<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mi>CaB</mml:mi></mml:mrow><mml:mrow><mml:mn>6</mml:mn></mml:mrow></mml:msub></mml:mrow></mml:math>: A New Semiconducting Material for Spin Electronics

Tromp, H.J.; Gelderen, Peter van; Kelly, Paul J.; Brocks, G.; Bobbert, Peter A.

doi:10.1103/physrevlett.87.016401

Cited by 144 publications

(112 citation statements)

References 32 publications

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“…Pseudopotential based GW calculations [3] yielded a sizable 0.8 eV band gap at X point, while recent all-electron GW results [21] showed an unexpected increase in band overlap relative to the LDA, perhaps related to the treatment of deep-core states. [22,23] The electronic structure of CaB 6 has also been the subject of some debate from an experimental point of view, although a semiconducting electronic structure has become more generally accepted now.…”

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confidence: 99%

“…show a tiny overlap [3,14,15]. This small difference in band structure is due to different choices of the LDA scheme, chemistry (Sr vs. Ca) and lattice structure as well as the approximations in using pseudopotentials.…”

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confidence: 99%

“…This is reminiscent of the situation in the rare-earth trihydrides, e.g. YH 3 . Those materials feature a semiconducting ground state, which is however predicted to be metallic in the LDA due to a band overlap between nominally occupied H derived states and nominally unoccupied metal states.…”

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confidence: 99%

“…To check this we did well converged general potential linearized augmented planewave (LAPW) calculations within the LDA for two structures. The first is the same experimental structure as used for Thus the WDA, with an appropriate choice of G, predicts CaB 6 to be a semiconductor with a gap comparable to that found in standard GW calculations [3] and in experimental spectroscopic measurements. [27,28,29] This shows that there exists a physical approximation to density functional theory that is continuous and has only short range non-locality and that gives both a reasonable band gap and ground state properties (crystal structure) in agreement with experiment for CaB 6 .…”

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confidence: 99%

“…Further, a semiconducting material, with ferromagnetism of this type, could potentially be of importance in producing room temperature spintronic devices. [2,3] Two different classes of theories were advanced early on in an effort to explain the strange ferromagnetism. The first was based on the doping of an excitonic or like system, i.e.…”

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Electronic structure of calcium hexaboride within the weighted density approximation

Singh

Cohen

2004

Phys. Rev. B

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We report calculations of the electronic structure of CaB 6 using the weighted density approximation (WDA) to density functional theory. We find a semiconducting band structure with a sizable gap, in contrast to local density approximation (LDA) results, but in accord with recent experimental data. In particular, we find an X-point band gap of 0.8 eV. The WDA correction of the LDA error in describing the electronic structure of CaB 6 is discussed in terms of the orbital character of the bands and the better cancelation of self-interactions within the WDA.

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confidence: 99%

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Electronic structure of calcium hexaboride within the weighted density approximation

Singh

Cohen

2004

Phys. Rev. B

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Organic Exciton Multiferroics

Ren

Wuttig

2011

Advanced Materials

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Boron Nanoparticles for Room‐Temperature Hydrogen Generation from Water

Rohani

Kim

Swihart

2016

Advanced Energy Materials

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solid energetic materials, including aluminum (31 kJ g −1 ). [8][9][10] In medicine, boron neutron capture therapy, a noninvasive cancer treatment using boron-10, is another important application. [ 11 ] Furthermore, boron has the highest gravimetric hydrogen generation potential among inorganic solids that can be used for chemical splitting of water, up to 277 g H 2 per kg B. For comparison, silicon, aluminum, and sodium hydride have gravimetric hydrogen generation potentials of 142, 111, and 98 g H 2 kg −1 , respectively. Thus, boron is very interesting for on demand generation of hydrogen by reaction with water.Hydrogen is an emission-free fuel with high gravimetric energy content (120 kJ g −1 ) that can be used effi ciently in well-developed proton exchange membrane (PEM) fuel cells. Hydrogen generation and storage has attracted considerable attention in the past few years because of practical limitations of conventional gas storage methods, such as high-pressure tanks, for hydrogen. On-demand generation of hydrogen from water is one means of providing hydrogen for fuel cells and other uses. The direct thermolysis of water into hydrogen and oxygen requires temperatures above 2500 K and is therefore impractical in most applications. [ 12 ] Chemical water splitting, by reacting water with a metal to produce a metal oxide and release hydrogen, is an attractive means of splitting water at much lower temperature. However, the reaction rate of metal hydrolysis usually decreases with time because of oxide formation at the surface of the metal particles. Thermodynamically, boron has great potential for on-demand hydrogen generation by reaction with water. However, boron is generally nonreactive with water; it requires either a catalyst or very high temperature to react. Several studies of water splitting by reaction with boron, using steam at elevated temperatures, were published in the past few years. Kinetics of heterogeneous, noncatalytic hydrolysis of boron (micron sized, with average diameter near 44 µm) were investigated over a range of temperatures and steam concentrations, demonstrating increased reaction rate with increasing temperature (from 500 to 800 °C). [ 13 ] Although they did not explicitly report the total hydrogen produced in each experiment, this quantity can be estimated from their plots of hydrogen fl ow rate versus time. For example, 100 mg boron and 0.5 mL min −1 water fl ow generated ≈90 mL hydrogen gas in 12 min at 700 °C. In another study, amorphous boron hydrolysis at somewhat lower temperatures (below Boron nanoparticles (BNPs) are of great interest for applications such as neutron capture therapy of cancer cells, hydrogen generation from water, and high energy density fuels. Boron is particularly interesting for chemical water splitting, because of its high gravimetric hydrogen generation potential of 277 g H 2 per kg B. However, only a few studies of water splitting by reaction with boron are available, and those have used high temperature steam with external heating. Room-temperature bo...

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CaB6: A New Semiconducting Material for Spin Electronics

Cited by 144 publications

References 32 publications

Electronic structure of calcium hexaboride within the weighted density approximation

Electronic structure of calcium hexaboride within the weighted density approximation

Organic Exciton Multiferroics

Boron Nanoparticles for Room‐Temperature Hydrogen Generation from Water

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