Negative Thermal Expansion Temperature Range Research Articles

Negative thermal expansion performance of (NaMg)xCr2-x(MoO4)3 (0≤x≤1) ceramics

Cr2Mo3O12 ceramics show negative thermal expansion (NTE) in a narrow high-temperature range due to the phase transition around 385 °C. To widen its NTE temperature range, a series of (NaMg)3+ co-doped Cr2Mo3O12 ceramics has been synthesized via a solid reaction process in this work. The effects of double cation (NaMg)3+ co-doping on the phase composition, morphology, phase transformation, and thermal expansion performance of Cr2Mo3O12 ceramics were studied using XRD, Raman, XPS, SEM, and TMA. Results indicate that double cation (NaMg)3+ can partially substitute Cr3+ in Cr2Mo3O12, which causes a phase transition from monoclinic Cr2Mo3O12 to hexagonal (NaMg)xCr2-xMo3O12. The single-phase (NaMg)xCr2-xMo3O12 ceramics with hexagonal structure is obtained when x = 0.5. (NaMg)3+ co-doping promotes the growth of grains and the density of hexagonal (NaMg)0·5Cr1·5Mo3O12 ceramics. (NaMg)3+ co-doping also successfully eliminates the temperature-induced phase transition of Cr2Mo3O12 at 385 °C. Hexagonal (NaMg)0·5Cr1·5Mo3O12 ceramics presents a better NTE with a coefficient of thermal expansion (CTE) of −3.97 × 10−6 °C−1 over a larger temperature range from 30 °C to 700 °C.

Effects of (KMn)3+ co-doping on the negative thermal expansion property of In2W3O12

At room temperature, monoclinic In2W3O12 ceramics exhibits positive thermal expansion. However, it transforms into an orthorhombic phase above 253 ℃, and then stably exhibits negative thermal expansion (NTE). In this work, to improve the NTE performance and extend the NTE temperature range of In2W3O12, the KxMnxIn2-xW3O12(0≤x≤0.5) ceramics were synthesized via the solid-state reaction method. The effects of (KMn)3+ double cation co-doping on the composition, microstructure, and thermal expansion behaviors of In2W3O12 ceramics were studied using XRD, Raman, XPS, SEM, and TMA. The results show that (KMn)3+ cations can replace In3+ in In2W3O12 ceramics. As the (KMn)3+ doping amount increases, monoclinic In2W3O12 gradually changed into monoclinic KxMnxIn2-xW3O12. Meanwhile, the grains grow up and the density of KxMnxIn2-xW3O12 ceramics was increased. Pure monoclinic KxMnxIn2-xW3O12 ceramics were prepared when x rises to 0.25 and 0.4. Among them, the thermal expansion coefficient of K0.4Mn0.4In1.6W3O12 ceramics in 100–700 ℃ is as high as -17.83×10-6 ℃-1, which was significantly improved compared to In2W3O12 ceramics. In addition, the structural phase transition of In2W3O12 ceramics around 253 ℃ was gradually eliminated and the NTE temperature range was widened. Double cation (KMn)3+ co-doping effectively improves the NTE performance of In2W3O12.

High‐Entropy Anti‐Perovskites with Enhanced Negative Thermal Expansion Behavior

AbstractThe negative thermal expansion (NTE) materials, which can act as thermal‐expansion compensators to counteract the positive thermal expansion, have great applications merit in precision engineering. However, the exploration of NTE behavior with a wide temperature range has reached its upper ceiling through traditional doping strategies due to composition limitations. In this paper, the unique sluggish characteristics and extended optimization space in empirically screened high‐entropy anti‐perovskite (HEAP) are utilized to broaden the NTE temperature range. Typically, the NTE temperature range in Mn3Cu0.2Zn0.2Ga0.2Ge0.2Mn0.2N is broadened to ΔT = 235 K (5 K ≤ T ≤ 240 K), which is two or three times wider than that of traditional low‐entropy doping systems. The neutron diffraction analysis reveals a unique sluggish characteristic in magnetic phase transition which survives in an ultra‐wide temperature range of 5 K ≤ T ≤ 350 K (ΔT = 345 K). The sluggish characteristic is further experimentally proved to come from disturbed phase transition dynamics due to distortion in atomic spacing and chemical environmental fluctuation observed by the spherical aberration‐corrected electron microscope. The demonstration provides a unique paradigm for broadening the temperature range of NTE materials through entropy engineering.

