchical Supramolecular Assembly of a Silole Derivative and Surface-Assisted Chemical Transformations

2015 ◽  
Vol 119 (7) ◽  
pp. 3857-3863 ◽  
Author(s):  
Lei Dong ◽  
Weihua Wang ◽  
Tao Lin ◽  
Katharina Diller ◽  
Johannes V. Barth ◽  
...  
Keyword(s):  
Supramolecular Assembly ◽  
Chemical Transformations ◽  
Two Dimensional

Fabrication and Surface Engineering of Two-Dimensional SnS Toward Piezoelectric Nanogenerator Application

MRS Advances ◽  
2018 ◽  
Vol 3 (45-46) ◽  
pp. 2809-2814 ◽  
Author(s):  
Naoki Higashitarumizu ◽  
Hayami Kawamoto ◽  
Keiji Ueno ◽  
Kosuke Nagashio
Keyword(s):  
Thermal Stability ◽  
Surface Morphology ◽  
Oxide Layer ◽  
Chemical Treatment ◽  
Surface Engineering ◽  
Lone Pair ◽  
Covalent Bonding ◽  
Two Dimensional ◽  
Lone Pair Electrons ◽  
Thermal Stability Of

ABSTRACTMechanical exfoliation is performed to fabricate ultrathin SnS layers, and chemical/thermal stability of SnS layers is discussed in comparison with GeS, toward piezoelectric nanogenerator application. Both SnS and GeS are difficult to be exfoliated under 10 nm using tape exfoliation due to strong interlayer ionic bonding by lone pair electrons in Sn or Ge atoms. Au-mediated exfoliation enables to fabricate larger-scale ultrathin SnS and GeS layers thinner than 10 nm owing to strong semi-covalent bonding between Au and S atoms, but GeS surface immediately degrades during Au etching in an oxidative KI/I2 solution. Although the surface of SnS after the Au-mediated exfoliation reveals several-nm oxide layer of SnOx, the surface morphology retains the flatness unlike the case of GeS. The SnS layers are more robust than GeS against the thermal annealing as well as the chemical treatment, suggesting that SnOx works as a passivation layer for SnS. Self-passivated SnS monolayer can be obtained by a controlled post-oxidation.

Mössbauer Study of Oxidized Iron Silicate Minerals

1969 ◽  
Vol 33 (2) ◽  
pp. 741-748 ◽  
Author(s):  
L. Häggström ◽  
R. Wäppling ◽  
H. Annersten
Keyword(s):  
Iron Silicate ◽  
Mössbauer Study ◽  
Silicate Minerals ◽  
Oxidized Iron

Correlations Between Physical and Crystallographic Parameters in the (Bi, Pb)2Sr2 (Ca, Y)Cu2O8+δ Superconductors

1998 ◽  
Vol 12 (29n31) ◽  
pp. 3306-3312 ◽  
Author(s):  
Laurent Manifacier ◽  
Gaston Collin ◽  
Nicole Blanchard
Keyword(s):  
Hole Concentration ◽  
Three Dimensional ◽  
Covalent Bonding ◽  
Insulator Transition ◽  
Type Ii ◽  
Two Dimensional ◽  
Metal Insulator Transition ◽  
Metal Insulator ◽  
Internal Parameters ◽  
Hole Localization

Systematic studies of the lead and yttrium substituted Bi-2212 phase were performed on various compositions ranging between 0 and 0.8 for Pb and between 0 and 0.9 for Y. Crystallographic measurements reveal that the two modulations observed in unleaded and highly Pb-substituted samples are closely linked, the main differences being that the commensurate component disappears in type II (lead type) modulation, along with the modulation of the Bi 3+ ion. We argue that this is due to a covalent bonding between Bi-O planes. The study of internal parameters, including modulation amplitudes, of the Bi2Sr2 ( Ca 1-x, Y x) Cu2O 8+x/2+δ system reveals three distinct regimes with very different behaviors, corresponding to the overdoped, underdoped and insulating regimes. By comparing these results to the variation of the diamagnetic shielding with Y and Pb contents, we conclude that yttrium and lead affect more the mobility of the holes than the hole concentration itself. Y seems to induce, rather than a metal/insulator transition, a switch from a three-dimensional to a two-dimensional regime with a hole localization in the CuO 2 planes.

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