Respon Pemberian Berbagai Dosis Silika (Si) Cair dan Interval Pemberian yang Berbeda terhadap Pertumbuhan dan Perkembangan Tanaman Bunga Pucuk Merah (Syzigium Oleana)

Pucuk merah adalah salah satu jenis tanaman hias yang saat ini sedang populer di Indonesia. Warna kemerahan pada daun-daun muda menjadi ciri khas sekaligus daya tarik pada tanaman ini. Maka tak heran jika pucuk merah terkenal sebagai tanaman pagar atau tanaman hias yang mampu mempercantik tampilan sebuah taman. Tanaman ini juga sering digunakan sebagai pembatas jalan baik di daerah perkotaan maupun di perkampungan. Pucuk merah merupakan tanaman hias yang memilik warna daun merah, hijau dan kaya fenol. Permasalahan pada tanaman pucuk merah adalah daun yang berwarna merah tidak sempurna kemerahannya, lambat tumbuh daun pucuk merahnya. Penelitian ini bertujuan untuk mengetahui pengaruh pemberian berbagai dosis Silika Cair dan interval pemeberian yang berbeda terhadap pertumbuhan dan perkembangan tanaman bunga pucuk merah. Penelitian ini dilaksanakan di Kelurahan Darma, Kabupaten Polewali Mandar yang berlangsung dari Juli - Oktober 2017. Penelitian ini menggunakan Rancangan Acak Kelompok dengan pola Faktorial, terdiri dari Faktor pertama adalah pemberian berbagai dosis Unsur Silika terdiri dari tiga taraf yaitu : 0, 2, 4 ml/ liter air. Faktor kedua adalah interval pemberian terdiri dari tiga taraf yaitu seminggu sekali, dua minggu sekali dan tiga minggu sekali. Hasil analisis statistik menunjukkan bahwa interaksi antara pemberian Silika Cair dan interval waktu yang berbeda tidak memberikan pengaruh nyata pada semua parameter yang diamati. Pemberian dosis 2 ml/ liter air dan pemberian 2 minggu sekali memberikan rata-rata tanaman tertinggi, tercepat pada waktu munculnya daun merah, jumlah daun berwarna merah terbanyak. Sedangkan pemberian 2 ml/liter air dengan pemberian 1 minggu sekali memberikan rata-rata tertinggi pada parameter jumlah daun berwarna hijau dan jumlah cabang keseluruhan

Structural, elastic, mechanical and thermodynamic properties of Terbium oxide: First-principles investigations

First-principles investigations of the Terbium oxide TbO are performed on structural, elastic, mechanical and thermodynamic properties. The investigations are accomplished by employing full potential augmented plane wave FP-LAPW method framed within density functional theory DFT as implemented in the WIEN2k package. The exchange-correlation energy functional, a part of the total energy functional, is treated through Perdew Burke Ernzerhof scheme of the Generalized Gradient Approximation PBEGGA. The calculations of the ground state structural parameters, like lattice constants a0, bulk moduli B and their pressure derivative B′ values, are done for the rock-salt RS, zinc-blende ZB, cesium chloride CsCl, wurtzite WZ and nickel arsenide NiAs polymorphs of the TbO compound. The elastic constants (C11, C12, C13, C33, and C44) and mechanical properties (Young's modulus Y, Shear modulus S, Poisson's ratio σ, Anisotropic ratio A and compressibility β), were also calculated to comprehend its potential for valuable applications. From our calculations, the RS phase of TbO compound was found strongest one mechanically amongst the studied cubic structures whereas from hexagonal phases, the NiAs type structure was found stronger than WZ phase of the TbO. To analyze the ductility of the different structures of the TbO, Pugh's rule (B/SH) and Cauchy pressure (C12–C44) approaches are used. It was found that ZB, CsCl and WZ type structures of the TbO were of ductile nature with the obvious dominance of the ionic bonding while RS and NiAs structures exhibited brittle nature with the covalent bonding dominance. Moreover, Debye temperature was calculated for both cubic and hexagonal structures of TbO in question by averaging the computed sound velocities

Over 15% efficient wide-band-gap Cu(In,Ga)S<inf>2</inf> solar cell: Suppressing bulk and interface recombination through composition engineering

The progress of Cu(In,Ga)S2 remains significantly limited mainly due to photovoltage (Voc) losses in the bulk and at the interfaces. Here, via a combination of photoluminescence, cathodoluminescence, electrical measurements, and ab initio modeling, we address the bulk and interface losses to improve ~ 1.6 eV bandgap (Eg) Cu(In,Ga)S2. The optoelectronic quality of the absorber improves upon reducing the [Cu]/[Ga+In] (CGI) ratio, as manifested by the suppression of deep defects, higher quasi-Fermi level splitting (QFLS), improved charge carrier lifetime, and higher Voc. We identify antisite CuIn/CuGa as a major performance-limiting deep defect by comparing the formation energies of various intrinsic defects. Interface recombination is suppressed using a Zn(O,S) buffer layer in Cu-poor devices, which leads to the activation energy of recombination equal to the Eg. We demonstrate efficiency of 15.2% with Voc of 902 mV from a H2S-free, Cd-free, and KCN-free process.The authors acknowledge Dr. Nathalie Valle and Dr. Brahime El Adib, Luxembourg Institute for Science and Technology (LIST), for SIMS measurement. Mohit and Damilola gratefully acknowledge partial funding of this research through the Luxembourgish Fond National de la Recherche FNR through the MASSENA project (FNR PRIDE/15/10935404). CL studies were supported by the EPSRC under grant number EP/R025193/1. Dr. Christian Monachon of Attolight is thanked for his ongoing support of the CL system. Diana Dahliah was financially supported by the Conseil de l’Action Internationale (CAI) through a doctorate grant ‘‘Coopération au Développment’’. We acknowledge access to various computational resources: the Tier-1 supercomputer of the Fédération Wallonie-Bruxelles funded by the Walloon Region (grant agreement no. 1117545), and all the facilities provided by the Université catholique de Louvain (CISM/UCL) and by the Consortium des Equipements de Calcul Intensif en Fédération WallonieBruxelles (CECI)

High-throughput calculations of charged point defect properties with semi-local density functional theory—performance benchmarks for materials screening applications

Abstract Calculations of point defect energetics with Density Functional Theory (DFT) can provide valuable insight into several optoelectronic, thermodynamic, and kinetic properties. These calculations commonly use methods ranging from semi-local functionals with a-posteriori corrections to more computationally intensive hybrid functional approaches. For applications of DFT-based high-throughput computation for data-driven materials discovery, point defect properties are of interest, yet are currently excluded from available materials databases. This work presents a benchmark analysis of automated, semi-local point defect calculations with a-posteriori corrections, compared to 245 “gold standard” hybrid calculations previously published. We consider three different a-posteriori correction sets implemented in an automated workflow, and evaluate the qualitative and quantitative differences among four different categories of defect information: thermodynamic transition levels, formation energies, Fermi levels, and dopability limits. We highlight qualitative information that can be extracted from high-throughput calculations based on semi-local DFT methods, while also demonstrating the limits of quantitative accuracy