The structural and electrical properties of 0.75BiFeO3–0.25BaTiO3 (BF25BT) ceramics, with and without heat treatment, were investigated. The polished and cut BF25BT ceramics were thermally annealed ...at 800°C for 20 h and then quenched in water at room temperature (heat-treated ceramics). The P–E hysteresis loop and S–E curve were significantly improved after the heat treatment process. Meanwhile, the leakage current density at an electric field of 50 kV/cm was reduced from 4.847 × 10−7 (as-sintered ceramics) to 3.213 × 10−8 A/cm2 (heat-treated ceramics). The heat-treated ceramics was poled at 120°C with applying a DC-bias field of 50 kV/cm, and the maximum phase angle was −39°, which was evaluated from the analysis of frequency-dependence of impedance and phase angle. Because of the small maximum phase angle obtained by poling under DC-bias field alone, the poling process was modified; that is, an AC-bias field was applied prior to the DC-bias field poling. The ceramics poled with the modified poling procedure exhibited the maximum phase angle of 63°. The appreciable increase of the maximum phase angle suggested the higher degree of domain alignment than that of its counterpart, and the effect was explained in terms of improved domain switching. The piezoelectric constant d33 was increased twice with adopting the modified poling process, which signifies that poling with both AC- and DC-bias field is highly effective in the lead-free Bi-based systems.
Layered titanate H1.08Ti1.73O4·nH2O (HTO) particles with plate-like morphology were used as a template for the fabrication of grain-oriented bismuth potassium titanate (Bi0.5K0.5)TiO3, or BKT ...ceramics by a reactive-templated grain growth method. Single perovskite-phase textured BKT ceramics were successfully fabricated with optimizing the preparation conditions such as mixing procedure of matrix and template particles with a binder solution, temperature programs for binder removal and sintering, and sintering conditions. Microstructure evaluation suggested that the sintering with or without weight-pressing and a temperature program used could significantly affect the degree of texture development. The debinding and sintering with weight-pressing helped on the proper alignment of oriented particles and/or grains along with promoting the growth of the oriented plate-like BKT particles, formed by an in situ topotactic transformation reaction of plate-like HTO templates, resulting in a high degree of orientation. Using optimum preparation conditions, single perovskite-phase BKT ceramics with grain-orientation over 85% were successfully fabricated for the first time via a conventional sintering method.
⟨111⟩-oriented BaTiO3 (BT) ceramics were prepared by a high magnetic field assisted electrophoretic deposition method using hexagonal-tetragonal co-existing BT powders. With increasing the hexagonal ...content, the ⟨111⟩-orientation factor increased, while piezoelectric strain constant d*33 increased up to the hexagonal content of 80% with attaining a maximum value of 627 pm V−1 and then rapidly decreased. In contrast, the decreasing trend of d*33 with increasing hexagonal content in the randomly oriented ceramics was observed. These results were discussed with the degree of the orientation and the possible twin defects in the BT ceramics.
The electric field-dependent crystal structures and electrical properties were investigated in the 0.67BiFeO3–0.33BaTiO3 (BF33BT) lead-free piezoelectric ceramics. The room temperature synchrotron ...radiation X-ray diffraction (SR-XRD) patterns measured, without the application of an electric field, revealed all the peaks to be single suggesting the cubic like crystal structure of the BF33BT system. The domain switching was ascertained in the P–E hysteresis loop and S–E curve meanwhile, SR-XRD patterns exhibited beyond doubt single peak. In order to study the electric field induced structural phase transition, SR-XRD was measured in BF33BT ceramics as a function of electric field. The electric field applied up to 40 kV/cm with bipolar cycling was parallel along the longitudinal lattice response direction that was similar for the piezoelectric response measuring method. The shift of SR-XRD peaks to lower and/or higher angle in comparison to the peak position of zero field-SR-XRD was found to depend on the direction and intensity of the applied electric field. The peak shape under maximum electric field was quite same that of SR-XRD patterns at zero electric field. Importantly, the single peak shape was maintained for all the SR-XRD measured under the electric field. Therefore, the electric field induced structural phase transition did not occur in the BF33BT ceramics.
Understanding the local communities' attitudes toward protected areas (PAs) is critical to PA management planning. However, what socio‐economic and demographic factors drive their attitude remains ...poorly studied. We interviewed 135 residents in three villages in the buffer zone of Bardia National Park, Nepal, to assess their perceived benefits and costs of the PA. We found that perceived benefits are skewed toward wealthy and influential people, whereas costs associated with wildlife‐caused damage (i.e., crop raiding) are borne disproportionately by poor people. The Tobit regression model showed that wealthy and educated residents who obtained direct tourism benefits from the park were significantly more likely to hold positive attitudes toward the PA. On the flip side, residents who had experienced conflict with park administration (park staff and military guards) and incurred a higher amount of crop loss in the recent past were likely to have negative attitudes. Our results showed that negative attitudes largely stemmed from park staff and military guards' behavior and inefficient service delivery from the national park office. In light of these findings, we suggest the park administration develop mechanisms to ensure efficient service delivery and pragmatic handling of community grievances concerning law enforcement and wildlife damage compensation. We also recommend directing park benefits to less educated and poor households and those suffering property losses from wildlife to improve park‐people relationships.
