A new series of environment-friendly reddish inorganic pigments based on AFeO3 (A = Ln, Y) with high NIR solar reflectance

Environment-friendly pigments based onAFeO3(A¼La, Pr, Nd, Sm, Gd, Tb, Y or Yb) with high near-infrared (NIR) reflectance were synthesised by a coprecipitation method at 1200 C. The Rietveldrefinement analysis showed single-phase orthorhombic perovskite for all compositions. All pigments,which showed reddish hues, offered good colour stability after mixing these pigments in powder formwith siloxane transparent paint and two different glazes. The powderepaint mixtures produced withGdFeO3, TbFeO3and YFeO3pigments have the highest NIR solar reflectance, reaching values ofR¼50%.The temperature shielding studies conducted using TbFeO3pigmentepaint mixture for a roof coatingyielded a reduction of 3.2 C in comparison to a commercial pigment. Moreover, the glazes that werepigmented using GdFeO3, TbFeO3and YFeO3compositions also presented the most intense reddishcolours. A study of the thermal and chemical stability of the pigment with the highest NIR solarreflectance showed good stability in both cases. The reddish pigments that were prepared can thereforebe good candidates for use in different applications such as cool pigments or pigments for ceramic glazesat high temperatures

The influence of Ca2+ and Zn2+ doping on the development of sustainable pigments based on GdFeO3 perovskite: From a reddish colour towards a pure black

Black pigments are very commonly used and arouse widespread interest in the ceramic industry. Nevertheless, these pigments contain toxic elements that are detrimental to human health. In view of this, the present work is focused on the development of sustainable black pigments prepared by a coprecipitation method at 1200 °C. Samples with the nominal formula (Gd1–xCax)(Fe0.95Zn0.05)O2.975–x/2 (x = 0.00, 0.05, 0.10) showed single-phase orthorhombic perovskite. The presence of dopants played an important role in the reduction of Fe3+ to Fe2+ and caused different local distortions in the structure which explained the final black colouration of these pigments in comparison with the red GdFeO3 sample. The loss of symmetry and the increase in the number of d-d transitions of iron may explain the aforementioned changes. Co-doped pigments reached low C* values, improving on the purest black colour obtained in a commercial black ceramic pigment, which contains toxic elements. In addition to presenting good NIR solar reflectance values of up to 8%, the final colours of these pigments were also stable after their application in a commercial transparent glaze at 1080 °C that could be used for tiles.Funding for open access charge: CRUE-Universitat Jaume

Optical smoke detector: an approach to semiconductors field for high level education students

Comunicació presentada a EDULEARN2019, 11th International Conference on Education and New Learning Technologies (July 1-3, 2019, Palma, Mallorca, Spain).Nowadays, it is undeniable that the amount of technological devices is having a sharp increase all around us, with important benefits and repercussions for the society. Despite this, students are not used to knowing the basic principles of its operations. Hence, it is of utmost importance to approach undergraduate students to a practical example of a device they can find in their daily life. It is a fact that science is interconnected with multiple disciplines, such as Physics and Solid State Chemistry, Materials Science and Engineering. A good example of it is a smoke detector because it combines both optical and electrical behaviour. Such a device contains a chamber inside which there is an infrared LED (light-emitting diode) and a photodiode (light detector). When the path of light is interrupted by the smoke, according to the principle of light scattering, the smoke will scatter a fraction of light into the photodiode, activating the detector. Thus, detecting low levels of smoke is vital for preventing the fire expansion and occupants can get more time to escape from the premises. The main purpose of this work is to help students to understand the work mechanism of the LED and photodiode in basis of their material composition. In order to do that, a smoke detector is disassembled and its different parts are observed. After that, the microstructure and composition of them are fully analysed by scanning electron microscopy (SEM) and energy dispersive X-ray spectroscopy (EDX) techniques. With these experiments, students have gained knowledge about semiconductors materials and got a more accurate understanding of their role in these devices. All in all, this experience has allowed them to keep in contact during the whole study with three main concepts of Materials Science: composition, structure and properties. This fact make the work interesting not only from the point of view of students, but also for teachers of Inorganic Chemistry and Materials Science owing to its pedagogical character employing a Problem Based Learning

Estudio de la formación de magnetita a partir de hematita

Treball final de Màster Universitari en Química Aplicada i Farmacològica. Codi: SIM138. Curs acadèmic 2015-2016En este trabajo, se han desarrollado diferentes métodos de síntesis, viables a escala industrial, para obtener magnetita (Fe3O4) a partir de hematita (α-Fe2O3). En primer lugar, se llevó a cabo la síntesis por el método sólido – sólido variando los agentes reductores (glucosa e hidrógeno), la temperatura máxima de trabajo y el tiempo de mantenimiento a esa temperatura. A partir de precursores industriales de hierro, se utilizó la glucosa como agente reductor pero la proporción de magnetita en el producto obtenido no alcanzó el 32 %. Al utilizar el hidrógeno como reductor el porcentaje de magnetita en el producto sintetizado no superó el 26 %. Además, se llevó a cabo la síntesis por el método sol – gel (Pechini) utilizando Tb(III) ya que en otros estudios [1] se observó que éste ayuda a la reducción de Fe(III) a Fe(II); con este método, siempre aparecieron fases secundarias de diferentes óxidos que contenían terbio siendo muy baja la cantidad de magnetita. Finalmente, se decidió llevar a cabo una síntesis hidrotermal en medio básico donde se logró obtener un producto que contenía 100 % magnetita

Com fomentar l’interès per la Física i Química?

