PL
 |
EN
Preferencje help
Polish version English version Język
Widoczny [Schowaj] Abstrakt
Liczba wyników

Znaleziono wyników: 4

Liczba wyników na stronie
first rewind previous Strona / 1 next fast forward last
Wyniki wyszukiwania
Wyszukiwano:
w słowach kluczowych:  order-disorder
help Sortuj według:

help Ogranicz wyniki do:
first rewind previous Strona / 1 next fast forward last
1
Content available Rietveld crystal structure refinement of the natural rhombohedral grossular-andradite garnet from Serbia
Tančić Pavle, Kremenović Aleksandar
Geological Quarterly
|
2022
|
Vol. 66, No. 1
art. no. 7
EN
Four macroscopically visible B–E (rim) zones of the natural grossular-andradite garnet with Grs58-64subAdr36-42>Sps2composition were crystallographically studied. The applied procedure includes the Rietveld refinements of the crystal structures in a series of six space groups, which were followed by the comparative analysis of the R-values, site occupancy factors, and the bond lengths and angles. It was established that it crystallized in the rhombohedral R-3c space group. Various polyhedral distortions and structural order-disorder variations between the studied zones were also observed, determined and discussed. Therefore, rhombohedral symmetry of the studied grandite could be treated as primary and residual strain as the second cause for its slight optical anisotropy.
2
Content available DTA Thermal Analysis of Alloys from Nickel-Rich Part of Ni-Al-Cr System
Maciąg T.
Archives of Metallurgy and Materials
|
2018
|
Vol. 63, iss. 2
981--986
EN
Thermal analysis allows for determination of temperature specific for the beginning and the end of phase transitions occurring in studied samples. In this paper results obtained from DTA (Differential Thermal Analysis) of alloys of chemical composition referring to nickel-rich part of Ni-Al-Cr system, specifically from section Ni75Al25÷Ni65Cr35 are presented. Those alloys are based on intermetallic phase Ni3 Al. Referring to measurements obtained during heating and cooling, characteristic peaks related to occurrence of phase transition of order-disorder type were noted as well as melting and solidification temperature of alloys was determined. Results of thermal analysis DTA of studied range were compared with results obtained for section Ni75Al25÷Ni75Cr25 and Ni75Al25÷Ni87Cr13, additionally results of measurements performed on high-temperature solution calorimeter were collated. Both methods presented good compatibility.
3
Content available DSC Analysis of Order–Disorder Transition in Ni3Al Based Alloys From Ni-Al-Cr System
Maciąg T., Rzyman K., Przeliorz R.
Archives of Metallurgy and Materials
|
2015
|
Vol. 60, iss. 3A
1871--1876
EN
Ni-Al-Cr system is significant for industrial alloys based on intermetallic phase Ni3Al, that crystallizes in crystal lattice L12. It is indicated as γ′, contrary to disordered phase γ which occurs with addition of chromium. DSC analysis was performed on alloys of chemical composition from Ni75Al25÷Ni75Cr25 range of Ni-rich part of Ni-Al-Cr system. In addition, few measurements were conducted using DTA method. Based on curves registered, it was possible to identify characteristic temperature during heating and cooling of the sample. It corresponds to existence of phase boundary γ′+γ / γ in examined alloys. Results of thermal analysis were compared with results obtained with other method performed by authors which is solution calorimetric method.
PL
Układ Ni-Al-Cr jest ważnym układem dla przemysłowych stopów na osnowie fazy międzymetalicznej Ni3Al, która krystalizuje w uporządkowanej sieci L12. Oznacza się ją jako γ′ w odróżnieniu od fazy nieuporządkowanej γ, która pojawia się wraz z dodatkiem stopowym chromu. Wykonano serię stopów, których skład chemiczny leży na linii Ni75Al25÷Ni75Cr25 w bogatej w nikiel części układu Ni-Al-Cr i poddano je analizie DSC. Dodatkowo wykonano kilka pomiarów metodą DTA. Na podstawie zarejestrowanych krzywych udało się zidentyfikować charakterystyczne temperatury podczas nagrzewania i studzenia próbki. Odpowiadają one miejscom występowania granicy międzyfazowej γ′+γ / γ w stopach. Wyniki analiz termicznych zestawiono z wynikami innej metody zastosowanej przez autorów tj. kalorymetrycznej metody typu rozpuszczania.
4
One and Two Dimensional 2H NMR Spectra in LaD2.85
Żogał O. J., Vajda P., Massiot D.
Polish Journal of Chemistry
|
2008
|
Vol. 82, nr 10
1905-1910
EN
Both one dimensional 2H MAS NMR and two dimensional (EXSY) NMR were used to study lanthanum sub-stoichiometric trideuteride (LaD2.85) at room temperature. Re mark - ably narrow (8 and 10 Hz) intense lines were observed at 3.06 and 2.97 ppm in addition to two additional (31 and 35 Hz wide) at 2.62 and 1.92 ppm. The shifts were measured with respect to the 2H NMR line in PMMA (poly(methylmethacrylate)). The positions and intensities of the lines are discussed in terms of the order-disorder situation in the octahedral D-sublattice of the lanthanum matrix.
first rewind previous Strona / 1 next fast forward last
JavaScript jest wyłączony w Twojej przeglądarce internetowej. Włącz go, a następnie odśwież stronę, aby móc w pełni z niej korzystać.