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論文

Dielectric and magnetocaloric study of TmCrO$$_{3}$$

吉井 賢資; 池田 直*

Journal of Alloys and Compounds, 804, p.364 - 369, 2019/10

ペロブスカイトTmCrO$$_{3}$$の誘電性と磁気熱量効果について調べた。この物質は最近、磁気秩序温度125K以下においてCrスピンの弱強磁性秩序と強誘電性が共存するマルチフェロイック物質であると報告されている。誘電応答からは、室温近傍で10000程度の大きな誘電率が観測されたものの、交流抵抗の解析などから、これは伝導キャリアの応答によるものであることが分かった。磁気熱量効果の測定からは、磁気転移温度125Kでの転移は2次であり、もしマルチフェロイックであれば期待されうる磁歪は存在しないことが強く示唆された。すなわち、この物質が強誘電性を持つことは示されなかった。

論文

Anomalous ferromagnetic ordering in EuCuP

伊覇 航*; 垣花 将司*; 松田 進弥*; 本多 史憲*; 芳賀 芳範; 竹内 徹也*; 中島 美帆*; 天児 寧*; 郷地 順*; 上床 美也*; et al.

Journal of Alloys and Compounds, 788, p.361 - 366, 2019/06

Ferromagnetic ordering of EuCuP is investigated on a single crystal sample grown from tin flux. Application of hydrostatic pressure up to 8 GPa stabilizes ferromagnetic ordering, suggesting divalent Eu is stable. The Hall effect and resistivity measurements show that EuCuP is a low-carrier ferromagnetic metal with a characteristic resistivity cusp appearing at the ferromagnetic transition temperature.

論文

Abnormally enhanced diamagnetism in Al-Zn-Mg alloys

西村 克彦*; 松田 健二*; Lee, S.*; 布村 紀男*; 島野 寛基*; Bendo, A.*; 渡邊 克己*; 土屋 大樹*; 並木 孝洋*; 戸田 裕之*; et al.

Journal of Alloys and Compounds, 774, p.405 - 409, 2019/02

 パーセンタイル:100(Chemistry, Physical)

Temperature and time dependences of magnetization of Al-1.0%Zn-4.2%Mg, Al-2.6%Zn-3.2%Mg, Al-4.1%Zn-1.1%Mg, and Al-5%Zn (at.%) alloys were measured in the range between 10 and 310 K after various periods of natural aging and peak-aged heat treatments. Enhanced diamagnetic contributions on the magnetization were observed for the as-quenched Al-Zn-Mg alloys for the first time. The enhanced diamagnetism observed in Al-2.6%Zn-3.2%Mg and Al-4.1%Zn-1.1%Mg were found to largely alter in natural aging, while that of Al-1.0%Zn-4.2%Mg little changed. After peak-aged heat treatments, the diamagnetism of Al-Zn-Mg was largely reduced. The binary Al-5%Zn showed neither enhanced diamagnetism nor natural aging effect on the magnetization. Isothermal time variations of magnetization of Al-Zn-Mg alloys at 300 K were found to be related with solute-vacancy clustering.

論文

Temperature stability of PIN-PMN-PT ternary ceramics during pyroelectric power generation

Kim, J.*; 茂呂 拓哉*; Kim, J.*; 山中 暁*; 村山 一郎*; 加藤 孝典*; 中山 忠親*; 武田 雅敏*; 山田 昇*; 西畑 保雄; et al.

Journal of Alloys and Compounds, 768, p.22 - 27, 2018/11

 被引用回数:1 パーセンタイル:52.95(Chemistry, Physical)

Relaxor-based ternary Pb(In$$_{1/2}$$Nb$$_{1/2}$$)O$$_3$$-Pb(Mg$$_{1/3}$$Nb$$_{2/3}$$)O$$_3$$-PbTiO$$_3$$ (PIN-PMN-PT) ceramics near a morphotropic phase boundary were grown, and their electrical properties at various temperatures were investigated in the electrothermodynamic cycle for the future environment-friendly automotive applications. Structural disordering, depending on the PIN content, influenced the diffuse phase transition between the tetragonal and cubic structures and contributed to the power-generating behavior. The net power-generating energies (P$$_{net}$$) were 2.43-3.01 mW/cm$$^3$$ at temperatures above 200$$^circ$$C and were maintained at above 1 mW/cm$$^3$$ over a temperature range of approximately 100 degrees. Therefore, the PIN-PMN-PT system has a possibility of a wider usage temperature range, the disordering of the perovskite crystal structure can be controlled, and it will be a candidate for the application of pyroelectric energy conversion system.