Design of zero thermal expansion and high thermal conductivity in machinable xLFCS/Cu metal matrix composites

Materials having good comprehensive performances, such as zero thermal expansion (ZTE), high thermal conductivity, and machinability are in great demand for electronics, precision instruments, and aerospace applications. However, the challenge is that very few materials meet such requirements. In this study, a multicomponent reinforcement with negative thermal expansion (NTE) is designed for metal matrix composites (MMCs) to achieve wide-temperature-range ZTE, high thermal conductivity, and certain machinability. Taking advantage of the giant NTE in La(Fe,Co,Si)13 system, its originally narrow NTE temperature range can be broadened in the multicomponent material (xLFCS). When xLFCS is used as a reinforcement in MMCs and combined with copper, the thermal expansion coefficient of the xLFCS/39.7 vol%Cu composite can be adjusted to nearly zero (−0.2 × 10−6 K−1) over a wide temperature range of 200–320 K. The thermal conductivity of this composite is 44.1 W m−1 K−1, which is about seven times that of LFCS itself. In addition, compared with other ZTE metal-based materials, the present composite has good machinability. This work reports a metal matrix composite with high thermophysical properties and proposes an easy-to-operate method for broadening the temperature range of NTE or ZTE.

Soft-mode anisotropy in the negative thermal expansion material ReO3

We use a symmetry-motivated approach to analyse neutron pair distribution function data to investigate the mechanism of negative thermal expansion (NTE) in ReO$_3$. This analysis shows that the local structure of ReO$_3$ is dominated by an in-phase octahedral tilting mode and that the octahedral units are far less flexible to scissoring type deformations than the octahedra in the related compound ScF$_3$. These results support the idea that structural flexibility is an important factor in NTE materials, allowing the phonon modes that drive a volume contraction of the lattice to occupy a greater volume in reciprocal space. The lack of flexibility in ReO$_3$ restricts the NTE-driving phonons to a smaller region of reciprocal space, limiting the magnitude and temperature range of NTE. In addition, we investigate the thermal expansion properties of the material at high temperature and do not find the reported second NTE region. Finally, we show that the local fluctuations, even at elevated temperatures, respect the symmetry and order parameter direction of the observed $P4/mbm$ high pressure phase of ReO$_3$. The result indicates that the motions associated with rigid unit modes are highly anisotropic in these systems.

Design of negative/nearly zero thermal expansion behavior over a wide temperature range by multi-phase composite

The negative thermal expansion (NTE) or nearly zero thermal expansion (NZTE) behaviors have been found in some magnetic metallic compounds with great application prospects. However, it is a big challenge for applications that the responding temperature range is not broad enough or far away from room temperature. Herein, a new method is put forward to design the wide temperature range of NTE and NZTE Behavior by NTE/NZTE multi-phase composite. In this method, the optimized volume fraction of the components achieves a concordant collaboration of multi-phase in the counteraction of NTE and positive thermal expansion (PTE) at several adjacent temperature ranges and thus the temperature range is broadened as expected. By this method, MnCuGeN-based NTE composite (290 K ≤ T ≤ 385 K, ΔT = 95 K) and MnCuZnSiGeN-based NZTE composite (200 K ≤ T ≤ 400 K, ΔT = 200 K) with excellent stability have been successfully designed and prepared. This idea will open an avenue to the multi-phase composite with designable NTE/NZTE properties, which would have important applications in aerospace and other modern industries.

Large Linear Negative Thermal Expansion in NiAs-type Magnetic Intermetallic Cr-Te-Se Compounds.

A large linear negative thermal expansion (NTE) and expanded NTE temperature range (ΔTNTE) were obtained in magnetoelastic CrTe1-xSex (0 ≤ x ≤ 0.15) compounds. For CrTe compound, its thermal expansion coefficient of volume (αV) was calculated to be -28.8 ppm K-1 with the temperature ranging from 280 to 340 K. Substituting Te with Se atoms, the NTE behavior and magnetic properties can be well manipulated. With increasing Se in CrTe1-xSex (0 ≤ x ≤ 0.15) compounds, the ΔTNTE increases from 60 K (280-340 K for x = 0), to 80 K (240-320 K for x = 0.05), to 95 K (200-295 K for x = 0.1), and finally to 100 K (170-270 K for x = 0.15). Furthermore, a linear NTE remains independent of temperature for samples with x ≤ 0.1. The relationship between tunable NTE and magnetic properties was analyzed in detail, indicating that the NTE in CrTe1-xSex compounds originates from the magnetovolume effect (MVE).

