Search

This research addresses the significant challenges of waste disposal and the need for sustainable production in the ceramics industry by introducing an approach to fabricating calcium-alumino-silicate-fluoride (CASF) based glass ceramics. Using recyclable materials such as waste soda-lime-silicate (SLS) glass and clam shells (CS) as primary precursors, a controlled melt-quenching process was employed to investigate how varying the CaO/CaF2 ratios influences the physical and structural properties of CASF glass ceramics. The waste materials and CASF glass ceramics were analyzed using X-ray fluorescence (XRF), X-ray diffraction (XRD), Fourier transforms infrared (FTIR), Scanning electron microscopy (SEM), and Energy dispersive X-ray (EDX) spectroscopy. XRD indicated the crystalline structure in all CASF glass ceramics samples while FTIR spectroscopy detected several linkages, including PO43−, Si-OH, Si-O-Si, CO2, and O-H indicating the development of CASF glass ceramics. SEM analysis showed a non-uniform distribution of particles and EDX analysis, shows the calcium-to-phosphate molar ratio (Ca/P) of CASF glass ceramics. The glass ceramics labeled as G6 possessed better properties, with a minor crystalline phase identified as fluorapatite (Ca5(PO4)3F), which is compatible with the commercial bioglass. These results demonstrate a cost-effective waste-derived bioglass system used in biomedical fields. [ABSTRACT FROM AUTHOR]

Air pollution is a global issue that demands urgent attention due to its detrimental effects on human health and the environment. Land Use and Land Cover (LULC) change is an essential factor that significantly impacts ambient air quality through alterations in emission sources, vegetation cover, natural processes, and urban design. This study investigates the spatio-temporal variation of key air pollutants resulting from urban LULC changes in the Delhi region. Findings reveal a notable increase in pollutant concentrations, particularly particulate matter, in 2019 (PM10: 318.65 ± 45.80 µg/m3) and 2023 (PM10: 383.70 ± 61.49 µg/m3), compared to 2008 (PM10: 246.76 ± 30.66). LULC change analysis demonstrates a rise in built-up areas 24.59%(2008 to 2019), 33.62% (2008 to 2023) and a decline in vegetation cover 27.49% (2008 to 2019),32.37% (2008 to 2023). Correlation analysis indicates a positive correlation between PM10 and urban indices (+ 0.63) and a negative correlation between PM10 and vegetation indices (− 0.61), highlighting the impact of LULC on air quality deterioration. Subsequently, a fuzzy inference system model integrates LULC information to develop an air quality index (AQI). Incorporating LULC changes in AQI assessment offers a realistic approach to address the complexity arising from combined air pollutant effects, surpassing conventional AQI calculation methods. The findings underscore the significance of understanding the impact of Land Use and Land Cover (LULC) change on ambient air quality in formulating effective air quality management programs and policies. Integrating this knowledge into policymaking is crucial for the successful abatement of air pollution in urbanized areas. [ABSTRACT FROM AUTHOR]

Melt-quenching bioglass-ceramics with the following chemical composition have been prepared 44SLS 11Na2CO3 24ES 6P2O5 6CaF2 9Al2O3 (wt%). The bioglass-ceramics were sintered at 650 °C, 750 °C, 850 °C, and 950 °C. The aim was to identify the optimal sintering temperature before glass crystallization. The physical properties were characterized by density and linear shrinkage. To characterize the structure properties, X-ray diffraction (XRD), scanning electron microscopy (SEM), and Fourier transform infrared spectroscopy (FTIR) were utilized. The high composition of Si and Ca in soda lime silica (SLS) glass and eggshells (ES), respectively, encourage the utilization of waste materials in the production of bioglass-ceramics. The results showed that at a sintering temperature of 950 °C, the crystallization of fluorapatite was the main phase. Moreover, the high density and optimum linear shrinkage were obtained as the sintering temperature increased. Additionally, grain growth and densification took place at this temperature. The compressive strength of bioglass-ceramics is influenced by sintering temperature and the optimal compressive strength is 136.58 MPa. [ABSTRACT FROM AUTHOR]