We did not find a substantial change in terms of the poor getting a fair share of benefits (i.e., tourism benefits) from the park even after two decades of buffer zone establishment and management guidelines as benefits are still skewed toward the rich and influential people. In contrast, costs (i.e., crop damage due to wildlife) are disproportionately borne by the poor. Therefore, despite calls for a more participatory approach with fair and equitable benefit sharing, much of the conditions remain as they used to be in the traditional “Fine and fence” type approach.
The lead-free x(Bi0.5K0.5)TiO3-0.23BaTiO3-0.02Bi(Mg0.5Ti0.5)O3-(0.75-x)BiFeO3 piezoelectric ceramics (x = 0.05, 0.07, 0.09, and 0.11) were prepared by solid-state reaction method. The increase of ...(Bi0.5K0.5)TiO3 concentration revealed a decrease of dielectric maximum temperature (Tm), however, the values were higher than 420 °C. The Rietveld structure refinement for each composition showed pseudo-cubic symmetry and the rhombohedral distortion (90 - αF) was gradually decreased from 0.27° to 0.09° for x = 0.05 and 0.11, respectively. The saturation and remanent polarization were increased and a coercive field was decreased, while the critical exponent (γ) was increased from 1.407 (x = 0.07) to 1.821 (x = 0.11) revealing more relaxor-like behavior with higher (Bi0.5K0.5)TiO3 content. The remanent polarization, coercive field, and piezoelectric strain constant of 31.9 μC/cm2, 23.6 kV/cm, and 315 pm/V, respectively, obtained in the composition with x = 0.11 are significantly higher than those reported previously for other Bi-based piezoelectric ceramics with Tm>250 °C.
Wild ungulate herbivores are crucial for maintaining terrestrial ecosystems and restoring population of top predators like tiger. Thus, it is essential to understand wild ungulates-habitat ...relationships to devise an effective strategy to conserve their population and top predators like tiger that depend on them. We have limited understanding about the ungulates and their habitat in sub-tropical lowlands. In this study, we conducted transect based occupancy surveys in December 2016 across 30 geographic grid cells of 3 km × 3 km spanning 270 km2. We used the occupancy modelling approach that accounts for the imperfect detection to test multiple hypotheses concerning ecological and anthropogenic correlates of site use pattern of five wild ungulate species in Shuklaphanta National Park, Nepal. The model-average estimates showed that proportion of site use was highest for spotted deer (0.83 ± SE 0.29) followed by blue bull (0.53 ± SE 0.22), hog deer (0.37 ± SE 0.12), swamp deer (0.23 ± SE 0.17), and lowest for barking deer (0.14 ± SE 0.05). While the proportion of forest had a positive influence on blue bull and barking deer, the proportion of grassland had a positive influence on spotted deer and swamp deer. Water availability positively influenced site use of barking deer. Human disturbance had a strong negative influence on the distribution of hog deer but blue bull had a positive association with human activities. Similarly, fire had a strong positive influence only on the habitat use of swamp deer. Overall, our results showed that these five wild ungulate species vary in their site use responses to natural habitat and anthropogenic factors suggesting that the consideration of species-specific habitat requirements is important for their conservation and management.
We fabricated thick and dense green ceramics consisting of the powders of (Bi0.5Na0.5)TiO3 (BNT) and hexagonal BaTiO3 (BT) with a molar ratio of 0.85:0.15 by electrophoretic deposition (EPD) in the ...suspension of iso-propanol of 200 ml with the mixed powders of 20 g, and investigated the effect of the ball-milling time and the surfactant (polyethylenimine, PEI) content for the suspension on the deposition weight and density of the green ceramics. When the ball-milling time was changed from 2 to 30 h with the PEI content of 0.2 g, the deposition weight was maximized at the ball-milling time of 15 h while the density monotonically increased with increasing ball-milling time for the EPD process of 1 h. When the PEI content was increased from 0.1 g to 0.2 and 0.3 g at the ball-milling time of 20 h, the deposit weight and density were increased. At the PEI content of 0.3 g, after the first EPD process was carried out and the cathode where the green ceramics were deposited was replaced without changing the suspension, the second green ceramics could be fabricated for the suspension ball-milled for 20 h, but not for the suspension ball-milled for 3 h. These results were explained by the size of the powders and the amount of PEI attached to the powders.
Biodiversity targets, under the Kunming‐Montreal Global Biodiversity Framework, prioritize both conservation area and their effectiveness. The effective management of protected areas (PAs) depends ...greatly on law enforcement resources, which is often tasked to rangers. We addressed economic aspects of law enforcement by rangers working in terrestrial landscapes across Asia. Accordingly, we used ranger numbers and payment rates to derive continental‐scale estimates. Ranger density has decreased by 2.4‐fold since the 1990s, increasing the median from 10.9 to 26.4 km2 of PAs per ranger. Rangers were generally paid more than the minimum wage (median ratio = 1.9) and the typical salaries in agriculture, forestry, and fishing sector (median ratio = 1.2). Annual spending on ranger salaries varied widely among countries, with a median of annual US71 km−2 of PA. Nearly 208,000 rangers patrolling Asian PAs provide an invaluable opportunity to develop ranger‐based monitoring plans for evaluating the conservation performance. As decision‐makers frequently seek an optimum number of law enforcement staff, our study provides a continental baseline median of 46.3 km2 PA per ranger. Our findings also provide a baseline for countries to improve their ranger‐based law enforcement which is critical for their Kunming‐Montreal Global Biodiversity Framework targets.
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