Treball Final de Màster Universitari en Professor/a d'Educació Secundària Obligatòria i Batxillerat, Formació Professional i Ensenyaments d'Idiomes. Codi: SAP119. Curs acadèmic: 2016/2017Aquest treball final de màster (TFM), d’acord amb la normativa del Màster Universitari en Professor d’Educació Secundària Obligatòria i Batxillerat, Formació Professional i Ensenyaments d’Idiomes, pertany a la modalitat de millora educativa. En aquest TFM es duu a terme una innovació a l’aula, on s’utilitza la tècnica investigació – acció. L’àrea de millora que es treballa és el desinterès que tenen els alumnes de 2n d’ESO de l’IES Vila-roja d’Almassora per l’assignatura de Física i Química i, per donar resposta a aquest problema es proposa un canvi en el procés d’ensenyança – aprenentatge on es passa de les classes tradicionals a sessions on els alumnes participen activament. Aquest treball inclou set sessions relacionades amb el tema El moviment; es realitza una avaluació inicial per detectar les idees prèvies dels alumnes respecte a conceptes del tema i en les següents sessions es realitzen activitats amb Tècniques d’Aprenentatge Col·laboratiu (TAC); es fa ús de tècniques simples com la tècnica 1,2,4, autoavaluació – coavaluació, llapis al centre, el número i un per tots i tècniques complexes com el puzle d’Aronson i treball d’investigació. A més, s’utilitzen Tecnologies de la Informació i la Comunicació (TIC), concretament la informàtica (xarxa per buscar informació i visualitzar simulacions, l’ús de PowerPoint i Excel) i es relacionen els conceptes de l’assignatura amb el dia a dia. Respecte a l’avaluació d’aquest pla d’acció, s’utilitza una triangulació múltiple on s’impliquen diferents fonts (investigador, alumnes i professor titular), moments (abans, durant i en finalitzar l’acció) i instruments (diari de l’investigador, elaboracions dels alumnes i observació del professor titular). Després de posar a la pràctica aquest treball i tenint en compte els indicadors d’avaluació definits per aquest treball (motivació, participació a l’aula i resultats acadèmics), es pot concloure que la forma de treball dissenyada ha estat ben rebuda pels alumnes, l’ús de les metodologies citades anteriorment ha motivat a l’alumnat i ha fomentat la participació activa a l’aula; l’objectiu proposat s’ha aconseguit: ha augmentat, de manera prou general, l’interès per la Física i Química. A més, a la fi d’aquest cicle s’han platejat propostes de millora, les quals poden donar pas a un nou cicle del procés d’investigació – acció

Determination of pharmaceutical compounds in water samples by solid phase extraction and liquid chromatography with photodiode array detector

Treball Final de Grau en Química. Codi: QU0943. Curs acadèmic 2014-2015In the present work, an analytical method for the simultaneous determination of four pharmaceutical compounds (carbamazepine, ketoprofen, naproxen and diclofenac), in water samples, was developed. The method involves sample treatment by solid phase extraction (SPE) using Oasis HLB cartridges and subsequent determination by high-performance liquid chromatography (HPLC) with photodiode array detector (PDA). SPE was optimized basis on three different elution solvents. Method was validated at three concentration levels (0,2 ng/mL, 2 ng/mL and 10 ng/mL) obtaining adequate results only for carbamazepine and naproxen. LC-PDA methodology developed was applied to the analysis of surface water coming from Millars River (Almassora, Castelló, Spain) and four treatment plants sited in Castelló province. None of pharmaceutical studied could be detected by LC-PDA. An alternative and sensitive method carried out by HPLC coupled to tandem mass spectrometry (MS/MS) confirmed the presence of several pharmaceuticals at low concentrations levels (below 1 ng/mL)

Study of the role of praseodymium and iron in an environment-friendly reddish orange pigment based on Fe doped Pr2Zr2O7: A multifunctional material

New environment-friendly reddish orange ceramic pigments based on the general formula Pr2Zr2- xFexO7-d (x ¼ 0, 0.05, 0.10, 0.15, 0.20, 0.25) were prepared by the coprecipitation method and fired at 1200 C. X-Ray Diffraction (XRD) showed a pyrochlore phase in all compositions, whereas Raman spectroscopy revealed the presence of a fluorite phase together with pyrochlore. Although the pyrochlore phase is the main phase, the amount of fluorite phase slightly increases with iron content. UV/Vis absorption measurements, photoluminescence and XPS were used to determine the oxidation state of praseodymium and iron, and a possible redox mechanism was proposed. A mixture of the oxidation states Pr(IV)/Pr(III) and Fe(II)/Fe(III) is present in all samples. All compositions offered good stability after mixing the powders with glass, polymer and paint. The color of the final products in powder and after mixing them with the different media was determined by CIEL*a*b* chromatic coordinates and CIEL*C*H parameters. Concentrations with x ¼ 0.15 and 0.20 have the highest values of a* and lowest values of H in all media and, therefore, the best reddish hue. The good stability and the color of this pigment in siloxane paint, as well as the high value of NIR reflectance, allows its application as a cool pigment, thus making this material a good candidate as an environment-friendly reddish orange pigment with multifunctional applications

