Ion beam epitaxy （IBE） technology is a significant method for preparing high pure and high quality rare-earth functional films at low growth temperatue. A new method of preparing rare-earth functional films by ion b...Ion beam epitaxy （IBE） technology is a significant method for preparing high pure and high quality rare-earth functional films at low growth temperatue. A new method of preparing rare-earth functional films by ion beam epitaxy was reviewed in details. The recent developments and application of IBE on rare-earth functional films is focused, particularly for high-K materials CeO2, photoluminescence materials Gd2O3 and magnetic semiconductor materials Si1-x Gdx.展开更多
The functions of rare earth metals in the automobile emission purification catalysts were reviewed, and it was clarified that with precious metals resources using up gradually emission regulations becoming more and mo...The functions of rare earth metals in the automobile emission purification catalysts were reviewed, and it was clarified that with precious metals resources using up gradually emission regulations becoming more and more strict, rare earth metals will play more and more important roles in the high performance, and in low price automobile emission purification catalysts, they can not be substituted by other elements, for example, precious metals.展开更多
Recently,much attention has been paid to the lanthanide luminescent materials based on the visiblelight sensitization for their potential applications in the fields of bio-imaging and optical devices.In this work,the ...Recently,much attention has been paid to the lanthanide luminescent materials based on the visiblelight sensitization for their potential applications in the fields of bio-imaging and optical devices.In this work,the lanthanide complexes have been covalently bonded to the ordered mesoporous titania（OMT） matrix,and the resulting titania-based hybrid ordered mesoporous materials（named as LnDBOMT,Ln = Eu,Sm,Yb,Nd） were characterized by using Fourier-transform infrared（FT-IR） spectroscopy,small-angle X-ray powder diffraction（SAXD）,N2 adsorption-desorption isotherms,transmission electron microscopy（TEM）,fluorescence spectroscopy,and thermogravimetric analysis.Generally,exciting with visible light is advantageous over UV excitation.Of importance here is that,under excitation with visible light,the LnDB-OMT all show characteristic visible（Eu3＋,Sm3＋） as well as nearinfrared（Sm3＋,Yb3＋,Nd3＋） luminescence of the corresponding Ln3＋ ions（multicolor emission covered from 500 to 1400 nm spectral region）,which is attributed to the energy transfer from the ligands to the Ln3＋ ions via an antenna effect.展开更多
Teroolymerization of enichlorohydrin（ECH）-maleic anhydride（MAn）-carbon dioxide（CO;） was carried out by using Y(P;);-Al（i-Bu）;as catalyst for the first time.The terpolymersobtained were characterized by IR and;...Teroolymerization of enichlorohydrin（ECH）-maleic anhydride（MAn）-carbon dioxide（CO;） was carried out by using Y(P;);-Al（i-Bu）;as catalyst for the first time.The terpolymersobtained were characterized by IR and;H-NMR.It was foundthat the composition of the teroolymer was influenced by theaddition mode,initial monomer charge ratio,etc.展开更多
Functional redundancy in soil microbial communities seems to contradict the notion that individual species have distinct metabolic niches in multi-species communities.All soil microbiota have the metabolic capacity fo...Functional redundancy in soil microbial communities seems to contradict the notion that individual species have distinct metabolic niches in multi-species communities.All soil microbiota have the metabolic capacity for"basic"functions(e.g.,respiration and nitrogen and phosphorus cycling),but only a few soil microbiota participate in"rare"functions(e.g.,methanogenesis and mineralization of recalcitrant organic pollutants).The objective of this perspective paper is to use the phylogenetic niche conservatism theory as an explanation for the functional redundancy of soil microbiota.Phylogenetic niche conservatism is defined as the tendency for lineages to retain ancestral functional characteristics through evolutionary time-scales.The present-day soil microbiota is the result of a community assembly process that started when prokaryotes first appeared on Earth.For