Crystallization Characteristics of Ge-Sb Phase Change Materials

2009 ◽  
Vol 1160 ◽  
Author(s):  
Simone Raoux ◽  
Cyril Cabral ◽  
Lia Krusin-Elbaum ◽  
Jean L. Jordan-Sweet ◽  
Martin Salinga ◽  
...  
Keyword(s):  
Phase Change ◽  
Phase Change Materials ◽  
Mass Density ◽  
Large Change ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Time Resolved ◽  
X Ray ◽  
Diffraction Peaks ◽  
Low X

AbstractThe crystallization behavior of Ge-Sb phase change materials with variable Ge:Sb ratio X between 0.079 and 4.3 was studied using time-resolved x-ray diffraction, differential scanning calorimetry, x-ray reflectivity, optical reflectivity and resistivity vs. temperature measurements. It was found that the crystallization temperature increases with Ge content from about 130 °C for X = 0.079 to about 450 °C for X = 4.3. For low X, Sb x-ray diffraction peaks occurred during a heating ramp at lower temperature than Ge diffraction peaks. For X = 1.44 and higher, Sb and Ge peaks occurred at the same temperature. Mass density change upon crystallization and optical and electrical contrast between the phases show a maximum for the eutectic alloy with X = 0.17. The large change in materials properties with composition allows tailoring of the crystallization properties for specific application requirements.

Phase transitions in Ge–Te phase change materials studied by time-resolved x-ray diffraction

2009 ◽  
Vol 95 (14) ◽  
pp. 143118 ◽  
Author(s):  
Simone Raoux ◽  
Becky Muñoz ◽  
Huai-Yu Cheng ◽  
Jean L. Jordan-Sweet
Keyword(s):  
Phase Transitions ◽  
Phase Change ◽  
Phase Change Materials ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray

Use of Differential Scanning Calorimetry and X-Ray Diffraction as Experimental Tools to Understand How Nucleating Agent Concentration Affects Supercooling in Microencapsulated Phase Change Materials

2005 ◽  
Author(s):  
Jorge L. Alvarado ◽  
Charles Marsh ◽  
Chang Sohn ◽  
Ty Newell ◽  
Jasmeet Singh Johar
Keyword(s):  
Differential Scanning Calorimetry ◽  
Phase Change ◽  
Phase Change Materials ◽  
Nucleating Agent ◽  
Experimental Results ◽  
Experimental Techniques ◽  
Heat Of Fusion ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray

In this paper, a description and explanation of the experimental techniques used to understand and quantify supercooling will be presented, including differential scanning calorimetry and x-ray diffraction. Differential scanning calorimetry experimental results indicate that supercooling in microencapsulated n-Tetradecane can be suppressed significantly when 4% to 6% of a homologous material is used as nucleating agent. X-ray diffraction experimental results elucidate how nucleating agent concentration affects the morphology of the phase change material after solidification. Both experimental techniques in unison prove to be valuable experimental tools and provide a better understanding of how inclusion of nucleating agents affects the solidification process. Quantitative characterization of microencapsulated n-Tetradecane thermal properties is also presented including latent heat of fusion and melting point data.

Polyamide as a Matrix for the Creation of Form-Stable Phase Change Materials

2009 ◽  
Vol 610-613 ◽  
pp. 414-418 ◽  
Author(s):  
Jing Guo ◽  
Nan Li
Keyword(s):  
Block Copolymer ◽  
Phase Change ◽  
Phase Change Materials ◽  
Polyamide 6 ◽  
Stable Phase ◽  
X Ray Diffraction ◽  
Thermal Reliability ◽  
Scanning Calorimetry ◽  
X Ray

