- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Systematic microstructural development with thermal diffusivity behaviour from nanometric to micronic grains of strontium titanate
摘要： Strontium titanate is a promising candidate for applications in thermoelectric, thermal management applications, and modern electronic devices because of its desirable thermal stability, chemical stability, and semiconducting behaviour. However, the absence of its important systematic development, having grain size from several nanometric up to micronic size with evolving thermal diffusivity behaviour, triggers the need for filling up the vacuum. Two different heat treatments have been carried out onto the samples which were with presintering and without presintering. Nanometer-sized compacted powder samples were sintered from 500 to 1400 °C using 100 °C increments. The parallel characterizations of structural, microstructural and thermal diffusivity properties were systematically carried out. Interestingly, three significant value-differentiated groups: weak, moderate, and strong thermal diffusivity were observed, resulting from the influence of different phonon-scattering mechanisms through a systematic development of microstructural properties for both heat treatments.
关键词： Strontium titanate,Thermal conductivity,Thermal diffusivity,Microstructure
更新于2025-09-23 15:21:21
-
Thermal conductivity and diffusivity of triple-cation perovskite halide materials for solar cells
摘要： We report on the measurement of thermal conductivity and thermal diffusivity by a modulated thermoreflectance microscopy technique on a mixed-cation perovskite material [Cs0.05(formamidinium0.83methylammonium0.17)0.95Pb(I0.83Br0.17)3] widely applied for solution-processed perovskite solar cells. Such materials are supposed to present improved thermal stability compared to methylammonium-based single cation perovskites. Our measurements are performed on perovskite/TiO2/SnO2:F/SiO2 structures, with perovskite thicknesses ranging between 250 nm and 1000 nm. This configuration is the one of a real solar cell, with the same substrate and intermediate layers as of an operating device. We measured a thermal conductivity kper of 0.26 ± 0.03 W m?1 K?1 and a thermal diffusivity Dper of 3.5 × 10?7 ± 0.5 m2 s?1. The value for thermal conductivity is comparable to the one measured on single cation perovskites, which is generally in the 0.2–0.6 range. The value for thermal diffusivity has not been reported previously.
关键词： perovskite solar cells,thermal conductivity,modulated thermoreflectance microscopy,thermal diffusivity
更新于2025-09-23 15:21:01
-
Green Synthesis of Silver Nanoparticles Contained in Centrifuged Citrus Oil and Their Thermal Diffusivity Study by Using Thermal Lens Technique
摘要： Thermal lens spectrometry is a very sensitive non-evasive technique that offers a reliable alternative for measurement of materials thermal diffusivity. In this work, silver nanoparticles from leaf extract of Azadirachta Indica (neem) and silver nitrate were synthesized using reverse micelle microemulsion. The thermal lens technique was used to obtain the thermal diffusivity of silver nanoparticles emulsions contained in grapefruit centrifuged oil. Thermal diffusivity of silver nanoparticles was measured as a function of concentration. The results showed an increase in the thermal diffusivity of the nanoemulsion with the increase in nanoparticle concentration. Also, the nanoemulsion exhibited improved thermal diffusivity in comparison with the base fluid. Transmission electron microscopy was used to determine the morphology of the nanoparticles. Results showed that they were spherical in shape with an average size of 35 nm. UV–Vis spectrometry was used to observe the absorption spectra of nanoparticles plasmon. This study has future applications in dermatological therapies against allergies, in tissue regeneration and in the cosmetic area, due to silver nanoparticles antibacterial properties.
关键词： Thermal diffusivity,Nanoparticles,Colloids,Thermal lens
更新于2025-09-23 15:21:01
-
Determination of Thermal Diffusivity of Basalt Fiber Reinforced Epoxy Composite using Infrared Thermography
摘要： In recent years, there is a great demand for ecofriendly, light weight and cost effective composites. Basalt fiber is one such naturally available fiber which offers exceptional properties over glass fibers. In this study a Basalt fiber reinforced composites were fabricated by vacuum bagging technique. Thermal properties of these composites were determined using infrared thermography. In-depth and in-plane thermal diffusivity are determined by using pulse thermography and space resolve method respectively. The in-plane thermal diffusivity was determined in the transmission and reflection modes. In-depth thermal diffusivity is validated using a Light flash method.
关键词： Infrared thermography,Non-Destructive Testing,thermal diffusivity,Basalt fiber reinforced composites,space resolved method
更新于2025-09-23 15:21:01
-
Design of Thermophysical Properties Test System by Laser Point Heat Source Method
摘要： Laser is widely used in material thermophysical properties testing because of its good test accuracy and test efficiency. However, due to the high market price of laser flash devices, their promotion space is limited. Based on the unsteady heat transfer model of a laser point heat source, the enantiomorphous heat source theory was introduced to modify the influence of an adiabatic boundary on the temperature rise of a measuring point. The thermal conductivity and thermal diffusivity of isotropic materials were calculated by numerical analysis combined with computer programming. A thermophysical property test system was developed, and the thermophysical properties of blast furnace firebrick, marble, and diatomite brick were studied. The results showed that the maximum repeatable accuracy error was 4.75%, and the maximum relative deviation from the reference value was 2.04%. The effective test range of the device was that the thermal conductivity was less than 3 W∕(m ? K). Compared with the laser flash method, the device does not require high test-time accuracy and data collection instantaneity in terms of test principles. Therefore, the device can use a general-level laser generator, temperature sensor, timer, data collector, and so on, and the hardware cost is greatly reduced.
