SYNTHESIS AND RADIOGRAPHY OF NEW ZIRCON-MANGANITES OF LANTHANUM AND ALKALINE EARTH METALS AND CALCULATION OF THEIR THERMODYNAMIC PROPERTIES

Annotation. The synthesis of LaMeIIZrMnO6 compounds (MeII – Mg, Ca, Sr, Ba) was carried out using ceramic technology in the range of 800-1200оС by the interaction of lanthanum (III) oxides of the " extra clean." qualification, zirconium (IV), manganese (III) and magnesium, calcium, strontium and barium carbonates of the " clean for analysis " brand.". The weights of the starting materials were weighed with an accuracy of up to the fourth decimal place. Stoichiometric amounts of the starting materials were carefully ground in an agate mortar, then poured into alund crucibles and subjected to heat treatment for solid-phase interaction in air in the "SNOL" furnace. X-ray methods have established that all synthesized zircon-manganites crystallize in cubic symmetry with the following lattice parameters: LaMgZrMnO6 – а = 13,46 ±0,02 Å; V0 = 2437,86 ±0,05 Å3; Z = 4; V° elem cell = 609,47 ± 0,02 Å3; r x-ray = 4,42 g/сm3; r picn = 4,35 ± 0,07 g/сm3; LaCaZrMnO6 – а = 14,50 ± 0,02Å; V0 = 3048,63 ± 0,06 Å3; Z = 4; V° elem cell = 762,16 ± 0,02 Å3; r x-ray = 3,67 g/сm3; r picn = 3,62 ± 0,05 g/сm3; LaSrZrMnO6 – а = 14,56 ± 0,02 Å; V0 = 3087,52 ±0,06 Å3; Z = 4; V° elem cell = 771,88 ± 0,02 Å3; r x-ray. = 4,03 g/сm3; r picn.= 3,99 ± 0,04 g/сm3, LaBaZrMnO6 – а = 14,79 ± 0,02Å; V0 = 3233,45 ± 0,06 Å3; Z = 4; V° elem cell = 808,36 ± 0,02 Å3; r x-ray = 4,25 g/сm3; r picn= 4,19 ± 0,05 g/сm3. It was found that with an increase in the ionic radii in the Mg® Ca®Sr®Ba series, the values of the parameter "a", the volumes of lattices and elementary cells of zircono-manganites increase. The calculation of the temperature dependence of the heat capacity and the standard heat capacity by indirect methods is carried out. The equations of temperature dependences of the investigated zircon-manganites of lanthanum and alkaline earth metals are derived.