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In this work the physical properties of the piezoelectric aluminum-scandium nitride (ASN) solid solution as a function of scandium concentration were studied using the density functional theory and experimental methods. The phase transition from the wurtzite phase to the rock salt phase at a Sc concentration of 43% was shown. The barriers of transformation from the wurtzite phase to the rock salt phase for various Sc concentrations were obtained. The behavior of the ASN piezoelectric constant d33 calculated by the piezoelectric constants e33, e31, and e15 shows a sharp increase with increasing Sc concentration compared to aluminum nitride AlN. The relationship between the increase in the piezoelectric response of ASN and the softening of the lattice, accompanied by a decrease in the main elastic constants C11, C33, C44 and C66, as well as a decrease in the c/a ratio with increasing Sc concentration, is shown. ASN films with a predominance of the crystal orientation (00·2) were obtained experimentally by magnetron sputtering. The structural properties of the films were studied by X-ray diffraction analysis. A comparison of the experimentally obtained dependence of the c/a ratio on the Sc concentration with the theoretical values showed a good correspondence. Studies of the physical properties of ASN thin films were performed using microwave multi-overtone composite resonators on diamond substrates with a longitudinal bulk acoustic wave (BAW) as the operating mode in the range of 0.5 – 20 GHz. The frequency dependences of the Q-factor of BAW-resonators with different ASN films were obtained, and the frequency dependences of the square of the modulus of the form factor as |m|2 were calculated. The dependences of the elastic constant С33 and the piezoelectric constant e33 for the ASN films with different Sc concentrations were calculated. The calculated and measured values of these constants are agreed within the experimental error.

We report the results of first-principles total-energy calculations for structural properties of scandium nitride (ScN) semiconductor compound in NaCl-type (B1), CsCl-type (B2), zincblende-type (B3), wurtzite-type (B4), NiAs-type (B81), CaSi-type (Bc), B-Sn-type (A5), and CuAu-type (L10) structures. Calculations have been performed with the use of the all-electron full-potential linearized augmented plane wave FP-LAPW method based on density-functional theory (DFT) in the generalized gradient approximation (GGA) for the exchange correlation energy functional. We predict a new phase transition from the most stable cubic NaCl-type structure (B1) to the B-Sn-type one (A5) at 286.82 GPa with a direct band-gap energy of about 1.975 eV. Our calculations show that ScN transforms from the orthorhombic CaSi-type structure (Bc) to A5 at 315 GPa. In agreement with earlier ab initio works, we find that B1 phase transforms to Bc, L10, and B2 structures at 256.27 GPa, 302.08 GPa, and 325.97 GPa, respectively. The electronic structure of A5 phase shows that ScN exhibits a direct band-gap at X point, with Eg of about 1.975 eV., Представлено результати повноенергетичних розрахункiв з перших принципiв структурних властивостей напiвпровiдника нiтриду скандiю (ScN) в структурах типу NaCl (B1), CsCl (B2), сфалериту (B3), вюрциту (B4), NiAs (B81), CaSi (Bc), B-Sn (A5), i CuAu (L10). Розрахунки виконано багатоелектронним повнопотенцiальним методом лiнеаризованих приєднаних плоских хвиль, заснованим на теорiї функцiонала густини в наближеннi узагальненого градiєнта для функцiонала обмiнної кореляцiйної енергiї. Передбачено новий фазовий перехiд iз найбiльш стабiльної кубiчного типу NaCl структури (B1) в структуру типу B-Sn (A5) при тиску 286,82 ГПа з величиною прямозонної щiлини близько 1,975 еВ. Ми показали, що ScN перетвориться з орторомбiчного типу CaS структури (Bc) в A5 при 315 ГПа. Вiдповiдно до вiдомих ab initio розрахункiв, ми знайшли, що B1 фаза переходить у Bc, L10 та B2 структури при 256,27 ГПа, 302,08 ГПа i 325,97 ГПа, вiдповiдно. Електронна структура фази A5 показує, що ScN має прямозонну щiлину в X точцi з Eg близько 1,975 еВ.

Magnetic tunnel junctions (MTJs) show great promise for implementation in high-performance STT-MRAM and novel computing regimes such as magnetic logic and neuromorphic computing. However, a handful of material setbacks stand in the way of the adoption of leading MgO MTJs over other emerging technologies, such as Resistive-RAM junctions, in next-generation architectures. Here, we explore the properties of iron / scandium nitride (ScN) magnetoresistive junctions using density functional theory (DFT) and find ScN a promising barrier material given its novel electron symmetry filtering properties, high TMR, and low RA-product. Magnetoresistance ratios exceeding 1900% are enabled by Δ2’ symmetry filtering through the barrier, in addition to the traditional Δ1 symmetries observed in MgO MTJs. The electronic properties of the diffusive Fe/ScN interface are resolved, with predicted half-metallicity that could amplify MR in realistic low-power ScN devices.

