Phase transition, Raman spectra, infrared spectra, band gap and microwave dielectric properties of low temperature firing (Na0.5xBi1−0.5x)(MoxV1−x)O4 solid solution ceramics with scheelite structures

Zhou, Di; Pang, Li‐Xia; Wang, Hong; Guo, Jing; Yao, Xi; Randall, Clive A.

doi:10.1039/c1jm14004c

Cited by 88 publications

(81 citation statements)

References 51 publications

(54 reference statements)

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…This shift may be indicative of a lowered V-O bond length, which is the interpretation used for Mo +6 and W +6 substitution onto the V +5 site, 15 but our observed shifting of this peak does not directly correlate with Mo concentration, for example along the Mo-Gd co-alloying lines the peak continues to shift downward as the concentration of Mo decreases, indicating a different cause for the alteration of this vibrational mode. Hardcastle et al 48 studied a variety of bismuth vanadate phases and noted that increased symmetry within the VO4 tetrahedron also shifts the symmetric V-O stretching mode (νs) to lower wavenumber, which is also noted by Gotić et al 47 and observed by Zhou et al 26 The trends in Figure 4 are commensurate with this phenomenon, with decreases in both (δs -δas) peak splitting and νs peak position resulting from lowered distortion of the VO4 tetrahedron, which is concomitant with lowered monoclinic distortion in the parent crystal structure.The composition map of the monoclinic distortion in Figure 5a, which includes the x ≈ 0.5 compositions of Figure 4 as well as the analogous x = 0.48 and x ≈ 0.52 compositions, is remarkably similar to the Pmax map of Figure 2d. The simplistic interpretation of this similarity is that lowered monoclinic distortion leads to higher Pmax, but quantification of this relationship is obfuscated by the co-variant compositional variables.…”

mentioning

confidence: 66%

“…26 with the non-alloy (y = 0) patterns matching those of stoichiometric m-BiVO4. With increased Mo content, both the splitting between the (200) and (020) XRD peaks and the splitting between δs and δas Raman peaks smoothly decrease as expected for a slightly reduced monoclinic distortion.…”

Section: Optical and Structural Trendsmentioning

confidence: 99%

“…15 To enable quantitative interpretation of the shifts we turn to inspection of alloy and temperature-dependent studies by Zhou et al 26,46 of alloys (Bi1-0.5nA0.5n)(V1-nMon)O4 where A = Li or Na. The temperature of m-BiVO4 to t-BiVO4 phase transition in this system was found to drop precipitously with addition of Mo (increase in n) by approximately 21 K and 25 K for every 1% of Mo on the V site for A = Li 46 and Na, 26 respectively. These works show very nicely that starting from m-BiVO4, either increasing temperature or increasing alloying lowers the monoclinic distortion continuously and smoothly until the highersymmetry t-BiVO4 phase is obtained.…”

Section: Optical and Structural Trendsmentioning

confidence: 99%

“…For example (Bi1-0.5nNa0.5n)(V1-nMon)O4 is a specific co-alloying design wherein substitutions of Na +1 on the Bi +3 site and of Mo +6 on the V +5 site provide n-invariant charge balance assuming a constant O stoichiometry. 26 To more generally explore alloying space, including the possible variation of O stoichiometry and any combination of interstitial and substitutional alloying, we designed a composition library that covers a range of alloy loading for each of 6 elements, and a range of both composition and loading for each pairwise combination (6-choose-2 = 15) of the alloying elements. The fabrication of this composition library on a single library plate facilitates establishment of composition-property trends with minimal convoluting factors.…”

Section: Experimental Library Design and Synthesismentioning

confidence: 99%

“…These bending modes are also referred to as deformation or ν2 modes, and in the t-BiVO4 phase there is a single mode (single Raman peak). 26,46,49 To quantify how the δs -δas Raman peak splitting relates to the monoclinic distortion, which we quantify using the ratio of monoclinic lattice constants (a/b), we use the XRD and Raman data by Zhou et al, 26 which indicates that the relationship is well-described by a/b = 1 + (δs -δas) * 4.82e-3 cm,where the proportionality constant is calculated from the a/b value of 1.020 and (δs -δas) value of 41.5 cm -1 for ambienttemperature, stoichiometric m-BiVO4. From this relationship, the Raman measurement of δs and δas enables distinction between t-BiVO4 and the family of m-BiVO4 with continuouslyvariable lattice parameters.…”

mentioning

confidence: 99%

See 4 more Smart Citations

Combinatorial alloying improves bismuth vanadate photoanodes via reduced monoclinic distortion

Newhouse

Guevarra

Umehara

et al. 2018

Energy Environ. Sci.