billions of years,microbiota have retained a highly conserved set of core genes that control the essential redox and biogeochemical reactions for life on Earth.These genes are passed from microbe to microbe,which contributes to functional redundancy in soil microbiota at the planetary scale.The assembly of microbial communities during soil formation is consistent with phylogenetic niche conservatism.Within a specific soil,the heterogeneous matrix provides an infinite number of sets of diverse environmental conditions,i.e.,niches that lead to the divergence of microbial species.The phylogenetic niche conservatism theory predicts that two or more microbial species diverging from the same clade will have an overlap in their niches,implying that they are functionally redundant in some of their metabolic processes.The endogenous genetic factors that constrain the adaptation of individuals and,thus,populations to changing environmental conditions constitute the core process of phylogenetic niche conservatism.Furthermore,the degree of functional redundancy in a particular soil is proportional to the complexity of the considered function.We conclude with a conceptual model that identifies six patterns of functional redundancy in soil microbial communities,consistent with the phylogenetic niche conservatism theory.展开更多
Rare earth elements （REE） compositions and discriminant function were successfully used to examine high resolution sediment source changes in the northern Okinawa Trough over the last 24.1 ka, especially for the inf...Rare earth elements （REE） compositions and discriminant function were successfully used to examine high resolution sediment source changes in the northern Okinawa Trough over the last 24.1 ka, especially for the influence from the Yellow River and the Tsushima Warm Current （TWC） that has not been well solved. Variations of these parameters were clearly divided into three distinct depositional units. During Interval 1 （24.1-16.0 ka BP）, the paleo-Yellow River and the paleo-Yangtze River mouths were situated near the studied area and could have played major roles in the sedimentation therein. In Interval 2 （16.0-7.3 ka BP）, these river mouths gradually retreated with global sea-level rise, leading to less fluvial inputs from them to the northern Okinawa Trough. Meanwhile, formation of the TWC could carry some sediment loads of Taiwan to the studied core, especially during its late phase （8.0-7.3 ka BP）. Modem oceanographic conditions, with a predominance of the TWC, were finally established since the beginning of Interval 3, causing more ten＇igenous contribution from Taiwan to the studied area. Subsequently, modem depositional environments mainly influenced by the Yellow River, the Yangtze River, and the TWC were finally formed.展开更多
The microstructures and textures of four rectangular extruded Mg alloys, Mg-3Gd, Mg-3Nd, Mg-1Gd-1Nd and Mg-1.5Gd-1.5Nd（all in wt%） were investigated by using optical microscopy（OM）, X-ray diffraction（XRD） and el...The microstructures and textures of four rectangular extruded Mg alloys, Mg-3Gd, Mg-3Nd, Mg-1Gd-1Nd and Mg-1.5Gd-1.5Nd（all in wt%） were investigated by using optical microscopy（OM）, X-ray diffraction（XRD） and electron backscatter diffraction（EBSD）. The results demonstrate that the extruded alloys all reveal fully recrystallized microstructure and weak non-basal texture.For textures of the four extruded alloys, it is shown that the basal planes of majority grains tilt away from the sheet plane normal toward the extrusion direction. Compared with two binary alloys, the ternary alloys possess weaker texture strengths. Through orientation distribution function analysis, two types of rare earth textures, {0113} 〈0223〉and {1215} 〈1213〉, were found in the extruded alloys.Texture component {1215} 〈1213〉 is relatively weak, but it plays a critical role in the low texture intensities of two ternary alloys. A pairing effect of Gd and Nd elements has an influence on the texture modification. Additionally,there is a difference in the sensitivities of experimental parameters between the microstructure and texture.展开更多