This paper reports a 2.3 GHz wideband acoustically coupled filter with large bandwidth reconfigurability realized in ferroelectric aluminum-scandium-nitride (Al 0.7 Sc 0.3 N) films. Benefiting from large electromechanical coupling of the Al 0.7 Sc 0.3 N film, bandwidths ∼3-times larger compared to state-of-art AlN acoustically coupled counterparts are achieved Furthermore, for the first time, we are demonstrating the use of the recently discovered ferroelectricity in Al 1-x Sc x N films (x>27%) for large bandwidth tuning of the filter. The acoustically coupled filter architecture provides superior characteristics compared to conventional electrically coupled filters (i.e. lattice, ladder, etc.) including the lithographical bandwidth definition through proper IDT patterning, and realization of the filter within a single / monolithic structure. Here $1\mu \mathrm{m}$ -thick Al 0.7 Sc 0.3 N films are acoustically engineered to implement 2.3 GHz filters with −3dB bandwidths (BW −3dB ) over 70-117 MHz are demonstrated with an insertion loss of −6dB (dominated by the routing line resistance). Large tuning of 15 MHz (∼15%) is achieved through application of ∼60 volts, DC, using a bias-tee. Such high-performance filters enable realization of reconfigurable RF front-end for emerging multi-band wireless systems that require extensive compatibility with a wide variety of communication standards in the forthcoming 5G landscape.

Thermodynamic properties of lead species in aqueous solution are collected. The chemical equilibria between various forms of Pb(II) are considered. The speciation diagrams for the equilibria 4[PbOH]+(aq) ⇄ [Pb4(OH)4]4+(aq) and 2[Pb3(OH)4]2+(aq) ⇄ [Pb6(OH)8]4+(aq), and the thermodynamic activity - pH diagram of Pb(II) species are plotted. Basic chemical and electrochemical equilibria for lead are calculated. The potential - pH diagram for Pb - H2O system is revised.

ScN films were grown on MgO(110) substrates and α-Al 2 O 3 ( 10 1 ¯ 0 ) substrates by a molecular beam epitaxy method, and their crystalline orientation, crystallinity, and electric properties were examined. (110)-oriented ScN films were epitaxially grown on MgO(110) substrates with the same crystal orientations, and ScN films with an orientation relationship (110)ScN || ( 10 1 ¯ 0 )α-Al 2 O 3 and [001]ScN || [ 1 2 ¯ 10 ]α-Al 2 O 3 were epitaxially grown on α-Al 2 O 3 ( 10 1 ¯ 0 ) substrates. Remarkably, electric-resistivity anisotropy was observed for ScN films grown on MgO(110) substrates, and the anisotropy depended on the growth temperature. The carrier concentration and Hall mobility of the ScN films grown on α-Al 2 O 3 ( 10 1 ¯ 0 ) substrates ranged from 10 19 –10 21 cm -3 and 10–150 cm 2 V -1 s -1 , respectively. The crystallinity, crystalline-orientation anisotropy, and electric properties of the films were strongly affected by growth conditions. For the growth of ScN films with high mobility on α-Al 2 O 3 ( 10 1 ¯ 0 ) substrates, a high temperature and an appropriate ratio of source materials were necessary.

Aluminum scandium nitride (Al1−xScxN/AlScN) (x = 0.32) Lamb wave resonators (LWR) have been fabricated and tested to demonstrate electromechanical coupling coefficients (kt2) in excess of 10%. The resonators exhibited an average kt2 and unloaded quality factor (Qu) of 10.28% and 711, respectively, when calculated from the measured data. Applying the Butterworth Van-Dyke (BVD) model to the measured data enabled the extraction of the resonator's lumped element parameters to calculate the motional quality factor (Qm), which neglects the contributions of the electrical traces. For the best measured resonator response, results from the BVD model showed a Qm of 1184 and a resulting figure-of-merit (FOM = K2 · Qm) of 100. Comparing the response of similar AlScN and AlN resonators shows that the AlScN LWR has a significantly lower motional resistance (Rm), suggesting that AlScN has a strong potential for use in piezoelectric microelectromechanical oscillators.

