Intrinsic zero thermal expansion in cube cyanurate K6Cd3(C3N3O3)4

2019 ◽  
Vol 6 (9) ◽  
pp. 2291-2295 ◽  
Author(s):  
Mingjun Xia ◽  
Fei Liang ◽  
Xianghe Meng ◽  
Yonggang Wang ◽  
Zheshuai Lin
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Broad Temperature Range ◽  
The Novel ◽  
Thermal Expansion Behavior ◽  
Temperature Range ◽  
Low Thermal Expansion ◽  
Expansion Behavior

The novel cubic cyanurate K6Cd3(C3N3O3)4 exhibits zero thermal expansion behavior with a very low thermal expansion coefficient of 0.06 MK−1 in a broad temperature range from 10 to 130 K.

Preparation and Anisotropic Lattice Thermal Expansion of Hexagonal Cordierite

2017 ◽  
Vol 726 ◽  
pp. 470-477
Author(s):  
Jin Hua Zhang ◽  
Chang Ming Ke ◽  
Hong Dan Wu ◽  
Ji Shun Yu
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Least Squares Method ◽  
Rietveld Method ◽  
X Ray Diffraction ◽  
Lattice Thermal Expansion ◽  
Thermal Expansion Behavior ◽  
X Ray ◽  
Expansion Behavior

The hexagonal cordierite was synthesized by the reverse coprecipitation-calcination method and characterized by powder X-ray diffraction. The lattice thermal expansion behavior of hexagonal cordierite was investigated by high temperature X-ray diffraction in the temperature range 298-1273 K. The lattice parameters of the hexagonal cordierite at different temperature were calculated by a least squares method. The hexagonal cordierite expressed anisotropic thermal expansion behavior with the average lattice thermal expansion coefficient were 2.13×10-6 K-1 along a or b axis and-1.03×10-6 K-1 along c axis from room temperature to 1273 K. The crystal structure of hexagonal cordierite at 298 K and 1273 K were refined by Rietveld method. The thermal expansion coefficient of the height of the [MgO6]-[AlO4] polyhedral layer is-1.8×10-6 K-1. Although the six-member ring expressed the normal positive thermal expansion along arbitrary direction, the height thermal expansion coefficient of the six-member ring is just 0.6×10-6 K-1.

scholarly journals Preparation of low-permittivity K2O–B2O3–SiO2–Al2O3 composites without the addition of glass

2019 ◽  
Vol 8 (1) ◽  
pp. 459-466 ◽  
Author(s):  
Yong Shang ◽  
Chaowei Zhong ◽  
Ruonan Jia ◽  
Huajing Xiong ◽  
Hao Li ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Flexural Strength ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
The Novel ◽  
X Ray Diffraction ◽  
Promising Candidate ◽  
Low Dielectric ◽  
Low Thermal Expansion ◽  
Low Permittivity

Abstract In the field of low temperature co-fired ceramic (LTCC), it remains a challenge to design the performance of LTCC with low permittivity less than 5. Here, the K2O– B2O3–SiO2–Al2O3 composites are prepared without the preparation of prior glass. Meanwhile, the factors of the CaO content on microstructure, phase structure and properties of the composites are considered systematically. The crystal structure measured by X-ray diffraction (XRD) shows that there are quartz and alumina as the crystal phases. The results reveals that the tailoring CaO content benefits sintering densification, low dielectric loss, great mechanical properties and low thermal expansion coefficient. As CaO content increases up to 2.8 wt%, the composites sintered at 850∘C have a dielectric constant of 4.94 and tanδ of 8 × 10−4 at 1 MHz, thermal expansion coefficient (CTE) of 8.5 ppm/∘C, and flexural strength of 150 MPa. As the mass fraction of CaO increases up to 3.2 wt%, the maximum flexural strength of 173MPa is achieved. The above study provides an effective approach for preparing the novel composites as a promising candidate for LTCC applications.

Large negative thermal expansion and phase transition in (Pb1−xCax)TiO3 (0.30 ≤ x ≤ 0.45) ceramics

2005 ◽  
Vol 20 (2) ◽  
pp. 350-356 ◽  
Author(s):  
Amreesh Chandra ◽  
Dhananjai Pandey ◽  
M.D. Mathews ◽  
A.K. Tyagi
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Negative Thermal Expansion ◽  
Ferroelectric Ceramics ◽  
X Ray Diffraction ◽  
Thermal Expansion Behavior ◽  
X Ray ◽  
Expansion Behavior ◽  
Wide Range

High-temperature dilatometric studies on (Pb1−xCax)TiO3 (x = 0.35, 0.35, 0.40, 0.45) ferroelectric ceramics reveal negative thermal expansion for x ≤ 0.40. The negative thermal expansion coefficient for x = 0.30, as obtained by dilatometry and powder x-ray diffraction, were found to be −8.541 × 10−6 K−1 and −11 × 10−6 K−1, respectively, which are comparable to those of other well-known negative thermal expansion materials like ZrW2O8, NaZr2(PO4)3. Results of temperature-dependent x-ray diffraction studies are also presented to show that the large negative thermal expansion behavior for x = 0.30 persists in a very wide range of temperatures, 70–570 K. Ca2+ substitution reduces the value of the negative thermal expansion coefficient of pure PbTiO3 crystal, but it enables the preparation of strong sintered ceramic bodies. The negative thermal expansion behavior is shown to disappear above the ferroelectric Curie point and is restricted to only the tetragonal compositions of (Pb1−xCax)TiO3.