論文

Impurity effects in the microscopic elastic properties of polycrystalline Mg-Zn-Y alloys with a synchronised long-period stacking ordered phase

細川 伸也*; 木村 耕治*; 山崎 倫昭*; 河村 能人*; 吉田 亨次*; 乾 雅祝*; 筒井 智嗣*; Baron, A. Q. R.*; 川北 至信; 伊藤 晋一*

Journal of Alloys and Compounds, 695, p.426 - 432, 2017/02

 被引用回数:2 パーセンタイル:60.17(Chemistry, Physical)

Inelastic X-ray scattering (IXS) was performed on polycrystalline Mg$$_{97}$$Zn$$_1$$Y$$_2$$ and Mg$$_{85}$$Zn$$_6$$Y$$_9$$ alloys with synchronized long-period stacking ordered (LPSO) phase for investigating the impurity effects in the microscopic elastic properties. Inelastic neutron scattering (INS) was also carried out on the former alloy. LA modes were clearly observed in the IXS spectra of both the LPSO alloys, while TA modes can mainly be detected in the second Brillouin zone. Broader inelastic signals and larger quasielastic peaks are characteristic due to the phonon scattering by the Zn/Y impurities. Only the TA excitation energies increase by adding the impurities, which indicates a harder stiffness of the bond angles relating to the L1$$_2$$-type clusters in the LPSO alloys. New dispersion-less excitation modes are observed at about 10 meV by adding the Zn/Y impurities. By comparing with the INS data, the contributions of the impurities to these excitations are discussed using differences in the scattering cross-sections between neutrons and X-rays.

論文

Hydrogenation of $$L$$1$$_{2}$$-type AlNi$$_{3}$$ alloy at high pressure and temperature

遠藤 成輝*; 齋藤 寛之; 町田 晃彦; 片山 芳則

Journal of Alloys and Compounds, 645(Suppl.1), p.S61 - S63, 2015/10

 パーセンタイル:100(Chemistry, Physical)

We investigated the hydrogenation of the $$L$$1$$_{2}$$-type AlNi$$_{3}$$ alloy at 3 GPa and 500$$^{circ}$$C using in situ synchrotron radiation X-ray diffraction measurements. An isotropic lattice expansion was observed to have occurred owing to the hydrogenation, and a novel hydride (AlNi$$_{3}$$H$$_{x}$$) was formed. Because of such isotropic lattice expansion, the hydrogen-occupied sites were the body-center sites of the $$L$$1$$_{2}$$ structure (P$$m$$-3$$m$$). In this case, the hydrogen content was calculated to be $$x$$ = 1.0, which is consistent with the experimental results. The AlNi$$_{3}$$H$$_{x}$$ hydride was stable under ambient conditions.

論文

Synthesis of Be-Ti-V ternary beryllium intermetallic compounds

金 宰煥; 中道 勝

Journal of Alloys and Compounds, 640, p.285 - 289, 2015/08

 被引用回数:1 パーセンタイル:86.18(Chemistry, Physical)

Beryllium intermetallic compounds (beryllides) such as Be$$_{12}$$Ti and Be$$_{12}$$V are the most promising advanced neutron multipliers in demonstration power reactors. We developed a new combined plasma sintering and rotating electrode method for the fabrication of beryllide rods and pebbles. Previously, we prepared a beryllide pebble with a Be-7.7 at.% Ti composition as the stoichiometric value of the Be$$_{12}$$Ti phase; however, Be$$_{17}$$Ti$$_{2}$$ and Be phases were present along with the Be$$_{12}$$Ti phase that formed as the result of a peritectic reaction due to re-melting during granulation using the rotating electrode method. This Be phase was found to be highly reactive with oxygen and water vapor. Accordingly, to investigate the Be phase reduction and applicability for fabrication of electrodes prior to granulation using the rotating electrode method, Be-Ti-V ternary beryllides were synthesized using the plasma sintering method. Surface observation results indicated that increasing plasma sintering time and V addition led to an increase in the intermetallic compound phases compared with plasma-sintered beryllide with a Be-7.7 at.% Ti composition. Additionally, evaluation of the reactivity of samples with water vapor at high temperature revealed that specimens with larger fractions of Be phases experienced larger weight gains and H$$_{2}$$ generation rates because of oxidation, as Be$$_{12}$$Ti and Be$$_{12}$$V phases have a similar oxidation tendency.