Bioactive glasses containing boron oxide have attracted substantial attention owing to their unique attributes and the promising prospects they offer for biomedical uses. The study explores boro calcium fluoro alumino silicate (BCFAS) glass containing boron oxide, highlighting its potential in biomedical applications. The glass was synthesized through melt-water quenching with varying B2O3 ratios, utilizing CaO from clam shell and SiO2 from soda lime silica glass waste. The investigation examined the physical and mechanical properties of the resulting samples. Results showed that increasing B2O3 content caused a reduction in crystallinity, as confirmed by XRD analysis. The incorporation of B2O3 into the glass structure was further supported by the emergence of B‒O‒B and Si‒O‒B bonds observed in FTIR spectroscopy, which may potentially influence the glass's dissolution and degradation characteristics. However, higher B2O3 content also reduced density, impacting the mechanical properties. Vickers microhardness and compressive strength decreased due to the introduction of the BO3 unit, which increased the fragility of the glass. While enhancing glass-like behavior and potentially increasing bioactivity, the addition of B2O3 adversely affected its mechanical attributes. [ABSTRACT FROM AUTHOR]

This research investigated the effect of chitosan as fine nucleation for the interactions among surface microstructure, secondary phases, and thermodynamic fluctuations of superconducting parameters during the superconducting transitions in YBa2Cu3O7-δ (Y-123) system. The study involved incorporating various low concentrations (0.0100 wt.% ≤ x ≤ 0.6000 wt.%) of chitosan (CHI) extracted from marine waste into the Y-123 matrix through a thermal treatment method annealed in an oxygen atmosphere. XRD results showed that all specimens crystallized into orthorhombic Y-123 as the main phase, with non-superconducting phases such as Y-211 and BaCuO2. These additions introduced different trends in grain degradation and appearance of nano-entities within the Y-123 matrix system. Investigations into the excess conductivity through DC resistivity measurements of these bulk granular specimens revealed a complete reduction in inter-layer coupling while preserving oxygen content and grain size. Furthermore, superconducting transition temperatures (Tc-onset, Tc-offset), superconducting transition width (ΔTc), and intergranular current density at zero temperature (Jc(0)) experienced significant improvements at lower concentrations, reaching an optimum at 0.0100 wt.%. The Jc(0) reached its peak value at 8.17 × 106 A/m2 for the specimen with 0.0100 wt.% CHI addition annealed in an oxygen atmosphere. This research underscores the potential of a sustainable approach involving the incorporation of low-concentration organic polymer (CHI), aligning with the principles of green materials and the advancement of superconductivity. [ABSTRACT FROM AUTHOR]

This research aims to investigate the potential of novel CaF2 − CaO − Na2O − B2O3−SiO2 glass systems and converted to bioactive glass-ceramics. The study involves examining the effects of different heat treatment temperatures and immersion periods, with the goal of exploring these materials as viable alternatives for various biomedical applications. A typical melt-quenching technique was used to synthesize the glass samples, followed by a controlled heat treatment. The main crystalline phases are cuspidine and wollastonite, which have the potential to promote bioactivity, especially in dental and bone-related applications. The sample heat-treated at 700 °C showed an increased microhardness and fracture toughness by more than 116% and 36%, compared to the initial value. Furthermore, the increase in pH and the observed weight loss/gain demonstrated the reactivity of the samples with the phosphate buffer-saline medium, indicating their bioactive properties. Remarkably, the microhardness and fracture toughness exhibited notable improvements after 14 days of immersion, with an enhancement of 4.71% and 4.66%, highlighting their potential durability and longevity in high-strength dental crown applications. Consequently, this research presents a promising method for developing sustainable novel glass and glass-ceramic materials devoid of phosphates. These materials boast enhanced mechanical properties while preserving bioactivity, making them well-suited for dental implants and restorative purposes. [ABSTRACT FROM AUTHOR]

The optimization of glass substrate optical properties for enhanced biosensor sensitivity has recently blossomed into a major research focus, yielding remarkable progress. Nevertheless, attaining precise control over nanoscale morphologies and their light-altering abilities remains a formidable hurdle, necessitating the exploration of diverse strategies to overcome this issue. This study was conducted to investigate how Er2O3 doping affects the physical, optical structural and elastic properties of ZnO-SiO2-B2O3 glasses, which were created using the melt-quenching method. The samples were confirmed to be amorphous and glassy using XRD and FTIR techniques. Many researchers used ultrasonic waves to measure the longitudinal and shear velocities of glasses using the pulse-echo method. The measurements were taken at a temperature within the typical room range and a frequency of 5 MHz. The addition of Er2O3 as a dopant resulted in both decreasing and increasing trends in the longitudinal, Young, shear and bulk moduli. These observations suggest a potential correlation between the increase in acoustic impedance and the presence of bridging oxygen, which leads to stiffer and more compact glass structures. The optical band gap of the material decreased from 3.43 eV to 3.23 eV as the weight percentage of Er2O3 increased from 0.00 to 0.05 wt.%. Surface plasmon resonance was investigated using the Otto configuration. The observed wavelength shift, approximately 6 nm with a gold nanolayer coating in the SPR results, indicated an increase in wavelength with increasing Er2O3 content (0.01-0.05 wt.%). This highlights the potential of this glass substrate for various optical applications, including optical biosensors. [ABSTRACT FROM AUTHOR]

