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Mg1/3A11/3A21/3Ta2O6 ceramics (where A1 and A2 represent Co, Ni, or Zn) were prepared using the solid‐phase reaction route. The results of X‐ray diffraction and Raman tests showed that (Co1/2Ni1/2)2+, (Co1/ 2Zn1/2)2+, and (Ni1/2Zn1/2)2+ ions replaced Mg2+ ions in the lattice of MgTa2O6, resulting in the formation of a pure tri‐rutile structure. All three complex ions could significantly reduce the sintering temperature of the ceramics (by 150°C–200°C) and could broaden the sintering window. The large deviation (48.8%–69.2%) between the porosity corrected relative permittivity εr‐corr. and the theoretical relative permittivity εr‐theo. might be due to the overestimation of the ionic polarizability of Ta5+ by Shannon. (Co1/2Ni1/2)2+ has the most significant effect of increasing the bond energy of ceramic A–O bonds, reducing the τf value from 51 to 36 ppm/°C. In addition, the mechanisms affecting their dielectric properties are discussed based on bond ionicity (fi), full width at half maximum (FWHM) of Raman peak, and bond energy (E). Mg1/3Co1/3Ni1/3Ta2O6 ceramic sintered at 1350°C have the most excellent microwave dielectric properties: εr = 26.8, Q × f = 86,000 GHz, and τf = 36 ppm/°C. [ABSTRACT FROM AUTHOR]

The luminescence properties and temperature sensing performances of Mg5Al7O16:Cr3+ are systematically studied in this paper, synthesized using the solid-state sintering method. Based on X-ray diffraction and first-principles calculations, Cr3+ is verified to occupy the octahedral Mg2+ and Al3+ sites in the host Mg5Al7O16. From the Tanable–Sugano diagram, Cr3+ is in a strong crystal environment to induce sharp line emissions of Cr3+ around 700 nm. As the temperature rises, the excitation and emission ranging from 303 to 543 K are recorded, and overlapping of emissions from 2E → 4A2 and 4T2 → 4A2 is observed. The emissions in the 303–543 K range are separated using deconvolution. The emission from 2E → 4A2 decreases with increasing temperature, which is a normal thermal quenching behavior. However, the emission from 4T2 → 4A2 increases with temperature until 523 K. Energy transfer through phonon assistance from 2E to 4T2 is verified using temperature-dependent excitation and decay curves. It is used for the temperature-reading method based on the luminescence intensity ratio (LIR). The highest relative sensitivity is 1.80% K−1 at 303 K and is retained at above 1.00% K−1 in the 303–403 K range. [ABSTRACT FROM AUTHOR]

SrB2O4:Eu2+ is prepared by the high‐temperature solid‐phase method. The structure is characterized by X‐ray diffraction, and the luminescence properties are analyzed using fluorescence spectroscopy and decay curves. SrB2O4:Eu2+ has strong absorption in the UV region and two broadband emissions in the 350–550 nm, located at 374 and 458 nm. The broadband emission around 374 nm belongs to Eu2+ emission at the Sr lattice position, and the emission around 458 nm belongs to interstitial Eu2+ ions. At low concentrations, Eu2+ replaces the position of Sr2+ first, and the emission peak of 374 nm is stronger than that of 458 nm in the emission spectrum. The luminescence at 458 nm enhances significantly as the concentration of Eu2+ ions increases. The fluorescence lifetime confirms the presence of two luminescent centers, the EuSr and the interstitial Eu2+ ions. The temperature dependence luminescence of SrB2O4:Eu2+ is explored, and the activation energy is calculated to be ΔEa = 0.3622 eV. The Commission Internationale de l'Éclairage (CIE) chromaticity coordinates of SrB2O4:Eu2+ are in the blue area. The results indicate that the interstitial Eu2+ benefits the color‐rendering index when SrB2O4:Eu2+ is used as a blue phosphor in UV light‐emitting diode (LED). [ABSTRACT FROM AUTHOR]

The efficient 810 nm laser energy conversion of glass frit had been proven to be the key to the long‐term hermetic encapsulation of Organic Light Emitting Display (OLED). A direct laser energy conversion laser‐assisted Bi2O3‐B2O3‐ZnO‐Nd2O3 sealing glass material without extra laser absorbent such as carbon black, was designed and systematically investigated. The addition of Nd2O3, as glass modifiers with higher cationic field strength, could be conducive to enhancing the polymerization of glass network structure, manifesting that the glass‐transition temperature Tg, onset‐crystallization temperature Tc and thermal stability ΔT (ΔT = Tc‐Tg) increased, while thermal expansion coefficient CTE dropped to 9.72×10−6/°C and advantageously matched with the glass substrate (8±1×10−6/°C). More importantly, the absorption rate of BBZ‐Nd glass was more than 50 % between 800∼810 nm owing to the 4f‐4f electron transition of Nd3+ ions, and yet the reflectivity and transmittance of the wavelength at 800–810 nm were lower. As optimal compositions, the addition of 3.0 wt% Nd2O3 in Bi2O3‐B2O3‐ZnO‐Nd2O3 glass frit with higher absorption coefficients (80 %) led to instantaneous bonding encapsulation between glass substrates without interfacial cracks or pores with the 808 nm wavelength of the laser at 20 W and 2.4 mm/s. [ABSTRACT FROM AUTHOR]

Multimode emission of Mn 2+ for multimode fluorescence anticounterfeiting is achieved by cation site and interstitial occupancy in Ca 2- x Mg x Ge 7 O 16 . The rings in Ca 2- x Mg x Ge 7 O 16 have a significant distortion for Mn 2+ ions to enter the ring interstitials with a luminescence center at 665 nm, which is supported by XRD refinement results and first-principles calculations. The interstitial Mn 2+ ion has good thermal stability with an activation energy of 0.36 eV. Surprisingly, these two luminescence centers, the cation site Mn and the interstitial Mn, have an obvious afterglow, and the disappearing afterglow will reappear by heating or irradiating with the 980 nm laser. The afterglow is significantly enhanced, as MnO 2 is used as the manganese source, which is explained in detail by the thermal luminescence spectrum. Finally, Ca 2- x Mg x Ge 7 O 16 :Mn 2+ fully demonstrates its excellent prospects in fluorescent anticounterfeiting, information encryption, and optical information storage.

With the rapid development of the microwave communication industry, microwave dielectric materials have been widely studied as the medium of signal transmission. Nowadays, with the increase in communication frequency, devices are miniaturized, and dielectric materials are required to have higher dielectric constants. At the same time, the miniaturization of devices brings about an increase in power density, which puts forward higher requirements for the thermal conductivity of materials. In this work, polysilylaryl-enyne (PSAE) and Ca 0.9 La 0.067 TiO 3 (CLT) were chosen as the matrix and filler, respectively, to construct a parallel model composite through a freeze casting method and a 0-3 model composite through the direct mixing method, respectively. After comparing the microstructures of the two models, their dielectric properties and thermal conductivity were measured and simulated. The parallel model composites in the stable range possess uniform parallel structures, and the solid content limit for them could be as high as 73.2%, which is much higher than that of the 0-3 model composites. While the 0-3 model composite possesses an optimal dielectric constant of 25.4 (@10 GHz) and a thermal conductivity of 0.965 W·m -1 ·K -1 , the parallel model composite possesses a 2 times higher dielectric constant of 76.2 (@10 GHz) and a 1 times higher thermal conductivity of 2.095 W·m -1 ·K -1 . Since the parallel model composite possesses much higher dielectric constant and thermal conductivity than traditional 0-3 model composites, it can be an excellent candidate for microwave communication.