Discovery of negative thermal expansion with giant thermal hysteresis in Fe3NiBx

Negative thermal expansion (NTE) behavior with giant thermal hysteresis exceeding 450 K has been observed in Fe3NiBx. This behavior is desirable in the field of pipe joint or encapsulation. The temperature dependent X-ray diffraction and magnetization indicate that NTE behavior with giant thermal hysteresis is related to crystal structure transition between face-centered cubic (fcc) and body-centered cubic (bcc), but not to the magnetic transition. The introduction of boron can reduce the NTE temperature range and stabilize the high temperature fcc phase. Therefore, we can obtain the NTE behavior below room temperature during cooling process, which is important for the practical application.

Avoiding the invasion of H2O into Y2Mo3O12 by coating with C3N4 to improve negative thermal expansion properties.

The hygroscopicity of Y2Mo3O12 has serious influences on its mechanic and negative thermal expansion (NTE) properties. The reported partial ion substitution for Y3+ in Y2Mo3O12 could reduce the hygroscopicity, however, the expected NTE properties disappear disappointedly. In this investigation, it is found that avoiding the invasion of crystal water and extending the NTE temperature range of Y2Mo3O12 to room temperature could be realized together by heating with CO(NH2)2. The X-ray diffraction patterns, infrared absorption spectra, scanning electron microscopy images and X-ray photoelectron spectra suggest the formation of small hydrophobic molecules (C3N4, C, etc.) coated on the surface, which could clog the microchannels in Y2Mo3O12 to avoid the invasion of crystal water. The investigation paves a way to improve the NTE properties by neglecting the influences of water molecules on the stretching vibrations of MoO4 tetrahedra and the transverse vibrations of bridge oxygen atoms.

Zero thermal expansion, electrical conductivity and hardness of Mn3Zn0.5Sn0.5N/Cu composites

Mn3Zn0.5Sn0.5N/Cu composites were successfully prepared by sintering at 723 K and 823 K. The results show that the thermal expansion of Cu decreases effectively by mixing Mn3Zn0.5Sn0.5N within its negative thermal expansion temperature range. The thermal expansion of composites can be tailored by adjusting the volume fraction of Mn3Zn0.5Sn0.5N. When the volume fraction of Mn3Zn0.5Sn0.5N is 40%, the composite shows a near zero thermal expansion, with the coefficient of thermal expansion of 0.268 × 10−6 K–1 Mn3Zn0.5Sn0.5N/Cu composites exhibit excellent electrical conductivity at the level of 104 S/cm, which is less than that of the matrix Cu. The hardness of composite is improved by adding Mn3Zn0.5Sn0.5N with high stiffness. Some classic models are used to predict the properties of composites and corrected according to the experiment data.

Magnetically driven negative thermal expansion in antiperovskite Ga1-xMnxN0.8Mn3 (0.1 ≤ x ≤ 0.3)

Negative thermal expansion (NTE) was investigated for Ga1−xMnxN0.8Mn3 (0.1 ≤ x ≤ 0.3). As x increases, the temperature range where lattice contracts upon heating becomes broad and shifts to lower temperatures. The coefficient of linear thermal expansion beyond −40 ppm/K with a temperature interval of ∼50 K was obtained around room temperature in x = 0.2 and 0.25. Local lattice distortion which was thought to be intimately related to NTE is invisible in the X-ray pair distribution function of x = 0.3. Furthermore, a zero-field-cooling exchange bias was observed as a result of competing ferromagnetic (FM) and antiferromagnetic (AFM) orders. The concomitant FM order serves as an impediment to the growth of the AFM order, and thus broadens the temperature range of NTE. Our result suggests that NTE can be achieved in antiperovskite manganese nitrides by manipulating the magnetic orders without distorting the local structure.

