Cubic NaZn13-type La(Fe1−xCox)11.4Al1.6 compounds were synthesized and extensively explored through crystal structure and magnetization analyses. By optimizing the chemical composition, the isotropic abnormal properties of excellent zero and giant negative thermal expansion in a pure form were both found at different temperature ranges through room temperature. Moreover, the temperature regions with the remarkable abnormal thermal expansion (ATE) properties have been broadened which are controlled by the dM/dT. The present study demonstrates that the ATE behavior mainly depends on special structural and magnetic properties. These diverse properties suggest the high potential of La(Fe1−xCox)11.4Al1.6 for the development of abnormal expansion materials.

Cubic La(Fe,Si)13-based compounds have been recently developed as promising negative thermal expansion(NTE) materials, but the narrow NTE operation-temperature window(∼110 K) restricts their actual applications. In this work, we demonstrate that the NTE operation-temperature window of LaFe13–xSix can be significantly broadened by adjusting Fe–Fe magnetic exchange coupling as x ranges from 2.8 to 3.1. In particular, the NTE operation-temperature window of LaFe10.1Si2.9 is extended to 220 K. More attractively, the coefficients of thermal expansion of LaFe10.0Si3.0 and LaFe9.9Si3.1 are homogeneous in the NTE operation-temperature range of about 200 K, which is much valuable for the stability of fabricating devices. The further experimental characterizations combined with first-principles studies reveal that the tetragonal phase is gradually introduced into the cubic phase as the Si content increases, hence modifies the Fe–Fe interatomic distance. The reduction of the overall Fe–Fe magnetic exchange interactions contributes to the broadness of NTE operation-temperature window for LaFe13–xSix.

Recently, La(Fe,Si)13-based compounds have attracted much attention due to their isotropic and tunable abnormal thermal expansion (ATE) properties as well as bright prospects for practical applications. In this research, we have prepared cubic NaZn13-type carbon-doped La(Fe,Si)13 compounds by the arc-melting method, and their ATE and magnetic properties were investigated by means of variable-temperature X-ray diffraction, strain gauge and the physical property measurement system (PPMS). The experimental results indicate that both micro and macro negative thermal expansion (NTE) behaviors gradually weaken with the increase of interstitial carbon atoms. Moreover, the temperature region with the most remarkable NTE properties has been broadened and near zero thermal expansion (NZTE) behavior occurs in the bulk carbon-doped La(Fe,Si)13 compounds.

The cubic NaZn13-type La(Fe,Al)13 compounds were synthesized, and their linear thermal expansion properties were investigated in the temperature range of 4.2–300 K. It was found that these compounds exhibit abnormal thermal expansion behavior, i.e., pronounced negative thermal expansion (NTE) or zero thermal expansion (ZTE) behavior, below the Curie temperature due to the magnetovolume effect (MVE). Moreover, in the La(Fe,Al)13 compounds, the modification of the coefficient of thermal expansion (CTE) as well as the abnormal thermal expansion (ATE) temperature-window is achieved through optimizing the proportion of Fe and Al. Typically, the average CTE of the LaFe13−xAlx compounds with x = 1.8 reaches as large as −10.47 × 10−6 K−1 between 100 and 225 K (ΔT = 125 K). Also, the ZTE temperature-window of the LaFe13−xAlx compounds with x = 2.5 and x = 2.7 could be broadened to 245 K (from 5 to 250 K). Besides, the magnetic properties of these compounds were measured and correlated with the abnormal thermal expansion behavior. The present results highlight the potential application of such La(Fe,Al)13 compounds with abnormal thermal expansion properties in cryogenic engineering.

A zero thermal expansion material in a pure form of NaZn13-type La(Fe,Si)13 was fabricated. Through optimizing the chemical composition, an isotropic zero thermal expansion material is achieved. The obtained materials exhibit a low expansion of |α| < 1.0 × 10−6 K−1 (α is the coefficient of linear thermal expansion) over a broad temperature range (15–150 K). The present study indicates that the thermal expansion behavior of the NaZn13-type La(Fe,Si)13 compounds depends mainly on the content of Si element. This new material is desirable in many fields of industry as a reliable and low-cost zero thermal expansion material.

