Kimia komputasi (Konduktivitas Ion)

Solid electrolyte materials with high oxide ion conductivity at low temperature are intensively investigated in order to have solid oxide fuel cell (SOFC) capable of operating at low temperature. One of oxide material that has high oxide ion conductivity is γ-Bi2VO5.5. As comparison to the materials widely used as a solid electrolyte material, such as yttria stabilized zirconia (YSZ), γ-Bi2VO5.5 has ionic conductivity of 1x10 −2 Scm −1 , which is around three orders of magnitude larger than YSZ at same temperature of 300 °C [1]. Therefore γ-Bi2VO5.5 has potential application as electrolyte in SOFC working at low temperature. The structure of Bi2VO5.5 can be derived from Bi2WO6 andγ-Bi2MoO6 by formation of oxide vacancies in the metal oxide layers; thus the compound can be formulated (Bi2O2)(VO3.5_0.5), where _ is the corresponding to intrinsic oxide vacancy [1, 2]. The Bi2VO5.5 goes to several structural transformations and known has several polymorphs but essentially, there are only three main polymorphs, namely α, β, and γ with the transformations: α → β at 447 °C and β → γ at 567 °C. The structures of α and β-phases are more ordered, larger in unit cell, and have lower conductivity. At the high temperature, γ-phase is formed and has maximum conductivity of 0.2 Scm−1 at 670 °C [3]. Experimental studies on the oxide conductivity of γ-Bi2VO5.5 have been reported elsewhere [4]. However, the experimental study could not reveal the detail of the mechanism of ionic conduction. Abraham and Krok proposed oxide conduction mechanism which was applied only to BIMEVOX with ME is divalent metal, and derived from crystallographic data [5]. In our knowledge, the conduction mechanism in parent structure of BIMEVOX, γ-Bi2VO5.5, has not been reported yet. Computational studies could be used to study the detail of ionic conductivity mechanism in the atomic level. Some computation study on the layered structure of Aurivillius phases similar to γ

Menjadi manusia yang Gatek (gagap teknologi-informasi) di tengah zaman yang begitu modern saat ini rasanya hampir bisa dipastikan bahwa manusia tersebut akan menjadi kelompok yang termarjinalkan dan akan menjadi kelompok yang aneh karena seluruh aspek kehidupan manusia telah dipengaruhi oleh maju dan pesatnya teknologi informasi. Mereka yang tidak mengikuti perkembangan akan terseret arus kemajuan teknologi. Hanya mereka yang dapat menguasai dan dapat memanfaatkan teknologi informasi itulah yang akan dapat memasuki persaingan baik dalam tataran regional, nasional maupun internasional. Perkuliahan Komputasi Kimia bagi mahasiswa di jurusan kimia dimaksudkan untuk memberikan bekal awal (bontot) agar mahasiswa dapat mengakses teknologi Informasi dan memanfaatkannya tidak hanya selama menempuh pendidikan di Unimed tetapi juga akan bermanfaat setelah menyelesaikan pendidikan. Bagi calon tenaga kependidikan, kepiawaian dalam memanfaatkan komputer dalam rangka pendiversifikasian sumber belajar sangat dibutuhkan terlebih dengan penerapan Kurikulum Berbasis Kompetensi atau terakhir lebih spesifik menjadi Kurikulum Tingkat Satuan Pendidikan (KTSP) yang menuntut guru untuk mampu membuat inovasi dalam media pendidikan. Komputer adalah perangkat yang mumpuni untuk tujuan itu. Juga bagi mahasiswa program studi kimia (lebih gaul disebut nondik) penguasaan teknologi komputer adalah hal yang mutlak dan tidak perlu ditawar lagi. Buku diktat untuk mendukung proses perkuliahan bagi mereka yang berbelanja matakuliah Komputasi Kimia ini, mengenalkan kepada mahasiswa software-software yang termasuk dalam keluarga MS Office, yaitu MS Word, MS PowerPoint, dan MS Excel. Disamping itu juga diperkenalkan software Kimia yang sederhana yaitu ISIS/Draw versi 2.3 untuk mendukung keleluasaan mahasiswa dalam penulisan struktur kimia, khususnya kimia organik yang belum tersedia perangkatnya di dalam MS Office. Buku ini sebenarnya adalah sumber minimal, mahasiswa dapat memperkayanya dengan melirik buku-buku praktis lainnya. Untuk kemahiran, dengan pertimbangan limitasi waktu praktikum, mahasiswa diharapkan dapat berlatih secara mandiri di luar jam kuliah. Buku sederhana ini tidak tertutup kemungkinan untuk digunakan oleh pemakai lainnya, khususnya untuk tujuan penulisan naskah yang sederhana, baik untuk presentasi, pengolahan data dll.

