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Enhanced energy storage density by inducing defect dipoles in lead free relaxor ferroelectric BaTiO 3 -based ceramics Applied Physics Letters 110, 132902 (2017); 10.1063/1.4979467On the phase identity and its thermal evolution of lead free (Bi 1/2 Na 1/2 )TiO 3 -6 mol% BaTiO 3 Journal of Applied Physics 110, 074106 (2011); 10.1063/1.3645054Influence of structural evolution on energy storage properties in Bi 0.5 Na 0. With the advent of modern power electronics, embedded circuits and nonconventional energy harvesting, the need for high performance capacitors is bound to become indispensible. The current state-of-art employs ferroelectric ceramics and linear dielectrics for solid state capacitance. However, lead-free ferroelectric ceramics propose to offer significant improvement in the field of electrical energy storage owing to their high discharge efficiency and energy storage density. In this regards, the authors have investigated the effects of compressive stress as a means of improving the energy storage density of lead-free ferroelectric ceramics. The energy storage density of 0.91(Bi 0.5 Na 0.5 )TiO 3 -0.07BaTiO 3 -0.02(K 0.5 Na 0.5 )NbO 3 ferroelectric bulk ceramic was analyzed as a function of varying levels of compressive stress and operational temperature .It was observed that a peak energy density of 387 mJ.cm -3

Water treatment, the hydrogen evolution reaction, and carbon capture are examples of the potential applications for solar photocatalysis. This has led to significant effort in the search for suitable heterogeneous catalysts. However, materials developed to-date often suffer from disadvantages such as charge recombination, low quantum efficiency, chemical instability, and poor economy of production/operation. These factors have made it difficult for the technology to develop beyond laboratory demonstrations. A potential solution to the problem lies with the appropriate design of the catalyst itself, particularly with respect to particle morphology. This review aims to highlight recent efforts directed towards the development and application of an anisotropic, bi-phasic heterodimer, or “Janus” catalyst. While the topic is in its relative infancy, it has been shown that a Janus morphology can improve catalyst performance by almost an order of magnitude. Hence, a systematic review has been undertaken to highlight and assess recent advances in this field. The review begins with the fundamentals of heterogeneous photocatalysis and proceeds to classify modern catalysts, including Janus particles. This is followed by a detailed description of the relevant studies involving Janus morphology and their demonstrated photocatalytic applications. Finally, an overview of the current challenges and future prospects is discussed along with a summary of the key highlights. It is observed that a Janus morphology can impart several intriguing advantages such as amplification of electric near-field and efficient charge separation. In order to unlock the full potential of Janus photocatalyst, further research in this direction is warranted.

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A highly efficient third generation catalyst, CaCu3Ti4O12 (CCTO) shows excellent photoelectrochemical (PEC) and photocatalytic ability. As only 4% part of the solar spectrum covers UV light, thus it is highly desirable to develop visible light active photocatalyst materials like CCTO for effective solar energy conversion. A direct band transition with a narrow band gap (1.5 eV) was observed. Under light irradiation, high photocurrent density was found to be 0.96 mA/cm2, indicating the visible light induced photocatalytic ability of CCTO. Visible light mediated photocatalytic and photoelectrocatalytic degradation efficiency of CaCu3Ti4O12 pellets (CCTO) was investigated for three classes of pharmaceutical waste: erythrosin (dye), ciprofloxacin (antibiotic) and estriol (steroid). It is found that the degradation process follows first order kinetic reaction in electrocatalysis, photocatalysis and photoelectrocatalysis and high kinetic rate constant was observed in photoelectrocatalysis. This was quite high in comparison to previously reported methods.

