Heat capacities, third-law entropies and thermodynamic functions of the negative thermal expansion material Zn2GeO4 from T=(0 to 400) K

The study of oxygen ion motion in Zn2GeO4 by Raman spectroscopy

“…The effect of increasing temperature can be seen as an increase in band width, a decrease in band intensity and a shift in phonon frequency. The high frequency modes of A g (1) , E g (3) , E g (4) and A g (2) shift to low frequency and start to broaden at 243 K, and then show a dramatic decrease in intensity and increase in width upon further heating. The width of E g (3) increases too fast to be detected at 473 K, which may be responsible for the motion of oxygen ion.…”

“…In contrast with high frequency region, it is interesting to notice that the low frequency modes of E g (1) at 65 cm −1 and E g (2) at 74 cm −1 almost remain invariable both in frequency and band width. These low energy modes are attributed to the motion of ZnO 4 -GeO 4 and responsible for property of negative thermal expansion (NTE) in Zn 2 GeO 4 [1]. As a common feather of many NTE materials, Zn 2 GeO 4 is built from relatively rigid ZnO 4 tetrahedra and GeO 4 tetrahedra joined by shared O atoms at flexible corners.…”

“…A unit cell contains six formula units and has lattice parameters a = 14.284 Å and c = 9.547 Å with the space group R-3 [1]. In the structure, the tetrahedral surrounding the Zn and Ge atoms alternate in a pattern of {Zn + Zn + Ge + Zn + Zn + Ge + ……} with the tetrahedra running parallel to the c-axis as shown in Fig.…”

Temperature-controlled synthesis of Zn2GeO4 nanowires in a vapor–liquid–solid mode and their photoluminescence properties

“…Accordingly, semiconductor nanowires are considered potential low-dimensional materials for use in nanoelectronics and optoelectronics [2][3][4]. A promising ternary oxide, zinc germinate (Zn 2 GeO 4 ) with a wide bandgap of 4.68 eV has useful properties and is known to exhibit negative thermal expansion below room temperature [5]. Mn-doped Zn 2 GeO 4 is known to emit green light [6], whereas undoped Zn 2 GeO 4 is a native defect phosphor exhibiting white luminescence under UV excitation [7].…”

Synthesis of ternary oxide for efficient photo catalytic conversion of CO2

“…For increasing the quantum efficiency of the photo catalysts, complex materials have been prepared and studied. A ternary oxide, zinc orthogermanate (Zn2GeO4), has been prepared and used for deep UV detection [4] and bright white-bluish luminescence [5]. Zn2GeO4 with a wide band gap is accepted to be a good photo catalyst, applied in photo catalytic overall water splitting [6], photo reduction of CO2 and removal of pollutants [7,8].…”