17ß-Estradiol (E2) is an endocrine-disrupting chemical that has become a matter of concern across the globe for more than a decade due to potential health risks. This study reports facile methods to fabricate label-free aptasensor based on the non-Faradaic impedance mode using amine-functionalized graphene oxide polypyrrole (NH2-GO/PPy)-modified gold interdigitated electrode for direct capacitive detection of 17β-estradiol. The as-prepared NH2-GO/PPy nanocomposites have been successfully characterized by field-emission scanning electron microscopy (FESEM), atomic force microscopy, Fourier transform infrared spectroscopy, and electrochemical impedance spectroscopy. The results show that NH2-GO/PPy/IDE was able to detect E2 binding through aptamer conformational change by simply observing the capacitance change before and after immobilization. In addition, the biosensor showed a dynamic range of detection from 100 nM to 1 pM with a low detection limit of about 0.13 pM. The recoveries result also presented in this paper was validated using HPLC exhibited high sensitivity for bisphenol-A (BPA) detection and was successfully applied to detect E2 in real water samples with good recoveries. [ABSTRACT FROM AUTHOR]

A new formulation of the bismuth-zinc-borate glass system has been fabricated using the conventional melt-quenching method. The amorphous phase of the glass sample has been confirmed by the nonexistent of any crystalline peak presented by X-ray diffraction patterns. The Fourier-transform infrared spectroscopy result displays several bands associated with the Zn–O and B–O–B bonding. The glass samples exhibited a density increase from 3.19 to 4.28 g/cm3 and the molar volume increased from 23.48 to 31.00 cm3/mol. The density of the glasses increases due to the addition of Bi2O3 which has a higher atomic mass compared to the other elements in glass compositions. The addition of Bi2O3 contributes more mass to the glass structure, leading to an increase in overall density. The incorporated Bi2O3 reduced the longitudinal (6134.41–5121.94 ms−1) and shear (3310.50–2848.15 ms−1) velocities. The elastic moduli resulted in a decreasing behavior when Bi2O3 concentration increased, and the values ranged from 120.04 to 112.21 GPa for longitudinal modulus, 34.96–34.69 GPa for shear modulus, 73.43–65.95 GPa for bulk modulus, and 90.52–88.56 GPa for Young's modulus. The Poisson's ratio presents the same trend as the modulus, while the microhardness shows an inversely proportional trend. The BiZnB4 sample demonstrates the lowest Poisson's ratio (0.276) and highest microhardness (5.18 GPa) values. These findings show that the physio-elastic properties are composition-dependent, suggesting potential applications as flexible glass panels for dynamic building glass design. [ABSTRACT FROM AUTHOR]

This study focuses on zinc-boro-soda-lime-silica (ZnO − B2O3 − SLS) glasses produced through fast-cooling melt-quenching. The influence of Eu3+ ions on glass properties is explored. As Eu3+ concentration rises, bulk density and molar volume increase from 3.423 to 3.484 g/cm3 and 21.760 to 23.768 cm3/mol, respectively. X-ray diffraction indicates amorphous phase dominance supported by glassy surface morphology. Ultrasonic measurements show the increasing and decreasing trend for ultrasonic velocities and elastic moduli with increasing Eu3+ concentration. Poisson's ratio of the samples signifies their low cross-link density behavior. Moreover, the ZBS-3Eu presents the highest microhardness value of 4.776 GPa. The sample's fractal bond connectivity varies from 1.814 to 2.051, suggesting a 2D structure. Likewise, the ZBS-3Eu glass sample exhibits the most rigidity attributed to its highest fg value of 0.075. These findings suggest that ZBS-3Eu has the potential for applications requiring high-strength glass. [ABSTRACT FROM AUTHOR]

