Impact of Mn2+/Tm3+ co-doping on the thermal stability, optical properties and photovoltaic performance of fluoride glasses

In this work, characterization of thermal performance and optical properties of a material using a new developed indoor facility is undertaken. The indoor facility is capable of independently controlling the temperature of the material and the flux incident on it. Thereby, allowing investigation of independent effect of temperature and flux on a material’s thermal performance and optical properties variations. An unpolished 304/304L stainless steel is selected as a candidate material. The selected material is machined to obtain a sample having 20 mm diameter and 10 mm thickness. The sample is exposed to five levels of homogenized fluxes in the range of 579.3 kW m−2 to 917.1 kW m−2 for the duration of 1000s and 3000s. It is found that the thermal performance of the materials decreases with the increase in incident flux but this decrement depends on the temperature of the material. The 21% decrement in the thermal performance is obtained when temperature of the material is changed by 159 K while only 6.7% decrement in thermal performance is observed under same condition when the temperature of the material changes by 22 K. The variation of optical properties also depends on the temperature of the material. Under the same flux of 917.1 kW m−2 and exposure duration of 1000s, the reflectance of the material changes by 26% and 7% when temperature of the material is maintained at 557 K and 368 K respectively.In this work, characterization of thermal performance and optical properties of a material using a new developed indoor facility is undertaken. The indoor facility is capable of independently controlling the temperature of the material and the flux incident on it. Thereby, allowing investigation of independent effect of temperature and flux on a material’s thermal performance and optical properties variations. An unpolished 304/304L stainless steel is selected as a candidate material. The selected material is machined to obtain a sample having 20 mm diameter and 10 mm thickness. The sample is exposed to five levels of homogenized fluxes in the range of 579.3 kW m−2 to 917.1 kW m−2 for the duration of 1000s and 3000s. It is found that the thermal performance of the materials decreases with the increase in incident flux but this decrement depends on the temperature of the material. The 21% decrement in the thermal performance is obtained when temperature of the material is changed by 159 K while only 6.7% d...

Ceramic-based packed bed solutions are becoming more common in the energy fields as both thermal energy storage and heat exchanger. Such solutions are usually designed for the working temperature ranges above 600 °C, thus thermal radiation becomes significant and even acts as the dominant heat transfer mechanism. Therefore, applying high-temperature coatings with different thermal properties could be an efficient way in enhancing the performance of these applications. In this work, the high-temperature long residency and cyclic thermal stability of six inorganic coatings applied on a ceramic substrate are investigated. Both qualitative and quantitative assessments are performed. The results show that HIE-Coat 840MX and Pyropaint 634 ZO exhibit excellent thermal stability performance both at high-temperature testing (1000 °C) and under thermal cycle testing (400 °C–800 °C). TiO 2 based coatings could be a viable solution if the powder is pre-treated to avoid polymorph transition during the operation. Stainless steel 304 powder-based coating could also be a possible solution, since the adhesive curbs the oxidation and hinders the coating from deterioration. Contrarily, Pyromark 2500 and MgO based coating show different degradation problems that limit their exploitation in high-temperature applications undergoing thermal cycles. The investigated coatings show a wide range of thermal emissivity (between 0.6 and 0.9), with stable or decreasing trends with temperature. This enables a potential 20% change of the effective thermal conductivity for the packing structure. This work is a stepping-stone towards further detailed experimental studies on the influence of coatings on various packed bed thermal storage systems, and thus offer a new option in improving the performances of the energy equipment with packed bed systems. • Thermal stability of six inorganic coatings on ceramic particles tested at 1000 °C. • Pyro-Paint 634-ZO and HIE-Coat 840MX show excellent thermal stability. • MgO coating on ceramic particles shows cracks after 30 thermal cycles (400–800 °C). • Optical properties of selected coatings are studied in the λ range 250–26000 nm. • Effective thermal conductivity increases of 27% at 1000 °C can be attained.

As one kind of well known amorphous transparent conductive oxide films, In–Ga–Zn–O (IGZO) based films were broadly used as electric functional layer in optoelectronic devices. As IGZO film is sensitive to temperature and oxygen, and its electrical and optical properties may probably be deteriorated after subsequent high temperature and air atmosphere. In this work, amorphous indium tin oxide (ITO) layer with two adjustable type of thickness were employed to improve the thermal stability of IGZO films. The doubled ITO/IGZO films were deposited on glass by magnetron sputtering and annealed at high temperatures subsequently to investigate its thermal stability. Accordingly, the crystal structure, optical and electrical properties of ITO/IGZO films were further studied. The XRD results demonstrated that the annealed IGZO films could keep amorphous structure, and the ITO/IGZO films were consisted of uniform small particles which showed comparable dense structure and closely integration with the glass substrate. Furthermore, the sheet resistance results indicated that the increased thickness of top ITO film could suppress oxygen and improve thermal stability of electrical property. Moreover, the transmittance in the visible range was about 85%, and showed a little increase after annealing. The protective ITO layer was found to keep improved thermal stability, good electrical and optical properties at temperatures up to 550 °C.

