Optoelectronic and thermoelectric properties of novel stable lead-free cubic double perovskites A2NaIO6 (A = Ca, Sr) for renewable energy applications.

Over the past decade, perovskites have received considerable attention because of their record power conversion efficiency (25.7%) in solar cells. These materials have also received recent research interest in thermoelectrics, most likely due to their high carrier mobility, large power factor, and ultralow thermal conductivity. Therefore, in the present work, we have examined the optoelectronic and thermoelectric properties of A2NaIO6 (A = Ca, Sr) double perovskites using first-principles calculations. Stability has been confirmed using reliable and accurate descriptors of formation energy and phonon calculations. The optimized lattice constant and volume show an increasing tendency with changing A site cation (Ca → Sr). The computed band structures depict the semiconducting nature with direct band gap values of 2.64 eV (Ca2NaIO6) and 2.48 eV (Sr2NaIO6). The absorption was found to start in the visible range where the reflectivity was less than 10%. Moreover, the high Seebeck coefficient, large electrical conductivity, and fairly low thermal conductivity result in ZT values of 0.724 for Ca2NaIO6 and 0.686 for Sr2NaIO6 at 1000 K. With their optimum band gap, excellent light absorption capacity, and high ZT values, A2NaIO6 emerge as promising candidates for optoelectronic and thermoelectric applications.

Epidemiology of substance use and mental health disorders among forced migrants displaced from the MENAT region: A systematic review and meta-analysis protocol.

BACKGROUND: Understanding the epidemiology of substance use disorders (SUDs) and mental health disorders (MHDs) among forced migrants from the Middle East and North Africa and Türkiye (MENAT) region is of utmost importance given their distinct challenges and vulnerabilities. Existing research on the topic is substantial; however, comprehensive systematic reviews are limited. We aim to conduct a systematic literature review to bridge this gap, providing a thorough understanding of SUDs and MHDs epidemiology among this population. METHODS: The systematic review will include original, peer-reviewed research articles published in English or Arabic between 2013 and 2023. It will encompass qualitative, quantitative, and mixed-methods studies focusing on SUDs and/or MHDs among forced migrants from the MENAT region. A Medline (via Ovid) search strategy was developed and will be translated into databases of EMBASE (via Ovid), Web of Science Core Collection (as licensed at Yale), and CINAHL. Risk of Bias in the included studies will be assessed using the Joanna Briggs Institute (JBI) checklist for observational studies and the Cochrane Risk of Bias (ROB) 2 tool for intervention studies. Meta-analysis using random-effects models will be conducted and subgroup analyses based on studies' data will be performed. The systematic review will be conducted based on the framework introduced by the Joanna Briggs Institute. Additionally, the PRISMA-P extension for systematic reviews was used to report the present protocol. The present systematic review protocol has been registered with PROSPERO, an international prospective register of systematic reviews. The review's registration ID is CRD42021286882. DISCUSSION: The systematic review aims to explore, identify and synthesize the evidence to reveal the epidemiology of SU and/or MH of forced migrants of the MENAT region as described in this protocol. In sum, the review will provide evidence to fill the gap in the literature and help the stakeholders, policymakers, and health providers to expand current knowledge of the prevalence and risk factors of SU and/or MH in humanitarian settings.

Structural, electronic, magnetic and thermoelectric properties of Tl2 NbX6 (X = Cl, Br) variant perovskites calculated via density functional theory.

This article presents detailed structural, electronic, magnetic, and thermoelectric properties of two experimentally existing isostructural variant perovskite compounds Tl2 NbX6 (X = Cl, Br) with the help of first principles calculations. As per requirement of stability in the device applications, the structural and thermodynamic stabilities were, respectively verified by tolerance factor and negative formation energies. The structural parameters in ferromagnetic phase were calculated and found in close agreement with the available experimental results. The electronic nature was found as half metallic from spin polarized calculations of electronic band structures and density of states, where the semiconductor nature was found in the spin down states and metallic nature in the spin up states. The magnetic moments of both the compounds were calculated as 1 µB majorly contributed by Nb atom. The Boltzmann transport theory was implemented via BoltzTraP for calculating the spin resolved thermoelectric parameters, such as Seebeck coefficient, electronic and thermal conductivities, and figure of merit. Overall, both the compounds were found suitable for use in spintronics and spin Seebeck effect for energy applications.