Growth of single crystals in the (Na1/2Bi1/2)TiO3-(Sr1-xCax)TiO3 system by solid state crystal growth

Ceramics based on (Na1/2B1/2)TiO3 are promising candidates for actuator applications because of large strains generated by an electric field-induced phase transition. For example, the (1-x)(Na1/2Bi1/2)TiO3-xSrTiO(3) system exhibits a morphotropic phase boundary at x = 0.2-0.3, leading to high values of inverse piezoelectric constant d*(33), which can be further improved by the use of single crystals. In our previous work, single crystals of (Na1/2B1/2)TiO3-SrTiO3 and (Na1/2B1/2)TiO3-CaTiO3 were grown by the solid state crystal growth technique. Growth in the (Na1/2B1/2)TiO3-SrTiO3 system was sluggish whereas the (Na1/2B1/2)TiO3-CaTiO3 single crystals grew well. In the present work, 0.8(Na1/2Bi1/2)TiO3-0.2(Sr1-xCax)TiO3 single crystals (with x = 0.0, 0.1, 0.2, 0.3, 0.4) were produced by the solid state crystal growth technique in an attempt to improve crystal growth rate. The dependence of mean matrix grain size, single crystal growth distance, and electrical properties on the Ca concentration was investigated in detail. These investigations indicated that at x = 0.3 the matrix grain growth was suppressed and the driving force for single crystal growth was enhanced. Replacing Sr with Ca increased the shoulder temperature T-s and temperature of maximum relative permittivity T-max, causing a decrease in inverse piezoelectric properties and a change from normal to incipient ferroelectric behavior

Future Fossil Fuel Electricity Generation in Europe: Options and Consequences

This study investigates the development of the fossil fuel fired power generation sector in Europe up to 2030 and identifies the critical factors that influence its evolution. Through the application of least-cost expansion planning theories, the technology and fuel mix of fossil fuel power plant portfolios emerging from twenty-four techno-economic scenarios are described. The different scenarios present alternative views for the role of non-fossil fuel (nuclear and renewable) power generation, the development of the world fuel and carbon markets and the carbon capture power generating technologies. The study estimates the needs for new fossil fuel capacity and identifies the optimal power plant mix for all possible combinations of the cases mentioned above. The impacts of the resulting portfolios on the objectives of the European energy strategy are assessed using as indicators the capital investment for the construction of the required capacity, the fuel consumption, the diversity of the fuel mix, the CO2 emission levels, and the average production cost of electricity from the fossil fuelled fleet. The report finds that high CO2 prices need to be maintained and carbon capture technology must be developed and become commercialised. If these conditions are met and medium or high fossil fuel prices prevail, the portfolio of fossil fuel power plants that will be deployed will be compatible with the European goal for the development of a more sustainable energy system. The key conclusion is that for a sustainable and safe energy system we need to invest, both in the increase of non-fossil fuel power generation and to ensure that carbon capture and storage technologies are ready to be deployed when needed