Investigation of optical and thermal properties in Er3+-doped Ga2O3-La2O3-Ta2O5 glasses fabricated by containerless solidification

Nanocomposites with thermal stability and tunable optical properties became essential for developed optoelectronic and electrochemical devices. This work represents an attempt to synthesize PVA–PEO polymeric blend and modifies its structural, optical, and thermal properties. This was performed by incorporating different ratios of double-layered hydroxide (Zn/Fe-LDH) nanoplates (NP) which were prepared by the co-precipitation process. XRD results revealed that the incorporation of LDH, 43 nm in size and rhombohedral phase, influenced the degree of crystallinity (X C) of the blend. FE-SEM analysis showed the uniform distribution of LDH NP in the polymer matrix until 7.0 wt% content, beyond this ratio some voids were formed in the blend surface and particle agglomeration took place. FTIR spectroscopy illustrated the good miscibility of the polymers forming the blend, the interaction, and complexation between LDH NP and the blend functional groups. UV–vis-NIR spectroscopy analysis was performed to study the transmittance of the nanocomposites, extinction coefficient, refractive index, and optical conductivity. Besides, the direct and indirect band gaps of the films were found to decrease with increasing LDH NP content until a certain limit, after which they increased again. TGA&DSC analysis revealed the thermal stability of the films until 240 °C, and the DSC curves indicated three endothermic peaks. The obtained results confirmed that LDH NP incorporation is an interesting approach for tuning the optical and thermal properties to widen the technological applications based on PVA–PEO blend.

It has long been known that certain compositions in the CaO–Al2O3 system form glasses, although they do not contain any strong network formers such as SiO2, B2O3 or P2O5 [1–7]. In addition, there has been much interest in the calcium aluminate (CA) glasses due to their unique optical properties. The CA glasses show sapphire-like infrared (IR) transmission and an IR cutoff of about 6 μm, whereas silicate glasses present strong absorption in the 3–5 μm region [4]. The CA glasses are low-loss optical materials, showing scattering value of approximately 0.04 dB km−1 at 1.55 μm [8]. This is considerably lower compared to that of silicate glasses, which have a scattering value of 0.16 dB km−1. The CA glasses are also applicable to photometric devices because they are photosensitive to ultraviolet radiation [9]. Moreover, the CA glasses have appropriate mechanical properties for a variety of applications. For example, the CA glass fibers have a higher elastic modulus than Sand E-glass fibers [10]. The combined optical and mechanical properties give the CA glasses their high potential of application. The ease of devitrification, however, is a critical limitation not only in the production but in the application of the CA glasses in various forms. Once devitrification initiates, their optical and mechanical properties would seriously deteriorate. Some effort has been spent in improving the glass-forming ability of the CA glasses. Earlier studies [1–3] focused on the addition of SiO2 to the CA glass to improve its glass-forming ability, but such addition was found to deteriorate the optical properties due to the stretching motion of the Si–O bonds. Sun [2] and Hafner et al. [4] studied the effect of the addition of several percentage points of alkali or alkaline– earth oxides to the composition of the CA glasses. Their results showed that the production of stable CA glasses with a large volume was possible without using any strong network former. Most of their glass compositions, however, contained several percentage points of iron oxide, which affects many optical properties. Uhlmann et al. [11] prepared calcium aluminate-based glasses containing 6 vol % of Na2O, BaO and/or SrO and compared the glass-forming ability and stability of each glass. Their results revealed that most of the glasses have a much-enhanced glass-forming ability and stability compared to the CA glass (64CaO– 36Al2O3) without the additives, and among them the CANB glass (52CaO–36Al2O3–6Na2O–6BaO) was found to be the best glass-former and the most stable glass. For this study, the calcium aluminate glass (61CaO– 39Al2O3) was prepared by air quenching. This composition has been intensively studied for the glass-fiber production via inviscid melt spinning (IMS) [12–15] because it has the lowest eutectic temperature in the CaO–Al2O3 binary system and thus is easy to melt. Also, the calcium aluminate glasses containing 5 or 10% of Na2O, BaO and/or SrO were prepared for the purpose of enhancing the glass-forming ability and stability of the CA glasses. Table I lists the compositions of glasses prepared for this study. High-purity powders of Al2O3, CaCO3, Na2CO3, CaCO3 and SrCO3 from Aldrich Chemical Company (Milwaukee, WI, USA) were used for glass preparation. Each powder mixture loaded inside a platinum crucible was heated to 1550 ◦C and held for 2 h in an air atmosphere. The weight of each glass melt was 10 g. The platinum crucible containing the glass melt was taken from the furnace at 1550 ◦C and cooled on a brass plate at room temperature. Each of the glasses formed by air cooling was examined for glass-forming ability by using optical microscopy. Also, differential thermal analysis (DTA; Setaram TGDTA-92, France) scans on the glasses were performed at a heating rate of 10 ◦C min−1 up to 1550 ◦C and at a cooling rate of 80 ◦C min−1 down to 1000 ◦C to investigate the glass-forming ability and stability. The DTA scans were performed using a 50 mg fragment of each glass in an air atmosphere. A 50 mg amount of alumina powder was used as a reference material, and platinum cups were used for the DTA scans. The DTA temperatures were calibrated using pure aluminum and copper. Table II lists the results of the glass-forming ability of each glass composition according to optical microscopy. The CANS composition showed the best glass-forming ability, while the CAN composition showed the worst one, showing complete opaqueness. The CAB, CAS and CA compositions showed small isolated crystals, while the CAS and CANB showed partial crystallization with a slightly large portion. The resulting glass-forming ability of the compositions in