Scandium nitride (ScN) films were grown on &alpha, Al2O3( 1 1 &macr, 02 ) substrates using the molecular beam epitaxy method, and the heteroepitaxial growth of ScN on &alpha, 02 ) and their electric properties were studied. Epitaxial ScN films with an orientation relationship (100)ScN || ( 1 1 &macr, 02 )&alpha, Al2O3 and [001]ScN || [ 11 2 &macr, 0 ]&alpha, Al2O3 were grown on &alpha, 02 ) substrates. Their crystalline orientation anisotropy was found to be small. In addition, [100] of the ScN films were tilted along [ 1 &macr, 101 ] of &alpha, 02 ) in the initial stage of growth. The tilt angle between the film growth direction and [100] of ScN was 1.4&ndash, 2.0&deg, and increased with growth temperature. The crystallinity of the ScN films also improved with the increasing growth temperature. The film with the highest Hall mobility was obtained at the boundary growth conditions determined by the relationship between the crystallinity and the nonstoichiometric composition because the film with the highest crystallinity was obtained under the Sc-rich growth condition. The decreased Hall mobility with a simultaneous improvement in film crystallinity was caused by the increased carrier scattering by the ionized donors originating from the nonstoichiometric composition.

Scandium nitride (ScN) films were grown on α-Al₂O₃( 1 1 ¯ 02 ) substrates using the molecular beam epitaxy method, and the heteroepitaxial growth of ScN on α-Al₂O₃( 1 1 ¯ 02 ) and their electric properties were studied. Epitaxial ScN films with an orientation relationship (100)ScN || ( 1 1 ¯ 02 )α-Al₂O₃ and [001]ScN || [ 11 2 ¯ 0 ]α-Al₂O₃ were grown on α-Al₂O₃( 1 1 ¯ 02 ) substrates. Their crystalline orientation anisotropy was found to be small. In addition, [100] of the ScN films were tilted along [ 1 ¯ 101 ] of α-Al₂O₃( 1 1 ¯ 02 ) in the initial stage of growth. The tilt angle between the film growth direction and [100] of ScN was 1.4⁻2.0° and increased with growth temperature. The crystallinity of the ScN films also improved with the increasing growth temperature. The film with the highest Hall mobility was obtained at the boundary growth conditions determined by the relationship between the crystallinity and the nonstoichiometric composition because the film with the highest crystallinity was obtained under the Sc-rich growth condition. The decreased Hall mobility with a simultaneous improvement in film crystallinity was caused by the increased carrier scattering by the ionized donors originating from the nonstoichiometric composition.

Ferroelectrics are a class of materials that possess a variety of interactions between electrical, mechanical, and thermal properties that have enabled a wealth of functionalities. To realize integrated systems, the integration of these functionalities into semiconductor processes is necessary. To this end, the complexity of well-known ferroelectric materials, e.g., the perovskite class, causes severe issues that limit its applications in integrated systems. The discovery of ferroelectricity in hafnium oxide-based materials brought a renewed interest into this field during the last decade. Very recently, ferroelectricity was also verified in aluminum scandium nitride extending the potential of seeing a wealth of ferroelectric functions in integrated electronics in the future. This paper discusses the prospects of both material systems in various applications.

Reduction of scandium nitride clusterfullerene, Sc3N@Ih-C80, by sodium fluorenone ketyl in the presence of cryptand[2,2,2] allows the crystallization of the {cryptand[2,2,2](Na(+))}2(Sc3N@Ih-C80(-))2·2.5C6H4Cl2 (1) salt. The Sc3N@Ih-C80˙(-) radical anions are dimerized to form single-bonded (Sc3N@Ih-C80(-))2 dimers.

An analytical approach is presented that allows one to determine the influence of the scandium concentration on the input electrical impedance of piezoelectric transducer based on aluminum scandium nitride. The scandium concentration dependences of the properties aluminum scandium nitride affecting on the transducer impedance were determined by means of the approximation of the dependences obtained from their experimental values for various Sc concentration. Based on the frequency dependences of the impedance the influence of Sc concentration in Al1-xScxN piezoelectric layer on the frequencies of the serious and parallel resonance of the unloaded and loaded transducer has been established.

The internal clusters in metallofullerenes usually exhibit certain motion that is potentially usable in molecular gyroscopes and nano-machines. Based on (45)Sc NMR, the motion of the scandium nitride cluster within the C80 cage was investigated via varying the temperature and modifying the cage, and by changing the cluster size.