Influence of structural evolution on energy storage properties in Bi 0.5 Na 0.5 TiO 3 -SrTiO 3 -NaNbO 3 lead-free ferroelectric ceramics Journal of Applied Physics 121, 054103 (2017) This study systematically investigates the phenomenon of internal clamping in ferroelectric materials through the formation of glass-ceramic composites. Leadfree 0.715Bi 0.5 Na 0.5 TiO 3 −0.065BaTiO 3 −0.22SrTiO 3 (BNT-BT-ST) bulk ferroelectric ceramic was selected for the course of investigation. 3BaO − 3TiO 2 − B 2 O 3 (BTBO) glass was then incorporated systematically to create sintered samples containing 0%, 2%, 4% and 6% glass (by weight). Upon glass induction features like remnant polarization, saturation polarization, hysteresis losses and coercive field could be varied as a function of glass content. Such effects were observed to benefit derived applications like enhanced energy storage density ∼174 k J/m 3 to ∼203 k J/m 3 and pyroelectric coefficient 5.7x10 −4 Cm −2 K −1 to 6.8x10 −4 Cm −2 K −1 by incorporation of 4% glass. Additionally, BNT-BT-ST depolarization temperature decreased from 457K to 431K by addition of 4% glass content. Glass incorporation could systematically increases diffuse phase transition and relaxor behavior temperature range from 70 K to 81K and 20K to 34 K, respectively when 6% and 4% glass content is added which indicates addition of glass provides better temperature stability. The most promising feature was observed to be that of dielectric response tuning. It can be also used to control (to an extent) the dielectric behavior of the host ceramic. Dielectric permittivity and losses decreased from 1278 to 705 and 0.109 to 0.107 for 6% glass, at room temperature. However this reduction in dielectric constant and loss increases pyroelectric figures of merit (FOMs) for high voltage responsivity (F v ) high detectivity (F d ) and energy harvesting (F e ) from 0.018 to 0.037 m 2 C −1 , 5.89 to 8.85 µPa −1/2 and 28.71 to 61.55 Jm −3 K −2 , respectively for 4% added ceramic-glass at room temperature. Such findings can have huge implications in the field of tailoring ferroelectric response for application specific requirements. C 2015 Author(s). All article content, except where otherwise noted, is licensed under a Creative Commons Attribution 3.0 Unported License. [http://dx

Bi 4 Ti 3À2x Nb x Ta xÀy Sb y O 12 (BTNTS) ceramics were investigated as a potential candidate of lead-free piezoelectric ceramics. X-ray diffraction results indicated that all samples have monoclinic structure. Scanning electron microscopic studies revealed that the addition of Sb 2 O 3 did not cause a suppressed grain growth for their morphological behavior. The Bi 4 Ti 2.98 Nb 0.01 Ta 0.002 Sb 0.008 O 12 (8BTNTS) ceramics possess a dielectric constant of 1328 at 100 kHz, a piezoelectric constant (d 33 ) of 35 pC/N and Curie temperature (T c ) of 6641C. The electrical properties of the investigated compositions exhibited a significant dependence on the content of Sb 2 O 3 addition. The electrical conductivity for 8BTNTS ceramics was lower than that of other investigated compositions. Dielectric and electrical transport properties have been carried out over a wide range of frequency and temperature in order to explore the conduction mechanism in the investigated samples. The activation energy associated with the electrical relaxation determined from the electric modulus spectra was found to be 1.070.03 eV, close to that of the activation energy for DC conductivity (1.0870.02 eV). It suggests that the movements of oxygen ions are responsible for both the ionic conduction as well as relaxation process.

Multicatalytic activities (photocatalysis, piezocatalysis, and pyrocatalysis) of ferroelectric ceramics Ba0.85Ca0.15Ti0.9Zr0.1O3 (BCZTO) were studied. Maximum degradations (89% and 81%) were achieved in piezo-photocatalytic experiments for degradation of Rhodamine B (RB) and ciprofloxacin. Similarly, 95% degradation of RB was achieved during pyrocatalysis in 250 heating/cooling cycles. Antibacterial performance of ceramics was analyzed with the help of Gram-positive and Gram-negative bacteria-killing processes. The bacterial colony formation drops to zero in 90 min with poled samples of BCZTO ceramics. The poled samples performed much better than that of the unpoled samples in all the catalytic reactions as well as in the bacterial killing process.