Search results for "Ingot"
showing 10 items of 26 documents
Fast determination of impurities in metallurgical grade silicon for photovoltaics by instrumental neutron activation analysis
2010
Standard wafer solar cells are made of near-semiconductor quality silicon. This high quality material makes up a significant part of the total costs of a solar module. Therefore, new concepts with less expensive so called solar grade silicon directly based on physiochemically upgraded metallurgical grade silicon are investigated. Metallurgical grade silicon contains large amounts of impurities, mainly transition metals like Fe, Cr, Mn, and Co, which degrade the minority carrier lifetime and thus the solar cell efficiency. A major reduction of the transition metal content occurs during the unidirectional crystallization due to the low segregation coefficient between the solid and liquid phas…
Newly discovered orichalcum ingots from Mediterranean sea: Further investigation
2021
Abstract In February 2016, 47 ingots were found in the seabed of Contrada Bulala (Gela, CL, Italy) near the site where 40 ingots had previously been recovered. The ingots composition was determined to be a Cu - Zn alloy, dated by the archaeologist to the VI century B.C. This specific alloy was then known as Orichalcum. From an archaeological point of view, the first question raised about the new discovery was whether the ingots of the first and the second excavations belonged to the same shipwreck. Following the previous study, an elemental analysis was performed on the ingots from the second finding by using ICP-OS and ICP-MS techniques. The chemometric treatment of the analytical results …
Bronze Sculptures and Lead Objects Tell Stories About Their Creators: Investigation of Renaissance Sculptures and Ancient Ingots by Means of Neutron …
2016
Renaissance bronze objects from the Rijksmuseum (Amsterdam) col- lection and lead ingots from ancient roman shipwrecks found near Sicily (Italy) were studied by means of neutron tomography. This was done with the aim to visualize and to measure the inner structures of the objects. In this way information about the manufacturing processes in the 16th century and the conservation status from the inside of the bronze sculptures was gained. Inscriptions found under the corrosion layer of the lead ingots gave hints about the trade routes in the past. Neutron imaging was proven perfect to transmit the relatively thick layers of Pb and Cu alloys while ceramic remains, soldering connections and cor…
Reduction of temperature coefficients in multicrystalline silicon solar cells after light-induced degradation
2015
This study focuses on the variations of the temperature coefficients after light-induced degradation (LID) of compensated multicrystalline silicon solar cells from three different ingots. The ingots have been chosen to see the effect of the compensation level, the resistivity and the impact of adding gallium to keep the resistivity as constant as possible along the ingot. The temperature coefficients of the efficiency experience a major decrease after LID on all ingots. We found that this decrease varies along the ingot height and does not correspond to the VOC drop. Moreover, no direct correlation with the interstitial oxygen concentration profiles could be seen.
Simulated and measured temperature coefficients in compensated silicon wafers and solar cells
2019
Abstract In this paper we perform a thorough investigation of the temperature coefficients of c-Si solar cells and wafers, based on both experimental data and device simulations. Groups of neighboring wafers were selected from different heights of four high performance multicrystalline silicon ingots cast using different dopants concentrations and Si feedstocks; Three different target resistivities of compensated silicon ingots based on Elkem Solar Silicon (ESS®), which are purified through a metallurgical route, and one non-compensated reference ingot. The wafers were processed into Al-BSF and PERCT type solar cells, as well as into lifetime samples subjected to selected solar cell process…
S&P 500 -indeksin osinkoperusteinen arvonmääritys pitkällä aikavälillä
2017
Tässä Pro gradu –tutkielmassa selvitettiin, kuinka osinkoperusteinen arvonmääritys toimii S&P 500 indeksiin kuukausittaisella otannalla 1871 – 2016. Tämän lisäksi kartoitettiin, kuinka eri taloudelliset tekijät voivat selittää osaketuottoja. Samalla kartoitettiin miten muuttujien relaatiot ovat muuttuneet pitkällä aikavälillä. Tutkielmassa luotiin eri hintaestimaatteja, joilla pyrittiin arvioimaan tulevaisuuden osakehintaindeksin tasoja ja testattiin, kuinka hyvin estimaatit osuivat. Muuttujien relaatioita tutkittiin yhteisintegraatiotesteillä ja Granger –kausaalisuustesteillä, joiden perusteella voitiin päätellä, miten muuttujat ovat yhteydessä toisiinsa. Tämän lisäksi testattiin, onko pit…
Temperature Coefficients of Compensated Silicon Solar Cells – Influence of Ingot Position and Blend-in-ratio
2015
Published version of an article in the journal: Energy Procedia. Also available on Science Direct: http://dx.doi.org/10.1016/j.egypro.2015.07.004 Solar-grade silicon made from a metallurgical route presents boron and phosphorus compensation. Earlier work has shown that cells made from such material produce more energy than reference polysilicon modules when the temperature and irradiance is high. In the present study, solar cells from two different ingots with different blend-in-ratios were made from wafers at varying ingot heights in order to investigate how the temperature coefficients vary with compensation level and ingot height. The results suggest that solar modules made with solar ce…
Enhanced thermoelectric performance in the p-type half-Heusler (Ti/Zr/Hf)CoSb0.8Sn0.2 system via phase separation
2014
A novel approach for optimization of the thermoelectric properties of p-type Heusler compounds with a C1b structure was investigated. A successful recipe for achieving intrinsic phase separation in the n-type material based on the TiNiSn system is isoelectronic partial substitution of Ti with its heavier homologues Zr and Hf. We applied this concept to the p-type system MCoSb0.8Sn0.2 by a systematic investigation of samples with different compositions at the Ti position (M = Ti, Zr, Hf, Ti0.5Zr0.5, Zr0.5Hf0.5, and Ti0.5Hf0.5). We thus achieved an approximately 40% reduction of the thermal conductivity and a maximum figure of merit ZT of 0.9 at 700 °C. This is a 80% improvement in peak ZT fr…
Design of parallel compensator and stabilizing controller to mitigate non-minimum phase behaviour of the Czochralski Process
2020
Abstract This paper addresses the design of a parallel compensator and a stabilizing controller for the simplified crystal growth dynamics of the Czochralski (CZ) process, i.e., the process for the production of monocrystalline silicon ingots of uniform diameter. The diameter control of the produced ingots is achieved by a CCD camera measurement used to sense the radius of the boundary between the base of the growing crystal and the surrounding glowing meniscus — a raised melt surface connecting the crystal ingot with the flatter melt surface. Due to the intrinsic nature of the process, the bright ring radius measurement signal exhibits a non-minimum phase behaviour. A combination of the pa…