論文

Comparative study of sinterability and thermal stability in plasma-sintered niobium and vanadium beryllides

金 宰煥; 中道 勝

Journal of Alloys and Compounds, 638, p.277 - 281, 2015/07

 被引用回数:1 パーセンタイル:86.18(Chemistry, Physical)

Niobium and vanadium-beryllium intermetallic compounds (beryllides) were synthesized by plasma sintering under different sintering times at 1273 K. The beryllide with 7.7 at.% Nb mainly consisted of various phases of Be, Be$$_{12}$$Nb, Be$$_{17}$$Nb$$_{2}$$, and Be$$_{2}$$Nb, whereas that with 7.7 at.% V consisted of Be$$_{12}$$V, Be$$_{2}$$V, and V. As the sintering time increased, area fractions of the target compositions Be$$_{12}$$Nb and Be$$_{12}$$V increased while that of Be decreased. A comparative analysis demonstrated that the beryllide with 7.7 at.% Nb a showed higher density as well as a greater hardness than that with 7.7 at.% V, due to there being less difference between the sintering temperature and the melting point. In terms of thermal phase stability, the beryllide with 7.7 at.% Nb showed good thermal phase stability with fewer pores and a smaller unhomogenized area, because the beryllide contained a smaller area fraction of the Be phase, which may cause evaporation resulting in pore formation.

論文

Preliminary synthesis and mechanical property of titanium beryllide pebbles with different chemical compositions

金 宰煥; 中道 勝

Journal of Alloys and Compounds, 585, p.63 - 68, 2014/02

 被引用回数:10 パーセンタイル:33.23(Chemistry, Physical)

Beryllide is well-known as the most promising candidate for advanced multipliers in demonstration fusion reactors. However, due to its brittleness, it is difficult to fabricate a pebble-type beryllide. Here, we report the synthesis and analysis of beryllide pebbles with different chemical compositions. In order to clarify the effect of the content of Ti on the fabrication of beryllide pebbles, a rotating electrode method was applied using a plasma-sintered beryllide rod jointed by two beryllide blocks and powder. The beryllide pebbles were successfully fabricated accompanied by phase changes induced by re-melting during the rotating electrode method. The SEM images of the rods and the cross-section of the pebbles demonstrated that the phases of the plasma-sintered beryllide rods with 6 at.%, 7 at.%, and 7.7 at.% Ti were transformed to the peritectic Be$$_{12}$$Ti phase with a Be$$_{17}$$Ti$$_{2}$$ phase due to re-melting whereas pebbles with 3 at.% and 5 at.% Ti showed similar phases as the plasma-sintered beryllide rods. Additionally, the dependence of the Ti amount on crush load depicted that the pebbles with the larger area fraction of Be indicated the higher crush load as well as longer displacement because the Be contributed to increase of ductility in the pebbles.

論文

Synergic effects of ion irradiations (La, Ce) and alkaline pretreatment (KOH) on hydriding kinetic property of a Mm-Ni based alloy

阿部 浩之; 青根 茂雄*; 森本 亮*; 内田 裕久*

Journal of Alloys and Compounds, 580(Suppl.1), p.S219 - S221, 2013/12

 被引用回数:3 パーセンタイル:67.03(Chemistry, Physical)

水素吸蔵合金の吸蔵能の1つに、水素吸蔵初期反応速度がある。今回、イオン照射による表面改質技術を目的に種々のイオンをMm-Ni系水素吸蔵合金に照射したところ希土類イオンであるLaイオン,Ceイオンが水素吸蔵初期反応速度を大きく向上させることが判明した。さらにこれらイオン照射後のサンプルをKOHアルカリ溶液にて化学処理を施した場合、イオン照射したサンプルよりも数倍の初期反応速度の向上が見られた。これら希土類元素は水素を吸収しやすい物質であるため、表面にLaやCeイオンを導入することで初期反応速度が促進されたと考えられる。さらにKOHのアルカリ溶液にて化学処理をすることで、表面酸化膜がエッチングされるとともに、カリウム原子が合金表面仕事関数を下げることで、初期反応速度が速くなると考えられる。

