Density functional theory study of hypothetical<mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:msub><mml:mtext>PbTiO</mml:mtext><mml:mn>3</mml:mn></mml:msub></mml:math>-based oxysulfides

Brehm, John A.; Takenaka, Hiroyuki; Lee, Chan‐Woo; Grinberg, Ilya; Bennett, Joseph W.; Schoenberg, Michael Rutenberg; Rappe, Andrew M.

doi:10.1103/physrevb.89.195202

Cited by 32 publications

(26 citation statements)

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“…For the PbTi(O,S)3 alloy, the decrease of ionic charge and increase in covalent bonding with increasing sulfur content was shown explicitly using electronic structure theory. 37 Experimental results have confirmed the decrease in band gap upon substituting sulfur for oxygen in perovskite-structured materials: from 3.6 to 1.8 eV for BaZrX3, and from 5.5 to 1.9 eV for CaZrX3 (X = O or S). 17,21,39,40 Recent results (by the authors and others) show that the ambipolar opto-electronic properties of complex chalcogenides are promising.…”

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confidence: 70%

“…Ae3B2S7 (Ae = Ca, Sr; B = Zr, Hf), ZnSnS3, and PbTi(O,S)3 are predicted by theory to be ferroelectrics with band gap in the range 1 -2 eV. 14,15,37,38 The Ca3Zr2S7 -Sr3Zr2S7 -Ba3Zr2S7 system may be functionally similar to the CaTiO3 -SrTiO3 -BaTiO3 (BST) system, with non-polar end-members (Ba3Zr2S7, space group P42/mnm; Sr3Zr2S7, space group P42/mnm; SrTiO3, space group Pm3 ̅ m; CaTiO3, space group Pnma) and one polar end-member (Ca3Zr2S7, space group A21am or Cmc21; BaTiO3, space group P4mm) in a binary system with complete solid solubility. For the PbTi(O,S)3 alloy, the decrease of ionic charge and increase in covalent bonding with increasing sulfur content was shown explicitly using electronic structure theory.…”

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confidence: 99%

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In praise and in search of highly-polarizable semiconductors: Technological promise and discovery strategies

Jaramillo

Ravichandran

2019

APL Materials

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The dielectric response of materials underpins electronics and photonics. At high frequencies, dielectric polarizability sets the scale for optical density and absorption. At low frequencies, dielectric polarizability determines the band diagram of junctions and devices, and nonlinear effects enable tunable capacitors and electro-optic modulators. More complicated but no less important is the role of dielectric response in screening bound and mobile charges. These effects control defect charge capture and recombination rates, set the scale for insulator-metal transitions, and mediate interactions among charge carriers and between charge carriers and phonons. Figure 1:Dielectric polarizability vs. band gap for semiconductors and complex oxides. 1-9 We use the low frequency dielectric constant ( 0 ) as to represent polarizability because it is widelyreported. The two points labeled CZTSSe represent low-and high-band gap Cu2ZnSn(S,Se)4. c-GST and a-GST represent crystalline and amorphous Ge2Sb2Te5. In FAPbI3 and MAPbI3, FA and MA represent formamidinium and methylammonium, respectively. The light orange region labeled "highly-polarizable semiconductors" represents a hypothesis and a suggested research focus. In search of highly-polarizable semiconductorsEstablished semiconductor material platforms are based on a motif of tetrahedral covalent bonding and relatively light elements obeying the octet rule. As a result, these materials have a narrow range of dielectric susceptibility, with low-frequency values ( 0 ) on the order of 10 being typical for group-IV, III-V, and II-VI systems (the dielectric constant for many of these semiconductors is enhanced at high-frequency, near the band gap); see Figure 1, where we present

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confidence: 70%

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In praise and in search of highly-polarizable semiconductors: Technological promise and discovery strategies

Jaramillo

Ravichandran

2019

APL Materials

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“…The corrective U eff values used in this study are 7 eV for the Ti 3d orbitals and 6 eV for the O 2p orbitals, as determined empirically on bulk tetragonal PbTiO 3 , leading to a band gap of 2.98 eV. This value is still a little underestimated with respect to experiment (giving values in the range 3.45 3.6 eV -(see [67] and references cited therein), but significantly improved relative to the GGA result (1.68 eV). Applying the correction also on Ru 4d states had no noticeable effect on the present results and therefore was discarded.…”

