Observation and enhancement through alkali metal doping of p-type conductivity in the layered oxyselenides Sr₂ZnO₂Cu₂Se₂ and Ba₂Zn_1−xO_2−xCu₂Se₂

The optoelectronic properties of two layered copper oxyselenide compounds, with nominal composition Sr2ZnO2Cu2Se2 and Ba2ZnO2Cu2Se2, have been investigated to determine their suitability as p-type conductors. The structure, band gaps and electrical conductivity of pristine and alkali-metal-doped samples have been determined. We find that the strontium-containing compound, Sr2ZnO2Cu2Se2, adopts the expected tetragonal Sr2Mn3SbO2 structure with I4/mmm symmetry, and has a band gap of 2.16 eV, and a room temperature conductivity of 4.8 × 10−1 S cm−1. The conductivity of the compound could be increased to 4.2 S cm−1 when sodium doped to a nominal composition of Na0.1Sr1.9ZnO2Cu2Se2. In contrast, the barium containing material was found to have a small zinc oxide deficiency, with a sample dependent compositional range of Ba2Zn1−xO2−xCu2Se2 where 0.01 < x < 0.06, as determined by single crystal X-ray diffraction and powder neutron diffraction. The barium-containing structure could also be modelled using the tetragonal I4/mmm structure, but significant elongation of the oxygen displacement ellipsoid along the Zn–O bonds in the average structure was observed. This indicated that the oxide ion position was better modelled as a disordered split site with a displacement to change the local zinc coordination from square planar to linear. Electron diffraction data confirmed that the oxide site in Ba2Zn1−xO2−xCu2Se2 does not adopt a long range ordered arrangement, but also that the idealised I4/mmm structure with an unsplit oxide site was not consistent with the extra reflections observed in the electron diffractograms. The band gap and conductivity of Ba2Zn1−xO2−xCu2Se2 were determined to be 2.22 eV and 2.0 × 10−3 S cm−1 respectively. The conductivity could be increased to 1.5 × 10−1 S cm−1 with potassium doping in K0.1Ba1.9Zn1−xO2−xCu2Se2. Hall measurements confirmed that both materials were p-type conductors with holes as the dominant charge carriers

Promoting responsibility, shaping behaviour: housing management, mixed communities and the construction of citizenship

This article examines housing policies aimed at establishing mixed income communities. Based on stakeholder interviews and case study analysis in England and Scotland, the article pays particular attention to the impact of interventions in housing management. The first part of the article considers the policy context for mixed communities and considers the conceptual basis underlying contemporary housing management through discourses of culture and social control. The second part considers how this agenda has resulted in the adoption of intensive management strategies within mixed communities; illustrated in the development of allocation policies, initiatives designed to tackle anti-social behaviour and proposals to develop sustainable communities. The main argument is given that the concept of mixed communities is based on the premise of social housing failure, citizenship has been defined largely in response to private sector interests. This approach to management has been a contributory factor in the construction of social housing as a form of second-class citizenship

An ideal Weyl semimetal induced by magnetic exchange

Weyl semimetals exhibit exceptional quantum electronic transport due to the presence of topologically-protected band crossings called Weyl nodes. The nodes come in pairs with opposite chirality, but their number and location in momentum space is otherwise material specific. Following the initial discoveries there is now a need for better material realizations, ideally comprising a single pair of Weyl nodes located at or very close to the Fermi level and in an energy window free from other overlapping bands. Here we propose the layered intermetallic EuCd$_2$As$_2$ to be such a system. We show that Weyl nodes in EuCd$_2$As$_2$ are magnetically-induced via exchange coupling, emerging when the Eu spins are aligned by a small external magnetic field. The identification of EuCd$_2$As$_2$ as a model magnetic Weyl semimetal, evidenced here by ab initio calculations, photoemission spectroscopy, quantum oscillations and anomalous Hall transport measurements, opens the door to fundamental tests of Weyl physics

(In)formalization and the civilizing process : applying the work of Norbert Elias to housing-based anti-social behaviour interventions in the UK

This paper uses Norbert Elias's theory of the civilizing process to examine trends in social conduct in the UK and to identify how problematic “anti‐social” behaviour is conceptualized and governed through housing‐based mechanisms of intervention. The paper describes how Elias's concepts of the formalization and informalization of conduct and the construction of established and outsider groups provide an analytical framework for understanding social relations. It continues by discussing how de‐civilizing processes are also evident in contemporary society, and are applied to current policy discourse around Respect and anti‐social behaviour. The paper uses the governance of “anti‐social” conduct through housing mechanisms in the UK to critique the work of Elias and concludes by arguing that a revised concept of the civilizing process provides a useful analytical framework for future studies

Differentiation and displacement: Unpicking the relationship between accounts of illness and social structure

This article seeks to unpack the relationship between social structure and accounts of illness. Taking dentine hypersensitivity as an example, this article explores the perspective that accounts of illness are sense-making processes that draw on a readily available pool of meaning. This pool of meaning is composed of a series of distinctions that make available a range of different lines of communication and action about such conditions. Such lines of communication are condensed and preserved over time and are often formed around a concept and its counter concept. The study of such processes is referred to as semantic analysis and involves drawing on the tools and techniques of conceptual history. This article goes on to explore how the semantics of dentine hypersensitivity developed. It illustrates how processes of social differentiation led to the concept being separated from the more dominant concept of dentine sensitivity and how it was medicalised, scientised and economised. In short, this study seeks to present the story of how society has developed a specific language for communicating about sensitivity and hypersensitivity in teeth. In doing so, it proposes that accounts of dentine hypersensitivity draw on lines of communication that society has preserved over time

The mechanics of housing collectivism: How forms and functions affect affordability

In countries worldwide, limited access to affordable housing is fuelling interest in collectivist solutions. Different organizational models are being developed to enable groups of people to own and control housing collectively. The benefits of such models have been widely promoted, not least in terms of delivering enhanced housing affordability for residents. However, evidence to support such claims is scarce and it remains unclear whether affordability is the product of collective forms and functions, or some other factor(s). To address this gap in knowledge, the paper presents findings from three case studies of English and Canadian housing collectives. Applying realist theories of causation, the processes affecting housing affordability are explained, conceptualizing two causal mechanisms which depict how organizational form, internal rules and regulatory activity, along with the unique role of the resident-owner, influence the setting of rents and prices. Further research is required to understand the prevalence of these mechanisms and their general application

Grudge spending:The interplay between markets and culture in the purchase of security

In the paper, we use data from an English study of security consumption, and recent work in the cultural sociology of markets, to illustrate the way in which moral and social commitments shape and often constrain decisions about how, or indeed whether, individuals and organizations enter markets for protection. Three main claims are proffered. We suggest, firstly, that the purchase of security commodities is a mundane, non-conspicuous mode of consumption that typically exists outside of the paraphernalia of consumer culture - a form of grudge spending. Secondly, we demonstrate that security consumption is weighed against other commitments that individuals and organizations have and is often kept in check by these competing considerations. We find, thirdly, that the prospect of consuming security prompts people to consider the relations that obtain between security objects and other things that they morally or aesthetically value, and to reflect on what the buying and selling of security signals about the condition and likely futures of their society. These points are illustrated using the examples of organizational consumption and gated communities. In respect of each case, we tease out the evaluative judgements that condition and constrain the purchase of security among organizations and individuals and argue that they open up some important but neglected questions to do with the moral economy of security