Phase change materials (PCMs) with storing and releasing energy properties have been widely used in lots of fields such as solar energy storing, smart housing, thermo-regulated fibers, and agricultural greenhouse. Here, PCMs based on polyamide 6 (PA6) blended with Polyethylene glycol (PEG) was studied. In order to improve the compatibility between PA6 and PEG, a PA6-PEG block copolymer was synthesized and added to the blends. The structure and properties of the block copolymer were determined by Fourier Transform Infrared (FTIR), differential scanning calorimetry (DSC), X-ray diffraction (XRD) and optics microscope (OM). The results of DSC analysis showed that tThe copolymer block is phase separated. DSC results also showed that the phase transition temperature of the blend is different from that of pure PEG, indicating the interaction occurrence between PEG and PA6 by using PA6-PEG block copolymer, the latent heat of PEG/PA6 blend increased with the mass percent of PEG. The results of tThermal cycling tests showed that the blend as a PCM has good long-term thermal reliability.

scholarly journals pH-controlled synthesis of sustainable lauric acid/SiO2 phase change material for scalable thermal energy storage

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Shafiq Ishak ◽  
Soumen Mandal ◽  
Han-Seung Lee ◽  
Jitendra Kumar Singh
Keyword(s):  
Electron Microscopy ◽  
Phase Change ◽  
Lauric Acid ◽  
Photoelectron Spectroscopy ◽  
Phase Change Materials ◽  
Precursor Solution ◽  
Thermal Reliability ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Heating And Cooling

AbstractLauric acid (LA) has been recommended as economic, eco-friendly, and commercially viable materials to be used as phase change materials (PCMs). Nevertheless, there is lack of optimized parameters to produce microencapsulated PCMs with good performance. In this study, different amounts of LA have been chosen as core materials while tetraethyl orthosilicate (TEOS) as the precursor solution to form silicon dioxide (SiO2) shell. The pH of precursor solution was kept at 2.5 for all composition of microencapsulated LA. The synthesized microencapsulated LA/SiO2 has been characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), X-Ray photoelectron spectroscopy (XPS), Scanning electron microscopy (SEM), and Transmission electron microscopy (TEM). The SEM and TEM confirm the microencapsulation of LA with SiO2. Thermogravimetric analysis (TGA) revealed better thermal stability of microencapsulated LA/SiO2 compared to pure LA. PCM with 50% LA i.e. LAPC-6 exhibited the highest encapsulation efficiency (96.50%) and encapsulation ratio (96.15%) through Differential scanning calorimetry (DSC) as well as good thermal reliability even after 30th cycle of heating and cooling process.

Synthesis and Properties of Thermotropic Liquid Crystalline Polyesters with Flexible Polymethylene Spacer

2010 ◽  
Vol 428-429 ◽  
pp. 126-131
Author(s):  
Wei Zhong Lu ◽  
Chun Wei ◽  
Qui Shan Gao
Keyword(s):  
Optical Microscopy ◽  
Liquid Crystalline ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
X Ray ◽  
Structure Morphology ◽  
Temperature Ranges ◽  
Ft Ir ◽  
Diffraction Peaks ◽  
Ubbelohde Viscometer

Polymethylene bis(p-hydroxybenzoates) were prepared from methyl p-hydroxybenzoate and different diols by melted transesterification reaction. Three liquid crystalline polyesters were synthesized from terephthaloyl dichloride and polymethylene bis(p-hydroxybenzoates). Its structure, morphology and properties were characterized by Ubbelohde viscometer, Fourier transform infrared spectroscopy (FT-IR), Differential scanning calorimetry (DSC), polarized optical microscopy (POM) with a hot stage, and wide-angle X-ray diffraction (WAXD). Results indicated that the intrinsic viscosities were between 0.088 and 0.210 dL/g. Optical microscopy showed that the TLCP has a highly threaded liquid crystalline texture and a high birefringent schlieren texture character of nematic phase and has wider mesophase temperature ranges for all polyesters. DSC analysis were found that the melting point (Tm), isotropic temperature (Ti) of TLCPs decreased and the temperature range of the liquid crystalline phase became wider with increased number of methylene spacers in the polyester. The WAXD results showed that TLCPs owned two strong diffraction peaks at 2θ near 19° and 23°.