The xCaF2–45SiO2–25CaO–10B2O3–10Na2O–(10-x)P2O5 based 45S5 bioactive glass, where x = 0, 2, 4, 6, 8 and 10 wt.%. have been fabricated by modified melt-quenching method. X-ray diffraction (XRD) and Fourier-transform infrared spectroscopy (FTIR) measurement indicate that the CaF2 addition into the SiO2–CaO–B2O3–Na2O–P2O5 glass increases the stability of the amorphous phase and not lead to the crystallization of the glasses. The field emission scanning electron microscopy (FESEM) micrographs and energy dispersive X-ray (EDX) analysis presented the non-uniform particle distribution and the amorphous glassy structure in all glass samples. The compressive strength (CS) of the glass samples increases with CaF2/P2O5 ratios from 46.80 ± 0.15 MPa to 48.98 ± 0.11 MPa. However, the decrement occurs when further increment in CaF2/P2O5 ratios, which is caused by the excessive CaF2 content in the glass structure. Vickers microhardness (VM) shows a similar trend, increasing from 2.00 ± 0.07 GPa to 3.09 ± 0.07 GPa and suddenly decreasing with the higher addition of CaF2 concentration. Consequently, the BG3F glass sample presents optimum conditions for physical and mechanical performance comparable to the human enamel. [ABSTRACT FROM AUTHOR]

In this study, the impact of thulium oxide on the structural and elastic characteristics of magnesium borotellurite glass systems produced through the melt-quenching technique is examined. The findings reveal a direct relationship between the thulium concentration and several elastic parameters in the glass sample, such as ultrasonic velocity and elastic modulus. The sample's density increased from 4.12 to 4.30 g/cm3, and its molar volume increased from 29.29 to 29.62 cm3/mol as Tm3+ concentration progressed. The XRD study confirmed that the samples were amorphous. The incorporation of Tm2O3 into the glass acts as a network modifier and leads to an increase in NBO content. Moreover, the shear and longitudinal velocities range within the respective ranges of 1966.02 to 2495.90 m/s and 3474.78 m/s to 4085.13 m/s. Young's modulus, bulk, shear, and longitudinal elastic moduli fall between 40.28 and 64.45 GPa, 28.51 and 36.07 GPa, 15.92 and 26.81 GPa, and 49.75 and 71.81 GPa, respectively. Moreover, the sample's Poisson ratio decreases from 0.26 to 0.20 with an increase in Tm3+ concentration. The experimental results are compared to the theoretically calculated results. By comparing to experimental data, the Mackenzie Makishima and Rocherulle models demonstrate a high level of accuracy. [ABSTRACT FROM AUTHOR]

In this work, Eu3+/Sm3+ co-doped zinc borosilicate glass was prepared by modified melt-quenching method. The effect of Eu3+/Sm3+ to the structural and optical properties was investigated. The optical band gaps increased from 5.023 to 5.179 eV, and 3.832 to 3.986 eV for both for direct/indirect transition. Urbach energy decreases from 0.713 to 0.697 eV, while refractive index also decreases from 2.203 to 2.173 with the progress of doping concentration. The photoluminescence measurement reveals the simultaneous amplification of Sm3+ and Eu3+ emission for the co-doping sample, suggesting a synergistic energy transfer between the two ions. The 1EuSmZBS glass samples show the highest emission intensity. The CIE chromaticity coordinates, CCT, and color purity of the glass sample present high intensity of reddish-orange emission color. In conclusion, Eu3+/Sm3+ co-doped zinc borosilicate glass can lead to enhanced and tunable luminescence properties, and potentially use as a glass host phosphor in optoelectronic applications. [ABSTRACT FROM AUTHOR]

Background: Acute pancreatitis (AP) is known to result in endocrine dysfunction (prediabetes, diabetes). The objective of this study was to determine the temporal incidence of endocrine dysfunction after onset of AP and determine the risk factors in Indian patients. Methods: In this prospective study, enrolled patients diagnosed with AP between February 2019 and May 2019 were followed at 3, 6, and 12 months until May 2020. Patients with recurrent AP, chronic pancreatitis, and pre-existing endocrine dysfunction were excluded. Demographic and disease severity (clinical, laboratory, and radiological) data were recorded. Mann-Whitney U and Chi-square tests were used to compare groups. Temporal trend for development of endocrine dysfunction was evaluated using the Extended Mantel Haenszel Chi-square test for trend. Logistic regression was used to identify independent risk factors. Results: Eighty-six patients (males 66, median [IQR] age 33.0 [26.0–44.2] years) who fulfilled enrolment criteria were finally analyzed. The most common etiology was alcohol (n=31 [36%]) followed by gallstones (n=17 [19.8%]). The proportion of patients with moderately severe acute pancreatitis and severe AP were 59.3% and 15.1%, respectively. Overall, the frequency of prediabetes and diabetes increased temporally across the follow-up period. These were 2 (2.33%) and 1 (1.16%) at 3 months, 11 (12.8%) and 5 (5.81%) at 6 months, and 20 (23.2%) and 9 (10.5%) at 1 year, respectively. On multivariable logistic regression, intervention for walled-off necrosis (WON) emerged as the single independent risk factor for endocrine dysfunction (odds ratio 9.01 [2.3–35.5]; p=0.002). Conclusions: Endocrine dysfunction is frequent after an episode of AP. Intervention for WON is an independent risk factor for endocrine dysfunction. [ABSTRACT FROM AUTHOR]