Aluminium scandium nitride (Al 1−x Sc x N) with its strongly enhanced piezoelectric response is the upcoming piezoelectric material of choice in next generation RF filters, sensors, actuators and energy harvesting devices. This paper will concentrate on the deposition technology for Al 1−x Sc x N films with high Sc content. Films with Sc concentrations close to 43 at% have been grown on 200-mm substrates using a cluster type sputter deposition tool. The piezoelectric response will be discussed and correlated with the deposition parameters and film structural properties. The steps required to deliver a high-volume production solution for high Sc concentration will be described.

A self-assembled Cu II -based nanocapsule enables efficient and straightforward isolation of Sc 3 N@C 80 from arc-processed raw soot. The newly designed Cu II -based supramolecular nanocapsule 5⋅(OTf) 8 was used to effectively entrap fullerenes and endohedral metallofullerenes (EMFs) with different affinities depending on their size and shape. Moreover, we took advantage of the sharply different entrapment abilities of the 5⋅(OTf) 8 cage in the solid state versus in solution to encapsulate all the species with the exception of Sc 3 N@C 80 (both I h and D 5h isomers), which remains pure in solution. HPLC quantification determined that up to 85 % of the total Sc 3 N@C 80 content in the initial mixture was recovered in very high purity ( > 99.5 %). The complete release of the encapsulated species with an orthogonal solvent-washing strategy regenerates 5⋅(OTf) 8 ready to be re-used. This approach opens new opportunities for EMFs purification We acknowledge financial support from MINECO-Spain for project CTQ2013-43012-P to X.R., CTQ2013-50306-EXP to M.C., and 2014 SGR 862 to M.C. L.E. thanks the US National Science Foundation (NSF) for generous support of this work under the NSF-PREM program (DMR-1205302) and CHE-1408865

Sputter deposited aluminum nitride (AlN) thin films have played a central role for the successful development of the thin film electro-acoustic technology. The development has been primarily driven by one device—the thin film bulk acoustic resonator, with its primary use for high frequency filter applications for the telecom industry. Recently, increased piezoelectric properties in AlN through the alloying with scandium nitride have been identified both experimentally and theoretically. This opens up new possibilities for the thin film electro-acoustic technology. Here expectations and discussions are presented on acoustic FBAR sensor performance when based on AlN as well as on such AlN alloys to identify possible benefits and limitations. Inhere, the distinction is made between direct and in-direct (acoustic) use of the piezoelectric effect for sensor applications. These two approaches are described and compared in view of their advantages and possibilities. Especially, the indirect (or acoustic) use is identified as interesting for its versatility and good exploitation of the thin film technology to obtain highly sensitive sensor transducers. It is pointed out that the indirect approach can well be obtained internally in the piezoelectric material structure. Original calculations are presented to support the discussion.

Piezoelectric c-textured Al(1−x)ScxN thin films, where the Sc relative concentration, x, varies in the range 0–0.15 have been studied in view of radio frequency (RF) electro-acoustic applications. Thin film bulk acoustic wave resonators (FBARs) employing these films were fabricated and characterized as a function of the Sc concentration for the first time. The measured electromechanical coupling is found to increase by as much as 100% in the above concentration range. The results from this work underline the potential of the c-textured Al(1−x)ScxN based FBARs for wide band RF applications.

Three coordination complexes of Co(II)/Fe(II) with 4,4′-trimethylenedipyridine (bpp) and pseudohalides (SCN−, SeCN− and N3−) have been synthesized. The complexes have been characterized by X-ray single crystal structure determination. They are isomorphous having 2D layers in which two independent wavy nets display parallel interwoven structures. Pseudohalide binds metal centers through N terminal and occupies the trans axial positions of the octahedral metal coordination environment. Pseudohalide remains pendant on both sides of the polymeric layer and help the stacking through hydrogen bonding. The conformation of bpp in the interpenetrated nets is observed to be dependent on the choice of pseudohalide.

Defect-selective etching was developed for scandium nitride (ScN) crystals. ScN crystals were etched in fused KOH/NaOH eutectic mixtures between 180 and 440 °C for up to 10 min. Several etch pit shapes were observed, and their formation was dependent on the etching temperature. The different etch pit shapes probably originated from different crystalline orientations and defect types. Square etch pits with steps formed at screw and mixed dislocations, as verified by transmission electron microscopy. The density of the etch pits was on the order of 104–106 cm−2 for bulk ScN crystals produced by sublimation.