Section: Computational Details and Model Structures 21 Methodsmentioning

confidence: 88%

Designing functional ferroelectric interfaces from first-principles: dipoles and band bending at oxide heterojunctions

et al. 2019

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The fundamental phenomena at ferroelectric interfaces have been the subject of thorough theoretical and computational studies due to their usefulness in a large variety of emergent electronic devices, solar cells and catalysts. Ferroelectricity determines interface band-bending and shifts in electron energies, which can be beneficial or detrimental to device performance. However, the underlying mechanisms are still the subject of debate and investigation, as a deeper understanding of the electrochemistry is required to develop bona fide design principles for functional ferroelectric surfaces and interfaces. Here, using first principles calculations within the GGA+U formalism, we investigate the problem of band alignment in non-defective, asymmetric SrRuO 3 /PbTiO 3 /SrRuO 3 capacitors with ultra-thin ferroelectric layers. The effects of the dielectric size on the polar distortion stability and interface-specific properties are analyzed. It is shown that the critical size of the dielectric for polarization switching is 2 nm » (5 PbTiO 3 u.c.). Below this limit there is no bulk-like region in the dielectric, the space charge accumulated at interfaces leads to the presence of gap states in the whole PbTiO 3 layer and ferroelectricity vanishes. We draw the band alignment diagrams as given by the band line-up and band structure terms, as well as by taking Ti 3s semi-core states as reference. In the ferroelectric structures, both approaches predict a strong effect of band-bending on the type of contact, Schottky or Ohmic, at the asymmetric interfaces. The effect of interface states on the interface dipole amplitude and band alignment is discussed.

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“…In particular, the density functional theory (DFT) approach offers an opportunity for a rational design of new materials with improved properties, even before they are observed experimentally. Brehm et al [17] reported physical and electronic properties of hypothetical PbTiO 3 -based oxysulfides, PbTiO 3-x S x using first-principles calculations. Theoretical analysis indicates that this compound should be considered a solar bulk photovoltaic material candidate [17].…”

Section: Introductionmentioning

confidence: 99%

“…Brehm et al [17] reported physical and electronic properties of hypothetical PbTiO 3 -based oxysulfides, PbTiO 3-x S x using first-principles calculations. Theoretical analysis indicates that this compound should be considered a solar bulk photovoltaic material candidate [17]. First-principles calculations conducted by Cohen [18] revealed that the strong interaction between the Ti 3d orbitals and O 2p orbitals, or in other words covalent bonding, is crucial for large polarization of lead titanate, PbTiO 3 .…”

Section: Introductionmentioning

confidence: 99%

Combined theoretical and nanoscale experimental study of Pb(Ca,Ba)TiO3, Pb(Sr,Ba)TiO3, and Pb(Sr,Ca)TiO3 complex perovskite structures: An investigation of the ferroelectric and electronic properties

Pontes

Bastos

Chiquito

et al. 2017

Journal of Alloys and Compounds

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Combined experimental and first-principles studies have been conducted to obtain a fundamental understanding of the effect of A-site chemical doping on the electronic structure and ferroelectric behavior of Pb(Ca,Ba)TiO 3 , Pb(Sr,Ba)TiO 3 , and Pb(Sr,Ca)TiO 3 perovskite complex solid solutions. Rietveld refinement of powder X-ray diffraction data shows that the crystal structure of all the three compounds is distorted from the ideal cubic perovskite structure. At the nanoscale, piezoresponse force microscopy (PFM) studies show low-performance ferroelectric properties of Pb(Sr,Ca)TiO 3 thin films when compared to Pb(Ca,Ba)TiO 3 and Pb(Sr,Ba)TiO 3 films. Theoretical analysis of the electronic band structure performed on the basis of density functional theory (DFT) allows to elucidate the origin of the different ferroelectric behaviors observed in Pb(Ca,Ba)TiO 3 , Pb(Sr,Ba)TiO 3 , and Pb(Sr,Ca)TiO 3 thin films. DFT-based computational calculations reveal that there is a strong correlation between the effects of Ti 3d non-bonding orbitals (responsible for p TieO bonding) and the ferroelectric polarization behavior of A(A 0 A 00)BO 3 complex perovskite solid solutions. In our study, very low Ti 3d xy, d xz , and d yz non-bonding electronic density state contributions were observed and the presence of mainly ionic CaeO and SreO bonds. These effects are the reason for the unusually weak polarization, low tetragonality, and poor ferroelectricity of Pb(Sr,Ca)TiO 3 thin films. This is in contrast to the observed behaviors of Pb(Ca,Ba)TiO 3 and Pb(Sr,Ba)TiO 3 thin films. However, our first-principles calculations agree well with the PFM-based experimental results obtained in the nanometer scale.

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Density functional theory study of hypotheticalPbTiO3-based oxysulfides

Cited by 32 publications

References 50 publications

In praise and in search of highly-polarizable semiconductors: Technological promise and discovery strategies

In praise and in search of highly-polarizable semiconductors: Technological promise and discovery strategies

Designing functional ferroelectric interfaces from first-principles: dipoles and band bending at oxide heterojunctions

Combined theoretical and nanoscale experimental study of Pb(Ca,Ba)TiO3, Pb(Sr,Ba)TiO3, and Pb(Sr,Ca)TiO3 complex perovskite structures: An investigation of the ferroelectric and electronic properties

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