scholarly journals A New Low-Expansion Composite in Lead Iron Niobate-Lead Titanate System

1997 ◽  
Vol 20 (2) ◽  
pp. 77-90
Author(s):  
V. V.S.S. Sai Sundar ◽  
A. M. Umarji
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Lead Titanate ◽  
X Ray ◽  
Temperature Range ◽  
Low Thermal Expansion ◽  
The Individual ◽  
Sintering Condition ◽  
Iron Niobate

A composite prepared between lead titanate (PT) and lead iron niobate (PFN) exhibits low thermal expansion coefficient (α) over the temperature range 300–673K. X-ray, DTA, and dilatometric measurements have been used to identify the optimum sintering condition, retaining the individual constituent identity, to achieve overall low bulk thermal expansion. The composite, PFN0.35PT0.65sintered at 1223K for 15 min. and at 1253K for 60 min. are sufficiently dense and show an overall α of –0.3 × 10–6/K and –1.2 × 10–6/K, respectively, in the temperature range 300–673K.

Thermal expansion behavior of bulk Bi-based (2223) superconductors

1996 ◽  
Vol 11 (7) ◽  
pp. 1627-1634 ◽  
Author(s):  
A. Bellosi ◽  
G. Celotti ◽  
E. Landi ◽  
A. Tampieri
Keyword(s):  
Thermal Expansion ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Applied Pressure ◽  
Secondary Phase ◽  
Oriented Sample ◽  
Thermal Expansion Behavior ◽  
Air Atmosphere ◽  
Expansion Behavior ◽  
Reported Data

The thermal expansion coefficient of Bi-based 2223 and 2212 ceramics has been measured using dilatometric apparatus. Different typologies of bulk superconducting samples have been tested, in particular (2223) phase fully dense hot-pressed samples both parallel and perpendicular to the direction of applied pressure, pressureless sintered samples, and finally hot-pressed (2212) phase specimen, in order to gather information on the contribution of secondary phase to thermal expansion behavior. From the observed α (thermal expansion coefficient) values, accounting for the sample orientation degree, it was possible to distinguish the contributions along the basic crystallographic directions and to determine the following for (2223) phase: αa = 12.2 × 10-6 °C-1, and αc = 20.8 × 10-6 °C-1 for temperatures 200–600 °C. Theoretical α values were then calculated for the different samples and successfully compared with the measured ones. As regards (2212) phase, thermal expansion coefficient was evaluated for the oriented sample, and a value for random one extrapolated; the results are very similar to that of (2223), but lower with respect to previously reported data in air atmosphere.

Crystallization Behavior and Performance of MgO-Al2O3-SiO2 Glass-Ceramics by Sintering

2010 ◽  
Vol 92 ◽  
pp. 65-71 ◽  
Author(s):  
Pei Xin Zhang ◽  
Li Gao ◽  
Qiu Hua Yuan ◽  
Hai Lin Peng ◽  
Xiang Zhong Ren ◽  
...  
Keyword(s):  
Thermal Expansion ◽  
Flexural Strength ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Crystallization Process ◽  
Glass Ceramics ◽  
X Ray Diffraction ◽  
Low Thermal Expansion ◽  
Main Crystalline Phase ◽  
And Performance

The glass-ceramics of MgO-Al2O3-SiO2 system were prepared by sintering technology. The crystallization process of MgO-Al2O3-SiO2 glass-ceramics was investigated with X-ray diffraction (XRD), scanning electron microscopy (SEM), and other techniques; the discussion of breaking strength, thermal expansion coefficient and relevant properties at different sintering temperatures was also presented. The results show that: (1) The main crystalline phase isα-cordierite at different sintering temperatures, and the samples show high flexural strength and low thermal expansion coefficient; (2) with the increase of sintering temperature, the content of crystal phase increases, while the thermal expansion coefficient decreases evidently, the flexural strength and tightness density rise up first, then go down.

Study on Preparation of Low-Thermal Expansion Coefficient Concrete with Fly Ash

2014 ◽  
Vol 599 ◽  
pp. 89-92 ◽  
Author(s):  
Sha Ding ◽  
Zhong He Shui ◽  
Teng Pan ◽  
Wei Chen
Keyword(s):  
Thermal Expansion ◽  
Fly Ash ◽  
Pore Structure ◽  
Thermal Expansion Coefficient ◽  
Expansion Coefficient ◽  
Cement Concrete ◽  
Thermal Expansion Property ◽  
Expansion Property ◽  
Low Thermal Expansion ◽  
Addition Level

The low-thermal expansion coefficient (CTE) of cement paste and concrete are designed and prepared with fly ash in this study. The thermal expansion property and pore structure of cement/concrete are tested by Thermal Dilatometer, MIP, and SEM. The test results show that the addition of fly ash lowers the thermal expansion rate and coefficient of hardened paste. The increase of addition level is accompanied by the decrease of the thermal expansion coefficient. The introduction of fly ash could improve the pore structure of concrete, thus improve the thermal expansion property of cement concrete.

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