Investigation of the role of morphology on the magnetic properties of Ca2Mn3O8 materials

Ca2Mn3O8 exhibits a complex layered structure comprised of Mn3O84- layers separated by Ca2+ ions. In contrast with the more traditional triangular Delafossite layered materials the Mn3O84- layers additionally exhibit an ordered vacancy which forms a 'bow-tie' like arrangement of the Mn4+ ions. We report a comprehensive study of the magnetic properties of a series of Ca2Mn3O8 materials with different morphologies. EXAFS and XANES analysis confirm no differences in either manganese environment or oxidation state between materials. Apparent differences in magnetic order from SQUID magnetometry can be rationalised by uncompensated surface spins arising as a result of changes to the surface:volume ratio between morphologies. Furthermore, these data suggest these materials are potentially frustrated in nature, due to the triangular connectivity of Mn4+ spins with a simple ‘spin-up/spin-down’ (↑↓) antiferromagnetic model unable to explain the data collected

Spin-glass behavior in KxRu4-yNiyO8 hollandite materials

We report the synthesis and comprehensive ac and dc susceptibility measurements of KxRu4−yNiyO8 hollandite. The value of the relative frequency shift, δTf , has been determined as 0.025 which is within the range expected for spin-glass systems (0.005–0.06). Additionally, the characteristic flipping time of a single spin flip, τ0, and the dynamical critical exponent, −zv, were determined to have values of 5.82×10−8 s and 6.1(3), respectively from the power law. While the value of τ0 is comparatively very large, −zv is consistent with what is expected for spin-glass systems. Field-cooled hysteresis behavior demonstrates a small increase in the remnant magnetization (at 2 K) on increasing the strength of the cooling field, suggesting that the degree of short-range correlations increases consistent with the formation of larger spin clusters. Thermoremnant magnetization data indicate an exponential-like decay of the magnetization as a function of time with the remnant magnetization remaining nonzero. However, it is clear from these data that multiple components contribute to the decay behavior. Collectively, these data confirm spin-glass character for K0.73(3)Ni1.9(5)Ru2.1(5)O8 and clearly demonstrate that the magnetic behavior of this material is far from simplistic

PZT-like structural phase transitions in the BiFeO3-KNbO3 solid solution

Despite the high prominence of the perovskites BiFeO3 and KNbO3 the solid solution between the two has received little attention. We report a detailed neutron and synchrotron x-ray powder diffraction, and Raman spectroscopy study which demonstrate an R3c → P4mm → Amm2 series of structural phase transitions similar to that exhibited by the PbZrO3 – PbTiO3 solid solution

Decarbonising the Swedish road transport sector

Road transport contributes to around one-fifth of the EU’s total CO2 emissions and is the only major sector in the EU where greenhouse gas emissions are still rising. Swedish road transport causes 30% of all emissions. Addressing transport emissions is therefore crucial for meeting the Paris Agreement commitments on climate change. The Swedish government aims to have a fossil-independent vehicle fleet by 2050; moreover, an emissions reduction target for the road transport sector of 80% (compared to 2010) by 2030 has been suggested. The government-initiated investigation ‘Fossilfrihet på väg’ sets out potential pathways, but a knowledge gap currently remains in regard to which path would be the most beneficial or least burdensome in terms of macroeconomic effects while still decarbonising the road transport sector. This paper contributes to fill that knowledge gap by applying a vehicle stock modelling framework and a demand-driven global econometric model (E3ME) and by evaluating different technology pathways for Sweden to meet the 2030 and 2050 government targets. The stock model has been adjusted to be consistent with ‘Fossilfrihet på väg’ and uses technology deployment and cost estimates to model the Swedish vehicle stock emissions in three technology-driven scenarios. The analysis shows that decarbonisation of transport can have positive impacts upon the Swedish economy, primarily through the replacement of imported fossil fuels with domestically produced electricity and biomass, while a further stimulus is provided by the construction of infrastructure to support electric vehicle recharging and fuel cell refuelling. Through quick action to encourage the deployment of new technologies and powertrains into the vehicle stock, plus policies aimed at promoting the domestic production of sustainable biomass, Sweden can maximise the potential gains from the decarbonisation process

Diversity, urban space and the right to the provincial city

Using three vignettes of the same physical space this article contributes to understanding of how the right to the city is contested in provincial England in the early twenty-first century. Oral history and ethnographic material gathered in Peterborough between 2010 and 2012 are drawn on to shed new light on the politics of diversity and urban space. This highlights the multiple place attachments and trans-spatial practices of all residents, including the white ethnic majority, as well as contrasting forms of active intervention in space with their different temporalities and affective intensities. The article carries its own diversity politics, seeking to reduce the harm done by racism through challenging the normalisation of the idea of a local, indigenous population, left out by multiculturalism. It simultaneously raises critical questions about capitalist regeneration strategies in terms of their impact both on class inequality and on the environment