The use of rare earth for inducing plant resistance was reviewed. The important developments in recent years were described, and rare earth can alleviate the pollution of acid rain, ozone, pesticide, heavy metals etc....The use of rare earth for inducing plant resistance was reviewed. The important developments in recent years were described, and rare earth can alleviate the pollution of acid rain, ozone, pesticide, heavy metals etc. in environment. The authors suggest that the mechanism of rare earth to inducing plant resistance and reducing plant injury is to control biochemical metabolism web in plant cell, to adjust its protection system of free radical, to maintain its photosynthesis, to protect cell membrane system and to carry through its function on mineral metabolism. Meanwhile some problems in the field were discussed as well.展开更多
Quantum density functional theory （DFT） results are reported for the building block [LaL^1（NO3）] of La complex [LaL^1（NO3）]NO3·5H2O （L^1 = （CH3）2CHCH2CH（NCHC4H3O）COO^-）. The structure was optimized an...Quantum density functional theory （DFT） results are reported for the building block [LaL^1（NO3）] of La complex [LaL^1（NO3）]NO3·5H2O （L^1 = （CH3）2CHCH2CH（NCHC4H3O）COO^-）. The structure was optimized and the calculation results show that the lanthanum ion is coordinated by one nitrogen atom and three oxygen atoms of L^1 and two oxygen atoms of nitrate ion. The bond length of La-N is 0.2637 nm and the average length of La-O is 0.2526 nm, which are consistent with the literatures. In addition, the stabilities, electronic structural characteristics and IR spectra of the complex have been analyzed, which describe the coordination of lanthanum ion with other atoms in detail.展开更多
The density of states （DOS） of 17 kinds of rare earths （RE） doped rutile TiO2 was by using first-principles density functional theory （DFT） calculation. The band gap widths of RE doped futile TiO2 were important...The density of states （DOS） of 17 kinds of rare earths （RE） doped rutile TiO2 was by using first-principles density functional theory （DFT） calculation. The band gap widths of RE doped futile TiO2 were important factors for altering their absorbing wavelengths. The results show that RE ions could obviously reduce the band gap widths and form of energy of ruffle TiO2 except Lu, Y, Yb and Sc, and the order of absorbing wavelengths of RE doped ruffle TiO2 were the same as that of the results of calculation. The ratio of RE dopant was another important factor for the photo catalytic ＇activity of RE doped rutile TiO2, and there was an optimal ratio of dopant. There was a constant for predigesting the calculation difficulty, respectively, which were 0.5mol.% and 100 mol^-1 under supposition. The band gap widths of RE doped rutile TiOz by DFT calculation were much larger than that by experiment. Finally, by transferring the calculation values to experiment values, it could be found and predicted that RE enlarged obviously the absorbing wavelengh of ruffle TiO2. In addition, the degree of RE ions edging out the Ti atom using the parameters of RE dements was computed.展开更多
Baotou Research Institute of Rare Earths(BRlRE)has completed construction of its new 5,000 tpa pilot production line for rare earth functional additives,which has now entered the equipment commissioning phase.The line...Baotou Research Institute of Rare Earths(BRlRE)has completed construction of its new 5,000 tpa pilot production line for rare earth functional additives,which has now entered the equipment commissioning phase.The line is scheduled to begin operation by the end of August and will be capable of producing rare earth heat stabilizers,flame retardants,and specialized PLA-modified polymer materials and products,with a daily capacity of up to 20 tonnes.展开更多
The structural,electronic,and magnetic properties of the Nd-doped Rare earth aluminate,La1-xNdxAlO3（x = 0%to 100%） alloys are studied using the full potential linearized augmented plane wave（FP-LAPW） method within...The structural,electronic,and magnetic properties of the Nd-doped Rare earth aluminate,La1-xNdxAlO3（x = 0%to 100%） alloys are studied using the full potential linearized augmented plane wave（FP-LAPW） method within the density functional theory.The effects of the Nd substitution in La AlO3 are studied using the supercell calculations.The computed electronic structure with the modified Becke–Johnson（m BJ） potential based approximation indicates that the La1-xNdxAlO3 alloys may possess half-metallic（HM） behaviors