The effectiveness of direct absorption solar collectors (DASCs) is limited due to the low photothermal conversion efficiency and poor heat transfer qualities of traditional fluids. One potential solution to address this problem is the development of innovative technologies to enhance the solar absorption ability and thermal conductivity of conventional fluids. New generation nanofluids where nanosized particles are dispersed in base fluids like water or ethylene glycol (EG) have attracted interest within diverse solar technologies owing to their superior optical and thermal properties. This study presents a novel TiO2/FeVO4/Ethylene glycol (TFV/EG) nanofluid which exhibits significant solar absorption and thermal stability characteristics. A thorough characterization of the samples was conducted utilizing X-ray diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Raman Spectroscopy, High-Resolution Transmission Electron Microscopy (HRTEM), nitrogen adsorption-desorption isotherms and Thermogravimetric Analysis (TGA). The stability, optical and rheological characteristics of TFV nanofluids were also examined. The study’s outcomes indicated that the integration of TFV nanoparticles into ethylene glycol (EG) markedly improved its optical absorption, especially at a concentration of 0.8 g/l TFV, which demonstrated robust absorption in the UV-visible light spectrum. Long-term stability assessments indicated sedimentation for all TFV concentrations following 65 days. A substantial 270% enhancement in thermal conductivity in comparison to EG base fluid was noted at 0.8 g/l TFV reaching 0.83 W·m⁻¹·K⁻¹. All nanofluids exhibited shear-thinning behavior, a hallmark of non-Newtonian fluids. The suggested TFV/EG represents a notable category of nanofluids that exhibited improved thermal performance and stability, rendering them very advantageous for efficient DASCs.

Novel organo-saponite (organo-SPT) films with excellent thermal stability and optical property were synthesized by solution casting. Na ion-exchanged saponite (pristine SPT), hexadecylammonium ion-exchanged SPT (C16-SPT), hexadecyltriphenyl phosphonium ion-exchanged SPT (C16PPh3-SPT), and tetraphenyl phosphonium ion-exchanged SPT (PPh4-SPT) were used to prepare clay films. We examined the relationship between the structures and properties of the various SPT films. SPT films were examined by means of wide-angle X-ray diffraction (XRD), electronic microscopy (FE-SEM), thermogravimetric analysis (TGA), ultraviolet-visible (UV-vis.) spectrometer. On the basis of these analyses, we sought to improve both the thermal stability and the optical properties. Clay films composed of C16PPh3-SPT and PPh4-SPT were found to be more thermally stable than those composed of pristine SPT or C16-SPT. On the other hand, the transmittance was not significantly affected by variations in the organo-SPT material.

Thermal properties and stability of Carica papaya fiber-reinforced MgO particulate epoxy composites for advanced thermal applications

Development of new acid-imide modified Mg-Al/LDH reinforced semi-crystalline poly(amide-imide) containing naphthalene ring; study on thermal stability and optical properties

Preparation and characterization of NIR cutoff antimony doped tin oxide/hybrid silica coatings

