In this paper, we propose a heterogeneous material for bulk thermoelectrics. By varying the quenching time of Na doped PbTe, followed by hot pressing, we synthesized heterogeneous nanocomposites, a mixture of nanodot nanocomposites and nanograined nanocomposites. It is well-known that by putting excess amounts of Na (i.e., exceeding the solubility limit) into PbTe, nanodots with sizes as small ...

We report the quantum efficiency of photoluminescence processes of Er optical centers as well as the thermal quenching mechanism in GaN epilayers prepared by metal-organic chemical vapor deposition. High resolution infrared spectroscopy and temperature dependence measurements of photoluminescence intensity from Er ions in GaN under resonant excitation excitations were performed. Data provide a ...

In this report, to tackle the thermal fluorescent quenching issue of II-VI semiconductor quantum dots (QDs), which hinders their on-chip packaging application to light-emitting diodes (LEDs), a QD-ZnS nanosheet inorganic assembly monolith (QD-ZnS NIAM) is developed through chemisorption of QDs on the surface of two-dimensional (2D) ZnS nanosheets and subsequent assembly of the nanosheets into a...

Several recent advances in turbulent dynamo theory are reviewed. High resolution simulations of small-scale and large-scale dynamo action in periodic domains are compared with each other and contrasted with similar results at low magnetic Prandtl numbers. It is argued that all the different cases show similarities at intermediate length scales. On the other hand, in the presence of helicity of ...

the micro-segregation in binary al-cu alloys containing 2.2, 3.7, and 4.8 wt.% copper was investigated by differential thermal analysis (dta) and numerical modeling. for this purpose, the alloys were melted using a dta furnace with the capability of quenching samples during solidification. the melted samples were cooled at 0.008 and 0.083 k/s and subsequently quenched from predetermined tempera...

In this paper, we systematically investigate three different routes of synthesizing 2% Na-doped PbTe after melting the elements: (i) quenching followed by hot-pressing (QH), (ii) annealing followed by hot-pressing, and (iii) quenching and annealing followed by hot-pressing. We found that the thermoelectric figure of merit, zT, strongly depends on the synthesis condition and that its value can b...

A contact-free diagnostic technique for examining position of the impurity energy level of p-type dopants in nitride semiconductors was proposed based on photoluminescence thermal quenching. The Mg ionization energy was extracted by the phenomenological rate-equation model we developed. The diagnostic technique and analysis model reported here are priorities for the design of highly effective p...

A novel blue-emitting Sr3.5Y6.5O2(PO4)1.5SiO4(4.5) :Eu2+ phosphor was synthesized via a solid-state reaction. Powder X-ray diffraction (XRD) analysis demonstrated that the Sr3.5Y6.5O2(PO4)1.5(SiO4)4.5 host had a hexagonal crystal structure in the space group P6(3) /m and unit cell parameters a = 9.418 Å, c = 6.900 Å. The as-prepared phosphor showed a blue emission and all the main emission peak...