Synthesis of Lithium Phosphorus Oxynitride (LiPON) Thin Films by Li3 PO4 Anodic Evaporation in Nitrogen Plasma of a Low-Pressure Arc Discharge

Thin amorphous films of LiPON solid electrolyte were prepared by anodic evaporation of lithium orthophosphate Li3 PO4 in an arc discharge with a self-heating hollow cathode at a nitrogen pressure of 1 Pa. Distribution of the arc current between two electrodes having an anode potential provided independent control of the evaporation rate of Li3 PO4 and the density of nitrogen plasma. Stabilization of the evaporation rate was achieved using a crucible with multi-aperture cover having floating potential. The existence of a threshold value of discharge current (40 A) has been established, which, upon reaching ionic conductivity over 10−8 S/cm, appears in the films. Probe diagnostics of discharge plasma were carried out. It has been shown that heating the films during deposition by plasma radiation to a temperature of 200◦ C is not an impediment to achieving high ionic conductivity of the films. Dense uniform films of LiPON thickness 1 µm with ionic conductivity up to 1 × 10−6 S/cm at a deposition rate of 4 nm/min are obtained. © 2021 by the authors. Licensee MDPI, Basel, Switzerland.Funding: The studies of the coatings were carried out with the financial support of Russian Federation represented by Ministry of Science and Higher Education (project No. 075-15-2021-1348) within the framework of event No. 1.1.12

Радиационно-гигиеническая оценка содержания и распределения 90Sr и 137Cs в ихтиофауне Обь-Иртышской речной системы

The aim of the work is the radiation-hygienic assessment of 90Sr and  137Cs content in fish of the Ob-Irtysh river system and the study of the basic laws of the radionuclides accumulation in the ichthyofauna of these rivers. To perform this task, long-term results of radioecological studies of fish from the Techa, Irtysh and Ob rivers for the period 2004-2016 were used. Fish as a food product was evaluated according to two criteria: a) permissible levels of radionuclides specific activity (SanPiN 2.3.2.1078-01); b) using the indicator of conformity В and uncertainty of its definition ΔВ (GOST 32161-2013 and GOST 32163-2013). It is shown that a higher content of radionuclides is observed in the ichthyofauna of the Techa river (1379.1 Bq/kg for 90Sr and 41.9 Bq/kg for 137Cs). On the Ob and Irtysh rivers, the average specific activity of radionuclides in fish was significantly lower and slightly changed during the surveyed area: for 90Sr in the range of 6.0 ÷ 8.1 Bq/kg (mean 6.8), for 137Cs – 0.6 ÷ 1.9 Bq/kg (mean 1.3). Assessment for compliance with radiation safety criteria using the indicator of compliance and its uncertainty (В+ΔВ) confirmed the unsuitability of use for food purposes by the radiation factor of all studied fish species from the Techa river (45÷55 >1). Fish from all other studied areas of the Ob-Irtysh river system can be used for food without restrictions (0,06÷0,53 < 1). The distribution of 90Sr and 137Cs in the ichthyofauna of the Ob-Irtysh river system part over a 2400 km is presented in the form of empirical regression models. The models describe a sharp decrease in the radionuclides specific activity in fish in the Techa and Iset rivers by two orders for 90Sr (from 2000 to 20 Bq/kg), and by one order for 137Cs (from 40 to 2 Bq/kg). With a high degree of reliability (R2>0.86 for 90Sr and R2>0.92 for 137Cs), the presence of power relationships between the content of radionuclides in the ichthyofauna and their content in water was shown, with adequacy confirmed by Fisher’s F-criteria. This can be used for a preliminary assessment of the radionuclides level in fish based on the results of measurements of the average annual concentrations of these radionuclides in water.Целью настоящей работы является радиационно-гигиеническая оценка содержания 90Sr и 137Cs в рыбе Обь-Иртышской речной системы и изучение основных закономерностей накопления радионуклидов в ихтиофауне этих рек. Для выполнения данной задачи были использованы многолетние результаты радиоэкологических исследований рыбы из рек Теча, Иртыш и Обь за период 2004–2016 гг. Выполнена оценка рыбы как пищевого продукта по двум критериям: а) допустимые уровни удельной активности радионуклидов (СанПиН 2.3.2.1078-01); б) с использованием показателя соответствия В и неопределенности его определения ΔВ (ГОСТ 32161-2013 и ГОСТ 32163-2013). Показано, что более высокое содержание радионуклидов наблюдается в ихтиофауне реки Теча (1379,1 Бк/кг по 90Sr и 41,9 Бк/кг по 137Cs). На реках Обь и Иртыш средние показатели удельной активности радионуклидов в рыбе были существенно ниже и слабо изменялись на протяжении обследованного участка: для 90Sr в диапазоне 6,0–8,1 Бк/кг (среднее 6,8), для 137Cs – 0,6–1,9 Бк/кг (среднее 1,3). Оценка на соответствие критериям радиационной безопасности с использованием показателя соответствия В и его неопределенности ΔВ (В+ΔВ) подтвердила непригодность использования в пищевых целях по радиационному фактору всех исследованных видов рыб из р. Течи (45–55 >1). Рыба из всех остальных исследованных участков Обь-Иртышской речной системы может быть использована в пищу без ограничений (0,06–0,53 < 1). Закономерности распределения 90Sr и 137Cs в ихтиофауне Обь-Иртышской речной системы на участке протяженностью 2400 км представлены в виде эмпирических регрессионных моделей. Модели описывают резкое снижение удельной активности радионуклидов в рыбе на участке рек Теча – Исеть на два порядка величин по 90Sr (с 2000 до 20 Бк/кг) и на один порядок по 137Cs (с 40 до 2 Бк/кг). С высокой степенью достоверности (R2 >0,86 для 90Sr и R2 >0,92 для 137Cs) показано наличие степенных зависимостей между содержанием радионуклидов в ихтиофауне и их содержанием в воде, с адекватностью, подтвержденной критериями Фишера. Это может быть использовано для предварительной оценки уровня содержания радионуклидов в рыбе на основе результатов измерений среднегодовых концентраций этих радионуклидов в воде

