Ferroelastic phase transition compositional dependence for solid-solution [(Li0.5Bi0.5)xBi1−x][MoxV1−x]O4 scheelite-structured microwave dielectric ceramics

Combinatorial alloying improves bismuth vanadate photoanodes via reduced monoclinic distortion

“…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,…”

“…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.…”

“…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.…”

Synthetic trends for BiVO4 photocatalysts: Molybdenum substitution vs. TiO2 and SnO2 heterojunctions

“…700 °C) [29] was applied in the synthesis of the proposed monoclinic BiVO 4 :Mo catalysts [23] -but no quantitative bulk analysis was provided to verify the reported Mo incorporation of 2 at% after thermal treatment [23]. As other studies reported on particle melting around 800 °C [24] and confirm the absence of monoclinic compounds [13] in Bi/V/Mo/O oxide systems, thorough analytical characterizations of doped monoclinic phases are indispensable. The first part of our systematic hydrothermal study is thus focused on synthesis-structure-activity relationships among BiVO 4 :Mo solid solutions in order to clarify the influence of V/Mo substitution on phase, particle shape, surface area, thermal stability and catalytic performance of the products.…”

“…with metals, cation or anion substitution or by combination with other oxide materials, and the resulting effects can be differentiated with respect to surface and bulk doping. Whereas loading of oxide materials with metal particles, such as Au, gives rise to surface plasmon resonance [12], structural substitution and solid solution formation [13] can improve band structure, efficient electron-hole separation and the morphological properties of the respective material, such as particle size or shape.…”