Temperature Dependence of Infrared Dispersion in Ionic Crystals LiF and MgO

Jasperse, J. R.; Kahan, A.; Plendl, J. N.; Mitra, S. S.

doi:10.1103/physrev.146.526

Cited by 337 publications

(104 citation statements)

References 26 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…5. The MgO films deposited at 300 • C and 375 • C exhibit broad absorption bands corresponding to the TO mode at 401.1 cm −1 , which is in good agreement with the wave number expected for single cubic MgO [17]. This TO mode appears at a slightly lower wave number (∼ 398 cm −1 ) for the film deposited at 225 • C. The phenomenon might be related to a residual amorphous component in the film.…”

Section: Hybrid Process (Cvd and Ald) For Mtjsupporting

confidence: 70%

Atomic Layer Deposition of Magnetic Thin Films

Mantovan¹,

Georgieva²,

Perego³

et al. 2007

Acta Phys. Pol. A

View full text Add to dashboard Cite

We report on the research effort towards the development of processes for the realization of magnetic tunnel junctions by atomic layer deposition. Our strategy follows two main schemes. The first is a hybrid process where the ferromagnetic layers are produced by chemical vapour deposition and the tunnel oxide is deposited by atomic layer deposition. As ferromagnetic electrodes we use Co and Fe3O4, while MgO, Al2O3, and HfO2 are employed as tunnel oxides. The second and most intriguing scheme is a full-oxide approach in which the ferromagnetic layers and the tunnel barrier layer are all oxides grown by atomic layer deposition. As ferromagnetic layers we focused on the growth of complex manganites (La 0.7 Sr 0.3 MnO 3 ) while as a tunnel oxide we propose La2O3. Film composition has been studied with time of flight secondary ion mass spectroscopy and Rutherford backscattering spectrometry. X-ray diffraction, X-ray reflectivity, and Fourier transform infrared spectroscopy have been used to investigate the structure and morphology of the layers. The magnetic properties of the films are measured by superconducting quantum interference device magnetometer.

show abstract

Section: Hybrid Process (Cvd and Ald) For Mtjsupporting

confidence: 70%

Atomic Layer Deposition of Magnetic Thin Films

Mantovan¹,

Georgieva²,

Perego³

et al. 2007

Acta Phys. Pol. A

View full text Add to dashboard Cite

show abstract

“…where 0 is the vacuum permittivity and is the static dielectric constant of MgO ( = 9.34 [27]). The band shift φ can be estimated to…”

Section: A Experimental Resultsmentioning

confidence: 99%

Defect complexes in Li-doped MgO

et al. 2015

View full text Add to dashboard Cite

Magnesium oxide (MgO) is used in a variety of industrial applications due to its low cost and structural stability. In heterogeneous catalysis, MgO and Li-doped MgO have been studied as catalysts for the oxidative coupling of methane. In this work, we analyze the structure and stability of defect complexes comprising Li dopants and oxygen vacancies in MgO, combining scanning tunneling microscopy, photon-emission experiments, and density-functional theory computations. The experimental results strongly indicate that after annealing Li-doped MgO to temperatures of 600 K and higher, Li evaporates from the surface, but Li defects, such as substitutional defects, interstitials, or defect complexes comprising Li remain in the bulk. Our calculations show that bulk defect complexes containing F 2+ color centers, that have donated their two electrons to two adjacent Li defects, are the most stable configurations at realistic pressure and temperature conditions.

show abstract

“…Here, g j is the respective mode Grüneisen parameter and α the volume thermal expansion of the material. While for most of the materials α can be approximated well by a linear temperature dependence, g j has a rather complex relation to the temperature (Jasperse et al 1966), which is often unknown. However, in many cases g j can be assumed as a constant value ranging between 0 and 2 (Lowndes 1970;Gervais & Piriou 1975), in which case δω j will show a quadratic temperature dependence.…”

Section: Theoretical Point Of Viewmentioning

confidence: 99%

“…While for Δω PI j the temperature dependence arose from the mode-specific excitation probability of the phonons (Bose-Einstein-distribution), the temperature dependence of ω j is due to the thermal expansion of the solid and can be approximated by the model of Grüneisen (Lowndes 1970;Jasperse et al 1966;Gervais & Piriou 1974a) with:…”

Section: Theoretical Point Of Viewmentioning

confidence: 99%

Optical constants of refractory oxides at high temperatures

Zeidler

Posch

Mutschke

2013

A&A

View full text Add to dashboard Cite

Context. Many cosmic dust species, among them refractory oxides, form at temperatures higher than 300 K. Nevertheless, most astrophysical studies are based on the room-temperature optical constants of solids, such as corundum and spinel. A more realistic approach is needed for these materials, especially in the context of modeling late-type stars. Aims. We aimed at deriving sets of optical constants of selected, astrophysically relevant oxide dust species with high melting points. Methods. A high-temperature, high-pressure cell and a Fourier-transform spectrometer were used to measure reflectance spectra of polished samples. For corundum (α-Al 2 O 3 ), spinel (MgAl 2 O 4 ), and α-quartz (SiO 2 ), temperature-dependent optical constants were measured from 300 K up to more than 900 K. Small particle spectra were also calculated from these data. Results. All three examined oxides show a significant temperature dependence of their mid-IR bands. For the case of corundum, we find that the 13 μm emission feature -seen in the IR spectra of many AGB stars -can very well be assigned to this mineral species. The best fit of the feature is achieved with oblate corundum grains at (mean) temperatures around 550 K. Spinel remains a viable carrier of the 13 μ feature as well, but only for T < 300 K and nearly spherical grain shapes. Under such circumstances, spinel grains may also account for the 31.8 μm band that is frequently seen in sources of the 13 μm feature and which has not yet been identified with certainty.

show abstract

Temperature Dependence of Infrared Dispersion in Ionic Crystals LiF and MgO

Cited by 337 publications

References 26 publications

Atomic Layer Deposition of Magnetic Thin Films

Atomic Layer Deposition of Magnetic Thin Films

Defect complexes in Li-doped MgO

Optical constants of refractory oxides at high temperatures

Contact Info

Product

Resources

About