scholarly journals Copper microsphere hybrid mesoporous carbon as matrix for preparation of shape-stabilized phase change materials with improved thermal properties

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Yi Liu ◽  
Yan Chen ◽  
Junwei Zhang ◽  
Junkai Gao ◽  
Zhi Han
Keyword(s):  
Thermal Properties ◽  
Phase Change ◽  
Photoelectron Spectroscopy ◽  
Mesoporous Carbon ◽  
Phase Change Materials ◽  
Copper Ions ◽  
Thermal Constant ◽  
Step Method ◽  
Scanning Calorimetry ◽  
X Ray

Abstract Copper microsphere hybrid mesoporous carbon (MPC-Cu) was synthesized by the pyrolysis of polydopamine microspheres doped with copper ions that were prepared using a novel, facile and simple one-step method of dopamine biomimetic polymerization and copper ion adsorption. The resulting MPC-Cu was then used as a supporter for polyethylene glycol (PEG) to synthesize shape-stabilized phase change materials (PEG/MPC-Cu) with enhanced thermal properties. PEG/MPC-Cu was studied by scanning electron microscopy, X-ray diffraction, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, thermogravimetric analysis, differential scanning calorimetry and thermal constant analysis. The results demonstrated that the thermal conductivity of PEG/MPC-Cu was 0.502 W/(m K), which increased by 100% compared to pure PEG [0.251 W/(m K)]. The melting enthalpy of PEG/MPC-Cu was 95.98 J/g, indicating that PEG/MPC-Cu is a promising candidate for future thermal energy storage applications. In addition, the characterization results suggested that PEG-MPC-Cu possessed high thermal stability. Therefore, the method developed in this paper for preparing shape-stabilized phase change materials with improved thermal properties has substantial engineering application prospects.

Crystallization Characteristics Of Phase Change Nanoparticle Arrays Fabricated By Self-Assembly Based Lithography

2008 ◽  
Vol 1072 ◽  
Author(s):  
Yuan Zhang ◽  
Simone Raoux ◽  
Daniel Krebs ◽  
Leslie E. Krupp ◽  
Teya Topuria ◽  
...  
Keyword(s):  
Phase Change ◽  
Self Assembly ◽  
Crystallization Behavior ◽  
Small Scale ◽  
Nanoparticle Arrays ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Nanodot Arrays ◽  
Patterned Materials

ABSTRACTPhase change nanodot arrays were fabricated using self-assembly diblock copolymer template PS-b-PMMA (polystyrene-poly (methyl-methacrylate)) and studied by time resolved X-ray diffraction. The size of the nanodots was less than 15nm in diameter with 40nm spacing. This method is quite flexible regarding the patterned materials, and can be used on different substrates. The crystallization behavior of small scale phase change nanodot arrays was studied for different materials, such as Ge15Sb85, Ge2Sb2Te5 and Ag and In doped Sb2Te. It was found that the nanodots had higher crystallization temperatures compared to their corresponding blanket films and crystallized over a broader temperature range.

A time-resolved diffraction study of the Ta–C solid combustion system

1993 ◽  
Vol 8 (7) ◽  
pp. 1533-1541 ◽  
Author(s):  
E.M. Larson ◽  
Joe Wong ◽  
J.B. Holt ◽  
P.A. Waide ◽  
G. Nutt ◽  
...  
Keyword(s):  
Combustion Synthesis ◽  
Carbon Diffusion ◽  
Time Frame ◽  
Combustion System ◽  
X Ray Diffraction ◽  
Time Resolved ◽  
X Ray ◽  
Reaction Proceeds ◽  
Diffraction Peaks ◽  
Product Powder