Spin-glass-like behavior and negative thermal expansion in antiperovskite Mn3Ni1−xCuxN compounds

The Cu-doping effect on the lattice and magnetic properties in Mn3Ni1−xCuxN (x = 0, 0.3, 0.5, 0.7, 1.0) was extensively investigated. We observed that the Cu-doping at the Ni site complicated the magnetic ground states, which induced the competition of antiferromagnetic and ferromagnetic interactions. Spin-glass-like behavior, arising from possible site-randomness and competing interactions of magnetism, was observed in compounds with x = 0.3, 0.5, and 0.7, and typically discussed by means of the measurement of ac magnetic susceptibility for x = 0.7. The negative thermal expansion (NTE) behavior, due to the magnetic ordering transition, was observed in Mn3Ni1−xCuxN compounds using variable temperature x-ray diffraction. It reveals that the introduction of Cu effectively broadens the temperature range displaying negative thermal expansion. The relationship between the local lattice distortion and the competing magnetic ground states might play an important role in broadening the NTE temperature range in this antiperovskite compound.

Design, fabrication and characterization of porous Ti-rich Ti-Ni alloy based composites with near-zero thermal expansion behavior

Porous Ti-rich Ti-Ni alloy based composites with near-zero thermal expansion (NZTE) behaviour tailored by micro-sized SiC particles were fabricated using powder metallurgy and a two-step designing strategy. At first, the Ni concentration was tuned to broaden the temperature range of negative thermal expansion (NTE) of porous Ti-Ni alloys; then micro-sized SiC particles of different amounts were introduced and co-sintered with mixed Ti and Ni powders having an optimized atomic ratio so as to obtain SiC/Ti-Ni composites with desirable thermal expansion performance. Results show that there is a clear correlation between the reverse martensitic transformation and NTE temperature range. The porous 12wt.%SiC/Ti-43.8at.%Ni composite exhibits very low coefficient of thermal expansion (CTE) of -0.976×10 −6 K −1 from 114.08 to 131.50 °C. It is proposed that the NTE behavior originates from the volume change accompanying the phase transition of the Ti-Ni matrix, and the NZTE performance of SiC/Ti-Ni composites is attributed to the combination of the NTE produced by the alloy matrix and the positive thermal expansion provided by the SiC phase.

Ab initiolattice dynamical studies of silicon clathrate frameworks and their negative thermal expansion

The thermal and lattice dynamical properties of seven silicon clathrate framework structures are investigated with ab initio density functional methods (frameworks I, II, IV, V, VII, VIII, and H). The negative thermal expansion (NTE) phenomenon is investigated by means of quasiharmonic approximation and applying it to equal time displacement correlation functions. The thermal properties of the studied clathrate frameworks, excluding the VII framework, resemble those of the crystalline silicon diamond structure. The clathrate framework VII was found to have anomalous NTE temperature range up to 300 K and it is suitable for further studies of the mechanisms of NTE. Investigation of the displacement correlation functions revealed that in NTE, the volume derivatives of the mean square displacements and mean square relative displacements of atoms behave similarly to the vibrational entropy volume derivatives and consequently to the coefficients of thermal expansion as a function of temperature. All studied clathrate frameworks, excluding the VII framework, possess a phonon band gap or even two in the case of the framework V.

Tuning negative thermal expansion in Bi1−x LnxNiO3 (Ln = La, Nd, Eu, Dy)

The compositional dependence of the negative thermal expansion (NTE) property of Bi1−xLnxNiO3 (Ln = La, Nd, Eu, Dy) was investigated. All x = 0.05 samples showed large NTE over αL = −70 ppm/K (αL: coefficient of linear thermal expansion) due to intermetallic charge transfer between Bi5+ and Ni2+. The temperature range of NTE shifted upward with decreasing ionic radius of Ln3+. Partial ordering of Bi/Ln is suggested to be the origin of this shift and the suppression of the broadening of the transition.

Direct observation of negative thermal expansion in SrCu<sub>3</sub>Fe<sub>4</sub>O<sub>12</sub>

We report a direct observation of the negative thermal expansion in an iron-based perovskite oxide SrCu3Fe4O12 by using a thermomechanical analyzer and strain gauge. Reversibility and small thermal hysteresis in the negative thermal expansion temperature range demonstrate that the negative thermal expansion of this compound is attributed to second-order phase transition.

Negative Thermal Expansion and Correlated Magnetic and Electrical Properties of Si‐Doped Mn3GaN Compounds

The negative thermal expansion (NTE) and correlated magnetic and electrical transport properties of Mn3GaxSi1−xN were investigated. For pure Mn3GaN, there is a large NTE effect corresponding to the antiferromagnetic to paramagnetic transition. Very interestingly, when partial Ga was replaced by Si, the NTE properties around the magnetic transition were changed. The NTE temperature range was broadened to ΔT=148 K for Mn3Ga0.75Si0.25N and the linear thermal expansion coefficient was estimated as β=−1.4 × 10−5 K−1 (272–420 K). Accordingly, the resistivity also showed a decrease from 327 to 395 K with temperature. With a further increasing Si content to x=0.5, the magnetic transition still occured, but the NTE effect did not appear. After careful observation, an anomaly was found at around 350 K in a–T, ρ–T, and DSC curves of Mn3Ga0.5Si0.5N, respectively. This phenomenon strongly implies the close correlation among lattice, spin, and charge in this series materials.