when doped with Nd of a finite density of states at the Fermi level（EF）.The direct and indirect band gaps are studied each as a function of x which is the concentration of Nddoped La AlO3.The calculated magnetic moments in the La1-xNdxAlO3 alloys are found to arise mainly from the Nd-4f state.A probable half-metallic nature is suggested for each of these systems with supportive integral magnetic moments and highly spin-polarized electronic structures in these doped systems at EF.The observed decrease of the band gap with the increase in the concentration of Nd doping in La AlO3 is a suitable technique for harnessing useful spintronic and magnetic devices.展开更多
We performed ab initio calculations of electronic structure and equilibrium properties for the rare earth superstoichiometric dihydride GdH2.25 （with the space group Pm-3m （No. 221）） using the full-potential linea...We performed ab initio calculations of electronic structure and equilibrium properties for the rare earth superstoichiometric dihydride GdH2.25 （with the space group Pm-3m （No. 221）） using the full-potential linearized augmented plane wave method （FP-LAPW） approach within the density functional theory （DFT） in the generalized gradient approximation （GGA） and local density approximation （LDA） as implemented in the WIEN2k simulation code at 0 K. The equilibrium properties were determined, the density of states, electronic density and the energy band structures were studied in details. It was concluded that the GGA optimized lattice parameter agreed much better with the experimental findings than the LDA one, The non negligible electronic density of states at the Fermi level confirmed that the GdH2.25 had a metallic character. The Fermi energy EF fell at a level where most of the states were rare-earth 5d-eg conduction states while negligible contributions of both interstitial （tetrahedral and octahedral） H s-states were observed near EF, From electronic density, the bonding between Gd and tetrahedral H atoms was of prominent covalency, while was ionic between Gd and octahedral H atoms.展开更多
Rare earth elements （REE） and their compounds years. The bioinorganic chemical research of REE during the are widely applied in agronomic and medical fields for many past few years indicates that REE play important ...Rare earth elements （REE） and their compounds years. The bioinorganic chemical research of REE during the are widely applied in agronomic and medical fields for many past few years indicates that REE play important roles in the promotion of photosynthetic rate as well as root absorption, regulation of hormone and nitrogen metabolism, and suppression of microbes, etc. The metallic or non-metallic targets of key biomolecule in various physiological processes can be chosen by REE for the chelation or replacement, which enables REE to regulate the biological functions or behaviors of those biomolecule and consequently leads to significant embodiment of biological function of REE in plants and microbes. Overdose of REE, however, shows an inhibitory effect on living organisms. Therefore, this paper proposes two suggestions that will be available in the extension of full use of REE＇s biological function. One is to obey the dose law of REE and control REE concentrations within a safe range. The other is to further test the bioaccumulation and long-period influence of REE on organisms.展开更多
文摘Ion beam epitaxy （IBE） technology is a significant method for preparing high pure and high quality rare-earth functional films at low growth temperatue. A new method of preparing rare-earth functional films by ion beam epitaxy was reviewed in details. The recent developments and application of IBE on rare-earth functional films is focused, particularly for high-K materials CeO2, photoluminescence materials Gd2O3 and magnetic semiconductor materials Si1-x Gdx.
文摘The functions of rare earth metals in the automobile emission purification catalysts were reviewed, and it was clarified that with precious metals resources using up gradually emission regulations becoming more and more strict, rare earth metals will play more and more important roles in the high performance, and in low price automobile emission purification catalysts, they can not be substituted by other elements, for example, precious metals.
