Large electrostrictive effect and high energy storage performance of Pr3+-doped PIN-PMN-PT multifunctional ceramics in the ergodic relaxor phase

The photoluminescence, dielectric relaxation, ferroelectric hysteresis, and field-induced strain properties of Pr³⁺-doped 0.24Pb(In_1/2Nb_1/2)O₃-0.42Pb(Mg_1/3Nb_2/3)O₃-0.34PbTiO₃ (PIN-PMN-PT:Pr³⁺) multifunctional ceramics have been investigated. It was found that Pr³⁺ doping enhanced the dielectric diffuseness and relaxation behavior of PIN-PMN-PT ceramics. Slim P-E loops and S-E curves appear in PIN-PMN-PT:Pr³⁺ ceramics when the Pr³⁺ doping concentration reaches 1.4 mol%. Local domain configurations associated with phase transitions were investigated by piezoresponse force microscopy (PFM). Large electrostrictive coefficient Q₃₃ (?0.03 m⁴/C²) and high energy-storage efficiency η (92%) were obtained in 2 mol% Pr³⁺-doped PIN-PMN-PT ceramic in the ergodic relaxor (ER) phase at room temperature. The giant electrostrictive effect and excellent energy-storage performance are related to the field-induced dynamic behavior of polar nanoregions (PNRs). The results show that the PIN-PMN-PT:Pr³⁺ system is an excellent multifunctional material for making electromechanical and energy storage devices.     

Energy analysis of the system of two-stage anaerobic processing of liquid organic waste with production of hydrogen- and methane-containing biogases

In recent years, public attention has been increasingly attracted to solving two inextricably linked problems - preventing the depletion of natural resources and protecting the environment from anthropogenic pollution. The annual consumption of livestock waste for biogas production is about 240 thousand m³ per year, which is 0.17% of the total manure produced at Russian agricultural enterprises. At present, the actual use of organic waste potentially suitable for biogas production is 2–3 orders of magnitude lower than the existing potential for organic waste. Currently, hydrogen energy is gaining immense popularity in the world due to the problem of depletion of non-renewable energy sources - hydrocarbons, and environmental pollution caused by their increasing consumption. Of particular interest is the dark process of producing hydrogen-containing biogas in the processing of organic waste under anaerobic conditions, which allows you to take advantage of both energy production and solving the problem of organic waste disposal. An energy analysis of a two-stage anaerobic liquid organic waste processing system with the production of hydrogen- and methane-containing biogases based on experimental data obtained in a laboratory plant with increased volume reactors was performed. The energy efficiency of the system is in the range of 1.91–2.74. Maximum energy efficiency was observed with a hydraulic retention time of 2.5 days in a dark fermentation reactor. The cost of electricity to produce 1 m³ of hydrogen was 1.093 kW·h with a hydraulic retention time of 2.5 days in the dark fermentation reactor. When the hydraulic retention time in the dark fermentation reactor was 1 day, the specific (in ratio to the processing rate of organic waste) energy costs to produce of 1 m³ of hydrogen were minimal in the considered hrt range, and amounted to 26 (W/m³ of hydrogen)/(m³ of waste/day). Thus, the system of two-stage anaerobic processing of liquid organic waste to produce hydrogen and methane-containing biogases is an energy-efficient way to both produce hydrogen and process organic waste.     

Thermodynamic performance analysis and environmental impact assessment of an integrated system for hydrogen and ammonia generation

A novel multigeneration plant that's using natural gas for power, hydrogen, ammonia, and hot water generation, is planned and analyzed, in the current paper. The suggested combined plant integrated with four sub-systems, which are the Brayton cycle, reheat Rankine cycle, the high-temperature steam electrolyzer for hydrogen production, and ammonia synthesis processes. Also, thermodynamic analysis and environmental impact assessment are conducted for the designed plant and sub-systems. Moreover, the sustainability index analysis of this proposed study is conducted. The effects of some important indicators on the performance and on the environmental impact of the modeled system and sub-processes are also studied. According to analyses results, it is noted that the energetic and exergetic efficiencies of the suggested system are 51.83% and 70.27%, respectively, and also the total CO₂ emission rate is 11.4 kg/kWh for the integrated plant. Furthermore, the total irreversibility rate is computed as 40007.68 kW, and furthermore, the combustion chamber has a maximum irreversibility rate with 20,033 kW, among the proposed plant components.     