The formation of TaC and Ta2C by combustion synthesis from their elemental constituents has been studied by time-resolved x-ray diffraction (TRXRD) using synchrotron radiation. The reactions have been followed with a time resolution down to 50 ms. Since the adiabatic temperatures for both reactions are well below any liquidus temperature in the Ta—C phase diagram, no melting occurs and these combustion reactions occur purely in the solid state. The phase transformations associated with these reactions are followed by monitoring the disappearance of reactant and appearance of product powder diffraction peaks in real time as the reaction front propagates through the combusting specimen. In the synthesis of TaC, the results show the formation of the subcarbide (Ta2C phase as an intermediate. In the synthesis of Ta2C, the reaction proceeds directly to the product with no discernible intermediate Ta–C phase within a 50 ms time frame. The chemical dynamics associated with the combustion synthesis of TaC may be described by an initial phase transformation to hexagonal Ta2C arising from carbon diffusion into the Ta metal lattice. As more carbon is available this intermediate subcarbide phase, which has one-half of its octahedral interstices occupied by the carbon, further transforms to the cubic TaC final product, in which all octahedral sites are now occupied. The time-resolved data indicate that the rate of formation of Ta2C is a factor of two faster than that of TaC.

scholarly journals Granulation Of Porous Materials with Phase Change Material (PCM)

2021 ◽  
Vol 20 (3) ◽  
pp. 135-144
Author(s):  
Tomasz Bien
Keyword(s):  
Mechanical Strength ◽  
Phase Change ◽  
Construction Industry ◽  
Phase Change Materials ◽  
Nitrogen Adsorption ◽  
X Ray Diffraction ◽  
Scanning Calorimetry ◽  
Method Of Production ◽  
Adsorption Desorption ◽  
Change Material

The paper describes the research on the method of production of granulated phase-change materials (PCM) used in construction industry for the accumulation of thermal energy. As mineral materials for the granules preparation zeolite from fly ash Na-P1 and natural diatomite dust were used which were impregnated with paraffinic filtration waste and granulated using a combined granulation method. Obtained granules were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), nitrogen adsorption/desorption isotherm, and differential scanning calorimetry (DSC). Mechanical strength of the materials was determined in a “drop strength” test. Performed analyses revealed that mineral composition and micromorphology of the diatomite and zeolite granules were varied, with zeolite granules having higher mechanical strength.

scholarly journals Blends of Carbohydrate Polymers for the Co-Microencapsulation of Bacillus clausii and Quercetin as Active Ingredients of a Functional Food

Polymers ◽  
2022 ◽  
Vol 14 (2) ◽  
pp. 236
Author(s):  
María Z. Saavedra-Leos ◽  
Manuel Román-Aguirre ◽  
Alberto Toxqui-Terán ◽  
Vicente Espinosa-Solís ◽  
Avelina Franco-Vega ◽  
...  
Keyword(s):  
Functional Food ◽  
Spherical Particles ◽  
X Ray Diffraction ◽  
Active Ingredients ◽  
Scanning Calorimetry ◽  
Modulated Differential Scanning Calorimetry ◽  
X Ray ◽  
Carbohydrate Polymers ◽  
Bacillus Clausii ◽  
Diffraction Peaks

A functional food based on blends of carbohydrate polymers and active ingredients was prepared by spray drying. Inulin (IN) and maltodextrin (MX) were used as carrying agents to co-microencapsulate quercetin as an antioxidant and Bacillus clausii (Bc) as a probiotic. Through a reduced design of experiments, eleven runs were conducted and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), and modulated differential scanning calorimetry (MDSC). The physical characterizations showed fine and non-aggregated powders, composed of pseudo-spherical particles with micrometric sizes. The observation of rod-like particles suggested that microorganisms were microencapsulated in these particles. The microstructure of the powders was amorphous, observing diffraction peaks attributed to the crystallization of the antioxidant. The glass transition temperature (Tg) of the blends was above the room temperature, which may promote a higher stability during storage. The antioxidant activity (AA) values increased for the IN-MX blends, while the viability of the microorganisms increased with the addition of MX. By a surface response plot (SRP) the yield showed a major dependency with the drying temperature and then with the concentration of IN. The work contributes to the use of carbohydrate polymers blends, and to the co-microencapsulation of active ingredients.

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