基金Project supported by the National Natural Science Foundation of China(21571125,21471144)National Key R&D Program of China(2016YFE0114800)the project from State Key Laboratory of Rare Earth Resource Utilization(RERU2016013)
文摘Recently,much attention has been paid to the lanthanide luminescent materials based on the visiblelight sensitization for their potential applications in the fields of bio-imaging and optical devices.In this work,the lanthanide complexes have been covalently bonded to the ordered mesoporous titania（OMT） matrix,and the resulting titania-based hybrid ordered mesoporous materials（named as LnDBOMT,Ln = Eu,Sm,Yb,Nd） were characterized by using Fourier-transform infrared（FT-IR） spectroscopy,small-angle X-ray powder diffraction（SAXD）,N2 adsorption-desorption isotherms,transmission electron microscopy（TEM）,fluorescence spectroscopy,and thermogravimetric analysis.Generally,exciting with visible light is advantageous over UV excitation.Of importance here is that,under excitation with visible light,the LnDB-OMT all show characteristic visible（Eu3＋,Sm3＋） as well as nearinfrared（Sm3＋,Yb3＋,Nd3＋） luminescence of the corresponding Ln3＋ ions（multicolor emission covered from 500 to 1400 nm spectral region）,which is attributed to the energy transfer from the ligands to the Ln3＋ ions via an antenna effect.
文摘Teroolymerization of enichlorohydrin（ECH）-maleic anhydride（MAn）-carbon dioxide（CO;） was carried out by using Y(P;);-Al（i-Bu）;as catalyst for the first time.The terpolymersobtained were characterized by IR and;H-NMR.It was foundthat the composition of the teroolymer was influenced by theaddition mode,initial monomer charge ratio,etc.
基金the Natural Sciences and Engineering Research Council of Canada(NSERC)through Discovery Grant(No.RGPIN-2017-05391).
文摘Functional redundancy in soil microbial communities seems to contradict the notion that individual species have distinct metabolic niches in multi-species communities.All soil microbiota have the metabolic capacity for"basic"functions(e.g.,respiration and nitrogen and phosphorus cycling),but only a few soil microbiota participate in"rare"functions(e.g.,methanogenesis and mineralization of recalcitrant organic pollutants).The objective of this perspective paper is to use the phylogenetic niche conservatism theory as an explanation for the functional redundancy of soil microbiota.Phylogenetic niche conservatism is defined as the tendency for lineages to retain ancestral functional characteristics through evolutionary time-scales.The present-day soil microbiota is the result of a community assembly process that started when prokaryotes first appeared on Earth.For billions of years,microbiota have retained a highly conserved set of core genes that control the essential redox and biogeochemical reactions for life on Earth.These genes are passed from microbe to microbe,which contributes to functional redundancy in soil microbiota at the planetary scale.The assembly of microbial communities during soil formation is consistent with phylogenetic niche conservatism.Within a specific soil,the heterogeneous matrix provides an infinite number of sets of diverse environmental conditions,i.e.,niches that lead to the divergence of microbial species.The phylogenetic niche conservatism theory predicts that two or more microbial species diverging from the same clade will have an overlap in their niches,implying that they are functionally redundant in some of their metabolic processes.The endogenous genetic factors that constrain the adaptation of individuals and,thus,populations to changing environmental conditions constitute the core process of phylogenetic niche conservatism.Furthermore,the degree of functional redundancy in a particular soil is proportional to the complexity of the considered function.We conclude with a conceptual model that identifies six patterns of functional redundancy in soil microbial communities,consistent with the phylogenetic niche conservatism theory.
基金supported by the Public Science and Technology Research Funds Projects of Ocean,State Oceanic Administration of the People’s Republic of China (201005003)the National Natural Science Foundation of China (41230959,41106043,41076030)the National Basic Research Program of China (2007CB815903)
文摘Rare earth elements （REE） compositions and discriminant function were successfully used to examine high resolution sediment source changes in the northern Okinawa Trough over the last 24.1 ka, especially for the influence from the Yellow River and the Tsushima Warm Current （TWC） that has not been well solved. Variations of these parameters were clearly divided into three distinct depositional units. During Interval 1 （24.1-16.0 ka BP）, the paleo-Yellow River and the paleo-Yangtze River mouths were situated near the studied area and could have played major roles in the sedimentation therein. In Interval 2 （16.0-7.3 ka BP）, these river mouths gradually retreated with global sea-level rise, leading to less fluvial inputs from them to the northern Okinawa Trough. Meanwhile, formation of the TWC could carry some sediment loads of Taiwan to the studied core, especially during its late phase （8.0-7.3 ka BP）. Modem oceanographic conditions, with a predominance of the TWC, were finally established since the beginning of Interval 3, causing more ten＇igenous contribution from Taiwan to the studied area. Subsequently, modem depositional environments mainly influenced by the Yellow River, the Yangtze River, and the TWC were finally formed.