論文

In situ synchrotron $$^{57}$$Fe M$"o$ssbauer spectroscopy of RFe$$_{2}$$ (R = Y, Gd) hydrides synthesized under ultra-high-pressure hydrogen

三井 隆也; 増田 亮*; 瀬戸 誠; 平尾 直久*; 松岡 岳洋*; 中村 優美子*; 榊 浩司*; 榎 浩利*

Journal of Alloys and Compounds, 580(Suppl.1), p.S264 - S267, 2013/12

 被引用回数:3 パーセンタイル:67.03(Chemistry, Physical)

An in situ $$^{57}$$Fe synchrotron radiation M$"o$ssbauer spectroscopy (SRMS) was performed on the C15 Laves RFe$$_{2}$$ (R=Y, Gd) under high-pressure hydrogen (H) in a diamond anvil cell. The H-absorption processes were monitored by the pressure dependence on the $$^{57}$$Fe isomer shift (IS): IS values increased for the amount of H-absorption into the RFe$$_{2}$$. In both cases, IS values showed a rapid increase at a few GPa, and once again showed a small increase at above 10 GPa. These results suggest that there are two steps in the H-absorption processes for the RFe$$_{2}$$ under high-pressure hydrogen. At the same time, two-step magnetic transitions have been also observed for the first time: ferromagnetic RFe$$_{2}$$ changed to paramagnetic RFe$$_{2}$$Hx$$_{1}$$ at the first H-absorption process, and a new ferromagnetic phase appeared in RFe$$_{2}$$Hx$$_{2}$$ at the second H-absorption process. In this conference, we report details on the SRMS experimental setup and the results.

論文

Epitaxial transformation of hcp-fcc Ti sublattices during nitriding processes of evaporated-Ti thin films due to nitrogen-implantation

Chen, Y.*; Feng, X.*; 粕壁 善隆*; 山本 春也; 吉川 正人; 藤野 豐*

Journal of Alloys and Compounds, 577(Suppl.1), p.S18 - S24, 2013/11

 パーセンタイル:100(Chemistry, Physical)

本研究では、原子力機構のイオン導入型400kV電子顕微鏡を利用して、チタン蒸着膜への窒素イオン注入窒化過程におけるチタン副格子の六方最密-面心立方(hcp-fcc)構造変化を、透過型電子顕微鏡法及び電子エネルギー損失分光法によりその場観察・評価し、分子軌道計算による電子状態の評価と合わせて窒化チタン薄膜の形成機構及び配向の制御性に関する知見を得てきた。本発表では、窒素イオン注入によるチタン薄膜の窒化過程と電子構造から考察したhcp-fccエピタキシャル構造変態について報告する。

論文

Optimization of synthesis conditions for plasma-sintered beryllium-titanium intermetallic compounds

金 宰煥; 中道 勝

Journal of Alloys and Compounds, 577, p.90 - 96, 2013/11

 被引用回数:3 パーセンタイル:74.89(Chemistry, Physical)

Plasma sintering method has been newly suggested as a synthesis method for beryllium titanium intermetallic compounds (beryllides) as an advanced neutron multiplier in a system of water cooled solid breeder demonstration fusion reactors. Not only synthesis of the beryllide but joining the beryllide could be successfully fabricated. We report on the optimization of the main sintering conditions, on the sinterabilityof the plasma-sintered beryllides in the light of sinterability, as well as consolidation to the Be$$_{12}$$Ti phase. The optimum sintering temperature for consolidation to the Be$$_{12}$$Ti phase was 1273 K and the area fraction of the Be$$_{12}$$Ti phase obtained when sintering at 1273 K, was approximately 83%. To increase the fraction of the Be$$_{12}$$Ti phase, increasing the sintering time was inevitable and this led to an increase in the Be$$_{12}$$Ti phase corresponding to 97.5%. However, as the sintering time increased, variation in grain size of the beryllides was observed. With regard to the sintering pressure, the higher the sintering pressure applied, the higher the sinterability, even though lower pressure may lead to better consolidation with respect to the absence of the Be$$_{2}$$Ti phase.

