No abstract

In an adiabatic process, the change in energies of select states may be inhomogenously scaled due to energy quantization. To illustrate this, we introduce a [Formula: see text] barrier turning up (turning down) in an adiabatic expansion (compression). We consider a quantum-mechanical Carnot engine employing a single particle confined in an infinite potential, assuming only the lowest two energy levels to be occupied. This cyclic engine model consists of two isoenergetic strokes where the system is alternatively coupled to two energy baths, and two adiabatic processes where the potential is adiabatically deformed with turning up or down a [Formula: see text] barrier. Having obtained the work output and efficiency, we analyze the efficiency at maximum power under the assumption that the potential moves at a very slow speed. We show that the efficiency at maximum power can be enhanced by energy quantization.

BaGd2O4:Eu3+ scintillating phosphors by Pr3+‐codoping were synthesized at 1300°C in air using a solid‐state reaction method. The as‐synthesized phosphors were characterized by X‐ray diffraction (XRD), photoluminescence (PL) including excitation and emission spectra, radioluminescence (RL) spectra excited by X‐ray and thermoluminescence (TL) spectra. Both the PL and RL spectra are composed of the featured trivalent europium (Eu3+) without any praseodymium (Pr3+) ions, and the PL and RL intensities as well as the lifetimes of BaGd2O4:Eu3+ scintillating phosphors decrease dramatically with an increasing concentration of Pr3+ ions. Finally, the TL spectra reveal the trap concentration of the existing defects decrease with an increasing concentration of Pr3+ ions, while the relative TL intensity ratio of the high temperature band to the low temperature one increases with an increasing concentration of Pr3+ ions, which results in the afterglow suppression of BaGd2O4:Eu3+ scintillating phosphors.