基金financially supported by the Natural Science Foundation of Jiangsu Province for Youths (No. BK20130519)Foundation of Jiangsu University (No. 12JDG094)
文摘The microstructures and textures of four rectangular extruded Mg alloys, Mg-3Gd, Mg-3Nd, Mg-1Gd-1Nd and Mg-1.5Gd-1.5Nd（all in wt%） were investigated by using optical microscopy（OM）, X-ray diffraction（XRD） and electron backscatter diffraction（EBSD）. The results demonstrate that the extruded alloys all reveal fully recrystallized microstructure and weak non-basal texture.For textures of the four extruded alloys, it is shown that the basal planes of majority grains tilt away from the sheet plane normal toward the extrusion direction. Compared with two binary alloys, the ternary alloys possess weaker texture strengths. Through orientation distribution function analysis, two types of rare earth textures, {0113} 〈0223〉and {1215} 〈1213〉, were found in the extruded alloys.Texture component {1215} 〈1213〉 is relatively weak, but it plays a critical role in the low texture intensities of two ternary alloys. A pairing effect of Gd and Nd elements has an influence on the texture modification. Additionally,there is a difference in the sensitivities of experimental parameters between the microstructure and texture.
基金Project supported by the National Natural Science Foundation of China ( 20471030 ) the Foundation of State Planning Committee (GFZ040628)
文摘The use of rare earth for inducing plant resistance was reviewed. The important developments in recent years were described, and rare earth can alleviate the pollution of acid rain, ozone, pesticide, heavy metals etc. in environment. The authors suggest that the mechanism of rare earth to inducing plant resistance and reducing plant injury is to control biochemical metabolism web in plant cell, to adjust its protection system of free radical, to maintain its photosynthesis, to protect cell membrane system and to carry through its function on mineral metabolism. Meanwhile some problems in the field were discussed as well.
基金This work was supported by the National Natural Science Foundation of China (20203011)
文摘Quantum density functional theory （DFT） results are reported for the building block [LaL^1（NO3）] of La complex [LaL^1（NO3）]NO3·5H2O （L^1 = （CH3）2CHCH2CH（NCHC4H3O）COO^-）. The structure was optimized and the calculation results show that the lanthanum ion is coordinated by one nitrogen atom and three oxygen atoms of L^1 and two oxygen atoms of nitrate ion. The bond length of La-N is 0.2637 nm and the average length of La-O is 0.2526 nm, which are consistent with the literatures. In addition, the stabilities, electronic structural characteristics and IR spectra of the complex have been analyzed, which describe the coordination of lanthanum ion with other atoms in detail.
基金supported by the Education Commission of Sichuan Province of China (2006A099)the National Defense Basic Research Foundation of China (A3120080126)
文摘The density of states （DOS） of 17 kinds of rare earths （RE） doped rutile TiO2 was by using first-principles density functional theory （DFT） calculation. The band gap widths of RE doped futile TiO2 were important factors for altering their absorbing wavelengths. The results show that RE ions could obviously reduce the band gap widths and form of energy of ruffle TiO2 except Lu, Y, Yb and Sc, and the order of absorbing wavelengths of RE doped ruffle TiO2 were the same as that of the results of calculation. The ratio of RE dopant was another important factor for the photo catalytic ＇activity of RE doped rutile TiO2, and there was an optimal ratio of dopant. There was a constant for predigesting the calculation difficulty, respectively, which were 0.5mol.% and 100 mol^-1 under supposition. The band gap widths of RE doped rutile TiOz by DFT calculation were much larger than that by experiment. Finally, by transferring the calculation values to experiment values, it could be found and predicted that RE enlarged obviously the absorbing wavelengh of ruffle TiO2. In addition, the degree of RE ions edging out the Ti atom using the parameters of RE dements was computed.
