Respondent

Stetskiv Andriy Ostapovych

Theme

Structural  chemistry  of  silicides,  germanides  and  stannides  of alkali and rare earth metals

Annotation

The  thesis  is  devoted  to  the  study  of  general  regularities  and  crystal  chemistry

characteristics of silicides, germanides and stannides of alkali and rare earth metals. As a

result of the research  isothermal sections  of  nine ternary systems of  La,  Tb, Dy}-Li-Si,

{La, Nd}-Li-Ge, {Y, Ce, Eu, Tb}-Li-Sn and parts of thirteen phase diagrams of quaternary

systems of {La, Sm}-Li-Co-Si, Tm-Li-Со-Sn, La-Li-Ni-Si, {La, Pr, Nd}-Li-Ni-Ge, {La,

Tb, Dy, Ho, Er, Tm}-Li-Ni-Sn. 131 ternary and quaternary compounds were synthesized

for the first time. For 122 of these intermetallic compounds crystal structures were fully

defined. They crystallize in 23 known structural types. In the studied and related to them

systems was confirmed the existence of 93 binary and ternary compounds. Parameters of

crystal lattices at different temperatures for 65 of these were specified by X-ray methods.

Formation  of  5  new  structural  types  was  found:  La2 LiGe4 Si2 , Tm2,2Co6Sn20,

TmLi2Co6Sn20,  Ce2Li0,39Ni1,61Si2  and  La2LiAlGe2. For all analyzed ternary systems the same

pattern was observed, the vast majority of the ternary phase is in areas of limited from 30

to 60 at.% content of elements of p-block. It was discovered that increasing the number of components in the system does not increase the number of intermetallic compounds but

causes more prevalent the formation of solid solutions.

Intermetallic compounds were systematized for the first time basing on the concept

of electronic localization as a reason for the formation of chemical bonds. Relying on the

crystallochemistry analysis it was found that most of the synthesized compounds through

primary metallic bonds have other bonds, for example covalent or ionic. It was established

that  the  ionization  of  atoms  can  lead  to  the  formation  of  structures  with  monatomic

cations/anions, polyatomic  polycations/polyanions, and structures with  layers of 2D and

3D  polycations/polyanions.  For  some  of  the  compounds  general  process  of  lithiation,

parameters  of  hydrogen  sorbtion  and  discharge  capacity  were  studied.  Some  of  the

synthesized  compounds  are  recommended  to  use  as  anode  materials  for  metal  hydride

power  sources  with  high  energy  capacitance,  absorbent  materials  for  hydrogen  storage,

electrode materials for lithium-ion batteries.

Key  words:  intermetallic  compounds,  alkali  metals,  rare  earth  metals,  phase

diagram,  isothermal  section,  crystal  structure,  coordination  of  atoms,  physical  and

chemical properties.

Defence Date

15.06.2017

Dissertation File

Autosummary File