Short-range ordering of vacancies and Fermi surface of TiO

Castles, J. R.; Cowley, J. M.; Spargo, A.E.C.

doi:10.1107/s0567739471000834

Cited by 58 publications

(8 citation statements)

References 6 publications

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“…There are waves of Ti and O ion vacancies every third (110) plane of the pseudocubic unit cell, and no tetrahedrally coordinated interstitial Ti ions could be detected. Castles, Cowley & Spargo (1971) first examined the diffuse intensity with electron diffraction from quenched specimens of the disordered phase; they showed that there was a strong correlation between some of this scattering and the Fermi surface, which was corroborated by . In the latter study, it was shown that the total diffuse intensity * On leave from Kwansei Gakuin University, Nishinomiya, Japan.…”

Section: Introductionmentioning

confidence: 95%

Short-range ordering of vacancies in TiO at 1323 K

Terauchi¹,

Cohen²

1979

Acta Cryst Sect A

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The diffuse X-ray scattering from a single crystal of disordered TiO was measured at 1323 K in a volume in reciprocal space. The short-range order parameters between vacancies and cations and anions were determined by Williams's [(1972). Report ORNL-5140. Oak Ridge National Laboratory, Tennessee] least-squares procedure for fitting the total intensity to contributions from this local order and up to quadratic terms in the atomic displacements. Computer simulations with the short-range order coefficients reveal that the local atomic arrangements are similar to those in the low temperature phase. The relationship between this local order and the electronic conductivity is discussed.

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Section: Introductionmentioning

confidence: 95%

Short-range ordering of vacancies in TiO at 1323 K

Terauchi¹,

Cohen²

1979

Acta Cryst Sect A

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“…Thus using ( 5 ) , ( l l ) , (14), (18), and (19) we obtain the equation for the total free energy P: To construct the equilibrium diagram one must represent the free energy (20)…”

Section: (17)mentioning

confidence: 99%

The Application of X‐ray Diffuse Scattering to the Calculation of the FeAl Equilibrium Diagram

Semenovskaya

1974

Physica Status Solidi (b)

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Absolute intensity measurements of diffuse X-ray scattering on single crystals of disordered equilibrium Fe-A1 alloys are made at (000), ( l l l ) , and ($ f +) points of the reciprocal lattice of b.c.c crystals. These measurements give the opportunity of obtaining thethrffi corresponding Fourier transforms of the interchange energies. According to Khachaturyan's theory these Fourier transforms are the energetic parameters which completely determine the thermodynamics of Fe-A1 alloys in a self-consistent field approximation. For the case of long-range interactions each of the three parameters obtained includes all of the interchange energies. The contribution to the free energy of the exchange interactions of the set of the local spins (So = 1) placed on Fe-atoms was evaluated. This result and obtained experimental values of the three energetic parameters allowed to calculate the Fe-A1 diagram. The calculated diagram is in a very good agreement with the most recent diagram by Swann, Duff, and Fisher obtained by an electron microscopic method (discrepancies with respect t o absolute temperature and compositions are everywhere less than 11%) though "adopt" parameters are nowhere used to "tie" the calculated and observed diagram to each other. It is shown that the equilibrium diagram depends essentially on the magnetic contribution to the total free energy.Es wurden Messungen der absoluten Intensitat der diffusen Rontgenstreuung von fehlgeordneten Einkristallen von Fe-Al-Gleichgewichtslegierungen an (000)-, (11 1)-und (4 + +)-Punkten des reziproken Gitters von kubisch-raumzentrierten Kristallen durchgefiihrt. Diese Messungen ergeben die Moglichkeit, die drei entsprechenden Fouriertransformierten der Austanschenergien zu erhalten. I n ifbereinstimmung mit der Theorie von Khachaturyan sind diese Fouriertransformierten die Energieparameter, die die Thermodynamik der Fe-Al-Legierungen in einer selbstkonsistenten Feldnaherung vollstiindig bestimmen. Fur den Fall langreichweitiger Wechselwirkungen schliel3t jeder der drei erhaltenen Parameter alle Austauschenergien ein. Der Beitrag der Austauschwechselwirkungen des Satzes der lokalen Spins (So = 1) an den Fe-Atomen zur freien Energie wurde berechnet. Dieses Ergebnis und die erhaltenen experimentellen Werte der drei Energieparemeter gestatten, das Fe-Al-Diagramm zu berechnen. Dieses berechnete Diagramm befindet sich in sehr guter ubereinstimmung mit dem neuesten Diagramm von Swann, Duff und Fisher, das mit einer elektronenmikroskopischen Methode erhalten wurde (Diskrepanzen bezuglich absoluter Temperatur nnd Zusammensetzung sind immer geringer als 1 lye), obwohl nirgendwo ,,adaptierte" Parameter benutzt wurden, uni die berechneten und beobachteten Diagramme ,,anzupassen". Es wird gezeigt, daB das Gleichgewichtsdiagramm wesentlich vom magnetischen Beitrag zur gesamten freien Energie abhangt.

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“…Short-range ordering of oxygen-vacancies, as chains of vacancies, have been attributed as responsible for diffuse streaks in many systems; these include oxygen-deficient stoichiometries of the superconductors YBa 2 Cu 2 O 7−δ , 41,42 and Nd 2−x Ce x CuO 4−y ; 43 and the perovskite CaFe x Ti 1−x O 3−x/2 . 39,40 Although there are different types of geometries possible for the ordering of oxygen-vacancies, and their existence has been shown by streaks in electron diffraction patterns, 44,45 in this report we concentrate on a simple chain geometry. Also, we emphasize that we did not model the lattice relaxation of the atoms near the vacancy; the simple approximation is physically based on the model that the lone pair of Bi 3+ fills the vacancy.…”

Section: B Random and Ordered Oxygen-vacanciesmentioning

confidence: 99%

Electron diffraction study of the sillenites Bi12SiO20, Bi25FeO39 and Bi25InO39: Evidence of short-range ordering of oxygen-vacancies in the trivalent sillenites

et al. 2014

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We present an electron diffraction study of three sillenites, Bi12SiO20, Bi25FeO39, and Bi25InO39 synthesized using the solid-state method. We explore a hypothesis, inspired by optical studies in the literature, that suggests that trivalent sillenites have additional disorder not present in the tetravalent compounds. Electron diffraction patterns of Bi25FeO39 and Bi25InO39 show streaks that confirm deviations from the ideal sillenite structure. Multi-slice simulations of electron-diffraction patterns are presented for different perturbations to the sillenite structure - partial substitution of the M site by Bi3+, random and ordered oxygen-vacancies, and a frozen-phonon model. Although comparison of experimental data to simulations cannot be conclusive, we consider the streaks as evidence of short-range ordered oxygen-vacancies.

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Short-range ordering of vacancies and Fermi surface of TiO

Cited by 58 publications

References 6 publications

Short-range ordering of vacancies in TiO at 1323 K

Short-range ordering of vacancies in TiO at 1323 K

The Application of X‐ray Diffuse Scattering to the Calculation of the FeAl Equilibrium Diagram

Electron diffraction study of the sillenites Bi12SiO20, Bi25FeO39 and Bi25InO39: Evidence of short-range ordering of oxygen-vacancies in the trivalent sillenites

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