•Negative thermal expansion of LaFe11.2Al1.8−xSix was improved by introducing Si.•The structure of LaFe11.2Al1.8−xSix was studied by X-ray diffraction measurement.•We analyze the mechanism of NTE in LaFe11.2Al1.8−xSix by magnetic measurement.The cubic NaZn13-type LaFe11.2Al1.8−xSix(x = 0.2, 0.3, 0.4 and 0.5) compounds with different Si content were fabricated by conventional arc-melting method, the structures of which were confirmed by powder X-ray diffraction (XRD) measurement at ambient temperature. Besides, the thermal expansion and magnetic properties of these samples were also researched by means of a strain gage and a physical property measurement system (PPMS). Significantly, it was found that the negative thermal expansion (NTE) behavior have been remarkably enhanced with substituting Al with Si atoms. Furthermore, the NTE operation-temperature window concurrently shifts toward a higher temperature region. The variable temperature XRD results indicate that LaFe11.2Al1.8−xSix retain cubic NaZn13-type structure when temperature varies from 20 K to 270 K, including the temperature region where NTE occurs. The further theoretical analysis combined with magnetic characterization reveal that the improvement of NTE behavior is attributed to the enhancement of Fe–Fe magnetic exchange interactions with doping Si atoms. It is noteworthy that this study displays a new pathway to improve the NTE property of La(Fe,Al)13-based compounds at low temperature region, which highlights the potential applications of NTE materials in cryogenic engineering.

•The NTE temperature-window could be regulated through optimizing chemical composition.•NTE starting temperatures are lower than that of other La(Fe,Si)13-based compounds.•Coefficient of thermal expansion (CTE) changes slightly with the increase of Mn content.•Such optimization promotes the potential applications in cryogenic engineering.The NaZn13-type La(Fe,Si)13-based compounds with Mn doping were synthesized, and the thermal expansion and magnetic properties were investigated. Results indicate that the negative thermal expansion temperature-window shifts toward lower temperatures, which is due to the decrease of Curie temperature (Tc) by increasing the amount of Mn element, whereas the average CTE around Tc changes slightly with the increase of Mn content in the LaFe11.5−xMnxSi1.5 compounds. Such optimization of Mn element in the La(Fe,Mn,Si)13 compounds with noteworthy negative thermal expansion properties at lower temperatures promotes their potential applications for cryogenic equipment and precise instruments.

Using spark plasma sintering (SPS), Mn3Cu0.6Ge0.4N crystallites have been fabricated with different crystallite sizes, and their magnetic properties and thermal behaviors were systemically investigated. With decreasing crystallite size, the magnetic transition becomes increasingly slow, accompanied by broadening of the negative thermal expansion (NTE) operation-temperature window. The NTE operation-temperature window for the 12-nm crystallite sample reaches at 140 K, which is about 75% larger than that of the 74-nm crystallite sample. The magnetic properties and NTE operation-temperature window can be tuned by varying the crystallite size. This discovery will promote an even wider range of practical applications in precision devices.

A very rare area negative thermal expansion phenomenon is observed in a newly discovered alkali beryllium borate LiBeBO3, which is characterized by [BeBO3]∞ double layers intraconnected by edge-sharing BeO4 tetrahedra. This unusual thermal behavior is attributed to the combined vibrational effects of the abnormal Be–O structures and Li+ cations.

Experiments have been performed to enhance negative thermal expansion (NTE) in the La(Fe,Co,Si)13-based compounds by optimizing the chemical composition, i.e., proper substitution of La by magnetic element Pr. It is found that increasing the absolute value of the average coefficient of thermal expansion (CTE) in the NTE temperature region (200–300 K) attributes to enhancement of the spontaneous magnetization and its growth rate with increasing Pr content. Typically, the average CTE of La1–xPrxFe10.7Co0.8Si1.5 with x = 0.5 reaches as large as −38.5 × 10–6 K–1 between 200 and 300 K (ΔT = 100 K), which is 18.5% larger than that of x = 0. The present results highlight the potential applications of La(Fe,Co,Si)13-based compounds with a larger NTE coefficient.

