• Juan Zhou

Articles written in Bulletin of Materials Science

• Piezoelectric properties of Sr3Ga2Ge4O14 single crystals

A new piezoelectric single crystal, Sr3Ga2Ge4O14 (SGG), has been grown successfully by the vertical Bridgman method with crucible-sealing technique. SGG crystal up to 2″ in diameter has been obtained. The relative dielectric constants, the piezoelectric strain constants, elastic compliance constants and electromechanical coupling factors have been determined with resonance and anti-resonance frequencies method by using the impedance analyzer (Agilent 4294A). The results show that the piezoelectric strain constants and electromechanical coupling factors of SGG single crystal are higher than those of LGS single crystals making it a potential substrate material for surface-acoustic wave applications.

• Fabrication and enhanced photoluminescence properties of NaLa(MoO$_4$)$_2$: Sm$^{3+}$, Bi$^{3+}$ phosphors with high efficiency white-light-emitting

The tetragonal scheelite-type Sm$^{3+}$/Bi$^{3+}$ ions co-doped with NaLa(MoO$_4$)$_2$ phosphors were synthesized by a facile sol–gel and combustion process using citric acid as complexing agent. The crystal structure and morphology of theseas-prepared samples were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). Furthermore,UV-absorption and the photoluminescence (PL) properties of these phosphors were systematically investigated and the PLof the phosphors shows strong white light emissions. Efficient energy transfer from the MoO$^{2-}_4$ group or Bi$^{3+}$ ions to Sm$^{3+}$ ions was established by PL investigation excited at 405 nm. The PL intensity of the studied materials was investigated asa function of different Sm$^{3+}$ and Bi$^{3+}$ concentrations. The PL investigations revealed that the phosphors exhibit apparentcharacteristic emissions, which is ascribed to the transition from the ground state energy level 4G5/2 to excited state energylevels ${}^6$H$_J$ ($J = 5/2$, 7/2, 9/2) and the NaLa(MoO$_4$)$_2$: 4 mol% Sm$^{3+}$ and NaLa(MoO$_4$)$_2$: 4 mol% Sm$^{3+}$, 8 mol% Bi$^{3+}$ present white emissions with the CIE coordinates of (0.350, 0.285) and (0.285, 0.229), respectively. The absolute quantum efficiencies of the phosphors are 40% (NaLa(MoO$_4$)$_2$: 4 mol% Sm$^{3+}$) and 52% (NaLa(MoO$_4$)$_2$: 4 mol% Sm$^{3+}$, 8 mol% Bi$^{3+}$), respectively.

• # Bulletin of Materials Science

Current Issue
Volume 42 | Issue 6
December 2019

• # Editorial Note on Continuous Article Publication

Posted on July 25, 2019