This paper reports on developing low-cost fluoride-containing glass–ceramics derived from eggshells waste as a source of calcium via the conventional melt-quenching method. The physical, structural, and mechanical properties of the samples before and after sintering is highlighted in this study. XRD and FTIR analysis confirmed the presence of fluorapatite, wollastonite, and cuspidine phases. It is worth noting that adding fluoride to the glass system would lead to the improvement of the mechanical properties of the final product. Among all, the sample sintered at 700 °C achieved the highest density and mechanical properties. It obtained a density value of 2.626 g/cm3, a microhardness result of 6.72 GPa, and fracture toughness of 3.55 MPa·m1/2. These results are better than commercial 45S5 bioglass (0.148 GPa–0.375 GPa) and comparable to the properties of human enamel (2.00 GPa–6.00 GPa). These findings would be believed to contribute to a low-cost waste-derived fluoride-containing glass–ceramics system in the dental application. [ABSTRACT FROM AUTHOR]

Eu3+-doped Zn2SiO4/ZnO phosphor-based composites were prepared using a simple thermal treatment method. The effect of Eu3+ content on the morphological and photoluminescence performance was examined using XRD, FTIR, FESEM, UV–Vis, and PL measurement. The existence of two crystal phases by the XRD measurement confirmed the development of zincite (ZnO) and zinc silicate (Zn2SiO4) crystal phases. Besides, the FTIR spectra and FESEM micrograph support the XRD result by verifying ZnO and Zn2SiO4 phase formation through the existence of their characteristic Zn–O–Si and Zn–O vibration modes with the decrement of SiO4 broad absorption band as the Eu3+ concentration increased. Also, UV–Vis absorption spectra presented by the composite samples displayed a broad absorbance that confirmed the addition of Eu3+ ions in the ZnO/Zn2SiO4 has caused the absorption edge of the curve having red shift. The photoluminescence spectrum showed red shift light emissions at 485 and 615 nm, associating with the Zn2SiO4 crystal phase, in addition to the ZnO crystal phase. From the interesting results achieved, this ZnO/Zn2SiO4 phosphor-based composite material can be a potent candidate in optoelectronic applications. [ABSTRACT FROM AUTHOR]

Four series of CaO-ZnO-B2O3-SLS (CZBS) glasses have been synthesized by using waste materials which are eggshell (EG) and soda lime silica (SLS) glass. We utilized eggshells to source calcium oxide (CaO) in this work, whereas we utilized SLS glass to substitute silica. CZBS1, CZBS2, CZBS3 and CZBS4 are the glass series containing weight percentages of CaO (15%, 20%, 25% and 30%) and SLS (70%, 65%, 60% and 55%), respectively, with the addition of 10% of B2O3 and 5% of ZnO in each sample. A conventional melt and quenching method was applied in this work to fabricate the CaO-ZnO-B2O3-SLS glass system. The glass transition temperature (Tg) was determined using differential scanning calorimetry (DSC), which revealed that the Tg increased from 714 to 735 °C, as the CaO content increased. Meanwhile, the glass structural properties were investigated, revealing an amorphous nature with no sharp peak. The experimental elastic moduli obtained by acquiring ultrasonic speeds using the ultrasonic pulse-echo method were compared to the hypothetical elastic moduli obtained by direct estimation of the hypothetical model. [ABSTRACT FROM AUTHOR]

