Valery Ioffe wrote:

The basic idea is that we try to find some materials in which bosonic
ions with sufficiently small effective mass are used as charge
carriers instead of Cooper’s pairs in order to provide high
temperature ionic superconductivity.

Unclear on the concept.

Among single-charged ions comprising ionic crystals only lithium
isotope Li6 can be used for that purpose.

[snip]

The results show that Bose-condensation temperature for Li6-ions is
of the order of 10-9K in all crystals.

[snip]

No ionic mobilty, either. Optical cutoff at 11.7 eV, 106 nm.

If, however, the crystal is
compressed so that the wave functions of neighboring lithium ions are
sufficiently overlapped, then Bose-condensation temperature of
Li6-ions can be increased significantly. Our estimates show that
compressing the crystals by 16% in all three directions one can rise
the Bose-condensation temperature in all crystals considered to above
room temperature.

That is plain silly. First, your approximations will break down long
before your diamond anvil cell cracks. Second, LiF is not a great
choice for being a compressible solid.

Proc. Phys. Soc. A 64 276-282 (1951)

Taking into account the well-developed semiconductor heteroepitaxial
technologies this high compression (in two dimensions) can be
accomplished in practice by MBE-growing the short-period
strained-lattice superlattices from very thin (several monolayers)
layers of corresponding ionic crystal interdisposed by relatively
thick layers of thoughtfully-chosen solid alloys. More information can
be found at the site: www.v-ioffe.ru.

Extraordinary claims require extraordinary proof. LiF has a lattice
constant of 4.026 A or a unit cell volume of 65.26 A^3. Where will
you find a smaller lattice to compress that 16% in each direction?
What will give you ion mobility?

You might have a chance with compressible (Li-6)D (cubic; a=4.0752,
293 K, z=4),

Acta Cryst. B 42 131 (1986)

or use your heads and (Li-6)3N (hexagonal; a = 3.646 A, c = 3.874 A at
233 K),

Acta Cryst. A38 568 (1982)
Acta Cryst. A37 507 (1981)
Acta Cryst. A36 390 (1980)
Acta Cryst. A35 309 (1979)
Acta Cryst. A34 999 (1978)
Phys. Rev. Lett. 54 1192 (1985)
Phys. Rev. B 17 884 (1978)

as ionic conductor. Lithium nitride is already 46 vol-% compressed
(13.5% linear average) vs. LiF, 44.599 A^3 unit cell vs. 65.26 A^3.
Count the number of lithium ions in each unit cell. Li3N is within
your stated lithium density needs and it is an intrinsic ionic
conductor. Is (Li-6)3N a room temperature bosonic supercon?

A mountain to a physicist is a mole hill to a chemist. Hey gits - you
don't make things (pompous engineers) until you have stuff (lab *****
chemists).