Forging furnace with thermochemical waste-heat recuperation by natural gas reforming: Fuel saving and heat balance

This paper considers thermochemical recuperation (TCR) of waste-heat using natural gas reforming by steam and combustion products. Combustion products contain steam (H₂O), carbon dioxide (CO₂), and ballast nitrogen (N₂). Because endothermic chemical reactions take place, methane steam-dry reforming creates new synthetic fuel that contains valuable combustion components: hydrogen (H₂), carbon monoxide (CO), and unreformed methane (CH₄). There are several advantages to performing TCR in the industrial furnaces: high energy efficiency, high regeneration rate (rate of waste-heat recovery), and low emission of greenhouse gases (CO₂, NO_x). As will be shown, the use of TCR is significantly increasing the efficiency of industrial furnaces – it has been observed that TCR is capable of reducing fuel consumption by nearly 25%. Additionally, increased energy efficiency has a beneficial effect on the environment as it leads to a reduction in greenhouse gas emissions.     

Energy storage performance of 0.55Bi0.5Na0.5TiO3-0.45SrTiO3 ceramics doped with lanthanide elements (Ln = La,Nd, Dy,Sm) using a viscous polymer processing route

Lead-free bismuth sodium titanate-strontium titanate (NBT-ST) dielectric ceramic materials have been extensively investigated energy storage materials because of their relaxor characteristics. In this study, four different lanthanide elements were introduced into the ferroelectric NBT-ST ceramic to improve their relaxor properties. The introduction of the lanthanide resulted in an increase in disorder at location A within the perovskite lattice and improved relaxor characteristics, leading to a stored energy density of more than 3.5 J/cm³. In particular, an ultrahigh recoverable stored energy density of 4.94 J/cm³ and efficiency of 88.45% were achieved at 440 kV/cm when the NBT-ST ceramic was modified with neodymium. The modified ceramic also exhibited good thermal stability in the range of 30–120 °C, as well as a fast discharge time of ～153 ns, indicating that Nd-incorporated NBT-ST is a promising candidate for electrical energy storage ceramic.     

Improved energy storage density and energy efficiency of Samarium modified PMNT electroceramic

We report the improved energy storage density and efficiency after 2.5% of Samarium substitution in ferroelectric Pb[(Mg_1/3Nb_2/3)_0.80Ti_0.20]O₃ (PMNT) electroceramic. The microstructure and surface morphology were analyzed and correlated with various functional properties. The energy storage density, leakage current density, ferroelectric and dielectric properties were investigated thoroughly, indicating that Samarium's substitution significantly modified the microstructure, the dielectric strength, breakdown electric field, and turned ferroelectric PMNT to relaxor ferroelectrics. Due to the relaxor nature, the gap between remanent polarization and maximum polarization increases with the substitution of Samarium in PMNT matrix, which further increases the recoverable energy storage density and energy efficiency. A nearly 100% increase in recoverable energy density and efficiency was obtained at an electric field strength of 35 kV/cm at room temperature (～296 K). The electroceramic shows maximum energy density near the ferroelectric phase transition temperature (325 K–345 K) region and provides a moderate energy storage density for possible applications in power microelectronics.     

The effect of rare-earth oxides on the energy storage performances in BaTiO3 based ceramics

In this work, 0.7BaTiO₃-0.3Sr_0.2Bi_0.7TiO₃ (0.7BT-0.3SBT) ceramics with 0.15 mol% various rare-earth oxides doped are designed and synthesized by the conventional solid-state route. All prepared samples exhibited a single perovskite phase and dense microstructure with fine grain size (0.2–0.5 μm) after sintering at 1180 °C. Especially, the Gd-doped 0.7BT-0.3SBT ceramics exhibited excellent energy storage performances; the corresponding recoverable energy density and efficiency were 3.2 J/cm³ and 91.5% under an electric field of 330 kV/cm, respectively. Meanwhile, doping with Gd caused the BT-based ceramics to possess excellent temperature (30–150 °C) and outstanding frequency stabilities (10–1000 Hz). Moreover, the pulsed charge-discharge experiments revealed that a high power density of 59 MW/cm³ and a fast discharge speed of 110 ns with outstanding temperature stability could be synchronously obtained in the Gd-doped composition. All these features are attractive for pulsed power applications.     