Preparation and characterizations of poly(pyrrole-co-pyrrole-3-carboxylic acid) (PPYPA) film on the surface of screen printed carbon electrode (SPE) has been discussed in the manuscript. Different ratios of monomer for PPYPA preparation will be applied to determine 17β-estradiol using cyclic voltammetry. The SPE was modified with PPYPA film using an electrodeposition method and followed by the immobilization of 75mer aptamer specifically binding to 17β-estradiol as a model study. The materials were characterized by cyclic voltammetry, Fourier transform infrared, electrochemical impedance spectroscopy and scanning electron microscopy. The redox peak potential was found to be at 0.13 V and 0.26 V. The appearance of cauliflower structure in the SEM image which indicates PPYPA film was formed on SPE. Moreover, PPYPA/SPE exhibited a lower charge transfer resistance (Rct) compared to bare SPE indicates a good conductivity of film. Our study shows that 3:1 ratio between PPY and pyrrole-3-carboxylic acid provided highly active surface area for the immobilization of 75mer aptamer for 17β-estradiol detection. [ABSTRACT FROM AUTHOR]

Willemite is an inorganic semiconductor material used for optoelectronic applications. The present study purposes a new polymer thermal treatment method involving calcination temperature to fabricate the willemite nanoparticles. The effects of polyvinylpyrrolidone (PVP) on the structural and optical properties of the material were thoroughly investigated. Thermogravimetric and its derivative confirmed the decomposition behavior of PVP. The minimum calcination temperature to decompose PVP was appraised at 740 °C. The FTIR and the Raman analyses confirmed the presence of organic source before the calcination process and the formation of the crystalline structure of the willemite nanoparticles after the heat treatment. The optimum PVP concentration in this study based on the FTIR results was found to be 40 g L−1. This is the minimum concentration at which the willemite nanoparticles remained pure with homogenous distribution. X-ray diffraction analysis of the PVP samples before calcination was confirmed to be amorphous, and upon calcination between 800 and 1000 °C, an α-willemite phase was obtained. The morphology and the average particle size were determined with FESEM and HR-TEM analysis. The average particle size is between 23.8 and 36.7 nm. The optical energy band was found to be increasing from 5.24 to 5.32 eV with the corresponding increase in PVP concentration from 20 to 50 g L−1. The findings in this study provides a new pathway to understand the effects of PVP concentrations on the structural and optical properties of willemite semiconductor nanoparticles as it may have key potential applications for future optoelectronic devices. The primary task of polyvinylpyrrolidone (PVP) is to serve as a capping agent and to stabilize the metallic salts. The interaction between the PVP and the metallic salts (zinc acetate dihydrate and silicon tetraacetate) is through the strong ionic bonds between the metallic ions and the amide group via oxygen in the PVP chain. The PVP stabilizes the dissolved metallic precursor by amide group steric and electrostatic stabilization. In the drying process at the temperature about 80 °C, the PVP decompose to the shorter polymer chains which they cap the metallic ions. In the step of calcination at the range of 900 °C for 1–4 h, the polymer content and unwanted anions are entirely removed and the nucleation of willemite nanoparticles achieved. [ABSTRACT FROM AUTHOR]

Microwave absorbers of cobalt ferrite and graphite composite have been fabricated to investigate the broadening of absorption frequency by mixing small and large particles and comparing single- and double-layer composites in order to broaden the absorption frequency and to enhance multireflection and scattering of electromagnetic wave. CoO and Fe2O3 precursors were mechanically alloyed and sintered at 800, 900, 1000 and 1100 ∘C in order to synthesise various particle sizes and shapes. A mixed sample of powders sintered at the above mentioned temperatures was also formed. The morphological, phase, and magnetic properties of these samples were studied. Two series of samples have been synthesised which were single- and double-layer composites. Single-layer composite consisted of mixed particles, and their thickness parameters were varied. Double-layer composite was also prepared with various particle sizes of CoFe2O4 as a layer and graphene as another layer. The effect of these layers as matching and absorbing layer was studied. The degree of crystallinity of CoFe2O4 was increased with increase of sintering temperature. Microstructural study showed the evolution of particle size and shape subjected to sintering temperature. Arrhenius plot showed two stages of growth process with activation energy calculated at 26.85 and 83.091 kJ/mol. The critical size of single domain of this sample plotted from the coercivity against particle size was 63.44 nm. Single-layer composite with mixed particle size was not able to show good electromagnetic (EM)-wave absorption; however double-layer composite showed good return loss. The mechanism of the EM-wave absorption of double-layer composite was discussed in this paper. [ABSTRACT FROM AUTHOR]

