When concentrating 1-3, part of the initial substance remains un-recrystallized, but when concentrating more than 5, a formation takes place besides the eulytite of crystalline phase with sillenite structure. The temperature is sufficient for the synthesis to be successful. That is why research works on higher temperature materials have not been carried out.
Here are a few suggestions for editing your translation:
"When concentrating 1-3, part of the initial substance remains un-recrystallized, but when concentrating more than 5, a formation takes place besides the eulytite of crystalline phase with sillenite structure. The temperature is sufficient for the synthesis to be successful. That is why research works on higher temperature materials have not been carried out."
Let me know what you think and once the edits are done I will set a poll.
At concentrations 1-3, ..., but at concentrations ...., in addition to eulytite the formation of crystalline phase with sillenite structure takes place.
As this translation is too literary, I propose suggestion for improving translation: When concentrations reach levels 1-3, some part of initial substance does not rest recrystallized, however when concentration reaches level 5 and more...
The initial text is too hard for understanding, if translator is not skilled in chemistry. I admit even Russian people do not catch the idea behind phrase "оиÑходит образование помимо Ñвлитина криÑталличеÑкой фазы...", as it can be understood as specific substance at crystalline phase (1) or that crystalline phase is byproduct (2).