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Thermal expansion

About: Thermal expansion is a research topic. Over the lifetime, 21040 publications have been published within this topic receiving 349407 citations. The topic is also known as: heat expansion.


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Journal ArticleDOI
TL;DR: Arising from the strain-released interface and condensed perovskite lattice, the best device achieves an efficiency of 10.65% with an ultrahigh open-circuit voltage of 1.70 V and significantly improved stability under persistent light irradiation and humidity attack over 120 days.
Abstract: Perovskite lattice distortion induced by residual tensile strain from the thermal expansion mismatch between the electron-transporting layer (ETL) and perovskite film causes a sluggish charge extraction and transfer dynamics in all-inorganic CsPbBr3 perovskite solar cells (PSCs) because of their higher crystallization temperatures and thermal expansion coefficients. Herein, the interfacial strain is released by fabricating a WS2 /CsPbBr3 van der Waals heterostructure owing to their matched crystal lattice structure and the atomically smooth dangling bond-free surface to act as a lubricant between ETL and CsPbBr3 perovskite. Arising from the strain-released interface and condensed perovskite lattice, the best device achieves an efficiency of 10.65 % with an ultrahigh open-circuit voltage of 1.70 V and significantly improved stability under persistent light irradiation and humidity (80 %) attack over 120 days.

132 citations

Journal ArticleDOI
TL;DR: In this paper, the effect of temperature on the thermal properties of different types of high-strength concrete (HSC) and self-consolidating concrete (SCC) was investigated.
Abstract: The knowledge of high temperature thermal properties is critical for evaluating the fire response of concrete structures. This paper presents the effect of temperature on the thermal properties of different types of high-strength concrete (HSC). Specific heat, thermal conductivity, and thermal expansion are measured for three concrete types, namely, HSC, self-consolidating concrete (SCC), and fly ash concrete (FAC), in the temperature range from 20–800°C. The effect of steel, polypropylene, and hybrid fibers on thermal properties of HSC and SCC is also investigated. Results from experiments show that SCC possesses higher thermal conductivity, specific heat, and thermal expansion than HSC and FAC in the 20–800°C temperature range. Data generated from tests is utilized to develop simplified relationships for expressing different thermal properties as a function of temperature. The proposed thermal property relationships can be used as input data for evaluating the response of concrete structures under fire conditions.

132 citations

Journal ArticleDOI
TL;DR: In this paper, the anharmonic properties of γ-(Mg, Fe)2SiO4 may be very close to those of MgAl2O4.
Abstract: Thermal expansion of γ-Mg2SiO4 was measured with X-ray powder diffraction method up to 750°C at atmospheric pressure. The data are analyzed in terms of Gruneisen's theory of thermal expansion and Gruneisen's parameter is obtained to be 1.27. Volume thermal expansion coefficient is 19 at 20°C and 27 at 500°C in unit of 10-6/K. These values are compared with those of γ-Fe2SiO4, MgAl2O4 and other spinel type compounds, and it is suggested that the anharmonic properties of γ-(Mg, Fe)2SiO4 may be very close to those of MgAl2O4.

132 citations

Journal ArticleDOI
TL;DR: In this article, optically transparent crystals of CdSiP 2 (CSP) have been grown for the first time from a stoichiometric melt using the horizontal gradient freeze (HGF) technique in high-temperature transparent furnaces.

132 citations

Journal ArticleDOI
TL;DR: Three Mg-formate frameworks, incorporating three different ammoniums, display structural phase transitions accompanied by prominent dielectric anomalies and anisotropic and negative thermal expansion, and the materials are all found to be thermally stable up to 470 K.
Abstract: We present three Mg-formate frameworks, incorporating three different ammoniums: [NH4][Mg(HCOO)3] (1), [CH3CH2NH3][Mg(HCOO)3] (2) and [NH3(CH2)4NH3][Mg2(HCOO)6] (3). They display structural phase transitions accompanied by prominent dielectric anomalies and anisotropic and negative thermal expansion. The temperature-dependent structures, covering the whole temperature region in which the phase transitions occur, reveal detailed structural changes, and structure-property relationships are established. Compound 1 is a chiral Mg-formate framework with the NH4(+) cations located in the channels. Above 255 K, the NH4(+) cation vibrates quickly between two positions of shallow energy minima. Below 255 K, the cations undergo two steps of freezing of their vibrations, caused by the different inner profiles of the channels, producing non-compensated antipolarization. These lead to significant negative thermal expansion and a relaxor-like dielectric response. In perovskite 2, the orthorhombic phase below 374 K possesses ordered CH3CH2NH3(+) cations in the cubic cavities of the Mg-formate framework. Above 374 K, the structure becomes trigonal, with trigonally disordered cations, and above 426 K, another phase transition occurs and the cation changes to a two-fold disordered state. The two transitions are accompanied by prominent dielectric anomalies and negative and positive thermal expansion, contributing to the large regulation of the framework coupled the order-disorder transition of CH3CH2NH3(+). For niccolite 3, the gradually enhanced flipping movement of the middle ethylene of [NH3(CH2)4NH3](2+) in the elongated framework cavity finally leads to the phase transition with a critical temperature of 412 K, and the trigonally disordered cations and relevant framework change, providing the basis for the very strong dielectric dispersion, high dielectric constant (comparable to inorganic oxides), and large negative thermal expansion. The spontaneous polarizations for the low-temperature polar phases are 1.15, 3.43 and 1.51 μC cm(-2) for 1, 2 and 3, respectively, as estimated by the shifts of the cations related to the anionic frameworks. Thermal and variable-temperature powder X-ray diffraction studies confirm the phase transitions, and the materials are all found to be thermally stable up to 470 K.

132 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023603
20221,249
2021683
2020742
2019759
2018767