Density-functional theory study of the effects of atomic impurity on the band edges of monoclinic<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" display="inline"><mml:mrow><mml:msub><mml:mrow><mml:mtext>WO</mml:mtext></mml:mrow><mml:mn>3</mml:mn></mml:msub></mml:mrow></mml:math>

Huda, M. N.; Yan, Yanfa; Moon, Chang Yoon; Wei, Su‐Huai; Al‐Jassim, Mowafak

doi:10.1103/physrevb.77.195102

Cited by 97 publications

(45 citation statements)

References 37 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…The computed G 0 W 0 band gap is converged within 0.1 eV with respect to all numerical parameters. In Table II we also report results of previous band gap calculations [46,48,49].…”

Section: Photoemission Gapmentioning

confidence: 92%

Optical properties of tungsten trioxide from first-principles calculations

2013

View full text Add to dashboard Cite

Tungsten trioxide (WO3) is an Earth abundant material of potential use as a light absorber for solar energy conversion processes. We carried out ab initio calculations of the band structure and absorption spectrum of WO3 using many body perturbation theory and we present a detailed comparison of our results with photoemission and absorption data. We show that it is necessary to take into account multiple effects, including spin-orbit and electron-phonon interaction, and exciton binding, in order to correctly predict the measured optical gap. The absorption spectrum obtained by solving the Bethe Salpeter equation compares well with experiments over a wide energy range, and our calculations correctly account for the red shift observed experimentally upon N2 intercalation in WO3.

show abstract

“…The computed G 0 W 0 band gap is converged within 0.1 eV with respect to all numerical parameters. In Table II we also report results of previous band gap calculations [46,48,49].…”

Section: Photoemission Gapmentioning

confidence: 92%

Optical properties of tungsten trioxide from first-principles calculations

2013

View full text Add to dashboard Cite

show abstract

“…WO 3 shows no proper melt; surface melting of crystalline 48 material occurs at 1746 K. Crystal growth proceeds typically 49 by sublimation and gas transport at temperatures below 50 1400 K. At the highest temperatures the structure is tetrag-51 onal (space group P 4/nmm) with strong antiferrodistortive 52 cation movements so that the WO 6 octahedra are strongly 53 distorted [30] in an antipolar pattern. Additional rotational 54 octahedral distortions condense in addition to the initial 55 tetragonal displacements when lowering the temperature.…”

mentioning

confidence: 99%

“…Numerous first-principles studies were performed on WO 3 79 in order to characterize its electronic structure (bulk, thin films, 80 and cluster phases [35][36][37][38][39][40][41]), the role of oxygen vacancies 81 [42][43][44][45], and cation doping [46][47][48][49][50][51][52][53]. In this paper we do not 82 only focus on the electronic structure but also extensively 83 study the structural stabilities and metastabilities of the 84 various phases.…”

mentioning

confidence: 99%

See 1 more Smart Citation

First-principles reinvestigation of bulk WO3

et al. 2016

View full text Add to dashboard Cite

6Using first-principles calculations, we analyze the structural properties of tungsten trioxide WO 3 . Our calculations rely on density functional theory and the use of the B1-WC hybrid functional, which provides very good agreement with experimental data. We show that the hypothetical high-symmetry cubic reference structure combines several ferroelectric and antiferrodistortive (antipolar cation motions, rotations, and tilts of oxygen octahedra) structural instabilities. Although the ferroelectric instability is the largest, the instability related to antipolar W motions combines with those associated to oxygen rotations and tilts to produce the biggest energy reduction, yielding a P 2 1 /c ground state. This nonpolar P 2 1 /c phase is only different from the experimentally reported P c ground state by the absence of a very tiny additional ferroelectric distortion. The calculations performed on a stoichiometric compound so suggest that the low-temperature phase of WO 3 is not intrinsically ferroelectric and that the experimentally observed ferroelectric character might arise from extrinsic defects such as oxygen vacancies. Independently, we also identify never observed R3m and R3c ferroelectric metastable phases with large polarizations and low energies close to the P 2 1 /c ground state, which makes WO 3 a potential antiferroelectric material. The relative stability of various phases is discussed in terms of the anharmonic couplings between different structural distortions, highlighting a very complex interplay.