論文

Sinterability and mechanical properties of plasma-sintered beryllides with different Ti contents

金 宰煥; 中道 勝

Journal of Alloys and Compounds, 556, p.292 - 295, 2013/04

 被引用回数:9 パーセンタイル:37.91(Chemistry, Physical)

The synthesis of plasma-sintered beryllide with different Ti contents was carried out to investigate the sinterability and mechanical properties as a function of the phase composition. The electron probe microanalysis clarified that the area fraction of the Be$$_{12}$$Ti phase increased up to a Be-7.7 at.% Ti and then sharply decreased while the area fraction of Be decreased. Specifically, in the Be-6 at.% Ti, Be$$_{17}$$Ti$$_{2}$$ and Be$$_{2}$$Ti phases began to be formed. For the Be-10.5 at.% Ti, a large amount of the Be$$_{17}$$Ti$$_{2}$$ phase was detected. These results are in good agreement with the X-ray diffraction profiles obtained for the plasma-sintered beryllide with different Ti contents. In addition, the Vickers micro-hardness test results clearly prove that with increasing Ti content, the hardness increased but then became saturated near Be-7.7 at.% Ti. This hardness variation does not seem to be related to the grain size effect because the grain size increased with increasing Ti content.

論文

Comparative study on arc-melted and plasma-sintered beryllides

金 宰煥; 中道 勝

Journal of Alloys and Compounds, 546, p.171 - 175, 2013/01

 被引用回数:9 パーセンタイル:37.91(Chemistry, Physical)

This study compares arc-melted and plasma-sintered beryllides, investigating the effects of density, hardness, microstructure, and annealing on stability. From the electron probe micro-analyzer and X-ray diffraction analysis results, it was obvious that the plasma-sintered samples, including those with 3 and 5atm% Ti, were composed of Be and Be$$_{12}$$Ti phases, while Be$$_{17}$$Ti$$_{2}$$ and Be$$_{2}$$Ti phases were additionally observed for the Be-7atm% Ti sample. In case of the arc-melted beryllides, it consisted of Be and Be$$_{2}$$Ti in the 3atm% Ti and 5atm% Ti samples, whereas the Be$$_{2}$$Ti phase surrounded Be$$_{10}$$Ti as a peritectic phase for Be-7atm% Ti. Density and hardness measurements confirmed that the plasma-sintered beryllides were sintered with higher density and hardness than the arc-melted beryllides. In addition, the annealing treatment at 1473 K for 5 h was carried out to investigate the homogenization of the compositional structure. From the results of observation analysis for the specimens denoted as Be-3atm% Ti and Be-5atm% fabricated by both methods, there was no change on compositional structure. However, for arc-melted Be-7atm% Ti, the Be phase was almost diminished, whereas there was a slight increase in the Be$$_{12}$$Ti phase and a slight decrease in the Be$$_{10}$$Ti phase. In the case of the plasma-sintered Be-7atm% Ti specimen, it was clarified that the Be$$_{17}$$Ti$$_{2}$$ and Be$$_{2}$$Ti phases were homogenized into the Be$$_{12}$$Ti phase.

論文

Phase diagram and equation of state of TiH$$_{2}$$ at high pressures and high temperatures

遠藤 成輝; 齋藤 寛之; 町田 晃彦; 片山 芳則; 青木 勝敏

Journal of Alloys and Compounds, 546, p.270 - 274, 2013/01

 被引用回数:4 パーセンタイル:60.42(Chemistry, Physical)

In the present study, we clearly determined the phase diagram of TiH$$_{2}$$ at high pressures and high temperatures, and were the first to report the equation of state (EoS) of TiH$$_{2}$$ with an fcc phase. Compression induced strain inhibited the phase transition from the low-temperature bct phase to the high-temperature fcc phase, making the phase diagram difficult to determine. Thus, the phase boundary was appropriately determined using a sample which was treated at high temperature to remove strain. The obtained phase boundary was considerably lower than the experimental data reported by Vennila et al (2008). Additionally, we successfully obtained the high temperature Birch-Murnaghan EoS of TiH$$_{2}$$, and reported the thermoelastic parameters of fcc TiH$$_{2}$$.

