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Development of sol-gel derived gahnite anti-reflection coating for augmenting the power conversion efficiency of polycrystalline silicon solar cells

100%

Kaliyannan G. V. , Palanisamy S. V. , Palanisamy M. , Subramanian M. , Paramasivam P. , Rathanasamy R.

Materials Science Poland

2019

tom Vol. 37, No. 3

465--472

The present research is focused on developing ZnAl2O4 (gahnite) spinel as an antireflection coating material for enhanced energy conversion of polycrystalline silicon solar cells (PSSC). ZnAl2O4 has been synthesized using dual precursors, namely aluminum nitrate nonahydrate and zinc nitrate hexahydrate in ethanol media. Diethanolamine has been used as a sol stabilizer in sol-gel process for ZnAl2O4 nanosheet fabrication. nanosheet was deposited layer-by-layer (LBL) on PSSC by spin coating method. The effect of ZnAl2O4 coating on the physical, electrical, optical properties and temperature distribution in PSSC was investigated. The synthesized antireflection coating (ARC) material bears gahnite (ZnAl2O4) spinel crystal structure composed of two dimensional (2D) nanosheets. An increase in layer thickness proves the LBL deposition of ARC on the PSSC substrate. The ZnAl2O4 2D nanosheet comprising ARC on the PSSC was tested and it exhibited a maximum of 93 % transmittance, short-circuit photocurrent of 42.364 mA/cm2 and maximum power conversion efficiency (PCE) 23.42 % at a low cell temperature (50.2 °C) for three-layer ARC, while the reference cell exhibited 33.518 mA/cm2, 15.74 % and 59.1 °C, respectively. Based on the results, ZnAl2O4 2D nanosheets have been proven as an appropriate ARC material for increasing the PCE of PSSC.

The high-hardness ceramic glazes based on basalt from Bali Province for ceramic body coatings

100%

Sundari K. N. , Subari , Birawidha D. C. , Prasetia H. , Mudra I. W. , Hendronursito Y.

tom Vol. 60, iss. 3

art. no. 190121

The ceramic glaze method is not only done to add color aesthetics but also to increase the hardness of the glaze. Basalt is one of the raw materials developed as a ceramic glaze material because it is cheap, easy to find, and has good characteristics. This research aims to determine glaze characteristics by varying the concentration of basalt rocks from the Ababi area, Karangasem Regency, Bali Province. The experiment used basalt at 45%-61%, Feldspar 27%-37%, Kaolin 3%-8%, and ZnO 7%-10% as raw materials for glaze, not frit glaze. Heating the glaze material layer at 1,250 °C for 3 hrs. The product characteristics of glaze ceramics include chemical composition, crystal phase, microhardness, porosity, density, thermal expansion coefficient, and surface morphology. Basalt from Bali is characterized by its high Fe2O3 content, reaching 20.07 wt%. Compared to basalt in generally, it has a different impact on the physical and mechanical characteristics of the ceramic glaze produced. Based on the observation of ceramic glaze products, the glaze composition with 56% basalt, 32% feldspar, 5% kaolin, and 7% ZnO showed the best coating, with a yellowish-brown color and an average thickness of 79.82μm. The hardness value of the glaze layer is 6.5 GPa, exceeding the standard hardness value of glazes on the market. Glazed ceramics contain the minerals Gahnite (ZnAl2O4) and Coesite (SiO2), which can increase the hardness of the glaze. This research demonstrates the tremendous potential and added value of using basalt from Bali Province as a raw material for glazed ceramics.

Wpływ glino-borowych wiskerów na strukturę pozostałości amorficznej matrycy szklano-ceramicznej w kompozytach z Al2O3

84%

Herman D.

tom T. 68, nr 4

310--314

Z udziałem tworzywa szklano-krystalicznego z układu ZnO-B2O3-Al2O3-SiO2 i mikrokrystalicznego tlenku glinu wykonano dwa rodzaje porowatych kompozytów ściernych bez (kompozyt A) i z udziałem fazy wiskerowej (kompozyt B). Po obróbce termicznej w 1050 °C przez 3 h w kompozycie A matrycę ceramiczną stanowiło tworzywo szklano-krystaliczne z drobnokrystaliczną fazą gahnitu, w kompozycie B dodatkową fazę w matrycy stanowiły wiskery Al4B2O9. Kompozyty B, z udziałem fazy wiskerowej, charakteryzują się bardzo równomiernym rozprowadzeniem spoiwa na ziarnach tlenku glinu, wynikającym ze zmiany struktury pozostałości amorficznej w porównaniu do pozostałości w kompozycie A. Metodą FTIR wykazano, że więźba glinokrzemianoborowego szkła resztkowego kompozytu A ulega przebudowie w kompozycie B. W wyniku krystalizacji wiskerów w pozostałości amorficznej matrycy dominują jednostki strukturalne [BO3], przez co temperatura mięknienia szkła resztkowego się obniża. Idealne rozprowadzenie cienkiej osnowy (matrycy) na ziarnach Al2O3 ma niewątpliwie dodatkowy, poza wiskerami, korzystny wpływ na wytrzymałość mechaniczną kompozytu.

Two types (A and B) of porous abrasive composites were produced with the participation of glass crystal material from the system of ZnO-B2O3-Al2O3-SiO2 and microcrystalline alumina. After the thermal processing of the composites at 1050 °C for 3 h, glass crystal material with a fine crystalline gahnite phase constituted the ceramic matrix of composite A; in composite B, Al4B2O9 whiskers constituted an additional phase in the matrix. Composites B with the participation of the whisker phase are characterized by a very uniform positioning of the adhesive on alumina grains, which was the result of a change in the amorphous structure of the residue as compared to the residues in the composite A. It was demonstrated by the FTIR method that the framewark of boric aluminium silicate residue glass in the composite A underwent a reconstruction in the composite B. As a result of crystallization of whiskers, structural units [BO3] dominate in the amorphous residue of the matrix, resulting in lowering the residue glass temperature. An ideal distribution of a thin matrix on Al2O3 grains possesses undoubtedly an additional (apart from whiskers) positive impact on the mechanical strength of the composite.