The effect of different sintering temperatures on structural and optical properties of ZnO-Zn2SiO4 composite was investigated. In this study, a ZnO-Zn2SiO4 composite was prepared by encapsulated zinc nitrate hexahydrate with amorphous silica nanoparticles in deionized water. The amorphous silica nanoparticles were prepared by reacting sodium silicate with ethanol. Zinc nitrate was mixed with the obtained amorphous silica nanoparticles with the ratio of 2:1 and 1.25:1 for Zn:Si and subjected to the different sintering temperatures from 600 to 1000 °C. Field emission scanning electron microscope (FESEM) microstructure showed that samples exhibit spherical morphology up to 700 °C and dumbbell morphology above 800 °C sintering temperature. The formation of Zn2SiO4 crystal phase appears from 700 °C and onwards together with ZnO crystal phase. The gaining of sintering temperature has also raised the amount of Zn2SiO4 phase and band gap values of the ZnO-Zn2SiO4 composite. [ABSTRACT FROM AUTHOR]

In this research, Tm2O3 doped zinc silicate based glass-ceramics were prepared by using conventional melt-quenching method and has been successfully derived from ZnO-WRHA glasses with control heat treatment process. The formation of zinc silicate phase affected by heat treatment process was investigated using X-ray diffraction. Fourier transform infrared reflection spectroscopy (FTIR) analysis was used to determine the crystallization of Zn2SiO4 in the glass matrix. FTIR analysis showed the appearance of Zn2SiO4 and SiO2 bands that supported the formation of Zn2SiO4 crystal phase in the glass matrix. The optical absorption and energy band gap of the glass and glass-ceramics was investigated using UV-Vis spectroscopy. The absorption edge shows the movement towards longer wavelength with increasing heat treatment temperature. Besides, the energy band gap decreased with the progression of heat treatment. This ability to enhance optical properties in glass-ceramics was expected to have bright future in the opto-electronics devices. [ABSTRACT FROM AUTHOR]

The microwave absorption properties of single- and double-layer doped strontium hexaferrite (SrCoZnFe16O27) and graphite nanocomposite were investigated. W-type SrCoZnFe16O27 nanoparticles was prepared via solid state reaction using high energy ball milling and sintered at different sintering temperatures. Microwave absorption properties of single- and double-layer structures of different thicknesses were investigated in the frequency range of 8-18 GHz using a network analyzer, and their behavior analyzed based on electromagnetic transmission line theory. The results show that double-layer absorbing material showed better microwave absorption properties than single-layer. Double-layer absorbing material which consisted of graphite as the matching layer and SrCoZnFe16O27 as the absorbing layer demonstrated higher reflection loss values of − 19.5 dB when both layers were 1 mm thick. The bandwidth corresponding to the reflection loss below − 10 dB (i.e. 90% absorption) was 3.8 GHz (11.0-14.8 GHz). The excellent microwave absorption properties of double-layer structures were influenced by good impedance match, multiple internal reflections and coupling interactions between the matching and absorbing layers. [ABSTRACT FROM AUTHOR]

Zinc silicate (ZnO-SiO) glass system were fabricated using melt-quench method with zinc oxide (ZnO) and white rice husk ash (WRHA) with compositions of (ZnO)(WRHA) where (x = 0.55, 0.60, 0.65 and 0.70 wt%). Energy Dispersive X-ray Fluorescence (EDXRF), X-ray diffraction (XRD), Fourier Transform Infrared (FTIR) spectroscopy and UV-Visible (UV-Vis) absorption spectroscopy were used to investigate the structural and optical properties of the samples. From XRD measurement, only one sample is glass and others were in crystalline form as WRHA is used to replace silica (SiO). This is because WRHA possess nucleating agents in its composition and this causes the samples to be highly crystalline. ZnO in the other hand is a highly crystalline material and encourages the formation of crystalline phase in the samples. FTIR analysis shows that the non-bridging oxygen's (NBO's) are formed as the amount of ZnO in the samples increases. The optical band gap shows that the optical band gap rises due to direct forbidden transition. ZnO-SiO glass system has variety of applicable characteristic because it possesses high level of chemical inertness for variety of chemical applications and it also gives various color emission which can be used in the plasma display panels (PDPs) and cathode-ray phosphor. [ABSTRACT FROM AUTHOR]