For n-type metal–oxide–semiconductor (NMOS) devices, a metal gate with a very low effective work function (Φm,eff) is necessary. In this paper, we evaluate the Φm,eff values of ScNx gates on both SiO2 and atomic-layer-deposited (ALD) HfO2. The ScNx/SiO2 samples have a wide range of Φm,eff values from ~3.9 to ~4.7 eV. However, the ScNx gates on HfO2 show a relatively narrow range of Φm,eff values from ~4.5 to ~4.8 eV due to the Fermi level pinning (FLP) effect. The generation of oxygen vacancies may result in the extrinsic FLP near the ScNx/HfO2 interface. Therefore, ScNx is an NMOS-compatible electrode on SiO2 and the extrinsic FLP should be suppressed for NMOS devices with HfO2.

8 pages; International audience; The hetero valence copper-based metal-organic framework structure {[CuII2(μ-L)(μ-H2O) 3H2O][CuI- (1,3-NCS)2]}n (2) was constructed from the aqua-bridged [Cu2] complex [Cu2(μ-L)(μ-H2O)]ClO4 3 1.5H2O (1 3 1.5H2O) of the N4O3 coordinating heptadentate imidazolidinyl phenolate Schiff base ligand, H3L (2-(20hydroxyphenyl)-1,3-bis[4-(2-hydroxyphenyl)-3-azabut-3-enyl]-1,3-imidazolidine). Thiocyanate coordination induced aqua bridge cleavage and reductive extrusion lead to the formation of Cu(NCS)2 - anions as a molecular building block and generation of one-dimensional (1D) anionic chains as an extended coordination framework host in 2 and quantitatively replace all the ClO4 - ions from 1 3 1.5H2O via anion metathesis. Once formed these chains trap the original [Cu2] cationic units in a layer. The copper atoms of 2 are in a distorted square-pyramidal environments around copper ions and are held together by phenolate, imidazolidinyl, and aqua bridges at 3.29 A ° intrametallic CuII 3 3 3 CuII separation. Within the anionic part the presence of two “symmetric” end-to-end thiocyanate bridges with CuI-SCN and CuI-NCS distances of 2.61 A ° (av.) and 1.924 A ° (av.), respectively, results in a CuI 3 3 3 CuI separation of 5.51 A ° (av.) within the linear chain. The cationic part of 2 exhibits a weak ferromagnetic exchange interaction (J/kB=þ13.0(5) K or J=þ9.0 cm-1 and g=2.25(1)) between the two CuII ions (S=1/2) and implies that the complex possesses an ST=1 spin ground state in good agreement with theMvs H data below 8 K.

Endohedral metallofullerenes (EMF) have attracted increasing attention during past decades for their potential applications in the fields of biomedicine and nanomaterials. Trimetallic nitride template endohedral metallofullerenes (TNT EMFs) are some of the most promising fullerene-based materials (e.g., as MRI and X-ray contrast agents) because of their high yields compared to classic endohedral metallofullerenes. This dissertation addresses the chemical reactivity and regioselectivity of TNT EMFs. Based on the extraordinarily high stability of TNT EMFs relative to empty cage fullerenes and classic endohedral metallofullerenes, macroscopic quantities of high purity TNT EMFs were obtained directly from crude soot in a single facile step by using a cyclopentadiene-functionalized resin to trap the more reactive species via Diels-Alder reactions, allowing the TNT EMFs to pass through. We also developed a support-free chemical separation method of TNT EMFs from Sc- and Lu-based soot extract that makes use of the differing solubilities of unreacted TNT EMFs versus 9-methylanthracene-derivatized empty cage fullerenes. The exohedral functionalization of metallofullerenes can fine-tune their chemical and physical properties. The first N-methylpyrrolidino derivatives of TNT EMFs (Ih Sc3N@C80 and Ih Er3N@C80) were synthesized via 1,3-dipolar cycloaddition of N-methylazomethine ylides (Prato reaction). The demonstration of planar symmetry in the N-methylpyrrolidino derivatives by 13C NMR spectroscopy suggested that the reaction exclusively took place at the 5,6-ring junction. However, both 5,6-ring and 6,6 ring junction adducts were obtained when Ih Sc3N@C80 reacted with N-triphenylmethyl-5-oxazolidinone, as characterized by NMR spectroscopy and X-ray crystallography. The kinetically favored 6,6-ring junction adduct was converted to the thermodynamic product, the 5,6-ring junction adduct, upon thermal equilibration. The synthesis of pyrrolidino derivatives was also extended to two other Sc-based TNT EMFs, D5h Sc3N@C80 and Sc3N@C78. The reactivity and regioselectivity of D5h Sc3N@C80 and Sc3N@C78 were demonstrated by NMR spectroscopy, X-ray crystallography and theoretical calculations. Another type of reaction, the Bingel-Hirsch cyclopropanation was carried out with D3h Sc3N@C78 for the first time, yielding a single Cs-symmetric monoadduct and a dominant C2v-symmetric diadduct for the first time. The symmetric diadduct clearly demonstrates the remarkable regioselectivity control exerted by the encapsulated Sc3N cluster. We employed a LUMO electron density surface computational approach to predict multiadduct docking sites on the ellipsoidal fullerene cage surface. We also successfully synthesized the first derivative of a non-IPR fullerene, the diethyl malonate derivative of Sc3N@C68 by a Bingel-Hirsch reaction. The reactivity and regioselectivity of Sc3N@C68 were investigated by NMR spectroscopy and theoretical calculations. Ph. D.

