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Thermal nonradiative depopulation processes of excited levels significantly influence the potential application of phosphors. The high efficiency of thermal quenching of luminescence can limit a phosphor's potential applications as well as reduce the temperature range in which such a material can be used. This work presents a new strategy of shifting of usable temperature range of luminescent thermometer based on Eu3+ ion emission that the molar ratio of (AsO4)3− in respect to (VO4)3− increases in YVxAs1−xO4 host material. Consequently, the thermometric performance of the luminescence thermometer based on the single band intensity ratio corresponding to the 5D0 → 7F1 of Eu3+ ions upon optical excitations matching to the 1A2(1T1) → 1B1(1T2) and 1E(1T1) → 1B1(1T2) electronic transition of (VO4)3− group can be optimized. As shown, the use of YV0.25As0.75O4:Eu3+ has an extended usable temperature range in respect to YVO4:Eu3+. This improvement, coupled with its high sensitivity (>1% K−1) make YV0.25As0.75O4:Eu3+ a more stable material for luminescence thermometer applications. The presented strategy for modulating the thermal properties of luminescent thermometers through the introduction of the (AsO4)3− groups is a step towards designing thermometers with on-demand thermometric performance. [ABSTRACT FROM AUTHOR]

By means of alternating current-electrochemical synthesis starting from a mixture of 2-imino-3-(prop-2-en-1-yl)-1,3-thiazolidin-4-one (3-allylpseudothiohydantoin, napt) and 2-allylamino-1,3-thiazol-4(5H)-one (allylaminopseudothiohydantoin, aapt) hydrochlorides and corresponding copper(II) salts five new π-complexes, [Cu(napt)Cl] (1), [Cu2(aapt)2Cl]NO3(2), [Cu2(aapt)2Cl]BF4(3), [Cu2(aapt)2Cl]ClO4(4) and [Cu2(aapt)2Cl]2SiF6·2H2O (5), were obtained and studied by X-ray single crystal diffraction and IR-spectroscopy. Napt and aapt molecules are selectively coordinated to Cu+depending on the anion type. In crystals of1and5, the organic ligands are attached to the metal in a chelating N,(C=C)-bidentate mode. The aapt molecule in2-4acts as a tridentate chelating ligand, being coordinated to the copper(I) ion through the heterocyclic N atom, carbonyl O atom, and C=C bond of allyl group, forming an original cationic [Cu2(aapt)2Cl]+fragment with both a bridging Cl–ion and O atom of the C=O group. In the presence of the doubly charged SiF62–anion, Cu(I) in5prefers to be bonded with two bridging Cl–ions, rather than the C=O group, causing [Cu2(aapt)2Cl]+units to associate into the infinite cationic chains. Crystals of3and4are the first known examples of the simultaneous BF4–/Cl–or ClO4–/Cl–participation in copper(I) π-complex formation. [ABSTRACT FROM PUBLISHER]

The crystal structure has been determined for (CH3NH3)2[KCo(CN)6] at temperatures 100 and 443 K. It crystallizes in the monoclinic space group C2/c (LT) and in the cubic one Fm3̅m (HT). The dielectric response has been investigated for single crystals of pure K3[A′(CN)6] and guest–hosts of (CH3NH3)2[KA′(CN)6], where A′ is a trivalent metal, Co or Fe. Their dielectric properties were measured in the frequency range between 135 Hz and 2 MHz in a wide temperature range between 200 and 460 K. The anisotropy of the electric permittivity for single crystals of (CH3NH3)2[KCo(CN)6] was analysed in terms of the crystal structure. The relaxation processes were observed in the case of the pure host K3Fe(CN)6 and the guest/host crystal (CH3NH3)2[KFe(CN)6]. The activation energies of the dielectric relaxation have been estimated to be equal to 44 and 40 kJ mol−1 for (CH3NH3)2[KFe(CN)6] and K3Fe(CN)6, respectively. The mechanism of the phase transitions found at 425 K and 421 K for (CH3NH3)2[KFe(CN)6] and (CH3NH3)2[KCo(CN)6], respectively, has been postulated. From the dielectric losses the value of the electric ac conductivity has been estimated and analyzed in terms of the activation process of the current carriers. [ABSTRACT FROM AUTHOR]

The multi component Fe74Hf4Ta1Cu1Gd1LaxSi15-xCu1Gd1LaxSi15-xB4 (x=0;7) alloys are promising candidates in the search for materials with unusual mechanical and magnetic properties. Amorphous nature of melt-spun samples was confirmed by X-ray diffractometry and Mössbauer spectroscopy. The X-ray diffraction patterns revealed a distinct amorphous halo. The low-field components of magnetic hyperfine field distributions on iron nuclei are observed in the Mssbauer spectra, with average hyperfine field values of 19.9 and 15.7 T for x=0 and x=7, respectively. Coercivity studied by vibrating sample magnetometer was about 12 A/m for x=0 and 82 A/m for x=7 at 300 K and about 600 A/m for x=0 and 1200 A/m for x=7 at 400 K. Remanence also changed with temperature, amounting to 0.64 T for x=0 and 0.36 T for x=7 at 300 K, while at 400 K it was 0.43 and 0.11 T for x=0 and x=7, respectively. It is shown that La addition has beneficial effect of shifting the Curie point towards lower temperatures together with the increase of magnitude of magnetization. [ABSTRACT FROM AUTHOR]

This brief review discusses the coordination behaviour of π-coordinated copper(I) in the structures of [Cu2(µ-dapp)(NH2SO3)4]⋅2H2O (1), [C4H12N2][Cu2(µ-dapp)(NH2SO3)6]⋅2H2O (2), [Cu2 (µ-dapp)(H2O)6] (SiF6)2⋅2H2O (3), [Cu2 (µ-dapp)(NO3)4(H2O)2]⋅2H2O (4), [Cu(µ-ahmta)(NO3)(H2O)](NO3)⋅H2O (5), and [Cu(µ-ahmta)(H2O)2](BF4)2⋅H2O (6) complexes (dapp = N,N'-diallylpiperazinium(2+), ahmta = N-allylhexamethylenetetraminium), obtained as single crystals by means of an alternating current electrochemical technique. The above π-complexes are formed respectively by CuSO3NH2, Cu2SiF6, CuNO3, and CuBF4 salts, unknown in a free state. [ABSTRACT FROM AUTHOR]