Radiation-hygienic assessment of the concentration and distribution of ⁹⁰Sr and ¹³⁷Cs in ichthyofauna of the Ob’-Irtysh river system

The aim of the work is the radiation-hygienic assessment of 90Sr and  137Cs content in fish of the Ob-Irtysh river system and the study of the basic laws of the radionuclides accumulation in the ichthyofauna of these rivers. To perform this task, long-term results of radioecological studies of fish from the Techa, Irtysh and Ob rivers for the period 2004-2016 were used. Fish as a food product was evaluated according to two criteria: a) permissible levels of radionuclides specific activity (SanPiN 2.3.2.1078-01); b) using the indicator of conformity В and uncertainty of its definition ΔВ (GOST 32161-2013 and GOST 32163-2013). It is shown that a higher content of radionuclides is observed in the ichthyofauna of the Techa river (1379.1 Bq/kg for 90Sr and 41.9 Bq/kg for 137Cs). On the Ob and Irtysh rivers, the average specific activity of radionuclides in fish was significantly lower and slightly changed during the surveyed area: for 90Sr in the range of 6.0 ÷ 8.1 Bq/kg (mean 6.8), for 137Cs – 0.6 ÷ 1.9 Bq/kg (mean 1.3). Assessment for compliance with radiation safety criteria using the indicator of compliance and its uncertainty (В+ΔВ) confirmed the unsuitability of use for food purposes by the radiation factor of all studied fish species from the Techa river (45÷55 >1). Fish from all other studied areas of the Ob-Irtysh river system can be used for food without restrictions (0,06÷0,53 < 1). The distribution of 90Sr and 137Cs in the ichthyofauna of the Ob-Irtysh river system part over a 2400 km is presented in the form of empirical regression models. The models describe a sharp decrease in the radionuclides specific activity in fish in the Techa and Iset rivers by two orders for 90Sr (from 2000 to 20 Bq/kg), and by one order for 137Cs (from 40 to 2 Bq/kg). With a high degree of reliability (R2>0.86 for 90Sr and R2>0.92 for 137Cs), the presence of power relationships between the content of radionuclides in the ichthyofauna and their content in water was shown, with adequacy confirmed by Fisher’s F-criteria. This can be used for a preliminary assessment of the radionuclides level in fish based on the results of measurements of the average annual concentrations of these radionuclides in water