Na-α′-GeGaON Solid Solution Analogous to α′-SiAlON: Synthesis, Crystal Structure, and Potentiality as a Photocatalyst

Abstract

We demonstrated, for the first time, formation of the Na-α'-GeGaON (NamGe12-(m+n)Gam+nOnN16-n) solid solution, an analogue of the well-established α'-SiAlON system. We successfully synthesized single-phase powder samples by reduction-nitridation of Na2CO3-GeO2-Ga2O3, in the solubility range of m ≈ 0.8-1.7 with n ≈ 0.2-0.3. The Rietveld refinement of powder X-ray diffraction data for Na-α'-GeGaON was conducted on the basis of the space group P31c of α'-SiAlON, and the refinement converged with RB = 1.78% and RF = 1.02% for the composition of Na1.26(1)Ge10.50Ga1.50O0.24(1)N15.76(1), indicating reliably the isomorphism between the SiAlON and GeGaON systems. The results of (23)Na solid-state nuclear magnetic resonance (NMR) spectroscopy clearly showed a single peak at the chemical shift of ∼ 16 ppm, further proving the accommodation of Na in the α'-GeGaON matrix with the expected coordination environment. The synthesized Na-α'-GeGaON exhibited stable photocatalytic activity for the evolution of H2 from water under ultraviolet irradiation, which was comparable to that attained by β-Ge3N4.

Quaternary Wurtzitic Nitrides in the System ZnGeN2–GaN: Powder Synthesis, Characterization, and Potentiality as a Photocatalyst

“…The powder samples of the system ZnGeN 2 –GaN were synthesized by using the gas-reduction–nitridation (GRN) method. − The oxide starting materials were prepared by simple wet mixing of ZnO (Sigma-Aldrich Co., no. 544906), GeO 2 (Sigma-Aldrich Co., 99.99%), and Ga 2 O 3 (Sigma-Aldrich Co., 99.99%) powders, with the target composition of Zn 1– x Ge 1– x Ga 2 x N 2 , where x = 0, 0.10, 0.20, 0.33 (1/3), and 0.50.…”

“…The photocatalytic test reactions were carried out by using a top irradiation-type cell connected to a closed-gas circulation system, as described in our previous work . The RuO 2 cocatalyst was loaded to the powder samples by impregnation from a RuCl 3 (Wako Pure Chemical Industries Ltd., 99.9%) ethanol solution, followed by the calcination in air at 400 °C for 4 h. Photocatalytic H 2 evolution was examined with ∼0.22 g of the RuO 2 -loaded samples dispersed in 200 mL of deionized water containing 10 vol % of methanol as an electron donor.…”

New Deep-Blue-Emitting Ce-Doped A4–mBnC19+2mX29+m (A = Sr, La; B = Li; C = Si, Al; X = O, N; 0 ≤ m ≤ 1; 0 ≤ n ≤ 1) Phosphors for High-Color-Rendering Warm White Light-Emitting Diodes

“…In Figure 3d, ) are given, showing that the onset for the host-lattice absorption of LaSr-sialon sample is at significantly longer wavelengths. The optical bandgaps, as derived from the diffuse reflectance spectra, 32 for Sr-sialon and LaSr-sialon are estimated to be 4.99 eV and 4.49 eV, respectively (inset Figure 3c). As a result of the smaller bandgap, LaSr-sialon:Eu has relatively more hostlattice absorption between 200 and 300 nm and, consequently, relatively less Eu 2+ 4f-5d absorption in the 200-300 nm region than Sr-sialon:Eu.…”

Quaternary Wurtzitic Nitrides (1 – x)ZnGeN2–2xGaN (x = 0.02, 0.05): Disorder-Induced Band-Gap Narrowing and Potentiality as a Solar-Active Photocatalyst

“…The powder specimens of the ZGGN system were synthesized by using the GRN method. ,− The oxide starting materials were prepared by simple wet mixing of ZnO (Sigma-Aldrich Co., no. 544906), GeO 2 (Sigma-Aldrich Co., 99.99%), and Ga 2 O 3 (Sigma-Aldrich Co., 99.99%) powders.…”

“…The photocatalytic test reactions were carried out by using a top irradiation-type cell connected to a closed gas circulation system, as described in our previous studies. , The RuO 2 cocatalyst was loaded to the powder specimens by impregnation from a RuCl 3 (Wako Pure Chemical Industries Ltd., 99.9%)/ethanol solution, followed by calcination in air at 400 °C for 4 h. Photocatalytic H 2 evolution was examined with ∼0.22 g of the RuO 2 -loaded samples dispersed in 200 mL of deionized water containing 10 vol % methanol as an electron donor. O 2 evolution was evaluated in an aqueous silver nitrate solution (0.01 M) without loading of the cocatalyst.…”