Judul: Sintesis Bahan Piezoelektrik Ba0.5Na0.5TiO3 – BaTiO3 dan Penambahan Gd2O3 dengan Metode Solid State Reaction
Abstrak: The synthesis of lead – free piezoelectric BNT – BT and addition Gd2O3 have done using solid state reaction. Synthesis of BNT – BT get a perovskite struktur with variation of % mol BT 3%, 7%, 12%. Diffraction pattern of 7% BT showed two peak ((002) and (200)) overlapping that is indicate transformation of phase from rhombohedral to tetragonal (MPB). Synthesis BNT – BT with addition Gd2O3 also a get perovskite struktur with variation of % weight Gd2O3 0.4%, 0.7%, 1%, 3%, 6%. Diffraction pattern of 0.4% Gd2O3 showed overlapping peak. At this komposition happen phase change from rhombohedral to tetragonal. At 0.4% - 0.7% komposition happen down significan point of c/a that is indicate in the komposition MPB of BNT – BT – Gd2O3
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Judul: Sintesis BaTiO3 dari Campuran Ba(OH)2 dan TiO2 dengan Tambahan PbO
Abstrak: Piezoelectric material can generate electric field in response to applied mechanical stress. Conversely, they can stretch and contract in response to an electric field. This material can be used for many applications such as transducer, microphone, ultrasound, and pressure gauge. Barium titanate is a ferroelectric material with piezoelectric properties that can be synthesized easily. The aim of this study is to synthesis barium titanate from mixture of Ba(OH)2 and TiO2, also observe its optimum temperature and the effect of PbO addition. The method of synthesis was solid-state reaction and sol-gel method, then the products were characterized with x-ray diffraction (XRD). Based on XRD analysis, the optimum temperature for both methods was 800°C. Addition of PbO to BaTiO3 in the solid-state reaction formed a compound with formula of Ba1-xPbxTiO3. The addition has changed diffraction pattern peak at 2θ and strengthened its tetragonal structure. The best result was obtained at x of 0.5 which will form a compound of Ba0.5Pb0.5TiO3.
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Judul: Potensi Dampak Spesies Asing Invasif Procambarus clarkii terhadap Macrobrachium rosenbergii berdasarkan Kompetisi Makanan.
Abstrak: Spesies invasif merupakan salah satu ancaman bagi keanekaragaman hayati dan fungsi ekosistem, karena spesies ini dapat merugikan secara ekonomi, kerusakan lingkungan, dan bahkan dapat mengganggu kesehatan manusia. Tujuan penelitian ini adalah membuktikan dampak ekonomi dan parameter pertumbuhan dari spesies asing invasif lobster air tawar (Procambarus clarkii). Penelitian ini dilakukan pada bulan Januari hingga April 2018. Ditemukannya Procambarus clarkii di kolam budidaya udang galah (Macrobrachium rosenbergii) membawa dampak negatif dimana sifat dan tingkah laku Procambarus clarkii merugikan spesies udang galah dan dianggap sebagai hama perikanan dan pertanian. Didapatkan nilai kerugian kompetitor inferior akibat Procambarus clarkii dalam penelitian ini sebesar Rp 141.700/kg lobster, dengan nilai jual sebesar Rp 50.000/kg, sehingga mendapatkan nilai kerugian bersih sebesar Rp 91.700/kg yang sangat merugikan dan mengakibatkan kepunahan pada udang galah dalam jangka panjang.
Keyword: invasif, Procambarus clarkii, krustase, kompetitor, inferior, ekonomi