Direct observation of strong surface reconstruction in partially reduced nickelate films.

The polarity of a surface can affect the electronic and structural properties of oxide thin films through electrostatic effects. Understanding the mechanism behind these effects requires knowledge of the atomic structure and electrostatic characteristics at the surface. In this study, we use annular bright-field imaging to investigate the surface structure of a Pr0.8Sr0.2NiO2+x (0 < x < 1) film. We observe a polar distortion coupled with octahedral rotations in a fully oxidized Pr0.8Sr0.2NiO3 sample, and a stronger polar distortion in a partially reduced sample. Its spatial depth extent is about three unit cells from the surface. Additionally, we use four-dimensional scanning transmission electron microscopy (4D-STEM) to directly image the local atomic electric field surrounding Ni atoms near the surface and discover distinct valence variations of Ni atoms, which are confirmed by atomic-resolution electron energy-loss spectroscopy (EELS). Our results suggest that the strong surface reconstruction in the reduced sample is closely related to the formation of oxygen vacancies from topochemical reduction. These findings provide insights into the understanding and evolution of surface polarity at the atomic level.

Adolescents with anxiety and depression: is social recovery relevant?

UNLABELLED: Social recovery has become a prominent aspect of mental health service design and delivery in the past decade. Much of the literature on social recovery is derived from first-person accounts or primary research with adult service users experiencing severe mental illness. There is a lack of both theoretical and empirical work that could inform consideration of how the concept of social recovery might apply to adolescents experiencing common (non-psychotic) mental health problems such as anxiety and depression. The current study was conducted to understand the process of experiencing anxiety and depression in young people. Semi-structured interviews were conducted with nine adolescents with anxiety and depression (seven girls and two boys aged 14-16 years) and 12 mothers who were recruited from a specialist Child and Adolescent Mental Health Service in the South of England. Thematic analysis indicated that young people do experience a process of 'recovery'; the processes participants described have some congruence with the earlier stages of adult recovery models involving biographical disruption and the development of new meanings, in this case of anxiety or depression, and changes in sense of identity. The accounts diverge with regard to later stages of adult models involving the development of hope and responsibility. The findings suggest that services should attend to social isolation and emphasise support for positive aspirations for future selves whilst also attending to young people's and parents' expectations about change. Methodological challenges face enquiry about 'recovery' given its connotations with cure in everyday language. KEY PRACTITIONER MESSAGE: Theoretical and empirical work on social recovery in young people and families is lacking. Using interviews, this study sought to understand the relevance of social recovery for adolescents with anxiety and depression and their mothers. Findings suggest some congruence with the earlier stages of adult recovery models involving meaning and identity. Findings diverge with regard to later stages of adult recovery models involving hope and responsibility. Social recovery in mental health services for young people needs significant empirical attention and critical debate.