Properties of Coated Slow-Release Triple Superphosphate (TSP) Fertilizers Based on Lignin and Carrageenan Formulations

International audienceCoated triple superphosphate (TSP) fertilizer with slow-release and water retention properties was prepared using lignin extracted from olive pomace (OP) biomass and k-carrageenan biopolymer. The aim of this work was to develop coating formulations that serve as a barrier to phosphorus diffusion through TSP fertilizers. Different formulations of lignin and k-carrageenan with or without polyethylene glycol (PEG 2000) were prepared. The chemical composition and morphological, mechanical, and surface properties of different formulations were characterized and compared. The blending of lignin with carrageenan in the presence of PEG enhanced the tensile properties of the formulation. Indeed, the mechanical properties of different formulation composites are classified in the order of lignin-carrageenan-PEG > lignin-carrageenan > lignin. After 6 h in water, the lignin@TSP formulation released two times less phosphorus (P) than the uncoated TSP. Lignin-carrageenan@TSP and lignin-carrageenan-PEG@TSP released only 28.21% and 13.51%, respectively, of phosphorus after 6 h compared to 72% for uncoated TSP. Indeed, lignin-carrageenan-PEG@TSP absorbs more water than TSP. The addition of plasticizer did not significantly modify the mechanical properties of the formulation composites. In the future, these products will be tested to evaluate their impact on chemical and biological soil properties

Impact of plasticizers on lignin-carrageenan formulation properties and on phosphorus release from a coated TSP fertilizer

A new coated slow-release triple superphosphate (TSP) fertilizer was developed using formulations based on lignin (L) derived from olive pomace (OP) and a κ-carrageenan (C) biopolymer, and different plasticizers were added: glycerol (G) and polyethylene glycol 200 (P200) and 2000 (P2000). The effect of the type and molecular weight of the plasticizer on the physicochemical properties of the composites and phosphorus (P) release was investigated. The results showed a slight improvement in the thermal stability of the LC composite upon the addition of polyethylene glycol, while the hydrophobicity decreased. The addition of the plasticizers also decreased the elasticity of all the films except for P2000. The coating materials decreased the P release from 100% within 3 days for uncoated TSP to 55–69% within 30 days for coated TSP. However, the LC plasticizer formulations did not decrease P release compared to the LC formulations

Phase transitions, energy storage performances and electrocaloric effect of the lead-free Ba0.85Ca0.15Zr0.10Ti0.90O3 ceramic relaxor

Lead-free Ba0.85Ca0.15Zr0.10Ti0.90O3 (BCZT) ceramic exhibits excellent dielectric, ferroelectric and piezoelectric properties at the morphotropic phase boundary (MPB). Previously, we demonstrated that the use of the anionic surfactant sodium dodecyl sulfate (SDS, NaC12H25SO4) could enhance the dielectric properties of BCZT ceramic using surfactant-assisted solvothermal processing [1]. In the present study, structural, dielectric, ferroelectric properties, as well as electrocaloric effect and energy storage performances of this BCZT ceramic were thoroughly investigated. X-ray diffraction (XRD) measurements revealed the presence of single perovskite phase at room temperature with the coexistence of orthorhombic and tetragonal symmetries. In-situ Raman spectroscopy results confirmed the existence of all phase transitions from rhombohedral through orthorhombic and tetragonal to cubic symmetries when the temperature varies as reported in undoped-BaTiO3. Evolution of energy storage performances with temperature have been investigated. BCZT ceramic exhibits a high energy storage efficiency of ~ 80% at 120 °C. In addition, the electrocaloric responsivity was found to be 0.164 × 10−6 K·m/V at 363 K

Enhanced near-ambient temperature energy storage and electrocaloric effect in the lead-free BaTi0.89Sn0.11O3 ceramic synthesized by sol–gel method

International audienceLead-free perovskite materials with high performance have high potential in clean energy storage applications and developments of electrocaloric devices. In this work, we report structural, dielectric, ferroelectric properties, energy storage and electrocaloric effectnear the ambient temperature in barium stannate titanate (BaTi 0.89 Sn 0.11 O 3, BTS 11) ceramic prepared by a sol-gel method. The formation of a single perovskite structure was confirmed using the X-ray diffraction analysis. An average grain size of 18.5µm was found by the mean of the SEM micrograph with a density of 5.91 g/cm 3 .The presence of the multiphase at very near ambient temperature was proved using temperature-dependent micro-Raman measurements and differential scanning calorimetry. The BTS 11 ceramic exhibits a high dielectric constant of 15460and a low dielectric loss (<0.055) with considerable temperature stability. Moreover, a high energy storage density of 122mJ/cm 3 was showed with an efficiency of 79%, and a maximum value of ECE (ΔT) of 0.86 K and finally, an electrocaloric responsivity (ΔT/ΔE) of 0.24 K.mm/kV under the external electricfield of 35 kV/cm near ambient temperature. The enhanced dielectric, ferroelectric and electrocaloric properties in BTS 11 ceramic makes it a great potential candidate for its uses in solid-state cooling technology and high-energy storage applications near ambient temperature

The paradigm of the filler's dielectric permittivity and aspect ratio in high- k polymer nanocomposites for energy storage applications