Nafis Ahyani

MODELING IONIK

Solid electrolyte materials with high oxide ion conductivity at low temperature are intensively investigated in order to have solid oxide fuel cell (SOFC) capable of operating at low temperature. One of oxide material that has high oxide ion conductivity is γ- Bi2VO5.5. As comparison to the materials widely used as a solid electrolyte material, such as yttria stabilized zirconia (YSZ), γ-Bi2VO5.5 has ionic conductivity of 1x10−2 Scm−1, which is around three orders of magnitude larger than YSZ at same temperature of 300 °C [1]. Therefore γ-Bi2VO5.5 has potential application as electrolyte in SOFC working at low temperature. The structure of Bi2VO5.5 can be derived from Bi2WO6 and γ-Bi2MoO6 by formation of oxide vacancies in the metal oxide layers; thus the compound can be formulated (Bi2O2)(VO3.5_0.5), where _ is the corresponding to intrinsic oxide vacancy [1, 2]. The Bi2VO5.5 goes to several structural transformations and known has several polymorphs but essentially, there are only three main polymorphs, namely α, β, and γ with the transformations: α → β at 447 °C and β → γ at 567 °C. The structures of α and β-phases are more ordered, larger in unit cell, and have lower conductivity. At the high temperature, γ-phase is formed and has maximum conductivity of 0.2 Scm−1 at 670 °C [3]. Experimental studies on the oxide conductivity of γ Bi2VO5.5 have been reported elsewhere [4]. However, the experimental study could not reveal the detail of the mechanism of ionic conduction. Abraham and Krok proposed oxide conduction mechanism which was applied only to BIMEVOX with ME is divalent metal, and derived from crystallographic data [5]. In our knowledge, the conduction mechanism in parent structure of BIMEVOX, γ-Bi2VO5.5, has not been reported yet. Computational studies could be used to study the detail of ionic conductivity mechanism in the atomic level. Some computation study on the layered structure of Aurivillius phases similar to γ-Bi2VO5.5 has been carried out and reported [6]. It could reveal defect energies and maximum dopant concentrations in Aurivillius as ferroelectric material. Here, we report the computational study of γ-Bi2VO5.5 structure that cover trajectory of oxide in γ-Bi2VO5.5. The study was aimed to investigate the oxide pathways that are possible in the γ-Bi2VO5.5 structure via vacancy defect in perovskite-like layer.

Nafis Ahyani

Tugas Kimia Komputasi

Solid electrolyte materials with high oxide ion conductivity at low temperature are intensively investigated in order to have solid oxide fuel cell (SOFC) capable of operating at low temperature. One of oxide material that has high oxide ion conductivity is γ-Bi2VO5.5. As comparison to the materials widely used as a solid electrolyte material, such as yttria stabilized zirconia (YSZ), γ-Bi2VO5.5 has ionic conductivity of 1x10−2 Scm−1, which is around three orders of magnitude larger than YSZ at same temperature of 300 °C [1]. Therefore γ-Bi2VO5.5 has potential application as electrolyte in SOFC working at low temperature. The structure of Bi2VO5.5 can be derived from Bi2WO6 and γ-Bi2MoO6 by formation of oxide vacancies in the metal oxide layers; thus the compound can be formulated (Bi2O2)(VO3.5_0.5), where _ is the corresponding to intrinsic oxide vacancy [1, 2]. The Bi2VO5.5 goes to several structural transformations and known has several polymorphs but essentially, there are only three main polymorphs, namely α, β, and γ with the transformations: α → β at 447 °C and β → γ at 567 °C. The structures of α and β-phases are more ordered, larger in unit cell, and have lower conductivity. At the high temperature, γ-phase is formed and has maximum conductivity of 0.2 Scm−1 at 670 °C [3]. Experimental studies on the oxide conductivity of γ Bi2VO5.5 have been reported elsewhere [4]. However, the experimental study could not reveal the detail of the mechanism of ionic conduction. Abraham and Krok proposed oxide conduction mechanism which was applied only to BIMEVOX with ME is divalent metal, and derived from crystallographic data [5]. In our knowledge, the conduction mechanism in parent structure of BIMEVOX, γ-Bi2VO5.5, has not been reported yet. Computational studies could be used to study the detail of ionic conductivity mechanism in the atomic level. Some computation study on the layered structure of Aurivillius phases similar to γ-Bi2VO5.5 has been carried out and reported [6]. It could reveal defect energies and maximum dopant concentrations in Aurivillius as ferroelectric material. Here, we report the computational study of γ-Bi2VO5.5 structure that cover trajectory of oxide in γ-Bi2VO5.5. The study was aimed to investigate the oxide pathways that are possible in the γ-Bi2VO5.5 structure via vacancy defect in perovskite-like layer.

Polimer elektrolit banyak ditemukan dalam bentuk baterai polimer ion litium. Baterai polimer ion litium merupakan salah satu baterai yang paling dibutuhkan, karena dapat di cas ulang, ringan, tahan lama, aman penggunaannya dan mudah diolah dalam berbagai bentuk. Penggunaannya terutama untuk peralatan-peralatan portable seperti kamera, laptop, handphone dan sebagainya. Baterai polimer ion litium itu sendiri terbuat dari ion litium yang di holding ke polimer elektrolit. Matriks pengisi yang digunakan dalam pembuatan baterai polimer ion litium umumnya adalah polimer sintetik. Beberapa polimer sintetik yang umum digunakan dalam pembuatan polimer elektrolit adalah PEO, PAN, PVC, PMMA, dan PVDF. Polietilen oksida (PEO) merupakan salah satu polimer sintetik yang memiliki daya tarik yang besar, karena memiliki titik leleh yang tinggi, kesatuan struktur yang tinggi, Temperatur transisi gelas yang rendah, toksisitas yang rendah dan bersifat biocompatible. Penelitian tentang PEOLiX based polimer elektrolit yang didopingkan dengan garam alkali dilaporkan pertama kali oleh Jingyu et.al, dan polimer elektrolit tersebut dapat meningkatkan konduktivitas ionik pada temperatur 65 o C. Walaupun telah terbukti dapat meningkatkan konduktivitas ionik, PEO yang mengandung garam litium tersebut cenderung akan mengkristal pada suhu kamar. Oleh karena itu, salah satu usaha yang dapat dilakukan adalah dengan menambahkan zat aditif yang dapat mengurangi potensi tersebut. Salah satunya dengan menggunakan filler. Filler yang telah dikembangkan saat ini untuk mengurangi material yang bersifat beracun dan berbahaya (non biodegradable) ialah filler yang berasal dari alam (biodegradable).

Tugas Konduktivitas Ion