Intrinsic point defect complexes in SrTiO3 under different chemical conditions are studied using density functional theory. The Schottky defect complex consisting of nominally charged Sr, Ti and O vacancies is predicted to be the most stable defect structure in stoichiometric SrTiO3, with a relatively low formation energy of 1.64 eV per defect. In addition, the mechanisms of defect complex formation in nonstoichiometric SrTiO3 are investigated. Excess SrO leads to the formation of oxygen vacancies and a strontium-titanium antisite defect, while a strontium vacancy together with an oxygen vacancy and a titanium-strontium antisite defect are produced in an excess TiO2 environment. Since point defects, such as oxygen vacancies and cation antisite defects, are intimately related to the functionality of SrTiO3, these results provide guidelines for controlling the formation of intrinsic point defects and optimizing the functionality of SrTiO3 by controlling nonstoichiometric chemical compositions of SrO and TiO2 in experiments.
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http://dx.doi.org/10.1039/c4cp01510j | DOI Listing |
Environ Sci Technol
January 2025
Geomicrobiology, Department of Geosciences, University of Tübingen, Tübingen 72076, Germany.
Defects are common features in hematite that arise from deviations from the perfect mineral crystal structure. Vacancy defects have been shown to significantly enhance arsenate (As) immobilization by hematite. However, the contributions from vacancy defects on different exposed facets of hematite have not been fully quantified.
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December 2024
Department of Gastrointestinal Surgery, Central Hospital Affiliated to Shandong First Medical University, China.
Tailgut cyst is an exceedingly rare congenital anomaly originating from embryonic remnants of the tailgut. Owing to its asymptomatic nature in the early stages, it is prone to clinical misdiagnosis. We present a case of a 55-year-old female with initial symptoms manifesting as sacrococcygeal pain.
View Article and Find Full Text PDFInorg Chem
January 2025
Guizhou Provincial Key Laboratory of Computational Nano-Material Science, Guizhou Education University, Guiyang 550018, China.
The n-type and p-type conductivity mechanisms from intrinsic defects and Group IIA and Group VIB element doping in the photocatalyst BiTaO are systematically investigated by employing hybrid density functional calculations. The results reveal that vacancies , , , and antisite Ta are the predominant defects, depending on growth conditions. Bi-rich, appropriate Ta-rich, and O-poor conditions can promote BiTaO to form n-type conductivity due to the presence of the Ta donor defect and its easier ionization.
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December 2024
Internal Medicine, University of Alexandria, Alexandria, EGY.
Aim: Thyroid nodules, based on high-resolution ultrasonography (HRUS), are among the most common endocrine abnormalities that affect the general population because of their high estimated prevalence rates. Fine needle aspiration cytology (FNAC) is a safe, cost-effective modality to differentiate between benign and malignant thyroid nodules based on the Bethesda System for Reporting Thyroid Cytopathology (BSRTC), thus avoiding unnecessary surgery. However, categories III and IV of BSRTC remain a controversial issue in clinical practice, encompassing a wide range of risks of malignancy.
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December 2024
Gastroenterology and Hepatology, Aberdeen Royal Infirmary Hospital, Aberdeen, GBR.
Intraductal papillary neoplasm of the bile duct (IPNB) is a precursor lesion to biliary tract carcinoma. It is characterised by papillary growth within the bile ducts. The diagnosis and management of IPNB are challenging due to its varying presentations and overlapping features with other biliary diseases.
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