The scandium dimer reacts with dinitrogen in solid argon to form the previously characterized planar cyclic Sc(mu-N)2Sc molecule, with the N-N bond being completely cleaved. The cyclic Sc(mu-N)2Sc molecules dimerize on annealing to form a cubic Sc4N4 cluster with tetrahedral symmetry, which is a fundamental building block for ScN nanoparticles and crystals.

Two electrochemical oxidation waves assigned to the D(5h) isomer of Sc(3)N@C(80) have been identified, and a 270-mV difference in the first electrochemical oxidation potentials of the I(h) and D(5h) isomers has been measured. On the basis of this oxidative potential difference, a strategy for isomeric purification involving a selective chemical oxidation of the D(5h) isomer is reported. Variable scan cyclic voltammetry of the resultingly pure Sc(3)N@C(80) I(h) isomer shows evidence of a rapid endohedral chemical reaction following the first reduction process.

This dissertation addresses the exohedral cage functionalization and potential applications of the Sc₃N@C₈₀ and Sc₃N@C₇₈ trimetallic nitride endohedral metallofullerenes. In addition, this dissertation discusses miscellaneous research that is relevant to the aformentioned metallofullerenes and their applications, such as the discovery of a new cage isomer (D5h) of Sc₃N@C₈₀, the synthesis of Lu₃N@C₈₀ as a novel X-ray contrasting agent, and the synthesis of Sc₃¹⁵N@C₈₀ with ¹⁵N₂ gas. The first derivative of Sc₃N@C₈₀ was synthesized by functionalizing the exterior of the cage via a [4 + 2] cycloaddition reaction with a ¹³C-labeled intermediate. Addition occurred across the [5,6] ring-juncture of the cage to form a mono-adduct, which has a mirror plane of symmetry as observed from the time-averaged ¹³C NMR spectrum. The structure of the mono-adduct was confirmed by X-ray crystallography. Diethyl and dibenzyl malonate adducts of Sc₃N@C₈₀ were synthesized, in addition to a ¹⁵N-labeled terminal amine derivative. Water-soluble metallofullerenols, Sc₃N@C₈₀(OH)~10(O)~10, were synthesized from polyanionic intermediates. The Sc₃N@C₇₈ metallofullerene was derivatized with a ¹³C-labeled reagent to afford mono-, di- and tri-adducts. A single structural isomer of the mono-adduct was found, while several isomers of the di- and tri-adducts were observed by HPLC. ¹³C and ¹H NMR data of the mono-adduct support a structure that results from addend addition to an asymmetric site on the C₇₈ carbon cage. The HPLC isolation and characterization of Lu₃N@C₈₀ is discussed. When irradiated with X-rays, Lu₃N@C₈₀ provided a small level of contrast that can only be attributed to the large atomic number (Z) of the lutetium atoms. Mixed-metal species that contains gadolinium and lutetium or holmium and lutetium could be employed as multifunctional contrasting agents for X-ray, MRI and radiopharmaceuticals, thereby eliminating the need for three separate agents. A new cage isomer of the Sc₃N@C₈₀ metallofullerene was synthesized and partially isolated by HPLC. This carbon cage possesses D5h symmetry, as indicated by the time-averaged six line ¹³C NMR spectrum with a 1:2:2:1:1:1 ratio. The internal metal-nitride cluster of Sc₃N@C₈₀ was synthesized with a ¹⁵N-label for studying the motion(s) of the cluster (within the carbon cage) at various temperatures using ¹⁵N NMR spectroscopy. Ph. D.