show abstract

“…Tais dados são importantes, pois em todos os trabalhos relacionados ao WO 3 , várias fases são mostradas por meio da difração de raios X, as quais afetam diretamente nas propriedades elétricas desse material. Esse óxido tem várias aplicações industriais, tais como em eletrocromismo, fotocromismos, sensores químicos e catalizadores [18][19][20][21][22][23][24][25]. Os materiais cerâmicos à base de WO 3 apresentam propriedades não-Ôhmicas, com características de varistores de baixa-tensão [11].…”

Section: Resultsunclassified

Varistores à base de WO3 - revisão

Oliveira¹,

Pessoa²,

Brito³

et al. 2016

Matéria (Rio J.)

View full text Add to dashboard Cite

RESUMOVaristores são elementos que fazem parte do sistema de transmissão e distribuição de energia elétrica ou de instalações elétricas especiais. Estes dispositivos são amplamente produzidos variando a escala, dependendo de sua aplicação, como dispositivos de baixa voltagem, com poucos grãos, exibindo ruptura de alguns volts, a vários kilovolts como usado em para-raios em rede de distribuição de energia. A física de operação dos varistores tem sido amplamente estudada e tem elementos comuns como barreiras Schottky formado na junção metal/semicondutor. Vários estudos têm sido desenvolvidos a fim de obter cerâmicas varistoras para aplicação em alta e baixa tensão. Dentre esses estudos encontram-se os varistores a base de ZnO, SnO 2 , TiO 2 e mais recentemente os de WO 3 . Diferente das três composições citadas, os a base de WO 3 apresentam comportamento varistor intrínseco devido a presença das fases monoclínica e triclínica. A adição de dopantes doadores e aceitadores de elétrons e o tratamento térmico em diferentes atmosferas também alteram as propiedades não lineares desses sistemas, uma vez que influencia na formação da barreira Schottky. Neste estudo foi realizada uma revisão sobre trabalhos relacionados a nova composição de cerâmica varistora a base de óxido de tungstênio (WO 3 ). Palavras-chave: propriedades elétricas, WO 3 , varistores. _______________________________________________________________________________________ ABSTRACTVaristors are elements that are part of electric power transmission and distribution systems or of special electrical installations. Varistors are manufactured in a wide variety of types, depending on their application, such as low-voltage devices with a layer of a few grains of thickness and low breakdown voltage, to varistors with a breakdown voltage of several kilovolts, such as those used in the lightning arresters of electric power distribution networks. Varistors, whose physical operation has been extensively studied, share common elements such as metal-semiconductor Schottky barrier junctions. Several studies have focused on the development of varistor ceramics for high and low voltage applications, including ZnO, SnO 2 , TiO 2 , and more recently, WO 3 -based ceramics. Unlike the first three compositions, WO 3 -based ceramics present an intrinsic varistor behavior because they contain monoclinic and triclinic phases. The addition of electron donor and acceptor dopants and heat treatments in different atmospheres also alter the non-linear properties of these systems, since they affect the formation of the Schottky barrier. This paper offers a review of the literature on the new varistor ceramic composition based on tungsten oxide (WO 3 ). Keywords: electrical properties, WO 3 , varistors. _______________________________________________________________________________________ INTRODUÇÃOVaristores, resistores não ôhmicos ou ainda resistores variáveis, são elementos que fazem parte do sistema de transmissão e distribuição de energia elétrica ou de instalações elétricas espec...

show abstract

Density-functional theory study of the effects of atomic impurity on the band edges of monoclinicWO3

Cited by 97 publications

References 37 publications

Optical properties of tungsten trioxide from first-principles calculations

Optical properties of tungsten trioxide from first-principles calculations

First-principles reinvestigation of bulk WO3

Varistores à base de WO3 - revisão

Contact Info

Product

Resources

About