View full text Add to dashboard Cite

Improving the efficiency of solar-power oxygen evolution is both critical for development of solar fuels technologies and challenging due to the broad set of properties required of a solar fuels photoanode. Bismuth vanadate, in particular the monoclinic clinobisvanite phase, has received substantial attention and has exhibited the highest radiative efficiency among metal oxides with a band gap in the visible range. Efforts to further improve its photoelectrochemical performance have included alloying one or more metals onto the Bi and/or V sites, with progress on this frontier stymied by the difficulty in computational modelling of substitutional alloys and the high dimensionality of co-alloying composition spaces. Since substituional alloying simultaneously changes multiple materials properties, understanding the underlying cause for performance improvements is also challenging, motivating our application of combinatorial materials science techniques to map photoelectrochemical performance of 948 unique bismuth vanadate alloy compositions comprising 0 to 8% alloys of P, Ca, Mo, Eu, Gd, and W along with a variety of compositions from each pairwise combination of these elements. Upon identification of substantial improvements in the (Mo,Gd) co-alloying space, structural mapping was performed to reveal a remarkable correlation between performance and a lowered monoclinic distortion. First-principles density functional theory calculations indicate that the improvements are due to a lowered hole effective mass and hole polaron formation energy, and collectively, our results identify the monoclinic distortion as a critical parameter in the optimization and understanding of bismuth vanadate-based photoanodes. IntroductionThe production of fuels via photoelectrochemistry (PEC) has been recognized as a promising method for capturing and storing intermittent solar energy, in particular as renewable transportation fuels. 1 Regardless of the fuel to be generated, the oxygen evolution reaction at the photoanode is critical; hence development of stable, efficient, n-type semiconductors composed of earth abundant elements and producible by scalable, cost-effective methods has received increasing research attention. [2][3][4] Bismuth vanadate, BiVO4, in particular has become the oxide semiconductor serving as the platform to develop and demonstrate a toolkit of techniques for improving and understanding the fundamental properties and photoelectrochemical performance of novel oxide-based semiconductors, despite its non-optimal bandgap. 2,5 As recently reviewed, the methods of improving the properties include heterojunction formation, alloying or doping, hydrogen or nitrogen annealing, nanostructuring to enhance charge collection, microstructuring for photon management, and surface coating to passivate surface defects and enhance catalysis. 3,4,[6][7][8][9] The highest performing BVO-based photoanodes reported to date have all incorporated several of these strategies in order to produce photocurrent densities in the range of app...

show abstract

mentioning

confidence: 66%

Section: Optical and Structural Trendsmentioning

confidence: 99%

Section: Optical and Structural Trendsmentioning

confidence: 99%

Section: Experimental Library Design and Synthesismentioning

confidence: 99%

mentioning

confidence: 99%

See 3 more Smart Citations

Combinatorial alloying improves bismuth vanadate photoanodes via reduced monoclinic distortion

Newhouse

Guevarra

Umehara

et al. 2018

Energy Environ. Sci.

View full text Add to dashboard Cite

show abstract

List of Low‐Loss Ceramic Dielectric Materials and Their Properties

2017

Microwave Materials and Applications 2V Set

View full text Add to dashboard Cite

AbbreviationsST = sintering temperature ( • C) r = relative permittivity , f = measurement frequency (GHz) f = coefficient of temperature variation of resonant frequency (ppm/ • C) No. = serial number Qf = quality factor frequency product (GHz)The table lists the key property data of microwave dielectric materials available from published materials. These data are the relative permittivity ( r ), the product of the Q-factor and the frequency (Qf ), the frequency of measurement (f), and the temperature coefficient of the resonant frequency ( f ). In tabulating these data, we make no judgment on the measurement method and the reliability of the result. It is known that the ceramic properties such as porosity, grain size, raw materials used, impurities, measurement methods, and equipment used for measurements affect the dielectric properties and readers should be aware that exact comparison of data on materials of identical composition and manufactured in different laboratories using different processing conditions and measured by different methods would be expected to lead to small variations in properties. The data of dielectric measurements carried out using impedance methods at low (MHz) frequency is excluded as the errors in these methods mean that a loss tangent less than 10 −3 is unreliable. The data are arranged in the order of increasing relative permittivity. The quality factor of the microwave dielectric ceramics decrease significantly with increasing relative permittivity, as shown in Figure A.1. The inset in the figure shows the variation of quality factor frequency product with Microwave Materials and Applications, First Edition. Edited by Mailadil T. Sebastian, Rick Ubic and Heli Jantunen.

show abstract

High Temperature Cofired Ceramic (HTCC), Low Temperature Cofired Ceramic (LTCC), and Ultralow Temperature Cofired Ceramic (ULTCC) Materials

Sebastian

Jantunen

2017

Microwave Materials and Applications 2V Set

View full text Add to dashboard Cite

Phase transition, Raman spectra, infrared spectra, band gap and microwave dielectric properties of low temperature firing (Na0.5xBi1−0.5x)(MoxV1−x)O4 solid solution ceramics with scheelite structures

Cited by 88 publications

References 51 publications

Combinatorial alloying improves bismuth vanadate photoanodes via reduced monoclinic distortion

Combinatorial alloying improves bismuth vanadate photoanodes via reduced monoclinic distortion

List of Low‐Loss Ceramic Dielectric Materials and Their Properties

High Temperature Cofired Ceramic (HTCC), Low Temperature Cofired Ceramic (LTCC), and Ultralow Temperature Cofired Ceramic (ULTCC) Materials

Contact Info

Product

Resources

About