文摘Baotou Research Institute of Rare Earths(BRlRE)has completed construction of its new 5,000 tpa pilot production line for rare earth functional additives,which has now entered the equipment commissioning phase.The line is scheduled to begin operation by the end of August and will be capable of producing rare earth heat stabilizers,flame retardants,and specialized PLA-modified polymer materials and products,with a daily capacity of up to 20 tonnes.
基金Project supported by the DST-SERB,Dy(Grant No.SERB/3586/2013-14)the UGCBSR,FRPS(Grant No.F.30-52/2014)+2 种基金the UGC(New Delhi,India)Inspire Fellowship DST(India)the Deanship of Scientific Research at King Saud University(Grant No.RPG-VPP-088)M P Ghimire thanks the Alexander von Humboldt Foundation,Germany for the financial support
文摘The structural,electronic,and magnetic properties of the Nd-doped Rare earth aluminate,La1-xNdxAlO3（x = 0%to 100%） alloys are studied using the full potential linearized augmented plane wave（FP-LAPW） method within the density functional theory.The effects of the Nd substitution in La AlO3 are studied using the supercell calculations.The computed electronic structure with the modified Becke–Johnson（m BJ） potential based approximation indicates that the La1-xNdxAlO3 alloys may possess half-metallic（HM） behaviors when doped with Nd of a finite density of states at the Fermi level（EF）.The direct and indirect band gaps are studied each as a function of x which is the concentration of Nddoped La AlO3.The calculated magnetic moments in the La1-xNdxAlO3 alloys are found to arise mainly from the Nd-4f state.A probable half-metallic nature is suggested for each of these systems with supportive integral magnetic moments and highly spin-polarized electronic structures in these doped systems at EF.The observed decrease of the band gap with the increase in the concentration of Nd doping in La AlO3 is a suitable technique for harnessing useful spintronic and magnetic devices.
文摘We performed ab initio calculations of electronic structure and equilibrium properties for the rare earth superstoichiometric dihydride GdH2.25 （with the space group Pm-3m （No. 221）） using the full-potential linearized augmented plane wave method （FP-LAPW） approach within the density functional theory （DFT） in the generalized gradient approximation （GGA） and local density approximation （LDA） as implemented in the WIEN2k simulation code at 0 K. The equilibrium properties were determined, the density of states, electronic density and the energy band structures were studied in details. It was concluded that the GGA optimized lattice parameter agreed much better with the experimental findings than the LDA one, The non negligible electronic density of states at the Fermi level confirmed that the GdH2.25 had a metallic character. The Fermi energy EF fell at a level where most of the states were rare-earth 5d-eg conduction states while negligible contributions of both interstitial （tetrahedral and octahedral） H s-states were observed near EF, From electronic density, the bonding between Gd and tetrahedral H atoms was of prominent covalency, while was ionic between Gd and octahedral H atoms.
文摘Rare earth elements （REE） and their compounds years. The bioinorganic chemical research of REE during the are widely applied in agronomic and medical fields for many past few years indicates that REE play important roles in the promotion of photosynthetic rate as well as root absorption, regulation of hormone and nitrogen metabolism, and suppression of microbes, etc. The metallic or non-metallic targets of key biomolecule in various physiological processes can be chosen by REE for the chelation or replacement, which enables REE to regulate the biological functions or behaviors of those biomolecule and consequently leads to significant embodiment of biological function of REE in plants and microbes. Overdose of REE, however, shows an inhibitory effect on living organisms. Therefore, this paper proposes two suggestions that will be available in the extension of full use of REE＇s biological function. One is to obey the dose law of REE and control REE concentrations within a safe range. The other is to further test the bioaccumulation and long-period influence of REE on organisms.
