Phase transition and dielectric properties of Li2-x NaxGe4O9 crystals (0.2 ≤ x ≤ 0.3)

Specific heat anomalies in ferroelectrics LiNaGe4O9 and Li1.1Na0.9Ge4O9

“…The monocrystals of LNG and Li 1.1 Na 0.9 Ge 4 O 9 , colourless and fully transparent, were grown in ambient atmosphere by the Czochralski method [1,2,8]. The a-plates approximately 0.4 mm thick were cut from the crystals.…”

“…The crystals are grown in ambient atmosphere by the Czochralski method [1,2]. The phase transition temperature depends on x and changes from about 110 K for lithium-sodium-tetragermanate LiNaGe 4 O 9 (LNG) to about 320 K for x = 0.2.…”

“…For 0 < x < 0.2 the solid solution seems to be a two-phase system and it is not possible to obtain a single crystal. The Li 2 Ge 4 O 9 crystal undergoes the phase transition at about 180 K [2]. At room temperature LNG crystallizes in orthorhombic structure belonging to the space group 8 2h D Pcca − [3] with the unit cell containing four formula units (Z = 4), and the lattice constants a = 9.31, b = 4.68 and c = 15.88 Å.…”

“…; the CurieWeiss constant has a value of 300 -400 K [1,2,7]. Due to the fact that these values are small LNG can be classified as pseudoproper [10] or weak [11] ferroelectric.…”

Dielectric and calorimetric studies of ferroelectric phase transitions in Li(2–x)NaxGe4O9 crystals

“…Monocrystals are grown in ambient atmosphere by the Czochralski method [1,2]. The phase-transition temperature depends on x and changes from about 110 K for lithium-sodiumtetragermanate LiNaGe 4 O 9 to about 320 K for x = 0.2.…”