In the last few years, the structure and properties of
doped LM have been the objective of much research.
The substitution of sodium, potassium, rubidium, cal
cium, strontium, barium, bismuth, and rareearth ele
ments for lanthanum, as well as vanadium, tungsten,
chromium, niobium, and tantalum for molybdenum,
has been reported [2–5]. At a certain concentration,
many of these additives, especially those substituting
for lanthanum, suppress the β → α transition and sta
bilize the cubic phase at room temperature. It is
kn