Plasma assists titanium nitride and surface modified titanium nitride nanoparticles from titanium scraps for magnetic properties and supercapacitor applications

Plasma methods are efficient processing for metal recovery from metal scrap, bearing minerals, electronic waste, etc. In this work, pure titanium nitride nanoparticles (TiN NPs) were synthesized from titanium scraps by the thermal plasma arc discharge (TPAD) method. TPAD synthesized TiN NPs have a highly crystalline nature with cubic and spherical morphologies with average particle sizes of 30–100 nm. Further, prepared TiN NPs involving surface modification (SM) or etching processes were investigated by using the non-thermal DC glow discharge plasma technique with air atmosphere at different processing times. SM@TiN NPs have a comparatively low crystalline, which was confirmed from the powder X-ray diffraction technique. SM@TiN NPs have very interesting core shell morphologies, which are due to the surface interactions of ionized air molecules. TiN and SM@TiN NPs have room-temperature ferromagnetic properties with high saturation magnetization (Ms) up to 2.6 and 3.0 emu/g and very high coercivity (Hc) of 235.5 Oe, respectively. TiN and SM@TiN NPs have superior energy storage performance with an outstanding specific capacitance of 192.8 and 435.1 F/g at a current density of 2 A/g with pseudocapacitive behavior. These results reveal that TiN and SM@TiN NPs have highly promising electrodes for supercapacitor applications.     

Effect of preparation method on physicochemical properties and catalytic performances of LaCoO_3 perovskite for CO oxidation

Perovskite oxides LaCoO_3 prepared by templating, co-precipitation and sol-gel method with different complexants were systematically characterized and its catalytic performances for CO oxidation were investigated. The samples were characterized by X-ray diffraction, thermogravimetry analysis and differential scanning calorimetry, N_2 physisorption, transmission electron microscopy, temperature program reduction of hydrogen, temperature program desorption of oxygen and X-ray photoelectron spectroscopy measurement, results of which show that the properties of LaCoO_3, such as surface morphology, surface area, surface compositions, redox capability, oxygen vacancy, as well as the calcination temperature and formation mechanism, depend intimately on the preparation method. Catalytic tests indicate that the sample prepared by carbon templating method shows the best activity for CO oxidation, with full CO conversion obtained at 135 ℃. In particular, the catalyst can be activated and significant increase of activity can be obtained with the increase of reaction time. The cyclic and longterm stability of catalysts were discussed and compared.     

A new integrated renewable energy system for clean electricity and hydrogen fuel production

In this paper, a new renewable energy-based cogeneration system for hydrogen and electricity production is developed. Three different methods for hydrogen production are integrated with Rankine cycle for electricity production using solar energy as an energy source. In addition, a simple Rankine cycle is utilized for producing electricity. This integrated system consists of solar steam reforming cycle using molten salt as a heat carrier, solar steam reforming cycle using a volumetric receiver reactor, and electrolysis of water combined with the Rankine cycle. These cycles are simulated numerically using the Engineering Equation Solver (EES) based on the thermodynamic analyses. The overall energetic and exergetic efficiencies of the proposed system are determined, and the exergy destruction and entropy generation rates of all subcomponents are evaluated. A comprehensive parametric study for evaluating various critical parameters on the overall performance of the system is performed. The study results show that both energetic and exergetic efficiencies of the system reach 28.9% and 31.1%, respectively. The highest exergy destruction rates are found for the steam reforming furnace and the volumetric receiver reforming reactor (each with about 20%). Furthermore, the highest entropy generation rates are obtained for the steam reforming furnace and the volumetric receiver reforming reactor, with values of 174.1 kW/K and 169.3 kW/K, respectively. Additional parametric studies are undertaken to investigate how operating conditions affect the overall system performance. The results report that 60.25% and 56.14% appear to be the highest exergy and energy efficiencies at the best operating conditions.