International audienceCeramic/polymer nanocomposites are promising materials for energy storage applications. The most common approach to optimize energy storage properties relies on combining a ceramic and a polymer having the highest possible dielectric permittivity and breakdown strength, respectively. It is also known that another significant factor is the aspect ratio of nanofillers where a higher aspect ratio gives rise to a higher effective dielectric permittivity of the composite. There is thus a duality between the dielectric permittivity of the ceramic and its aspect ratio that we propose to study in this paper. To achieve this, high-k nanocomposites were designed based on biodegradable polymer matrix polylactic acid (PLA) and different inorganic nanofillers having different shapes (spherical, rod and wire) and dielectric properties. The effects of the aspect ratio, core–shell structure, dielectric permittivity and volume fraction of the nanofillers on the dielectric and energy storage performances of PLA-based nanocomposites were assessed. An enhanced energy storage density and recovered energy density of 3.63 and 1.80 J cm−3, respectively, were obtained in nanocomposites based on rod-like fillers. We discussed, from a theoretical model, that, below the percolation threshold, the obtained properties resulted from a compromise between both the dielectric permittivity and the aspect ratio of the ceramic. This investigation provides an exciting opportunity to advance our knowledge of ceramic/polymer nanocomposites for energy storage applications

Low-temperature synthesis and characterization of lead-free BaTi0.89Sn0.11O3 piezoelectric powders

International audienceBarium stannate titanate (BaTi0.89Sn0.11O3, BTS11) is one of the reported lead-free materials that exhibit high dielectric and piezoelectric properties near ambient temperature. In this work, BTS11 powders were elaborated via a soft chemistry method at very low temperatures using two synthesized approaches combining sol-gel and hydrothermal processes. In the first approach, the effect of the barium precursor on the purity and the crystallinity of the BTS11 powders were studied. In contrast, in the second approach, the influence of the hydrothermal temperature on the BTS11 proprieties was analyzed. As a result, pure and uniform fine powders were obtained at 180 °C. The appropriate mass fraction of BTS11, which leads to high suspension stability in water, is below 3%. These eco-friendly and pure piezoelectric powders can be used without further heat-treatment in several applications such as lead-free piezoelectric decontamination of organic pollutants and photocatalyst, hydrogen generation and as fillers in flexible nanocomposites nano-generators for energy harvesting and energy storage

Novel lead-free BCZT-based ceramic with thermally-stable recovered energy density and increased energy storage efficiency

The eco-responsible lead-free piezoelectric ceramics have been intensively searched for more than a decade, however, the final goal to replace toxic ceramics like lead zirconate titanate (PZT) with lead-free compounds, having comparable or even better performance has not yet been reached. In this road, the lead-free ceramics Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT), possessing excellent dielectric, ferroelectric, and piezoelectric properties are regarded as serious candidates for the PZT replacement. Besides, nanostructuring BCZT is of paramount importance to enhance these functionalities even more. Here, BCZT multipodes are designed by template-growth hydrothermal synthesis using hydrogen zirconate titanate nanowires. We demonstrate that the fabricated BCZT multipodes exhibit high dielectric permittivity of 5300 with a temperature stability coefficient of ±5.9% between 20 and 140 °C. A significant recovered energy density of 315.0 mJ/cm3 with high thermal stability and high energy storage efficiency of 87.4%, and enhanced large-signal piezoelectric coefficient (310 pm/V) are found. Compared to the traditional BCZT ceramics reported in the literature, relying on high-temperature processing, our sample exhibits boosted energy storage parameters at a much lower temperature. These outcomes may offer a new strategy to tailor eco-responsible relaxor ferroelectrics toward superior energy storage performance for ceramic capacitor applications

Enhanced dielectric and electrocaloric properties in lead-free rod-like BCZT ceramics

Ba0.85Ca0.15Zr0.10Ti0.90O3 (BCZT) lead-free ceramics demonstrated excellent dielectric, ferroelectric, and piezoelectric properties at the morphotropic phase boundary (MPB). So far, to study the effect of morphological changes on dielectric and ferroelectric properties in lead-free BCZT ceramics, researchers have mostly focused on the influence of spherical grain shape change. In this study, BCZT ceramics with rod-like grains and aspect ratio of about 10 were synthesized by surfactant-assisted solvothermal route. X-ray diffraction (XRD) and selected area electron diffraction (SAED) performed at room temperature confirm the crystallization of pure perovskite with tetragonal symmetry. Scanning electron microscopy (SEM) image showed that BCZT ceramics have kept the 1D rod-like grains with an average aspect ratio of about 4. Rod-like BCZT ceramics exhibit enhanced dielectric ferroelectric (ɛr = 11,906, tanδ = 0.014, Pr = 6.01 μgC/cm2, and Ec = 2.46 kV/cm), and electrocaloric properties (ΔT = 0.492 K and gZ = 0.289 (K·mm)/kV at 17 kV/cm) with respect to spherical BCZT ceramics. Therefore, rod-like BCZT lead-free ceramics have good potential to be used in solid-state refrigeration technology

Morphogenesis mechanisms in the hydrothermal growth of lead-free BCZT nanostructured multipods

Due to growing environmental concerns about the toxicity of lead-based piezoelectrics, the replacement of Pb-based materials with homologs with comparable piezoelectric properties but without lead is an emergent task. Since 2009, Ba0.85Ca0.15Zr0.1Ti0.9O3 (BCZT) materials have aroused considerable attention as a replacement due to their excellent dielectric, ferroelectric and piezoelectric properties. Nanostructuring of BCZT can enhance these functionalities even more. Here, templated-growth of BCZT nanostructured multipods with hydrogen zirconate titanate nanowires (HZTO-NWs) was investigated under hydrothermal conditions. The effects of the precursor's concentrations and the hydrothermal reaction time on the morphological formation of BCZT nanostructures were investigated. Besides, composition, structure and phase analysis studies were carried out, and the growth mechanism of BCZT multipods was proposed. It was found that the precursor's concentrations and dwell time in hydrothermal reactions play a critical role in the formation of BCZT multipods, and the desirable BCZT phase was obtained in samples using low barium and calcium concentrations and at a short reaction time. This research has general validity and can be extended to design more complex perovskite oxides