Dynamics of the Negative Thermal Expansion in Tellurium Based Liquid Alloys

Negative thermal expansion (NTE) in tellurium based liquid alloys (GeTe6 and GeTe12) is analyzed through the atomic vibrational properties. Using neutron inelastic scattering, we show that the structural evolution resulting in the NTE is due to a gain of vibrational entropy that cancels out the Peierls distortion. In the NTE temperature range, these competing effects give rise to noticeable changes in the vibrational density of states spectra. Additional first principles molecular dynamics simulations emphasize the role of the temperature dependance of the Ge atomic environment in this mechanism. For comparison, we extended our study to Ge2Sb2Te5 and Ge1Sb2Te4 phase-change materials.

Preparation and characterization of ZrWMoO8 powders with different morphologies using hydrothermal method

Materials that exhibit negative thermal expansion (NTE) property are of considerable scientific and technological interests [1–5]. Their use in composites facilitates the control of bulk thermal expansion properties to avoid cracks or separation at interfaces between the two components, which is especially needed for various applications in optics, electronics, and other fields where exact positioning of parts is crucial [6, 7]. For use in composite, an ideal NTE material should have isotropic and linear negative thermal expansion properties during a large temperature range including room temperature [8]. It is desirable that the material is thermodynamically stable over its NTE range and can be prepared in a low-cost and efficient way. The most promising NTE material to date is ZrW2O8 family due to its’ isotropic NTE property over a wide temperature range. The typical material, ZrW2O8, undergoes isotropic NTE behavior from 0.3 K to 1050 K [9,10]. Unfortunately, for use in composites, there are some drawbacks. For example, ZrW2O8 undergoes an order-disorder phase transition around 430 K and the linear coefficient changed from – 8.8 · 10 K to –4.9 · 10 K[11]. It also undergoes a phase transition to a more dense structure (with a significantly lower coefficient of NTE) at around 0.2 Gpa. While structurally related phases such as ZrMo2O8 and ZrW2–xMoxO8 solid solution do not undergo phase transition over the NTE temperature range, which makes it desirable in preparing composite materials [12–14]. Cubic ZrWMoO8 is a typical ZrW2–xMoxO8 solid solution. But it is difficult to prepare due to the volatilization of WO3 and MoO3 when conventional solid state techniques is used. The breakthrough in this area came when dehydration of the precursor method was put forward [15]. But this method was far from optimal because the solution usually was aged and gelatinized for weeks. Recently, a rapid synthetic route, hydrothermal method was approached and highly crystallized cubic ZrWMoO8 powders were achieved without the aging procedure [16]. As used as fillers in composites, for decreasing the innerstress, proper morphology is important. But to date, most NTE materials have been synthesized as powders without controlling in morphology due to the difficulty in synthesis. In this paper, ZrWMoO8 powders with different morphologies were prepared by hydrothermal method using HCl, HClO4, HNO3, H2SO4 and CH3COOH as acid media respectively. The influence of the kind of acid on the morphologies of the obtained ZrWMoO8 was also investigated. All the chemical reagents were analytical grade purity without further purification. In the typical procedure, zirconium oxynitrate [ZrO (NO3)2 5H2O], ammonium tungstate [N5H37W6O24 H2O] and ammonium molybdate [N5H37Mo6O24 H2O] were dissolved separately in distilled water according to the mole ratio of Zr:W:Mo=1:1:1. First, W solution and Mo solution were mixed, and then Zr solution was added slowly under vigorous stirring. After that, acid solution (HCl, HClO4, HNO3, H2SO4, CH3COOH(HOAc)) was added slowly to the above solution with continuous stirring for another 3 h. The Q.-Q. Liu J. Yang X.-J. Sun X.-N. Cheng (&) G.-F. Xu X.-H. Yan School of Materials Science and Engineering, Jiangsu University, Zhenjiang, Jiangsu 212013, China e-mail: xncheng@ujs.edu.cn