关键词： thermophysical properties,thermal diffusivity,test system,thermal conductivity,laser point heat source
更新于2025-09-23 15:19:57
-
Thermophysical Properties of Silicon-Carbide-Based Ceramic Composite Materials Obtained by Spark Plasma Sintering (SPS)
摘要： The factors influencing the thermal conductivity of SiC-based ceramic composite materials obtained by the spark plasma sintering technology with relative density 99% and B4C, AlN, Si3N4, Y2O3, Al2O3, and HfB2 as additives are examined. The thermophysical properties were determined in the temperature range 20 – 1300°C: specific heat, thermal diffusivity, and thermal conductivity of composites. The thermal diffusivity and specific heat were measured by the laser-spark method. The measurements of specific heat are supplemented by measurements performed with a DSC and adiabatic calorimeter. The thermal conductivity is calculated using data on the thermal diffusivity, specific heat, and density.
关键词： laser flash method,specific heat,adiabatic calorimeter,thermal conductivity,ceramic composite materials,thermal diffusivity,thermophysical properties,differential scanning calorimetry (DSC)
更新于2025-09-19 17:15:36
-
In-Situ Testing of the Thermal Diffusivity of Polysilicon Thin Films
摘要： This paper presents an intuitive yet effective in-situ thermal diffusivity testing structure and testing method. The structure consists of two doubly clamped beams with the same width and thickness but different lengths. When the electric current is applied through two terminals of one beam, the beam serves as thermal resistor and the resistance R(t) varies as temperature rises. A delicate thermodynamic model considering thermal convection, thermal radiation, and film-to-substrate heat conduction was established for the testing structure. The presented in-situ thermal diffusivity testing structure can be fabricated by various commonly used micro electro mechanical systems (MEMS) fabrication methods, i.e., it requires no extra customized processes yet provides electrical input and output interfaces for in-situ testing. Meanwhile, the testing environment and equipment had no stringent restriction, measurements were carried out at normal temperatures and pressures, and the results are relatively accurate.
关键词： in-situ testing,thermal diffusivity,process control monitoring (PCM),thin film
更新于2025-09-19 17:15:36
-
Measuring the in-plane thermal diffusivity of moving samples using laser spot lock-in thermography
摘要： In this work we deal with samples that move at constant speed and are illuminated by a modulated and focused laser beam. We have obtained a general expression for the surface temperature of these moving samples: it is valid not only for opaque and thermally thick materials, but also for thermally thin and semitransparent samples. Moreover, heat losses by convection and radiation are taken into account in the model. Numerical calculations indicate that the temperature (amplitude and phase) profiles in the directions parallel and perpendicular to the sample motion are straight lines with respect to the distance to the laser spot. The slopes of these straight lines depend on sample speed, modulation frequency and in-plane thermal diffusivity of the sample. Provided the two first experimental parameters are known, the in-plane thermal diffusivity can be retrieved in a simple manner. Measurements performed on materials covering a wide range of thermal diffusivity values, from insulators to good thermal conductors, confirm the validity of these linear methods.
关键词： Infrared thermography,Lock-in thermography,Photothermal techniques,Thermal diffusivity
更新于2025-09-19 17:13:59
-
Improving Thermal Diffusivity Measurements by Including Detector Inherent Delayed Response in Laser Flash Method
摘要： Laser flash experiments are a widely used to determine thermal diffusivity of matter. Especially for thin samples or high diffusive materials, the laser pulse-time delay and its shape may become crucial for precise measurements (“finite pulse-time effect”). An additional delayed response and modification of the shape of the signal can be caused by time delays of detectors and electronic components (e.g., electronic filters) and may be inherent to Laser Flash Apparatuses (LFA). Similar to the correction of the finite pulse-time effect, this detector system inherent delayed response needs to be taken into account, especially for thin or high diffusive materials. To correct for this additional delay, detector signals of direct laser pulses were measured and for correction of this systematic errors a transfer function is derived. It reproduces the detector signal using the pulse shape measured by a diode within the apparatus and thus takes into account the actual laser pulse shape and detector behavior. For the used experimental setup, systematic errors caused by this effect are in the same range than the often considered finite pulse-time effect. As the detector related time delay is system inherent, the developed transfer function can be used to effectively eliminate both, the finite pulse-time delay and the detector inherent delayed response. Besides experimental determinations, synthetic temperature response data are used to quantify the systematic errors related to the additional detector inherent retardation for various thermal diffusivities and sample thicknesses. By not taking the additional delay into account systematic errors > 10 % may arise for both, high and low temperature detectors, indium antimonide (InSb) and MCT (HgCdTe), respectively.
关键词： Uncertainty,Thermal diffusivity,Finite pulse-time effect,Laser flash method
更新于2025-09-19 17:13:59
-
Enhanced thermal diffusivity of water in the presence of iron oxide nanoparticles: a laser induced thermal lens measurement
摘要： Iron oxide nanoparticles are prepared using co-precipitation method and its thermal diffusivity as a function of concentration in distilled water is measured using laser induced thermal lens technique. The morphology, distribution and particle size are determined using SEM measurements. The elemental composition and optical properties of the sample are obtained from EDAX and UV–visible absorption spectra. It is found that the thermal diffusivity of the nanoparticle solution is larger than that of pure water at low concentrations but it is decreasing with increase in concentration of the nanoparticles. Variation of electrical conductivity and magnetic susceptibility of the same sample are also studied.
关键词： thermal lens,iron oxide nanoparticles,thermal diffusivity
更新于2025-09-16 10:30:52