Environmental-friendly red-orange ceramic pigment based on Pr and Fe co-doped Y2Zr2O7

A new environmental-friendly red-orange ceramic pigment based on the general formula Y2-xPrxZr2-yFeyO7-δ was prepared by polymeric sol-gel method at 1400 °C. The solid solution range with defect fluorite structure was determined by XRD and SEM/EDX. The oxidation states of the dopants were studied by UV/Vis absorption measurements, XPS and photoluminescence, and a possible redox mechanism was proposed. The colour of the pigment was determined by CIEL*a*b* chromatic coordinates in powder, glass, paint and polymer. All compositions presented a good stability in powder and in glass, the Y1.75Pr0.25Zr1.75Fe0.25O6.875 composition being the best red good colouration. This composition also showed an optimal NIR reflectance 80% in paint to be applied as “cool pigment” for roof isolation. The solid solutions were also tested in PMMA showing a good stability in the sunlight. Therefore, a red-orange environmental-friendly pigment was synthesised with potential applications in the field of the ceramic tiles, cool roofing materials and polymers

“MasterChemist”: A Novel Strategy for Reviewing Stoichiometry and Introducing Molecular Gastronomy to Chemistry Students

This article presents and discusses the results of an educational innovation that seeks to introduce the world of molecular gastronomy in chemistry lessons as a means to review stoichiometry and offer an alternative way to learn. In the literature to date, there is no evidence of haute cuisine having been employed to contextualize stoichiometry problem statements with its everyday applications. The proposed novel strategy, called “MasterChemist”, involved the participation of Spanish first-year university students taking the subject General Chemistry in the Bachelor’s Degree in Chemical Engineering. A Game-Based Learning (GBL) approach was used to solve the exercises and make the activity more appealing and interesting by adding fun to the learning process. The problems were contextualized in the use of siphons, isomalt sugar, and the spherification technique. Furthermore, dividing students into groups also boosted their cooperative skills. The students’ answers to a final survey revealed that the general opinion regarding the activity was highly positive. The undergraduates reviewed some stoichiometry concepts which we had previously observed that they had problems understanding. In addition, the attractive theme of haute cuisine made the activity dynamic and enjoyable both for students and for the teacher.Funding for open access charge: CRUE-Universitat Jaume

A TEACHING STRATEGY TO UNDERSTAND THE SOLID STATE CHEMISTRY FOR HIGH LEVEL EDUCATION STUDENTS: AN EXPERIENCE WITH A PHOSPHORESCENCE MATERIAL

Proceeding of 10th International Conference on Education and New Learning Technologies (EDULEARN2018), 2nd-4th July 2018, Palma, Mallorca, SpainSolid state chemistry has attracted the attention of many fields due to its wealthy chemistry as well as the versatility of its applications. Among the wide fields in this area, the light interaction with a solid has been selected in this experience to understand the phosphorescence process in a material. This experience will allow students to understand an amazing phenomena which occurs in our quotidian life as the light emission of fireflies, stickers or fireworks. A teaching strategy has been proposed for undergraduate chemistry students, introducing them to the concepts of phosphorescence as well as different techniques of characterization through a simple laboratory session based in the synthesis of a phosphor material. Nowadays, it is a challenge to encourage students to properly understand chemistry and materials science due to the importance that represents in our society. Luminescence is a spontaneous light emission coming from excited electronic states after the absorption of UV/visible light. These processes include triboluminescence, fluorescence, phosphorescence, chemiluminescence and bioluminescence. In particular, phosphorescence visible light on slow (minute to hour) time scales after the excitation source has been removed. Lanthanidedoped strontium aluminate (Eu:SrAl2O4) is one of the most widely used phosphor owing to its green environmental properties and their excellent features, like their long-lasting phosphorescence or their potential applications in optoelectronic devices. The aim of this work is showing an example to understand this energetic concept from the preparation of a phosphorescent material based on the strontium aluminate structure. A new methodology of synthesis derived of the Pechini’s method has been introduced to the students. The importance of lanthanides ions has also been highlighted. Two common characterization techniques in Solid State Chemistry are presented to the students: X-Ray Diffraction and Electron Microscopy. Finally, phosphorescence properties have been studied in order to bring them closer in the complete preparation of a material. It has allowed them to keep in contact during the whole experiment with the three main concepts of Materials Science: synthesis, structure and properties. This fact makes the work interesting not only from the point of view of students, also for teachers of inorganic chemistry and material science and undergraduate students owing to its pedagogical character employing a Problem Based Learning