•The crystallite size could be tailored through adjusting the sintering temperature.•Decreasing crystallite size will broad NTE operation temperature window (ΔT).•ΔT is much larger than that of other Mn3ZnN-based material by solid-state reaction.•This material with large ΔT around room temperature is more useful for applications.Anti-perovskite manganese nitrides Mn3Zn0.6Ge0.4N with different crystallite size were prepared by spark plasma sintering (SPS) at different sintering temperatures. Their negative thermal expansion (NTE) properties were investigated. It was found that the width of NTE operation-temperature window (ΔT) broadens with decreasing crystallite size. Typically, a broad ΔT of 105 K was obtained in the compound Mn3Zn0.6Ge0.4N with average crystallite size of 54 nm sintered at 700 °C, of which the average linear thermal expansion coefficient was estimated to be −13.5 × 10−6 K−1 in the NTE operation-temperature window. This antiperovskite manganese nitride Mn3Zn0.6Ge0.4N with broadened ΔT around room temperature is more useful for practical applications.

•The sample sintered at 650 °C shows a near ZTE behavior from 220 K to170 K.•The temperature regions of NTE can be tailored by varying the sintering temperature.•ΔT is much larger than that of other Mn3CuN-based material by solid-state reaction.•This material with ZTE behavior is desirable for cryogenic application.Antiperovskite manganese nitride Mn3Cu0.6Ge0.4N was fabricated by spark plasma sintering (SPS) at different temperatures and its negative thermal expansion behavior was investigated. It is observed that the width of negative thermal expansion (NTE) operation-temperature window becomes broader when the sintering temperature decreases. Moreover, it is significantly larger than that of other Mn3CuN-based antiperovskite manganese nitrides prepared by solid-state reaction. More interestingly, the Mn3Cu0.6Ge0.4N sintered at 650 °C shows near zero thermal expansion (ZTE) behavior in the temperature range of 220–170 K. The average linear coefficient of thermal expansion (CTE) is estimated to be −0.9 × 10−6 K−1. Magnetic measurement shows that the process of the magnetic transition becomes slow when the sintering temperature decreases. This antiperovskite manganese nitride Mn3Cu0.6Ge0.4N with ZTE behavior is much useful for applications in the fields of cryogenics and applied superconductivity.

•The PAA film was deposited on MWCNTs by using a plasma approach.•The film was uniform and the thickness was estimated about 3 nm.•The modified MWCNTs composites showed greater improvement on impact strength.•The dispersion and interfical bonding of MWCNTs in composites were improved.The ultrathin acrylic acid polymer film was deposited on multi-wall carbon nanotubes (MWCNTs) by using a plasma polymerization approach. MWCNTs reinforced cyanate ester/epoxy nanocomposites were prepared and the mechanical properties of nanocomposites were studied. The transmission electron microscopy (TEM) results showed that the film was uniformly deposited on the surface of MWCNTs. The functional groups on the surface of MWCNTs were confirmed by X-ray photoelectron spectroscopy (XPS). Moreover, it is observed that the functionalized MWCNTs reinforced epoxy/cyanate ester based nanocomposites demonstrated improved impact strength than that of as-received MWCNTs filled nanocomposites. This has been attributed to the enhanced dispersion of MWCNTs and the enhanced interfacial bonding between the functionalized MWCNTs and matrix.

Boron-free glass fiber reinforced isopropylidenebisphenol bis[(2-glycidyloxy-3-n-butoxy)-1-propylether]/triglycidyl-p-aminophenol (IPBE/TGPAP) epoxy matrix composite cured by diethyl toluene diamine (DETD) was prepared by vacuum press impregnation (VPI). The thermal behaviors of the composite, such as thermal expansion coefficient and thermal conductivity, between room temperature (RT) and liquid nitrogen temperature (77 K) were investigated before and after 1 MGy of 60Co γ-ray radiation. In addition, thermogravimetric analysis and Fourier transform infra-red spectroscopy were used to evaluate thermal stability and chemical structural changes of epoxy matrix. Results revealed that the thermal properties of the composites and the chemical structure of epoxy resin matrix was not affected by the γ-ray radiation with a dose of 1MGy.Highlights► Boron-free glass fiber reinforced composite was prepared by VPI process. ► The thermal expansion coefficient of the composite was investigated. ► The thermal conductivity of the composite was investigated.