論文

Fast and real-time observation of hydrogen absorption kinetics for palladium nanoparticles

松村 大樹; 岡島 由佳*; 西畑 保雄; 水木 純一郎

Journal of Alloys and Compounds, 509(Suppl.2), p.S849 - S852, 2011/09

 被引用回数:8 パーセンタイル:44.26(Chemistry, Physical)

パラジウム微粒子の水素吸蔵反応に伴う動的な原子構造及び電子構造変化を、分散型光学系を有したX線吸収分光によって、「その場観測」かつ「実時間分割観測」を行った。水素吸蔵反応に伴って、パラジウム微粒子は10pmもの原子間距離の膨張を示した。原子間距離の膨張における水素分圧依存性を、50Hzの測定レートによって観測することに成功した。200kPaの水素分圧では、わずか50ms秒で、パラジウム微粒子の原子間距離の膨張が完了することが判明した。また、水素の吸蔵反応は強い水素分圧依存性を持っていることがわかった。速度論的解析を行った結果からは、水素分子のパラジウム微粒子表面における表面解離吸着反応が、反応律速となっていることが示された。

論文

Relativistic density-functional study of solid solubitilty of tansiton metal/$$gamma$$-uranium alloys; The Roll of d-d orbital interactions

栗原 正義*; 尾上 順*; 平田 勝; 鈴木 知史

Journal of Alloys and Compounds, 509(4), p.1152 - 1156, 2011/01

 被引用回数:2 パーセンタイル:75.13(Chemistry, Physical)

$$gamma$$相ウランにおける遷移金属(TM)の固溶挙動を、相対論DV-X$$alpha$$分子軌道法を用いて検討した。固溶性の評価には、遷移金属のd軌道のエネルギー(Md)、及び、遷移金属とウランの原子軌道間の軌道結合次数(OOP)を用いた。この分子軌道法による計算結果から、U 6dとTM dとの相互作用が、$$gamma$$-U/TM合金の最大固溶度(MSS)について、重要な役割を果たしていることがわかった。また、MSSの値は、d-d軌道相互作用による安定化エネルギーにより説明され、MdとOOPはこの安定化エネルギーに影響していることがわかった。

論文

Controls of chromium and third element contents in nickel-base alloys for corrosion resistant alloys in hot HNO$$_3$$-HF mixtures

竹内 正行; 中島 靖雄; 星野 国義*; 河村 文雄*

Journal of Alloys and Compounds, 506(1), p.194 - 200, 2010/09

 被引用回数:4 パーセンタイル:62.77(Chemistry, Physical)

Corrosion resistance of nickel-base alloys in HNO$$_3$$-HF mixtures was investigated to apply them to FLUOREX process, which is advanced hybrid process of fluoride volatility and solvent extraction for next-generation spent nuclear oxide fuel reprocessing. Many types of Ni-Cr and Ni-Cr-X (X= Mo, W, Nb, Ti, Si, Cu) ingots were experimentally manufactured and the desirable chromium and third element contents in nickel-base alloys were discussed in narrow range to improve the corrosion resistance in hot HNO$$_3$$-HF mixtures. From the results of corrosion tests, Ni-45Cr-0.25Mo alloy exhibited the best corrosion resistance in this study. The corrosion rate was 0.17mm/y in 8M HNO$$_3$$-0.1M HF solutions at 373K and it provided good performance as corrosion resistant materials. In conclusion, it was found that the control of higher chromium content and a small amount of molybdenum in nickel-base alloys are significant to improve the corrosion resistance in HNO$$_3$$-HF mixtures.

論文

Formation and crystal growth process of AlH$$_{3}$$ in Al-H system

齋藤 寛之; 岡島 由佳; 米田 安宏; 町田 晃彦; 川名 大地; 綿貫 徹; 片山 芳則; 青木 勝敏

Journal of Alloys and Compounds, 496(1-2), p.L25 - L28, 2010/04

 被引用回数:13 パーセンタイル:32.87(Chemistry, Physical)

The hydrogenation process of aluminum is observed at high pressure and temperature by angle-dispersive ${it in situ}$ X-ray diffraction method. At 10 GPa and 600 $$^{circ}$$C, single crystals of AlH$$_{3}$$ about 20 $$mu$$m in size are found to grow through three steps: self-pulverization of aluminum, hydrogenation of pulverized aluminum, and solid-state grain growth of hydride. The self-pulverization seems to be the precursor of the hydrogenation reaction because it occurs at pressure temperature conditions where AlH$$_{3}$$ is thermodynamically stable.

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