Low-cost Mn-doped willemite (α-ZnSiO:Mn) based glass-ceramics were synthesized by conventional melt-quenching technique using waste soda lime silica (SLS) glasses, zinc oxide (ZnO) and Manganese oxide (MnO) as precursors. The effect of different MnO percentage doping on physical, structural, optical and luminescent performance α-ZnSiO:Mn based glass-ceramics were comprehensively studies in this work. The presence of α-ZnSiO:Mn crystal phase and microstructure was confirmed by X-ray diffraction and field emission scanning electron microscopy spectroscopy. From the Scherrer's formula, α-ZnSiO:Mn have an average crystallite size of 30-40 nm, respectively. Fourier transform infrared reflection spectroscopy displays the structural growth of α-ZnSiO:Mn crystal. The green emission centered at about 527 nm from the α-ZnSiO:Mn crystal exhibit a resulted from T-A energy transition of Mn ions. Intense emissions of Mn ions at 260 nm excitation were occurs may be caused by the increase of Mn ions into α-ZnSiO crystal structure with lower phonon. Based on the results achieved, this low-cost α-ZnSiO:Mn based glass-ceramic exhibit a huge potential to act as a green phosphor in opto-electronic devices. [ABSTRACT FROM AUTHOR]

This paper presents a comprehensive study on thermal, structural and optical properties of novel willemite glass-ceramics. The precursor glass in the ZnO-SLS glass system was successfully prepared using conventional melt-quenching technique and willemite (ZnSiO) glass-ceramics were derived from this precursor glass by a control crystallization process. The effect of heat-treatment temperature on the phase transformation, morphology and size of ZnSiO crystal phase was examined using X-ray diffraction (XRD), field-emission scanning electron microscopy (FESEM) techniques. Furthermore, fourier transform infrared reflection (FTIR) spectroscopy was used to evaluate the ZnSiO crystal structural evolution. The average size of ZnSiO crystallite obtained from calculation of XRD is found to be in the range 30-60 nm, whereas the grain size observed in FESEM is in range of 200-400 nm. The appearance of SiO, ZnO and Zn-O-Si bands detected from FTIR indicate the formation of ZnSiO crystal phase. Besides, the study of the optical band gap has found that optical band gap of the glass-ceramics decreased as the heat treatment temperature increased. The photoluminescence spectra of willemite glass-ceramics exhibit two different emissions around 525 nm (green) and 585 nm (yellow); exhibit a characteristic of broad absorption band around 260 nm. These two different spectra reveal that the luminescence performance of the willemite glass-ceramics was enhanced with the progression of heat treatment temperature due to different located energy levels of the β-ZnSiO and α-ZnSiO crystalline phase. Such luminescent glass-ceramics was expected to find potential applications in phosphors and opto-electronic devices. [ABSTRACT FROM AUTHOR]

This paper reported the uses of ark clam shell calcium precursor in order to form hydroxyapatite (HA) via the wet chemical precipitation method. The main objective of this research is to acquire better understanding regarding the effect of sintering temperature in the fabrication of HA. Throughout experiment, the ratio of Ca:P were constantly controlled, between 1.67 and 2.00. The formation of HA at these ratio was confirmed by means of energy-dispersive X-ray spectroscopy analysis. In addition, the effect of sintering temperature on the formation of HA was observed using X-ray diffraction analysis, while the structural and morphology was determined by means of field emission scanning electron microscopy. The formation of HA nanoparticle was recorded (~35-69 nm) in the form of as-synthesize HA powder. The bonding compound appeared in the formation of HA was carried out using Fourier transform infrared spectroscopy such as biomaterials that are expected to find potential applications in orthopedic and biomedical industries . [ABSTRACT FROM AUTHOR]

This paper presents a study on synthesis and optical properties of ZnSiO:1 wt% Eu at different heat treatments. The objective of the research is to synthesize ZnSiO:1 wt% Eu phosphor by using low cost solid state reaction method with recycled waste bottle glasses as the silicate source. The X-ray diffraction results showed that the prepared ZnSiO:1 wt% Eu phosphors have a sharp diffraction peak as the heat treatment temperatures were increased from 600 to 1000 °C. Furthermore, the morphology from the Field emission scanning electron microscope analysis were shown the formation of well crystalline samples with dense packed grains due to the increment of heat treatment temperatures. Fourier transform infrared spectra has confirmed the present elements in ZnSiO:1 wt% Eu phosphors while the narrow width of Raman line spectra were observed at temperatures ranging from 700 to 1000 °C indicates good homogeneity and crystallinity of synthesized powders. In addition, the energy band gap of europium doped zinc silicate increased dramatically up to 3.62 eV at temperature of 1000 °C. Photoluminescence measurements has also exhibited the red emission corresponding to the D → F (600 nm) when viewed under blue excitation. [ABSTRACT FROM AUTHOR]