Anti-perovskite manganese nitrides Mn3Cu0.6AgxSn0.4−xN (x = 0–0.3) were synthesized by mechanical ball milling followed by solid state sintering. Their negative thermal expansion (NTE) coefficient and electrical resistivity were investigated in the temperature range of 80–300 K. It is found that the transition temperature of NTE gradually moves toward lower temperature and the NTE operation-temperature window (ΔT) becomes narrower with increasing Ag content within the testing temperature ranges. Interestingly, though the electrical resistivity of the samples shows a metallic behavior, the variation of electrical resistivity appears to be nearly independent of temperature above the transition temperature of NTE. The present discovery highlights the potential application of NTE materials in cryogenic engineering.Highlights► Ag and Sn-doped anti-perovskite manganese nitrides were successfully obtained. ► All samples show NTE behavior within the testing temperature ranges. ► The operation-temperature window of NTE was affected by the ratio of Ag/Sn. ► The resistivity appears to be independent of temperature at elevated temperature.

The cubic NaZn13-type La(Fe,Al)13 compounds were synthesized, and their linear thermal expansion properties were investigated in the temperature range of 4.2–300 K. It was found that these compounds exhibit abnormal thermal expansion behavior, i.e., pronounced negative thermal expansion (NTE) or zero thermal expansion (ZTE) behavior, below the Curie temperature due to the magnetovolume effect (MVE). Moreover, in the La(Fe,Al)13 compounds, the modification of the coefficient of thermal expansion (CTE) as well as the abnormal thermal expansion (ATE) temperature-window is achieved through optimizing the proportion of Fe and Al. Typically, the average CTE of the LaFe13−xAlx compounds with x = 1.8 reaches as large as −10.47 × 10−6 K−1 between 100 and 225 K (ΔT = 125 K). Also, the ZTE temperature-window of the LaFe13−xAlx compounds with x = 2.5 and x = 2.7 could be broadened to 245 K (from 5 to 250 K). Besides, the magnetic properties of these compounds were measured and correlated with the abnormal thermal expansion behavior. The present results highlight the potential application of such La(Fe,Al)13 compounds with abnormal thermal expansion properties in cryogenic engineering.

A zero thermal expansion material in a pure form of NaZn13-type La(Fe,Si)13 was fabricated. Through optimizing the chemical composition, an isotropic zero thermal expansion material is achieved. The obtained materials exhibit a low expansion of |α| < 1.0 × 10−6 K−1 (α is the coefficient of linear thermal expansion) over a broad temperature range (15–150 K). The present study indicates that the thermal expansion behavior of the NaZn13-type La(Fe,Si)13 compounds depends mainly on the content of Si element. This new material is desirable in many fields of industry as a reliable and low-cost zero thermal expansion material.

Cubic NaZn13-type La(Fe1−xCox)11.4Al1.6 compounds were synthesized and extensively explored through crystal structure and magnetization analyses. By optimizing the chemical composition, the isotropic abnormal properties of excellent zero and giant negative thermal expansion in a pure form were both found at different temperature ranges through room temperature. Moreover, the temperature regions with the remarkable abnormal thermal expansion (ATE) properties have been broadened which are controlled by the dM/dT. The present study demonstrates that the ATE behavior mainly depends on special structural and magnetic properties. These diverse properties suggest the high potential of La(Fe1−xCox)11.4Al1.6 for the development of abnormal expansion materials.

Recently, La(Fe,Si)13-based compounds have attracted much attention due to their isotropic and tunable abnormal thermal expansion (ATE) properties as well as bright prospects for practical applications. In this research, we have prepared cubic NaZn13-type carbon-doped La(Fe,Si)13 compounds by the arc-melting method, and their ATE and magnetic properties were investigated by means of variable-temperature X-ray diffraction, strain gauge and the physical property measurement system (PPMS). The experimental results indicate that both micro and macro negative thermal expansion (NTE) behaviors gradually weaken with the increase of interstitial carbon atoms. Moreover, the temperature region with the most remarkable NTE properties has been broadened and near zero thermal expansion (NZTE) behavior occurs in the bulk carbon-doped La(Fe,Si)13 compounds.

A very rare area negative thermal expansion phenomenon is observed in a newly discovered alkali beryllium borate LiBeBO3, which is characterized by [BeBO3]∞ double layers intraconnected by edge-sharing BeO4 tetrahedra. This unusual thermal behavior is attributed to the combined vibrational effects of the abnormal Be–O structures and Li+ cations.