Atiek Rostika Noviyanti

LSO apatite-YSZ composite as a solid electrolyte for solid oxide fuel cells

LSO (Lanthanun Silicate Oxide) Apatite-YSZ (Yttria-stabilized zirconia) composite has been synthesized by combining the LSO apatite with commercial YSZ with different composition ratio (LSO Apatite:YSZ = 60:40wt.% and 50:50 wt. %). Structure, morphology, and conductivity of sintered pellets composite (sintered at 1330oC for 3 hours) were characterized by XRD, SEM, and impedance spectroscopy, respectively. The sintered density of the composite materials with 50:50 wt. % and 60:40 wt. % (apatite: YSZ) ratios were 3.785 g.cm−3 and 3.770 g.cm−3, respectively. The typical peak of LSO and YSZ were observed in the X-ray pattern of the composite materials. The conductivity of the LSO apatite : YSZ composite 50:50wt. % and 60:40 wt. % ratios showed high level of ionic conductivities with values of 1.26 × 10−3 S/cm and 1.60 × 10−4 S/cm, respectively,with very low level of activation energy (0.95–1.02 eV) at 700 °C. These results indicate that the LSO-YSZ composite materials are good conductors that can be used as s...

Sintesis Silika Metode Sol-Gel Sebagai Penyangga Fotokatalis TiO2 Terhadap Penurunan Kadar Kromium dan Besi

SINTESIS SILIKA METODE SOL-GEL SEBAGAI PENYANGGA FOTOKATALIS TiO 2 TERHADAP PENURUNAN KADAR KROMIUM DAN BES I. Silika merupakan material yang menarik perhatian para peneliti karena aplikasinya yang luas dan pembuatannya yang mudah. Salah satu metode pembuatan silika adalah metode sol-gel. Silika yang dihasilkan bersifat amorf dengan densitas yang rendah sehingga dapat digunakan sebagai penyangga fotokatalis. Penelitian ini bertujuan untuk membuat fotokatalis TiO 2 -SiO 2 untuk menurunkan kadar logam kromium dan besi dalam air. Tahapan penelitian adalah sintesis silika dengan variasi konsentrasi amonia dan suhu kalsinasi, imobilisasi TiO 2 pada SiO 2 , dan uji fotokatalisis TiO 2 -SiO 2 terhadap kadar logam kromium dan besi dari air Sungai Cikijing. Untuk mengetahui gugus fungsi, morfologi, bentuk kristal, komposisi TiO 2 dalam fotokatalis TiO 2 -SiO 2 , dan kadar logam dilakukan analisis dengan menggunakan Fourier Transform - Infra Red (FT-IR), Scanning Electron Microscope (SEM-EDX), X-Ray Diffractometry (XRD), dan Atomic Absorbtion Spectroscopy (AAS).Dalam penelitian ini, jumlah konsentrasi amonia dan suhu kalsinasi divariasikan yaitu; 12,5% dan 25% dengan suhu kalsinasi 400C, 500C, dan 600C. Hasil analisis FT-IR menunjukkan bahwa puncak silika muncul pada bilangan gelombang 3447 cm-1 (regang –OH), 1638 cm-1 (regang Si-O) dan 1107 cm-1 (regang Si-O-Si). Hasil pengukuran TiO 2 -SiO 2 10% dengan XRD menunjukkan bahwa puncak pada 2θ = 25,26 ° adalah TiO 2 anatase dan 2θ = 23,86 ° adalah SiO 2 amorf sehingga diketahui bahwa TiO 2 terimobilisasi pada SiO 2 dengan komposisi TiO 2 sebesar 10,05% dari hasil pengukuran SEM-EDX. Uji fotokatalisis TiO 2 -SiO 2 10% memiliki aktivitas optimum dalam menurunkan kadar logam kromium sebesar 95,30% dan besi sebesar 93,62% pada konsentasi awal kromium 3,832 mg/L dan besi 2,039 mg/L.

Tin Dioxide Thin Films As Carbon Monoxide Sensor

Abstract : This research aims to create SnO2 thin films that have the size of micrometers to nanometers for detecting CO gas. The method used in this research is a sol-gel method where all precursors such as tin dichloride, distilled water, ethanol, and ammonium fluoride 5%-10% (w/w) are mixed together to form a colloidal system . The colloidal systems with the addition of palladium are precipitated on a glass substrate. The substrate is heated at the temperature of 70 o C and 100 o C. Then the resistance value is determined using the avometer. The SnO 2 thin films are characterized by SEM and XRD. The result of this research is that SnO 2 thin films show the best sensitivity in colloidal systems with the addition of ammonium fluoride 10% (w/w). The result of the characterization of SEM and XRD concludes that SnO 2 thin films can be obtained by a sol-gel method with a nanometer-scale size and it can respond to the CO gas. Keywords: carbon monoxide, metal oxides, sol-gel method, thin films

Synthesisofc-lifepo4 composite by solid state reaction method

In this research, the enhancement of LiFePO4 conductivity was conducted by doping method with carbon materials. Carbon-based materials were obtained from the mixture of sucrose, and the precursor of LiH2PO4 and α-Fe2O3 was synthesized by solid state reaction. Sintering temperature was varied at 700°C, 800°C, 900°C and 1,000°C. The result showed that C-LiFePO4 could be synthesized by using solid state reaction method. Based on the XRD and FTIR spectrums, C-LiFePO4 can be identified as the type of crystal, characterized by the appearance of sharp signal on (011), (211) and typical peak of LiFePO4 materials. The result of conductivity measurement from C-LiFePO4 at sintering temperature of 900°C and 1,000°C was 2×10-4 S/cm and 4×10-4S/cm, respectively. The conductivity value at sintering temperature of 700°C and 800°C was very small (<10-6 S/cm), which cannot be measured by the existing equipment.

Preparation and conductivity of composite apatite La9.33Si6O26 (LSO) - Zr0.85Y0.15O1.925 (YSZ)

A great challenge to reduce high operating temperature of solid oxide fuel cell (SOFC) to intermediate temperature SOFC (IT-SOFC, 500-750 °C), is the development of solid electrolyte materials with high ionic conductivity at intermediate temperature range. In response to this challenge, here we report a novel composite material La9.33Si6O26 (LSO)-Zr0.85Y0.15O1.925 (YSZ). LSO-YSZ composite synthesis was carried out by combining LSO with commercial YSZ (9:1, 8:2, 7:3) using hydrothermal method. In order to get dense pellet, all of the product were sintered at 1450 °C for 3 hours. X-ray diffraction pattern of the entire pellets show typical both of LSO and YSZ pattern which indicate that the composite was succesfully formed. The highest conductivity was detected in YSZ-7LSO (YSZ:LSO = 7: 3), i.e 1.72 × 10−4 Scm−1 at 700 °C and also has low activation energy (0.88 eV). This result suggests that the LSO-YSZ composite materials are good oxide ion conductor and potential to be used as an alternative solid electr...