Scandium borides

ScB2 scandium boride 12007-34-0 25,00 3.1700 1 4481 SrCI2H1206 strontium chloride hexahydrate 10025-70-4 25.00 1. youu ... 

We have performed ab initio calculations on the diatomic molecule scandium boride cation, ScB", determining the electronic structure both of its ground state and of a series of low-lying excited states. 

The structures of many binary and ternary scandium borides and carbides may be deducted from other structure types by a multiple substitution of larger atoms by B-B or C-C pairs or by the inclusion of B or C atoms into the cavities of the parent structure types. The same is valid for the structures of scandium intermetallics with the 6B elements. The Ti7Si2, NiAs, ErAgSc2 and Al2Mg04 structure types can be obtained by an inclusion of cations of metals into the octahedral and tetrahedral cavities of different packings (usually close ones) of 6B anions. Frequently the inclusion of atoms causes a distortion of the parent close-packed structure. 

The ternary Sc-Ni phases observed are in accordance with literature data ScNis (CaCuj-type), ScjNi, (Ce2Ni7-type), ScNiz (MgCuj-type), ScNi (CsCI-type) and ScjNi (TijNi-type). For a discussion of nickel and scandium borides, see Y-Ni-B and Sc-Co-B, respectively. 

Co2B dicobalt boride [12045-01-1] ">1285 ScB6 scandium hexaboride [12785-49-8] ... 

It has been reported that ScBi2 has a tetragonal modification of the UBi2-type structure with lattice parameters of a = 5.22 A and c = 7.35 A with the space group of I4/mmm (Hamada et al., 1993 Paderno and Shitsevalova, 1995). Due to the small size of scandium as compared to the other rare earth atoms, scandium phases have been observed to form anomalous higher boride structures compared to the heavy lanthanides and yttrium, as will be discussed later in Sections 9 and 11. Small amounts of metal replacement for Sc in Sci xMxBi2 (x as small as 0.1, M = Y, Tm, Lu) have been reported to stabilize the structure in the normal cubic UBi2-type. 

TABLE 10 Crystallographic data of scandium higher borides... 

As noted in previous sections, the scandium phases of compounds have sometimes been observed to have different structures compared to the other rare earths, because of the relatively small size of scandium. The scandium higher borides have been found to be a particular fertile ground for the formation of new higher boride structures. 

As noted in the previous Section 3.1.4 on dodecaborides, the scandium phase of a series of rare earth compounds sometimes take different structures because of the small size of scandium compared to the other rare earths. Various scandium higher borides have been observed that do not form for other rare earth phases, One such phase is the ScBi9 compound, which is tetragonal (space group P41212 or P4i2 2). It is isostractural with the structure type a-AlBn. 

Transition temperatures (in K) of scandium substituted ternary borides. 

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