Electrical conduction in non-metallic rare-earth solids

Lal, H. B.; Gaur, Kanchan

doi:10.1007/bf01153989

Cited by 73 publications

(40 citation statements)

References 13 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Oxygen diffusion is more likely due to the very large size of the dysprosium ions. The n-type behavior was also observed by Tare and Schmalzried [30] from 667 to 860°C while a later report by Lal et al [31] suggests that Dy 2 O 3 is a p-type semiconductor at 627°C with a 0.011 cm À2 V À1 s À1 hole mobility and 0.010 cm À2 V À1 s À1 electron mobility. Pethe et al [21] also notes that the parabolic rate constant remains constant (within the experimental error) from 1% to 13% O 2 at 600°C.…”

Section: Resultssupporting

confidence: 52%

High temperature oxidation kinetics of dysprosium particles

Jaques

Butt

2015

Journal of Alloys and Compounds

View full text Add to dashboard Cite

a b s t r a c tRare earth elements have been recognized as critical materials for the advancement of many strategic and green technologies. Recently, the United States Department of Energy has invested many millions of dollars to enhance, protect, and forecast their production and management. The work presented here attempts to clarify the limited and contradictory literature on the oxidation behavior of the rare earth metal, dysprosium. Dysprosium particles were isothermally oxidized from 500 to 1000°C in N 2 -(2%, 20%, and 50%) O 2 and Ar-20% O 2 using simultaneous thermal analysis techniques. Two distinct oxidation regions were identified at each isothermal temperature in each oxidizing atmosphere. Initially, the oxidation kinetics are very fast until the reaction enters a slower, intermediate region of oxidation. The two regions are defined and the kinetics of each are assessed to show an apparent activation energy of 8-25 kJ/mol in the initial region and 80-95 kJ/mol in the intermediate oxidation reaction region. The effects of varying the oxygen partial pressure on the reaction rate constant are used to show that dysprosium oxide (Dy 2 O 3 ) generally acts as a p-type semiconductor in both regions of oxidation (with an exception above 750°C in the intermediate region). Published by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

show abstract

Section: Resultssupporting

confidence: 52%

High temperature oxidation kinetics of dysprosium particles

Jaques

Butt

2015

Journal of Alloys and Compounds

View full text Add to dashboard Cite

show abstract

“…[52][53][54][55][56][57] Unfortunately, the reported activation energies of n-type conduction in PrO 2 substantially scatter, namely, from 0.8 ͑Ref. 55͒ to 2.1 eV, 56 so that a correlation with our study is at present difficult. Interestingly, the electronic band diagram in Fig.…”

Section: B Electrical Characterizationmentioning

confidence: 91%

“…Pr oxides form a number of so-called nonstoichiometric phases in the stoichiometry range between PrO x with x = 1.5 ͑Pr 2 O 3 ͒ and x =2 ͑PrO 2 ͒ with semiconducting properties changing from p-type ͑x Ͻ 1.75͒ to n-type ͑x Ͼ 1.75͒. [52][53][54][55][56][57] Unfortunately, the reported activation energies of n-type conduction in PrO 2 substantially scatter, namely, from 0.8 ͑Ref. 55͒ to 2.1 eV, 56 so that a correlation with our study is at present difficult.…”

Section: B Electrical Characterizationmentioning

confidence: 99%

Dielectric properties of single crystalline PrO2(111)/Si(111) heterostructures: Amorphous interface and electrical instabilities

Seifarth

Walczyk

Łupina

et al. 2009

Journal of Applied Physics

View full text Add to dashboard Cite

Single crystalline PrO 2 ͑111͒ / Si͑111͒ heterostructures are flexible buffers for global Ge integration on Si. A combined materials science-electrical characterization is carried out to study the influence of postdeposition annealing in 1 bar oxygen at 300-600°C on the dielectric properties of PrO 2 ͑111͒ / Si͑111͒. The materials science transmission electron microscopy and x-ray reflectometry studies reveal that postdeposition oxidation of the PrO 2 ͑111͒ / Si͑111͒ boundary results in an amorphous interface ͑IF͒ layer, which grows in thickness with temperature. Nondestructive depth profiling synchrotron radiation-based x-ray photoelectron spectroscopy and x-ray absorption spectroscopy methods demonstrate that this amorphous IF layer is composed of two Pr-silicate phases, namely, with increasing distance from Si, a SiO 2 -rich and a SiO 2 -poor Pr silicate. The electronic band offset diagram shows that the wide band gap dielectric Pr silicate results in higher band offsets with respect to Si than the medium band gap dielectric PrO 2 . The electrical characterization studies by C-V measurements show that ͑a͒ well-behaved dielectric properties of the PrO 2 ͑111͒ / IF/ Si͑111͒ are achieved in a narrow postdeposition oxidation window of 400-450°C and that ͑b͒ defects are distributed over the Pr-silicate IF layer. Temperature-dependent J-V studies report furthermore that the formation of the single crystalline PrO 2 /amorphous Pr-silicate bilayer structure on Si͑111͒ results in ͑a͒ improved insulating properties and ͑b͒ strong electrical instability phenomena in the form of a Maxwell-Wagner instability and dielectric relaxation.

show abstract

“…In Table III, we compare the calculated band gaps for the A-type structure, to the experimental values, as obtained respectively from optical 35 (column 4) and conductivity 36,37 (columns 5 and 6) measurements. The two sets of conductivity measurements refer respectively to temperature regions above 36 (column 5) and below 37 (column 6) T=800 K.…”

Section: The Re-sesquioxidesmentioning

confidence: 99%

First-principles study of rare-earth oxides

et al. 2005

View full text Add to dashboard Cite

The self-interaction-corrected local-spin-density approximation is used to describe the electronic structure of dioxides, REO 2 , and sesquioxides, RE 2 O 3 , for the rare earths, RE=Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy and Ho. The valencies of the rare earth ions are determined from total energy minimization. We find Ce, Pr, Tb in their dioxides to have the tetravalent configuration, while for all the sesquioxides the trivalent groundstate configuration is found to be the most favourable. The calculated lattice constants for these valency configurations are in good agreement with experiment.Total energy considerations are exploited to show the link between oxidation and f -electron delocalization, and explain why, among the dioxides, only the CeO 2 , PrO 2 , and TbO 2 exist in nature.Tetravalent NdO 2 is predicted to exist as a metastable phase -unstable towards the formation of hexagonal Nd 2 O 3 .

show abstract

Electrical conduction in non-metallic rare-earth solids

Cited by 73 publications

References 13 publications

High temperature oxidation kinetics of dysprosium particles

High temperature oxidation kinetics of dysprosium particles

Dielectric properties of single crystalline PrO2(111)/Si(111) heterostructures: Amorphous interface and electrical instabilities

First-principles study of rare-earth oxides

Contact Info

Product

Resources

About