Er3+-doped tellurite glasses with molar compositions of 75TeO2–20ZnO–(5 − x) Na2O–xEr2O3 (x = 0, 0.5, 1, 2, 3, and 4 mol%) have been elaborated from the melt-quenching method. The effects of Er2O3 concentration on the thermal stability and optical properties of tellurite glasses have been discussed. From the differential scanning calorimetry (DSC) profile, the glass transition temperature T g, and crystallization onset temperature T x are estimated. The thermal stability factor, defined as ∆T = T x − T g, was higher than 100 °C. It suggests that tellurite glass exhibits a good thermal stability and consequently is suitable to be a potential candidate for fiber drawing. Furthermore, the stability factor increases with Er2O3 concentration up to 2 mol% then presents a continue decrease suggesting of beginning of crystallization of highly doped tellurite glasses. The refractive index and extinction coefficient data were obtained by analyzing the experimental spectra of tanΨ and cos∆ measured by spectroscopic ellipsometry (SE). The complex dielectric functions (e = e1 + ie2) of the samples were estimated from regression analysis. The fundamental absorption edge has been identified from the optical absorption spectra and was analyzed in terms of the theory proposed by Davis and Mott. The values of optical band gap for direct and indirect allowed transitions have been determined. An important decrease of the optical band gap was found after Er doping. It was assigned to structural changes induced from the formation of non-bridging oxygen. The absorption coefficient just below the absorption edge varies exponentially with photon energy indicating the presence of Urbach’s tail. The origin of the Urbach energy is associated with the phonon-assisted indirect transitions.

In this study, a series of pyridine‐ring based poly(azomethine‐urethane)s were synthesized to investigate the effect of electron‐donating group on some physical properties such as thermal stability, optical, and electrochemical properties. For this reason, firstly the Schiff bases were synthesized using amino‐methyl pyridines (2‐amino‐3‐methyl pyridine, 2‐amino‐4‐methyl pyridine, and 2‐amino‐6‐methyl pyridine) with 2,4‐dihydroxy benzaldehyde by the condensation reaction. Then, these Schiff bases were converted to poly(azomethine‐urethane) derivatives via step‐polymerization reaction. Secondly, structural characterizations were carried out by FTIR, NMR, and UV–Vis. Cyclic voltammetry was used to determine the electrochemical oxidation‐reduction characteristics. Optical properties were investigated by UV–vis and fluorescence analyses. Thermal properties were clarified by TG‐DTA and DSC techniques. The molecular weight distributions of polymer were determined by size exclusion chromatography. POLYM. ENG. SCI., 54:1664–1674, 2014. © 2013 Society of Plastics Engineers

In the present work, thermal and nonlinear properties of tellurite glasses doped with Tm2O3 were investigated by means of thermal lens, thermal relaxation and z-scan measurements. The composition of the samples was (78 − x) TeO2 + 4.5 Bi2O3 + 5.5 ZnO + 10.5 Li2O + 1.5 Nb2O5 + xTm2O3 (x = 0.05, 0.1, 0.5, 1.0 and 1.5 mol%). Thermal diffusivity (D), specific heat (ρc), thermal conductivity (K) and optical path change with temperature (ds/dT) were determined as a function of Tm3+ concentration. Concerning thermal–optical properties, our results show that the 0.5 mol% Tm doped is the most suitable sample for laser applications as it presented the lowest ds/dT and highest thermal diffusivity (conductivity). Third-order nonlinearities were observed and discussed in 1.0 and 1.5 mol% samples. The nonlinear indices (n2) found were 1.16 × 10−13 and 3.89 × 10−13 cm2 W−1, respectively. The data obtained show that the Tm3+-doped TBZLN glasses have potential for future opto-electronic devices.

ABSTRACTTelechelic hydroxylated poly(3‐hydroxybutyrate) (PHB‐diol) oligomers have been successfully synthesized in 90–95% yield from high molar mass PHB by tin‐catalyzed alcoholysis with different diols (mainly 1,4‐butanediol) in diglyme. The PHB‐diol oligomers structure was studied by nuclear magnetic resonance, Fourier transformed infrared spectroscopy MALDI‐ToF MS, and size exclusion chromatography, whereas their crystalline structures, thermal properties and thermal stability were analyzed by wide angle X‐ray scattering, DSC, and thermogravimetric analyses. The kinetic of the alcoholysis was studied and the influence of (i) the catalyst amount, (ii) the diol amount, (iii) the reaction temperature, and (iv) the diol chain length on the molar mass was discussed. The influence of the PHB‐diol molar mass on the thermal stability, the thermal properties and optical properties was investigated. Then, tin‐catalyzed poly(ester‐ether‐urethane)s (PEEU) of Mn = 15,000–20,000 g/mol were synthesized in 1,2‐dichloroethane from PHB‐diol oligomers (Pester) with modified 4,4'‐MDI and different polyether‐diols (Pether) (PEG‐2000, PEG‐4000, and PPG‐PEG‐PPG). The influence of the PHB‐diol chain length, the Pether/Pester ratio, the polyether segment nature and the PEG chain length on the thermal properties and crystalline structures of PEEUs was particularly discussed. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2017, 55, 1949–1961