Reflection Data and XRD Data for the Solid Solution Series ZnFe2O4-ZnAl2O4 (Franklinite-Gahnite)

Reflection data and XRD data for the solid solution series ZnFe2O4-ZnAl2O4 The data shown here were measured on samples of the solid solution series ZnFe2-xAlxO4 with x=0 to 2.0 is provided. All samples belong to the spinel group and show a cubic crystal structure (Fd3m, No. 227). The reflectance measurements can be used to determine the bandgap of the material, while the XRD data were used to determine the lattice parameters.Additional data on the electrical conductivity, application as active material in spinel|aq. electrolyte|zinc battery cells and magnetic susceptility can be found in the referenced publications. Sample preparation Samples were produced in a Pechini-type synthesis process: Zn(NO3)2∙6H2O, Fe(NO3)3∙9H2O and Al(NO3)2∙9H2O were mixed in distilled water according to the nominal composition. When the salts were fully dissolved, citric acid (ncitric acid = 2ncations) was added and the mixture was stirred for 1 h at 50 °C. Afterwards, 1,4-butylene diol was added (ndiol = 4ncations), the temperature was increased to 80 °C and stirred for further 30 minutes. Then, the temperature was increased to 300 °C to dry the gel. The gel was put in glazed alumina crucibles and calcined at 200 °C for 2 and then 600 °C for 4 h in a muffle furnace. The received powder was thoroughly ground in an agate mortar. Pellets were pressed with a pressure of 100 bar and sintered at 1200 °C for 6 h in alumina sintering boxes with a heating/cooling rate of 200 K/h. Subsequently, the ceramics were ground in an agate mortar and reflection measurements and XRD measurements were performed. Reflection Data The Edinburgh Instruments FS920 spectrometer combined with a Teflon-coated integrating sphere was used to analyze the reflection. For measurements, a Xe900 arc lamp from Edinburgh Instruments with 450 W and a R928 detector from Hamamatsu, Peltier-cooled to -20 °C, wwere applied. Measurements were initially taken in the wavelength range from 250 nm to 500 nm with a step size of 1.0 nm and then from 480 nm to 800 nm with a 455 nm filter and a step size of 1.0 nm. Both spectra were then combined at 490 nm. Barium sulfate (BaSO4; 99.99%; Sigma-Aldrich) was used as the reflection standard. The data set includes the data without before and after correction with the BaSO4 standard as well as measurements for the standard itself. The individual data files are named with the "composition_raw" for the data before correction and with "composition_reflection" for the corrected data. XRD Data: Powder X-ray diffraction of ground ceramic samples was measured using a D8 Advance (Bruker Corporation, USA) with CuKα radiation and a 2Θ range of 10-120° and a measurement duration of 3 h. The individual data files are named after the nominal compostion of the samples.